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View Full Version : 496HO, pulled my turbulators and........



Chromegorilla
04-24-2005, 02:27 PM
picked up almost 3 MPH! I couldn't believe it. On the rev limiter hard now. Need more steel to swing. Here you go with my new best.....
http://www.donzi.net/forums/attachment.php?attachmentid=11043

WILD LAVEY
04-24-2005, 02:29 PM
wow thats impressive, i plan on doing that this weekend.

Kachina26
04-24-2005, 02:55 PM
How long did it take? Are the gaskets separate from the turd-u-lators?

Beer-30
04-24-2005, 03:20 PM
Just pullem. You'll see. It's real self explanatory. Once the risers come off. With no effort, I might add. The plates just come out and then just put the two pieces back together with both gaskets.
I put mine back together and checked. No leaks. :smile:

phebus
04-24-2005, 03:31 PM
Just pullem. You'll see. It's real self explanatory. Once the risers come off. With no effort, I might add. The plates just come out and then just put the two pieces back together with both gaskets.
I put mine back together and checked. No leaks. :smile:
I pulled mine, but didn't see as dramatic results. I assume you have twin 496HO's in your 30?
As far as those that plan on pulling them, it is really easy. I took the hose clamps off the two hoses going to the riser, loosened the four bolts, and seperated the riser from the manifold. I didn't need to remove the exhaust hose, it pivoted on it. Once the riser is seperated from the manifold, there is a gasket on the manifold, and a gasket on the riser with the turbulator sandwiched between. The turbulator is a stainless steel plate, and didn't stick at all to the gaskets, it slid right out. I bolted everything back together, tightened the clamps, and it was done. Checked for leaks the next day out, and there were none. With the two gaskets, and seals up good.

Beer-30
04-24-2005, 04:10 PM
I assume you have twin 496HO's in your 30?
Nope. Single HO. Didn't want the maint or fuel of the twins.

LHC30Victory
04-24-2005, 04:58 PM
I pulled mine, but didn't see as dramatic results. I assume you have twin 496HO's in your 30?
As far as those that plan on pulling them, it is really easy. I took the hose clamps off the two hoses going to the riser, loosened the four bolts, and seperated the riser from the manifold. I didn't need to remove the exhaust hose, it pivoted on it. Once the riser is seperated from the manifold, there is a gasket on the manifold, and a gasket on the riser with the turbulator sandwiched between. The turbulator is a stainless steel plate, and didn't stick at all to the gaskets, it slid right out. I bolted everything back together, tightened the clamps, and it was done. Checked for leaks the next day out, and there were none. With the two gaskets, and seals up good.
Did the same with my twins and picked up about 200rpm... I pulled the risers from the hoses though, because I wanted to get to those plastic pieces in the hoses. Had enough flapper, so I figured I don't need them.

Beer-30
04-24-2005, 05:05 PM
Had enough flapper, so I figured I don't need them.
yeah, my metal tip (internal) flappers were making a hell of a rattle. I heard that with the black rubber flappers, which it has, you don't need the internal ones. More of a Mercruiser warranty type thing (must have two flappers).
So, I knocked them out when I had the hoses off for the turbulators. Much nicer! No annoying idle rattle! Plus, they are not recommended for muffler apps, since the flapper could come loose and plug the muffler.
For when I bolt the mufflers on, that is.

phebus
04-24-2005, 05:11 PM
Nope. Single HO. Didn't want the maint or fuel of the twins.
So, you're getting 77.9mph from a single 496HO in a 30' boat? Doesn't sound right, but I guess I can't argue with gps. Are you sure you didn't leave it on on your trip to the lake? I've never heard of a boat doing 77.9 with a 496HO, and a 30 footer, damn.

Beer-30
04-24-2005, 05:21 PM
So, you're getting 77.9mph from a single 496HO in a 30' boat? Doesn't sound right, but I guess I can't argue with gps. Are you sure you didn't leave it on on your trip to the lake? I've never heard of a boat doing 77.9 with a 496HO, and a 30 footer, damn.
No, no, that was Chromegorilla, at the top. I WISH!

WILD LAVEY
04-24-2005, 05:30 PM
so you guys re installed the riser with both gaskets? i thought you were supposed to use only one. :confused:

Beer-30
04-24-2005, 05:48 PM
Ask the riser if it cares?
The gaskets have given up a little of their material to the plate. Using the two just insures there is adequate gasket material.
It would probably be just fine with one. In fact, one of the first ones to do it said he just used one of the originals and it was fine. I just figure niether the riser or the manifold cares whether it has one or two, so might as well use them both.
Either way, it seems to work just fine.

WILD LAVEY
04-24-2005, 05:51 PM
thanks for the info

phebus
04-24-2005, 06:11 PM
No, no, that was Chromegorilla, at the top. I WISH!
My bad, I see that was in a 22' Donzi. Makes more sense now. I need to pay more attention. :hammerhea

phebus
04-24-2005, 06:14 PM
so you guys re installed the riser with both gaskets? i thought you were supposed to use only one. :confused:
I talked with Aaron at Absolute before I did mine, and he said to just bolt it up with both gaskets. I also asked him if he saw any harm in removing the turbulators, and he said no, he thought it would be a good thing.

