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Checkmate
08-30-2001, 10:42 AM
I have an original Checkmate, 1986 Senator, 19"7" with an Alpha 1, 260. The merc has 4" exhaust headers, thru the hull exhaust and a Quadra jet carb. with the original small flame arrestor. Anyone know if you can pick up a bit more by using a K & N or a larger 454 flame arrestor. Also, will this make the engine run to lean?
I have read the other options, Cam, heads, to expensive until I get everything else like new.

spectras only
08-30-2001, 12:13 PM
Checkmate, K @ N is a good filter [I have it in my Mustang],however I would recommend a larger wiremesh USCG filter from one of the advertisers from hot boat [I know K @ N has one of those uscg appr too].If you listen carefully to the K @ N advertisement on TV by the president,even he's careful to mention that K @ N filters flow better than "factory equipped paper filters".There's no such thing as a paper filter on boat applications!If you have a decent filter ,it makes no difference in power if you have it on or off.The only reason you have to have it is to arrest flames!Cars encounter fine dust particles that needed to be filtered out,and K @ N does a good job doing it with good flow versa paper filters.The metal flame arresters only need washing occasionally,the K @ N's need to be reoiled with filtercharger [more maintenance],but I think that's unneccesary in boat applications,hence the lack of dust on the water.If you trailer your boat without cover ,you should have a cover for the carb to keep road dirt and dust out.
[This message has been edited by spectras only (edited August 30, 2001).]

GottaHaveIt
09-17-2001, 09:56 PM
Checkmate, I had a '94 Wellcraft 21' bowrider
with the Mercruiser 260HP 350 Magnum. I did
several things to try and get more HP out of
it and the best bang for the buck was a set
of Competition Cams 1.6:1 "roller tip"
rocker arms. The stockers are 1.52:1 ratio;
by replacing them with the 1.6's you in
effect are making the engine perform as if
it has a bigger cam. The overall valve lift
and camshaft duration is icreased. Even the idle went from
a "blub blub blub" to a choppy "rumpity rump"
and I noticed a big improvement in holeshot,
midrange accelleration and a little on the
top end, enough that I could have gone with
a larger prop since after installing the
rockers, I could easily hit the rev limiter
without having to trim the drive way out.
The rockers are easy to change and not real
expensive.
-Chris

GottaHaveIt
09-17-2001, 10:07 PM
OOps..I have done this twice now. I forgot
to click on a "smileyface" icon and got the
frowner..
Here is the link for the part number of the
rocker arms that I described in the previous
post:Part # 1418-16 (http://www.competitioncams.com/catalog/283.html)
Well, I see you have a pre-87 engine which
means you PROBABLY need part # 1416-16. The
'87 and later valvetrain design incorporated
self-aligning rocker arms that were somewhat
different than the earlier ones.
-Chris
[This message has been edited by GottaHaveIt (edited September 17, 2001).]

Checkmate
09-18-2001, 05:55 AM
Thanks, will try this. Did you do anything to the standard flame arrester to increase th e carb. flow rate. I am going to purchase the 454 flame arrester to make certain that I do not have any restrictions.
Regards,

GottaHaveIt
09-18-2001, 09:02 AM
Nope, I used the stock round metal flame
arrestor. It looked like stacked thin metal
disks and if I recall was about 1.5" high.
I don't know what the difference is compared
to the 454 flame arrestor. If it is larger
then go for it!
-Chris

Desert Rat
09-21-2001, 01:45 PM
Would this setup also work on the Merc 5.7 235 horse engine (1992)

GottaHaveIt
09-21-2001, 08:45 PM
Yup, yours is a '92..check the rocker arms
at the tip where they contact the top of the
valve stem. The pre-87 rockers have a flat
face, the latter ones should have a concave
surface that keeps the rocker tip aligned
with the end of the valve stem. The 1.6
Comp rockers will have a roller tip flanked by two washers that are a bit larger
in diameter than the roller that
contacts the valve stem, to maintain valve-
train geometry.

Mirage
09-27-2001, 08:02 PM
I would reccomend cold air induction and a better breathing intake. Cold air direct to the carb made my boat have solid topend speed and cruise much smoother. Cheap too Adapt the 3 or 4 inch flexible tube directly to your vents and turn forward with both holes with the tubes ran to the carb. Make sure your other side of the boat is facing backwards to remove fumes if there is not enough ventilation.