carbs & intakes

[madison]

Hey, thanks for all of the feedback on torque shift props
everyone,.......I went with a quicksilver s/s and am pleased
with the results. Now I'm looking to up my HP...I have a 4.3
V6 mercruiser, with the two barrel carb and cast iron intake.
I'd like to source out a kit with all the goodies to convert to
a four barrel carb: alluminum higher flow intake, carb (holley
?) and any additional hardware required. Any ideas where
one might find these goodies? (Mercury Marine wants nothing
to do with conversions & Holley shows no marine applications
on their website.

[Liqui-Fly]

You could get into a 305 or 350 for much less than modifying that 4.3. LF

[Raceman]

Edlebrock ought to have a complete component kit that should scratch your itch. Why don't you call their tech line and get some help from them? Changing to a small block V8 will require manifolds (expensive) and some other hardware that'll run your cost up. If you decide to spec it yourself, just remember it's not a car engine and the needs are different. Incidentally, Crane has a boat guy in their tech department also that can help with marine camshaft advice. Be prepared to tell any of them what you expect from it, meaning RPM range, if strong low end is preferred (skiing frequently?), what kind of gas you're willing to buy, etc., etc.

[Markus]

Check with the folks over at www.offshoreonly.com. There are a lot of modified Mercruisers over there, although I would assume not too many V6s.

[W. Tripp]

A couple of years back, a friend decided to modify the 4.3L in his family ski boat instead of replacing it with a small block V8. We used the Edelbrock carbed manifold and a 500 cfm Edelbrock 4v carb with the Performer camshaft kit. We then cleaned up the bowls in the head, and cut the valves and seats for 5 angle valve job - plus a 30 degree back cut on the valves. The exhaust manifold entry was matched to the gasket 3/4 inch deep - NOT the head. The head was then cut to give TRUE 9.1:1 compression.

I have flow bench, and this gave us a 20% increase in static flow. In the end, we gained more low end torque for skiing, more mpg, and more rpm with a bigger prop for more mph. This is still not a V8, but my friend is extreemly happy with the engine combination.

The latest 4.3 I have built is in a low 10 second Syclone truck- but that is not related to boating. I hope this helps.

[madison]

Hello Wayne, I've just installed an edelbrock 2111
intake manifold, a 1409 600cfm carb & a 9X2/34" K&N spark arrestor on my 1991 merc. 4.3L V6. It has a little bit more power
but I am definitely not satisfied. Edelbrock recommends this carb
because it's the smallest one that is coast gaurd approved. But in
my opinion, it's way too much carb for a 4.3L. Which part# did your friend use? Was it #1404? I've been told by a few different
parties that I would be better off using a Holly carb because of the vacuum secondaries which offer better low to mid range torque for planing/waterskiing etc. Holly does offer a 450cfm four
barrel. What do you think?

[captcarb]

They are different from the auto carbs, and more expensive. Holley does not sell the parts to convert an auto carb to marine.

They have J-tubes on the bowl vents (whistles) and different seals on the throttle shafts.

They have different model numbers stamped in the body also which the insurance adjusters are very familiar with if you have a fire.

Jim

[JFN]

Holley does have a marine catalog. I have a 99 cat and the part no. is L30608. They list any thing from a 300 cfm to 1250 cfm carbs. Blowers, fuel injection and cams and manifolds, etc. Pretty good catalog. Phone no. 502-782-2900.
One item I found that works well for me was a K-N stub stack. If your running a holley you should have one. Best product for the buck, two or four barrel. I installed it in one of K-N's new 14" marine spark arresters.