Hey smokin', I too will be building a SBC, hopefully soon, and I want an opinion. You mentioned some break in proceudres. I was always led to believe that breaking in with synthetic is a no no because its too slick and the rings would never seat properly. Is that an old wives tale that's not applicable with modern machining practices? Did I make this up or has nanybody else heard this? I'm going to run a roller cam/lifters so I shouldn't have any cam break in issues and everything I'm hearing is that old school break in of a motor doesn't really apply anymore. Break the cam in (if applicaple), put the motor through a couple of heat cycles, change oil a couple of times, re-torque everything, and drive it like you stole it-Aluminum Squirt
Well A.S, I have heard similar from "old hands" but unfortunately haven't polled anyone really on it.
I do have some oil usage on the 454, but, she's still really a young engine IMO (only arround 30 hours) and I suffered a major leakage this summer (oil filter got loose)so I really cannot define just how bad it is. It is looking initialy like about a quart over about 20 hours of run time, but don't score that as very accurate. I have no smoking or exhaust residue from it, just oil "vanishing" ...... It could easilly be vapor going up the un-baffled PVC and being burned there. I had some oil usage before the motor was rebuilt, a similar time frame, and not leakage
I have read where today's bore finishes are far smoother than they were 20 years ago and thus ring seal is almost immediate.
The folowing is stuff I have dug up for ya AS,
From Mobil-1's website FAQ area ....
Is it true that new engines need a break-in period using conventional motor oil?
That is a myth. In the past, engine break-in was necessary to remove any metal flashing (called swarf) or abrasive material left inside the engine after machining, as well as to allow the valves and rings to seat properly. Todays engines are built with much tighter tolerances, much improved machining and under much cleaner conditions compared to the engines of 10 or 20 years ago. Current engine-manufacturing technology does not require a break-in period using petroleum-based motor oils.
In fact, Mobil 1 has shown excellent results in industry-standard ASTM tests, most of which use completely rebuilt engines for each new test run. Mobil 1s outstanding results in these tests demonstrate that proper break-in using Mobil 1 is not a concern. Mobil 1 can be used in an engine from the day you drive off the showroom floor.
Can I use Mobil 1 as a break-in oil for a rebuilt engine?
Yes, but the timing of your first oil change will depend largely on the quality of the rebuild. Due to the tighter tolerances and improved machining of todays engines, the traditional concept of engine break-in is not as critical. However, if the engine rebuilder is using older machining equipment or lower-quality components, abrasive material can be left inside the engine. In this case, you should use a short drain interval on your initial oil fill.
From elsewhere:
CathKen Enterprises:
COMMON QUESTION AMONG NEW VEHICLE OWNERS is about the effect of synthetic oil on engine break in. Many dealers, mechanics and owners recommend against using synthetic oil during break-in. They accept the myth that an engine does not break-in properly when using synthetic oil. When questioned about this belief, most reply that synthetic oil is to slippery and does not allow the moving metal parts to seat themselves against one another.
This is simply not true; one of the very best things one can do for a new engine is to fill it with high quality synthetic oil before it runs the first time. A half century ago, car and motorcycle engines needed significant break-in time and care if they were going to give relatively long and reliable service. This fact of motoring life was mainly due to the roughness of the finishes on the parts that had to work close together. Piston rings and cylinder walls, for example, were not as precise or smooth as they now are. It is this roughness that requires break-in.
There is more of the same out on the internet, I'm trying to find stuff not from the oil makers or dealers, but is hard to.
Personally, I don't think I have a problem, and I don't think you will.
Scrap the vortec heads. for the same $ you can get something a whole lot better. The iron vortecs on a boat with open cooling are no better than the 624 casting for durabilty or performance.
Not disagreeing with you, but can you explain why? The vortecs flow over 20% more with the same port size.