Chromegorilla
04-24-2005, 07:27 PM
I used both gaskets. Everything is A O K after a weekend of HARD running in nasty shit during a poker run.

mike37
04-24-2005, 07:54 PM
I pulled mine and it hits the rev limiter now
it was so easy the your wife could do it

moneypit
04-24-2005, 08:02 PM
I pulled mine and it hits the rev limiter now
it was so easy the your wife could do it
Time to re-prop?

Outnumbered
04-24-2005, 10:20 PM
More info please. What are these things supposed to do? Is it some sort of back-flow preventer in the riser?
Thanks

Outnumbered
04-24-2005, 10:40 PM
Found my answer on OSO from Raylar:
I will see if I can intelligently answer the questions and put a final light on the Mercury "Turbulator" plate in the 496 engines. First, all the 496's I have seen or checked seem to have the plate irregardless of year of manufacturer. Thats not to say Mercury has or will not change on certain production years and models. As I understand from Mercury engineers themselves, these plates wetre designed to catch small amounts of exhaust moisture, not reversion!, no plate will stop reversion, reversion is a function of cam timing and overlap and it does not exist per say in the 496 Mag or HO engines. Exhaust moisture, depending on the individual boat , exhaust design and exhaust system exit heights coupled with silent choice or otherwise can sometimes be a greater water generator issue in some hulls more than others. The plate was designed to provide a substantial shelf to catch small amounts of actual water and provide a place where exhaust heat could cook it off and keep it from entering the exhaust manifold and possibly getting to the exhaust valve, especially after the motor is shut off. The idea is not a bad one but the execution was not the best. first the inside diameter of this hole in the "turbulator is just over 2-1/4" inches in size. This does not seem like a serious dimension, however you need to understand that the inside diameter of the Mercury sweep riser is over 3" and about 3-1/2" at the location of the "turbulator" plate. This small opening becomes a substantial restriction to the exhaust gas flow at higher rpms, especially under full WOT periods. Remember this is a fairly high horsepower 500 cubic inch engine! We have done actual flow bench runs on the manifold and riser, with and without the turbulator plate and I can personaly tell you that removing the plate has a considerable affect on how much exhaust gas the manifold & riser plate can flow at what would be higher rpms and throttle positions. I wish the manifold designer-Gil? had just designed a little more down angle to the exhaust port entrance at the cylinder head flange and any need for the turbulator plate would have been completetly eliminated. The low pocket this would have created would cook off small amounts of water., but what the heck, I didn't design the manifold, and it's really not a half bad part. This manifold is every bit a good as a normal aftermarket cast manifold such as Stainless Marine, Gil, Eddie or Imco standard . If you have a boat that has a s-pipe drop tube between the riser na d the transom exit tip or your boat has a moderate drop between the riser exit height and the transom exit you should be able to eliminate the plate and get the horsepower benefits accordingly. If your transom exit height is close to the bottom of the Merc riser height, you have a silent choice system which you keep set closed for through the prop exit a lot or you are one of these boaters with a below the water line tip exit, swim platform cap over the tip and you back down hard a lot of the time, then you may be better off keeping the turbulator plates installed. If you can safefly remove them, especially with our BIGPOWER kit you will gain power at higher rpms. Remember any impediment to air flow into or out of a high performance large cubic inch engine, especially in marine use will have a negative affect on performance. Otherwise no one would need to purchase marine header or high performance marine manifold systems. I hope this clears the air and clarifies the issue. "Will the real Turbulator plate please stand up!"
Good Luck,
Ray @ Raylar
__________________

mike37
04-25-2005, 05:01 AM
Time to re-prop?Iv got a 28 whating to go on nex time out

DEMOMAN
04-25-2005, 05:51 AM
Outnumbered, based on that description is it ok to pull these in our Ultras??

desertbird
04-27-2005, 11:49 AM
Although most of you are doing it, I wouldn't recommend the double gaskets. Gaskets make thier seal with pressure and the amount of it that is keeping the material against the metal. Two gaskets leaves a split right down the middle, and a potential leak path. (BTW you wont see any WATER because it's the Mercury Dry Joint, that's what the hoses do)
I'm taking mine out, but I bought 2 new gaskets. ONE for each side.

spectras only
04-27-2005, 12:37 PM
[QUOTE=desertbird]path. (BTW you wont see any WATER because it's the Mercury Dry Joint, that's what the hoses do)
QUOTE] Right on :D . One gasket per manifold will suffice !
The surface of the manifolds and risers are machined .
A high heat copper gasket maker would work as well .
I never used gaskets ,only copper gasket maker on wet logs for my jetboats :coffeycup .

Outnumbered
04-27-2005, 12:45 PM
Outnumbered, based on that description is it ok to pull these in our Ultras??
Sounds like it should be fine. Our risers are much higher than the tips. My tips also have internal and external flappers. Once I am out of warranty I will probaly do it. Let me know if you see any gains. Are you running a HO or NO-HO? :)

spectras only
04-27-2005, 01:00 PM
Our risers are much higher than the tips. My tips also have internal and external .
Mercruiser put these restrictors in to catch condensation to burn it up after shutdown. The droplets are pooling around the catch while the s/s plates are still warm for a long time. Most people reported rpm increase ,so there's some benefit by removing them :D .

spectras only
04-27-2005, 01:02 PM
DDP :D

sigepmock
04-27-2005, 01:35 PM
Phuggit brought this up to me but does anyone know if any of the other Merc motors have them? Does my little 6.2L have them too? Or just the 496's.
Chris

Chromegorilla
04-27-2005, 01:48 PM
Hold on, I have a parts diagram/drawing, let me take a look at the 6.2...brb

Chromegorilla
04-27-2005, 01:51 PM
Nope, they are not present on any 6.2 motors.

sigepmock
04-27-2005, 02:16 PM
Sweet....thanks CG.
Chris

spectras only
04-27-2005, 02:21 PM
Nope, they are not present on any 6.2 motors.
Are you sure ? model 2000 and before had the wet joint. From 2001 merc went to dry joint and added the restrictor. You can tell the diff by looking at your riser. The newer models have two water passages cast into the manifold and riser.

sigepmock
04-27-2005, 02:34 PM
Are you sure ? model 2000 and before had the wet joint. From 2001 merc went to dry joint and added the restrictor. You can tell the diff by looking at your riser. The newer models have two water passages cast into the manifold and riser.
So my 6.2L Merc in my 05 Ultra has them or doesn't have them or should I just pull them to make sure????? :confused:

spectras only
04-27-2005, 02:41 PM
I put money on that you have them. Pull them out and let us know if you gained rpms. I'm hitting my rev limiters as is with 26 P Bravo 1's .I'll pull mine off after you guniea pigs find good results :D

desertbird
04-27-2005, 02:47 PM
On the 496 it's easy enough to tell. Just look at the joint! You'll see either a pair of gaskets and thin metal, or just a gasket......
http://www2.***boat.com/image_center/data/505/2501Turb.JPG
Look closeley, you can actually see the 2 gaskets and the metal in between.

sigepmock
04-27-2005, 02:51 PM
I put money on that you have them. Pull them out and let us know if you gained rpms. I'm hitting my rev limiters as is with 26 P Bravo 1's .I'll pull mine off after you guniea pigs find good results :D
Thanks for the help :D :hammer2: I'll climb in the boat tonight and see if I can see the gaskets and plate.

spectras only
04-27-2005, 02:59 PM
Sigepmock. The pre 2001 risers had straight sides up from the manifold. The 2001 and up you'll see the bulges front and back to accomodate water through the manifold.
You'll see the gasket will follow this contour.

Outnumbered
04-27-2005, 03:07 PM
.
Mercruiser put these restrictors in to catch condensation to burn it up after shutdown. The droplets are pooling around the catch while the s/s plates are still warm for a long time. Most people reported rpm increase ,so there's some benefit by removing them :D .
Ya, but most peeps have the HO that are doing this and reporting a few MPH/RPMs. Just wondering if the NO-HO would benefit.

DEMOMAN
04-27-2005, 03:17 PM
Outnumbered, thanks for the info. I am running an HO. If it helps the HO I imagine it would help the no-ho just the same.

Outnumbered
04-27-2005, 03:20 PM
Outnumbered, thanks for the info. I am running an HO. If it helps the HO I imagine it would help the no-ho just the same.
What does that thing run with the HO motor in it? Apparently, I can reprogram my computer and get pretty close to the same power. Just curious.
Thanks

spectras only
04-27-2005, 03:59 PM
Ya, but most peeps have the HO that are doing this and reporting a few MPH/RPMs. Just wondering if the NO-HO would benefit.
The no HO merc exhaust is pretty restrictive when compared to an aftermarket manifold. So I would say removing the restrictor won't hurt one bit ;)

spectras only
04-27-2005, 04:01 PM
Ya, but most peeps have the HO that are doing this and reporting a few MPH/RPMs. Just wondering if the NO-HO would benefit.
The no HO merc exhaust is pretty restrictive when compared to an aftermarket manifold. So I would say removing the restrictor won't hurt one bit ;) .The change in exhaust flow won't be drastic ,so I think the computer would relearn quickly.

Outnumbered
04-27-2005, 05:26 PM
The no HO merc exhaust is pretty restrictive when compared to an aftermarket manifold. So I would say removing the restrictor won't hurt one bit ;) .The change in exhaust flow won't be drastic ,so I think the computer would relearn quickly.
I thought they were the same manifolds as the HO motor. :confused:

Beer-30
04-27-2005, 05:34 PM
I thought they were the same manifolds as the HO motor. :confused:
I would think so, too. I think he meant compared to other than Mercury parts. Gil, EMI, Lightning, etc.

Chromegorilla
04-27-2005, 06:49 PM
OK as far as I can tell there is no turbulator in the exhaust system on a 6.2 motor. First diagram is a 6.2 and clearly there is no turbulator, just a gasket. Second diagram is a 496HO. Part 19 is the turbulator. I am no expert by any means but by the look of the drawings to me it is clear that it is not present on a 6.2 motor.
http://www.donzi.net/forums/attachment.php?attachmentid=11168
http://www.donzi.net/forums/attachment.php?attachmentid=11169
Hope this helps. And yes. Exhaust on a regular 496 and HO are the same.