Not disagreeing with you, but can you explain why? The vortecs flow over 20% more with the same port size.
well...time for my .02 cents...i "totally" agree...scrap the Vortec heads...look for an early set of FI heads (2.02x1.60) 64cc...chg the int's to 2.05, do a little (mild) port work, port the exh a little to match the ex manif's & match the intake ports to the manuf...also...chit can ur present int manif & look for an EB RPM Air Gap (they work great on BBC, ask Smoke about that!, so should/will work great on SBC)...u can hot tank the ex manif or sand blast them to almost new condition...as far as ur build goes...if it were me, i would have taken the 305 block & put a 383 stroker kit in it (more torque than u can believe!)...just my suggestions
fastrat
p.s. AS...the 383 might be the way to go for ur build!!!
well...time for my .02 cents...i "totally" agree...scrap the Vortec heads...look for an early set of FI heads (2.02x1.60) 64cc...chg the int's to 2.05, do a little (mild) port work, port the exh a little to match the ex manif's & match the intake ports to the manuf...also...chit can ur present int manif & look for an EB RPM Air Gap (they work great on BBC, ask Smoke about that!, so should/will work great on SBC)...u can hot tank the ex manif or sand blast them to almost new condition...as far as ur build goes...if it were me, i would have taken the 305 block & put a 383 stroker kit in it (more torque than u can believe!)...just my suggestions
fastrat
p.s. AS...the 383 might be the way to go for ur build!!!
Again, not disagreeing, but some of this goes against everything I know about engine building, but like I said.. I've never built one for marine engines. Just wondering why some of this would work better.
I'm only revving to 5000 and only making 300 hp, so is there a specific reason why the RPM manifold is a better match? It shines at higher RPMs that I'll never see. Same thing with the heavily modified heads; why spend thousands modifying heads beyond where I need flow, when I can put a brand new set of good vortecs on for $400 that more than suit the need?
The 305 can't become a 383. Its not possible because of the very small bore on the 305. 383s come from taking a 350 30-over and using a 3.75" crank. Also, my 305 is wasted... as in the oil pan has been sitting full of water for 5 years. There is nothing salvageable from inside that engine except maybe a pushrod or two
Again, not disagreeing since I know nothing about marine engines, I'm just wondering why I should scrap vortec heads that flow 240 cfms in favor of heads that flow 211 cfms, then sink hundreds into larger valves and porting to get them to flow 270 cfms? I think the vortecs are not only PERFECTLY matched to this build, but also a hard-to-beat bargain at $250-300 for a rebuilt set. If there is a compelling reason that I'm not seeing in the marine application I'll do it, but I'm getting confused.
Hey Smokin, good info, thanx. Its taking me awhile to digest some of these new break in procedures. I guess I'm stubborn. I see perefect examples of zero break in at work everyday and the cars go 100,000 miles every time w/o hardly any problems. Anyway, thanx for the info. My build is probably going to be pretty slow so I'll have plenty of time to formulate what approach I'm going to take.
Curtis73, I can't comment very intelligently on flow characteristics of different heads, but I would tend to agree with the porting recommendation. At your performance level, there is a significant amount of HP waiting to be released by doing some porting and port matching. I'm not talking about spending $100's here either (isn't there a sticky topic around here about head porting???). Anyway, with some simple head porting and port matching there should be some pretty good HP in there. You don't have to get crazy, just be conservative, clean the bowls up, take out some of the casting flash, port match to your gaskets, etc. May as well clean up the oil drain back holes while you are there. Most of this can be done with 5-10 hours of careful work, a little bit of planning, and a few dollars in grind stones, sanding drums etc for your drill or dremel-Aluminum Squirt
curtis73, I am going with the performer manifold which is designed for torque at low rpms and off idle. I also think the vortec heads are a good match for our application although I am looking at a conservative porting and port matching as Aluminium Squirt suggests. Not difficult and some extra ponies for 2-3 evenings work.
I am not sold on the 383 with what we are doing. I am not sure the cost is worth it. For my build the 350, vortecs and roller retrofit will give me as much or more power than my hull size and shape can handle. Pic attatched.
I am looking at a set of NEW GM vortec heads with these specs.
-1.940"/1.500" Stainless High Flow Valves
-Hi Performance Springs Good To (.500 lift)
-PC seals
-Hardened Locks,Retainers and Seats
-5 Angle Valve Job
-CBN Finished Deck
-3/8" Studs
-Fully Machined For High Lift Up To .550" lift
Looks good for my application?
I'll show you why I don't need a 383. Take a look at the dyno charts. These are the absolutely exact same motors, but I just changed the stroke to make it a 383. Same exact 300 hp, but it peaks 250 RPMs lower. First of all, I have an Alpha which doesn't like more than 300, especially with as much skiing duty this boat might see. Secondly, its a 2600-lb 19' boat that doesn't need the extra holeshot torque especially with the alpha.