DEMOMAN
04-27-2005, 07:14 PM
What does that thing run with the HO motor in it? Apparently, I can reprogram my computer and get pretty close to the same power. Just curious.
Thanks
It will hit 72 with 3 big Odessey batteries, skis, amps, sub box etc. They never seem fast enough huh.

spectras only
04-27-2005, 07:50 PM
OK you guys ,here it is. 2001 up 6.2 MX. part # 12 ,restrictor plate.
http://media.stemtostern.com/LSDATA/LSDATA_FULL/CRUISER/884717/1692.GIF

2NDTIMEAROUND
04-27-2005, 10:34 PM
So then i talke it that my 2003 6.2 has these restrictor plates.

Chromegorilla
04-28-2005, 04:08 AM
OK you guys ,here it is. 2001 up 6.2 MX. part # 12 ,restrictor plate.
http://media.stemtostern.com/LSDATA/LSDATA_FULL/CRUISER/884717/1692.GIF
Both of our daigrams are for a 2001 and up 6.2 The one I posted was for serial#'s OM300000 - OM599999 the link you provided is for serial #'s OM600000 and up.
Using www.stemtostern.com and referencing the drawing in the link you posted, part 12 is listed as a gasket ( 12 27-864850A02Gasket - Elbow to be exact) not a restrictor plate or turbulator.

Chico&Zeus
04-28-2005, 05:59 AM
So on the 350 MPI with captains call exhaust, is this a part I can remove for more power/speed or not??? I do run through prop exhaust sometimes and really don't want to get water in the exhaust valves.

spectras only
04-28-2005, 09:10 AM
Gilla, I wished you were right :cool: . Unfortunately , my 2003 6.2's have the restrictors . My warranty runs out next month, so they'll go :D.
BTW , I have these plates in my hand from another 2003 350 merc [ guy cracked his block, manifolds :cry: this past winter] and they're at least 20-30% smaller than the manifold/riser openings just by looking at it.I'll be running over to vanc island this saturday with the rsetrictors in, and will post my rpm at WOT. After that run , I'll remove the plates for the upcoming fun run to Roche harbour and post new numbers .I have total 640 prop HP , and even only 20 HP increase per engine should give me at least 1 MPH :wink:. You were lucky to gain so much speed that you've posted.

Chromegorilla
04-28-2005, 11:16 AM
I guess the proof is in the pudding. Takem apart and you see it, aint no arguing with that. I was just looking at drawings. I learn somethin new eveyday. ;)

spectras only
04-28-2005, 11:32 AM
Gilla ,I know you have a nice classic 22 .I'll take some running videos from my boat of my buddy's 33 Donzi [502's] on the way back from the Island for you .

Chromegorilla
04-28-2005, 01:29 PM
Sweet! Love them Donzi's. Especially the new ZR's. They kick major ass.
DONZI- OFFSHORE SINCE '64 :D

spectras only
04-28-2005, 01:51 PM
My buddy's Donzi is an older 1992 :cry: .
Here she is in Maple Bay =
http://www3.telus.net/spectrasonly/donzi1.jpg

Kachina26
05-01-2005, 04:25 PM
I picked up 2-3 mph out of mine!!! I can't believe it.

Beer-30
05-01-2005, 07:26 PM
I picked up 2-3 mph out of mine!!! I can't believe it.
I don't doubt it. That's quite the little restrictor. Just the opposite of a NASCAR restictor plate. Gotsta get the bad air out!

WILD LAVEY
05-02-2005, 05:31 AM
pulled the plates off this weekend and i picked up a solid 3 mph. very happy with it. it only took me 20 min. to take them off.

NuckinFutz
05-02-2005, 02:16 PM
I'm ready to pull my turbulators now, but I can see some additional baffles in the exhaust. I have rubber flappers on the back and internal metal flappers, (I believe Eddie Marine), but lookin in the exhaust from the rear it appears there is a plastic type baffle in the rubber hose between the internal baffle and the connection to the riser. Any clues what this is for? It looks like a cone shaped piece with the small end towards the rear and about 5-6 inches long. It appears to be as restrictive as the turbulator. While looking at the rubber hose inside the engine compartment I can see where a hose clamp is possibly holding this baffle in place.

Outnumbered
05-02-2005, 02:22 PM
You guys that picked up 3mph, are you both running HO's?

LHC30Victory
05-02-2005, 02:24 PM
Futz, take them out if you have good flappers installed to keep the water out of the manifolds.

NuckinFutz
05-02-2005, 02:31 PM
LHC30VICTORY, Looks like you made it hope safe. We got stupid a drove straight home, made it at 5:30 this morning. Good meeting you this weekend and I'll go mechanic and hope for the best in increased speed. Hopefully you have good luck with your issues as well. Thanks for the advice.

WILD LAVEY
05-02-2005, 02:48 PM
You guys that picked up 3mph, are you both running HO's?
im running a ho and so is kachina26. just do it.

Outnumbered
05-02-2005, 06:55 PM
im running a ho and so is kachina26. just do it.
As soon as I'm out of warranty. I probably do it this winter.

Beer-30
05-02-2005, 07:40 PM
im running a ho and so is kachina26. just do it.
So am I! I did it. It's just too easy. It's almost criminal.

mike37
05-02-2005, 07:51 PM
turbulators in
http://www2.***boat.com/image_center/data/520/253turbulators_in.JPG
and turbulators out
http://www2.***boat.com/image_center/data/520/253turbulators_out.JPG
tools you need
http://www2.***boat.com/image_center/data/520/253turbulators_on_the_bench.JPG

NuckinFutz
05-02-2005, 07:57 PM
Mine are done now. Pulled the baffles and the turbulator. The baffle ended up being closer to 3 inches long once I got it out. Now looking forward to seeing how it runs. Just waiting for some more days off.

Outnumbered
05-02-2005, 10:07 PM
So I guess the comp will automatically adjust the air-fuel mixture when it flows more air.

Beer-30
05-03-2005, 07:22 AM
So I guess the comp will automatically adjust the air-fuel mixture when it flows more air.
OH, it can handle it. I'm even going to start dropping fuel pressure a pound at a time until the plugs / exhaust start to "brown" up. I don't know about yours, but mine is really rich. Merc sets them up rich.

Outnumbered
05-03-2005, 09:51 AM
OH, it can handle it. I'm even going to start dropping fuel pressure a pound at a time until the plugs / exhaust start to "brown" up. I don't know about yours, but mine is really rich. Merc sets them up rich.
I'm getting a little soot. But it does not smell rich like my old 460 carb motor did at idle :). Its funny that they are running rich when they are certified as "Ultra Low Emissions". Usually they run them lean as hell in cars and bikes to pass the ULM tests. Does not make sense to me.

shadow
05-03-2005, 11:24 AM
I'm getting a little soot. But it does not smell rich like my old 460 carb motor did at idle :). Its funny that they are running rich when they are certified as "Ultra Low Emissions". Usually they run them lean as hell in cars and bikes to pass the ULM tests. Does not make sense to me.
Merc sets them up to run rich,This keeping them turn key and bullet proof for the most part.(idiot proof) while under warranty there should be no cylinder temp issues leading to piston/valve damage due to lean cond = less warranty repairs for Merc to pay for.Beware the 496's are notorious for soot due to burning oil.Not burning it through guides,seals or rings but the mating surface from the intake to cylinder head don't match up 100% and oil passes from the valley into the intake passages,causing oil consumption concerns.

Beer-30
05-03-2005, 03:30 PM
Merc sets them up to run rich,This keeping them turn key and bullet proof for the most part.(idiot proof) while under warranty there should be no cylinder temp issues leading to piston/valve damage due to lean cond = less warranty repairs for Merc to pay for.Beware the 496's are notorious for soot due to burning oil.Not burning it through guides,seals or rings but the mating surface from the intake to cylinder head don't match up 100% and oil passes from the valley into the intake passages,causing oil consumption concerns.
I have watched mine a few times during start-up to check, and it doesn't have any "blue" puffs during start. I put 10 hours on the thing and it hadn't used a noticeable amount on the stick. Kept checking since there has been mention of them using oil. I probably took most of what was gone just by pulling and wiping the stick so much! Didn't see an carbon build-up in the manifold either (oil), just sooty black film (fuel).

shadow
05-03-2005, 04:09 PM
I have watched mine a few times during start-up to check, and it doesn't have any "blue" puffs during start. I put 10 hours on the thing and it hadn't used a noticeable amount on the stick. Kept checking since there has been mention of them using oil. I probably took most of what was gone just by pulling and wiping the stick so much! Didn't see an carbon build-up in the manifold either (oil), just sooty black film (fuel).
They don't all use oil but if someone happens to have one where oil consumption is a concern this is one of the places to check.Pretty common.
Sounds like yours is in good shape.I was also one of the lucky ones,never had any issues with oil consumption after many hrs of hard use.Also did a cylinder leakdown on all cylinders and was pleased with the results before i did any upgrades.

rivercrazy
05-03-2005, 04:13 PM
I've had great experience with my 496HO. 158 hours and not one problem. Doesn't burn any noticable amount of oil between changes. A little black transom but its ECM related with all 496's. One thing I've noticed is that its less with 87 octane name brand gas (Arco, 76, Shell), than with some other brands.

Beer-30
05-03-2005, 04:16 PM
They don't all use oil but if someone happens to have one where oil consumption is a concern this is one of the places to check.Pretty common.
Sounds like yours is in good shape.I was also one of the lucky ones,never had any issues with oil consumption after many hrs of hard use.Also did a cylinder leakdown on all cylinders and was pleased with the results before i did any upgrades.
Cool. I never doubt your word, as I know you have intimate details of this motor. It's so unlike GM to be so sloppy with detail stuff. The intake mis-match, and the choked heads/cylinders issue. It does, however, show what potential these motors have. If they got 422 on the dyno in stock trim.....
Another question, since you have plenty of knowledge. This is not a 496 question, but a Bravo-1 question:
Should there be a very slight "twist" in the splines of the propshaft? I had mine off and was changing the lube. Noticed the splines did a slight jog towards the "beginning" of them where the shaft is solid, and then becomes splined. This is my first outdrive, so I wasn't sure if this is a pre-load thing?

shadow
05-03-2005, 04:16 PM
I've had great experience with my 496HO. 158 hours and not one problem. Doesn't burn any noticable amount of oil between changes. A little black transom but its ECM related with all 496's. One thing I've noticed is that its less with 87 octane name brand gas (Arco, 76, Shell), than with some other brands.
I've also had a great history with mine.I say they are great turn key motors.
Can be modified if someone wants and still reliable.