So why would I double the cost of this project to get power I neither want nor need?
I'll also answer the roller question for myself (even though I'm going with a flat). As an automotive engine builder for years now, I see the advantages of rollers and they are undeniable. Faster ramp profiles, much longer life, more area under the curve, less friction, longer oil life, better at dry startup after sitting winterized for 5 months, more usable torque, broader hp curves... need I go on? Even just for peace of mind and reduced friction are enough reason for me. Flat tappet cams are technology from the 1920s that was almost fully replaced in the 80s by either rollers or OHC, so while flats are still viable, I think its safe to say that in almost every way, rollers are better even if they didn't offer any more power.
I TRULY appreciate the suggestions, but I think we're getting a little off the spirit of its original intention. Since I'm building this engine myself and it really only needs a hot tank and re-assembly, total cost to buy AND build the shortblock will be under $400, plus I have a spare set of new pistons and used heads that I can sell on Ebay to recoup some of the costs. A 383 requires a crank, rods, and pistons and the cheapest kits I've seen are $638 for chinese castings that often require journal polishing before you can use them. Not that I couldn't buy it, but I don't wanna buy it since my projected power curve looks perfect as-is.
- I'm looking for 285-310 hp MAX, which is why I chose the Vortecs. They flow 230-240 cfm intake out of the box, have far superior chamber designs, and they're cheap even new.
- While I agree that porting is a GREAT way to get optimum power from the least port volume, what you have suggested is to buy heads that flow 210 cfms and then port them for more. While I agree that's a great idea for higher power, I already have a head choice that will meet my goals as-cast.
- Again, I have to ask why an RPM??? The performer's powerband is matched EXACTLY to my power band. Why would I buy an intake that sacrifices a few lb-ft down low only to add a few HP at 5500 rpm... which I'll never see? In effect I'll be giving up power... period. This isn't a race boat, its a performance pleasure cruiser that will absolutely max out at no more than 5000.
You have to understand that my last two boats were a 1958 Sea King 14' runabout with a 25-horse merc and a 1968 Glassmaster Tri-hull with a Merc 70. Now I'm talking about 300 hp and 70 mph in a 19' baja, so for now I think I'll be happy with what I have and there is plenty of room to grow. A small cam swap with those vortecs can take me to 350 real easy. Then maybe port the vortecs and I'm suddenly at 400.
Anyway, here's a quick screen cap of why I personally don't need a 383
Here's the boat that's getting my 350, mtnrat:
You are building a stock motor. You now have a short block....before you didn't. If you had to do a bottom end it is the same price to do either the 383 or a 350. I can buy a kit for the same price that it would cost me to have the machine work done
Ahh... I see. Read what I wrote, I don't need $600 of machine work. I need $150 worth of hot tank, lifters, and bearings. The shortblock is just dirty from sitting 5 years, not in need of a rebuild.
No arguements over the advantage of a roller set-up but you seemed to be concerned over $ spent so at the 285 to 300 hp level why waste the $
Which is why I'm using a flat. I was defending mtnrat's choice of roller
I can buy Darts here for the same $ as the vortecs and they will stand up better and make more power with no other changes
You can get new darts for $400 a pair assembled? Normally they're somewhere north of $1000. I'll take fourMy problem with the dart S/S OR the iron eagle line is that the ports are bigger and they BOTH flow 30 cfm LESS than the vortecs at 170cc. You're right, they're a much beefier head, but I still think the vortecs are a better performance choice for me since they offer adequate flow at this power level without the extra port work required.
The performer is a copy off the stock GM intake, if you are going to spend the cash buy a good intake that you can use as you upgrade in the future.....or use the cast one you already have
I see your recommendation based on that info, but we'll just have to agree to disagree. If you put a stock chevy intake (any of them) beside an edelbrock performer, you'll see that they are vastly different. They flow much better with softer turn radii and keep fuel atomized much better. But I understand why you recommend the RPM, I just don't agree with your assesment of performer intakes. I have no problem switching intakes, I just don't see the need for a 6500-rpm-capable intake for this build which is only ever going to see 5000.
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