Beer-30
05-03-2005, 04:18 PM
I've had great experience with my 496HO. 158 hours and not one problem. Doesn't burn any noticable amount of oil between changes. A little black transom but its ECM related with all 496's. One thing I've noticed is that its less with 87 octane name brand gas (Arco, 76, Shell), than with some other brands.
One thing I do know, is that it's not an ECM thing so much as it's a fuel pressure thing. The ECM controls the pulse-width of the opening/closing of the injectors. Higher fuel pressure means more fuel jumps through each injector. Lower means less. Open/close rate stays the same.

Beer-30
05-03-2005, 04:20 PM
Shadow, please look back at post #75 (page 3) of this thread. I had a question for you. Thanks.

shadow
05-03-2005, 04:53 PM
Cool. I never doubt your word, as I know you have intimate details of this motor. It's so unlike GM to be so sloppy with detail stuff. The intake mis-match, and the choked heads/cylinders issue. It does, however, show what potential these motors have. If they got 422 on the dyno in stock trim.....
Another question, since you have plenty of knowledge. This is not a 496 question, but a Bravo-1 question:
Should there be a very slight "twist" in the splines of the propshaft? I had mine off and was changing the lube. Noticed the splines did a slight jog towards the "beginning" of them where the shaft is solid, and then becomes splined. This is my first outdrive, so I wasn't sure if this is a pre-load thing?
Not a dive expert there are plenty around here that know more about Bravos than me.I twisted my shaft not just a little but alot before i had it upgraded.
From what i understand it's from getting air and not getting out of the throttle
prop spinning upon re entry.Made sense to me.I always try and back out of the throttle if the boat gets air but it's impossible to do 100% of the time.Considering i got about 100 hrs before that happened it wasn't to bad to step up and bite the bullet and upgrade the drive at that time.I'd say if it's just very slight i wouldn't worry yet and i'd keep an eye on it.You might want to check with someone more knowledgeable about drives.

mike37
05-03-2005, 05:00 PM
shadow
I cant find the tread where you told us how to adjust the fuel pressure

Beer-30
05-03-2005, 05:06 PM
shadow
I cant find the tread where you told us how to adjust the fuel pressure
There is a schrader valve on the fuel rail. The adjustable regulator is under the ECM. You need the special "tamper-proof" TORX bit (I don't know what size) to adjust it.
Put a (0-100) fuel press gauge on the schrader, take the vacuum hose off of the regulator (to view static pressure) and twist out (unscrew) to lessen.
I haven't done it yet, but will probably start at 2 lb drop and then 1 at a time from there.

shadow
05-03-2005, 05:33 PM
http://www.hotboatpics.com/pics/data/500/5472DSCF1529-med.JPG shadow
I cant find the tread where you told us how to adjust the fuel pressure
Heres a pic.I just drilled a hole through the plate so i have access.You need to hook a fuel press gauge to the shrader valve and start the boat then adjust.You will need a tamper proof torx bit,i belive it is a t15 or t20.
The one problem you might run into is that Merc painted the fuel pressure regulator along with evrything else on the engine.The paint build up may not let you insert the torx bit or it will be stuck from the paint.I ended up buying a new fuel pressure regulator.If you buy a merc regulator be prepared to shell out a couple hundred $$.Go to the nearest GM dealership and i think i paid $30-$40.

mike37
05-03-2005, 05:34 PM
thank
Ijust got a responcefrom merc on the black stuff they told me that there has ben some isues resolved and that I should take it to a merk mecanice and he can get with there teck and it could be fixt now I dont know if it will cost
There is a schrader valve on the fuel rail. The adjustable regulator is under the ECM. You need the special "tamper-proof" TORX bit (I don't know what size) to adjust it.
Put a (0-100) fuel press gauge on the schrader, take the vacuum hose off of the regulator (to view static pressure) and twist out (unscrew) to lessen.
I haven't done it yet, but will probably start at 2 lb drop and then 1 at a time from there.

mike37
05-03-2005, 05:37 PM
http://www.hotboatpics.com/pics/data/500/5472DSCF1529-med.JPG
Heres a pic.I just drilled a hole through the plate so i have access.You need to hook a fuel press gauge to the shrader valve and start the boat then adjust.You will need a tamper proof torx bit,i belive it is a t15 or t20.
The one problem you might run into is that Merc painted the fuel pressure regulator along with evrything else on the engine.The paint build up may not let you insert the torx bit or it will be stuck from the paint.I ended up buying a new fuel pressure regulator.If you buy a merc regulator be prepared to shell out a couple hundred $$.Go to the nearest GM dealership and i think i paid $30-$40.
did you need to ajust for the raylar kit to

shadow
05-03-2005, 05:42 PM
Yeah Mike i'm running 50psi.I think stock if i remember correct was either 43psi or 47psi.

Beer-30
05-03-2005, 05:43 PM
did you need to ajust for the raylar kit to
That was my question. What PSI did you guys end up at for the RAYLAR kit? Or, are the injectors replaced? Does the stock fuel pump feed it?

shadow
05-03-2005, 05:51 PM
That was my question. What PSI did you guys end up at for the RAYLAR kit? Or, are the injectors replaced? Does the stock fuel pump feed it?
Stock injectors,stock fuel pump.No need to change either of those.Just need to adjust fuel pressure slightly and the ecm will adjust the pulse width.

Raylar
05-03-2005, 06:06 PM
Beer 30
The Mercury fuel system pump is capable of pumping enough fuel to make 600HP in a modified 496 motor with the stock injectors. The problem is that Mercury bypasses the regulator on the GM fuel rail and puts a non-adjustable regulator on the "cool fuel" cooler in the plastic housing on the lower left side of the motor thats preset and not adjustable to be at about 43psi. You won't be able to adjust the fuel pressure at the GM regulator unless you have one of our kits with a fuel system bypass modification. I would not adjust your stock motor fuel pressure to much anyway since the motor has an air fuel ratio between 12.8 and 13.2 to 1 with the stock 43psi setting. Most of the soot and black transom that stock 496 owners see on there transomes come from burning 91 octane fuel and some from the additives they put in the fuel today, especially California "summer formulation." We see this same thing on every motor we dyno and run no mater how nominal the oil usage is and no matter what the fuel pressure is. The 496's running our 525HP kits are burning a lot more air with their fuel and the burn itself is quicker and better so these boats will see less soot, but its still not going away completely just do to the "rot gut gas and additives." My suggestion for anyone with a stock 496 Merc engine is remove the turbulators, run 87 octane fuel and leave the rest of the motor alone until you are ready to improve the motor. When you are, add our kits and enjoy the higher power levels and same reliability that these motors will provide.
"If it ain't broke, don't fix it!
Ray @ Raylar

shadow
05-03-2005, 06:23 PM
Beer 30
The Mercury fuel system pump is capable of pumping enough fuel to make 600HP in a modified 496 motor with the stock injectors. The problem is that Mercury bypasses the regulator on the GM fuel rail and puts a non-adjustable regulator on the "cool fuel" cooler in the plastic housing on the lower left side of the motor thats preset and not adjustable to be at about 43psi. You won't be able to adjust the fuel pressure at the GM regulator unless you have one of our kits with a fuel system bypass modification. I would not adjust your stock motor fuel pressure to much anyway since the motor has an air fuel ratio between 12.8 and 13.2 to 1 with the stock 43psi setting. Most of the soot and black transom that stock 496 owners see on there transomes come from burning 91 octane fuel and some from the additives they put in the fuel today, especially California "summer formulation." We see this same thing on every motor we dyno and run no mater how nominal the oil usage is and no matter what the fuel pressure is. The 496's running our 525HP kits are burning a lot more air with their fuel and the burn itself is quicker and better so these boats will see less soot, but its still not going away completely just do to the "rot gut gas and additives." My suggestion for anyone with a stock 496 Merc engine is remove the turbulators, run 87 octane fuel and leave the rest of the motor alone until you are ready to improve the motor. When you are, add our kits and enjoy the higher power levels and same reliability that these motors will provide.
"If it ain't broke, don't fix it!
Ray @ Raylar
There Ya have it! From someone that knows more about the 496 than most of us will ever know. :cool:
Ray thanks for the info,You always seem to step in at the right time and clear up all the questions.

INSman
05-03-2005, 07:19 PM
Beer 30
The Mercury fuel system pump is capable of pumping enough fuel to make 600HP in a modified 496 motor with the stock injectors. The problem is that Mercury bypasses the regulator on the GM fuel rail and puts a non-adjustable regulator on the "cool fuel" cooler in the plastic housing on the lower left side of the motor thats preset and not adjustable to be at about 43psi. You won't be able to adjust the fuel pressure at the GM regulator unless you have one of our kits with a fuel system bypass modification. I would not adjust your stock motor fuel pressure to much anyway since the motor has an air fuel ratio between 12.8 and 13.2 to 1 with the stock 43psi setting. Most of the soot and black transom that stock 496 owners see on there transomes come from burning 91 octane fuel and some from the additives they put in the fuel today, especially California "summer formulation." We see this same thing on every motor we dyno and run no mater how nominal the oil usage is and no matter what the fuel pressure is. The 496's running our 525HP kits are burning a lot more air with their fuel and the burn itself is quicker and better so these boats will see less soot, but its still not going away completely just do to the "rot gut gas and additives." My suggestion for anyone with a stock 496 Merc engine is remove the turbulators, run 87 octane fuel and leave the rest of the motor alone until you are ready to improve the motor. When you are, add our kits and enjoy the higher power levels and same reliability that these motors will provide.
"If it ain't broke, don't fix it!
Ray @ Raylar
The KING has spoken !!! :D I love this Ray guy, and wish he would adopt me !!! :cool:

mike37
05-03-2005, 07:20 PM
thank for the info guys
wanted to post this for every one
just got it from them
Thank you for your recent inquiry. MerCruiser has seen a few sooting
issues with 496 engines in certain boat designs. Please have the boat
taken into an authorized MerCruiser service dealership for inspection of
the condition. They should then work with MerCruiser Dealer Technical
Service to determine the adequate solution. I believe MerCruiser Dealer
Technical Service has been known to assist with certain PCM 555
modifications/recalibrations that have resulted in positive results with
sooting issues. I hope this information is helpful and leads to the
resolution of your sooting issue.
Mike Sheline
MerCruiser Consumer Service Specialist

shadow
05-03-2005, 07:30 PM
thank for the info guys
wanted to post this for every one
just got it from them
Thank you for your recent inquiry. MerCruiser has seen a few sooting
issues with 496 engines in certain boat designs. Please have the boat
taken into an authorized MerCruiser service dealership for inspection of
the condition. They should then work with MerCruiser Dealer Technical
Service to determine the adequate solution. I believe MerCruiser Dealer
Technical Service has been known to assist with certain PCM 555
modifications/recalibrations that have resulted in positive results with
sooting issues. I hope this information is helpful and leads to the
resolution of your sooting issue.
Mike Sheline
MerCruiser Consumer Service Specialist
Thanks for posting Mike.Nice to see customer service in full affect.
If your local mercruiser dealership and merc technical service can't come to a conclusion have them give Ray & Larry a call. :D
I'm sure that Merc is already watching Raylar closely. :rollside:

mike37
05-03-2005, 07:38 PM
Thanks for posting Mike.Nice to see customer service in full affect.
If your local mercruiser dealership and merc technical service can't come to a conclusion have them give Ray & Larry a call. :D
I'm sure that Merc is already watching Raylar closely. :rollside:
you better keep a eye on that kit a the Naci bash or it my come up missing

shadow
05-03-2005, 07:48 PM
you better keep a eye on that kit a the Naci bash or it my come up missing
I'm not bringing it!I'm brining my pontoon boat. ;)

Beer-30
05-03-2005, 08:21 PM
Yeah, thanks again Ray. Your info always makes sense and puts the rumors to rest.
I would never presume to know more about these motors than you. The only rebuttle I would have to your last paragraph is that black spark plugs are black spark plugs. I have tuned carbureted, mechanical FI, EFI, turbocharged and normally aspirated boat, car, truck, and airplane engines. One basic thing is: spark plugs are always the first thing anyone will tell you to look at when setting air/fuel (without a gauge). This is just a truck motor at heart, as everone has pointed out. My 7.4 1998 Dually has slightly white to light brown plugs and this should technically have the same. Granted, the Vortec has an O2 sensor (well, 4 actually) and the Merc doesn't. They are both burning the same fuel from the same pumps, as I run 87 in both. And, I would not feel safe running at white-brown in a boat application. I would, however, feel much better seeing dark brown to lightly black instead of solid black.
I sincerely doubt your kits are producing black plugs and inner manifolds when you are done tuning. If so, then I would be curious as to why.

Outnumbered
05-03-2005, 09:47 PM
Beer 30
The Mercury fuel system pump is capable of pumping enough fuel to make 600HP in a modified 496 motor with the stock injectors. The problem is that Mercury bypasses the regulator on the GM fuel rail and puts a non-adjustable regulator on the "cool fuel" cooler in the plastic housing on the lower left side of the motor thats preset and not adjustable to be at about 43psi. You won't be able to adjust the fuel pressure at the GM regulator unless you have one of our kits with a fuel system bypass modification. I would not adjust your stock motor fuel pressure to much anyway since the motor has an air fuel ratio between 12.8 and 13.2 to 1 with the stock 43psi setting. Most of the soot and black transom that stock 496 owners see on there transomes come from burning 91 octane fuel and some from the additives they put in the fuel today, especially California "summer formulation." We see this same thing on every motor we dyno and run no mater how nominal the oil usage is and no matter what the fuel pressure is. The 496's running our 525HP kits are burning a lot more air with their fuel and the burn itself is quicker and better so these boats will see less soot, but its still not going away completely just do to the "rot gut gas and additives." My suggestion for anyone with a stock 496 Merc engine is remove the turbulators, run 87 octane fuel and leave the rest of the motor alone until you are ready to improve the motor. When you are, add our kits and enjoy the higher power levels and same reliability that these motors will provide.
"If it ain't broke, don't fix it!
Ray @ Raylar
Thanks for the tip.

Beer-30
05-05-2005, 11:51 PM
The IF IT AINT BROKE, DONT FIX IT thang doesn't work for me, Ray.
Technically, the 496s aint broke, but you guys are fixing it?
Believe me, I am not running down you or your kit. I fully plan on purchasing one in the future and I know you have done your homework.
My belief is simple. ANY motor can benefit from a little careful tuning. You guys started doing it to 496s and ended up where you are. Just like the exhaust plates. Why even bother to pull them out if "it ain't broke?" Well, because the engine will benefit from it.

Nordicflame
05-06-2005, 12:30 PM
The soot is an ECM issue. Both of the 496HOs ECMs in my boat were replaced under warranty in 2002 for this very issue.
The soot has been gone since.
The ones who compained at the time were taken care of :cry:

Deano
05-06-2005, 01:44 PM
refering back to the "black soot" on the transom.
What octaine are you guys running??
I was having the same issue with my boat and got some advise from board members here to run only 87 octaine. It worked. The ecm is programmed to run 87, anything higher is just a waist of money and the motor actually runs worse.

Beer-30
05-06-2005, 02:20 PM
refering back to the "black soot" on the transom.
What octaine are you guys running??
I was having the same issue with my boat and got some advise from board members here to run only 87 octaine. It worked. The ecm is programmed to run 87, anything higher is just a waist of money and the motor actually runs worse.
Nope, all she gets is 87.

desertbird
07-12-2007, 10:56 AM
:d