I think I will look into the fuel pump. I think what you're saying is very possible. I see a lot of people just add the electric pump to the current mechanical pump. I wonder if that's a better idea or not. Might give you a false sense of security, because if the electric pump fails, the engine continues to run, but with not enough fuel pressure therefore destroying the engine again.


Griff,

I seriously don't think an 800 cfm carb is going to do me any good. From what my engine guy said, the carbs I have are plenty for the cu. in. I have. I've seen some calculators at the Holley web site, and they say the same thing. Am I missing something?

Yeah... I like the Victor Jr. I've heard of people adding the bosses to the rear water jackets on the intake. Have you ever seen that done to the Victor Jr.?

Also, how crucial is port matching? What's the recommended and realistic tolerance?

Griff is right. The smallest you should have on that engine is a 750cfm carb. 800cfm would be better. TThe cfm of a marine carb should be about 130% of the calculated required cfm for an auto application. I bet you engine guy is a car guy.

The best you could do on an intake is to find an oval port to speed up the velocity of your mix. There are oval ports that work with rect port heads. I believe holley made one. If not and if you are interested I have a couple near new dart single planes I would sell pretty cheap.

BT

I'd also go with the 800cfm .My little 351 in my ski boat ,runs a 600cfm holley. Boat engines love big carbs. As for the port matching, no reason not to. It only costs you some time with the dremill.


Darrell.

The calculation for CFM versus CI is based on perfection. The theory is if your engine burns a fuel and air mix at 100% efficiency, you would need a directly correlated ratio akin to the engine's ability to take in the mixture which is governed by it's displacement. So, in theory, if you had a volumetrically perfect and sealed 454 Ci for example, which had the capacity to ingest (for want of a better term) approximately 600cfm of air / fuel per stroke, the engine would then burn the mixture and discharge the expended gasses with no margin for loss or unburnt fuel mix out the exhaust. This is not the case and as a result, an engine must take in greater than it's capacity to ingest so as to ensure sufficient volume ratios. Your engine with 600cfm in the equivalent of trying to drink a super-sized slurpee through a coffee stirrer stick. You engine cannot supply enough oxygen and I doubt your carb could even be jetted big enough to feed those heads in the first place without massive throttle cams that would flood your engine at idle.

I'd recommend the BG Demon because I have one, but any Holley DP Marine above 750cfm (I'd start at 850 with those heads if I were you) will do you much more justice than your Pinto carbs you run now!

I once ran a 2.8l V6 race car on a 750cfm if that gives you an indication.

Good Luck!

A stock 454 Mag uses a 750cfm carb
A stock HP500 uses a 800cfm carb
A stock 350mag uses a 600cfm carb

You need more carb on a marine engine than a car engine to make maximum hp.

What he said!

OK. Time to clear the air.

I was a little upset this weekend because of the above comments about the carbs, and the thought that my engine guy said my carbs are fine. He's supposed to be one of the best. Yes, he's a car guy (IHRA Pro-Mod Champion) http://www.jancen.com/racingteam.htm
But, being in the business for so many years, he's done lots of boats.
Well turns out, I gave out some bad information.
My carbs are 4160 (not 4150) Holley Vacuum Secondaries. Mike said, they are big enough in a voice that suggested bigger wouldn't hurt, but probably wouldn't do me any good. Probably because they are 4160's p/n 9015 Marine, with modified secondary plate for adjustable jetting. That's 750 cfm and the jets have been changed and tuned for this motor.
Which brings me to my second problem... heads. My Canfield heads are being replaced because of a broke off INTAKE valve. None of the valves show signs of burn issue, and the broke one doesn't look like it was a result of poor jetting (running lean). Does anyone have a pic of a valve that was a result of running lean? I will post a pic of my broken valve soon, but I am wondering if it's a defective balve... btw they are Ferea valves.

So Brodix is my first choice, Victor Jr. is my second choice. Now does anybody have a pair of intakes they would like to part ways with?

Also want to point out that a pair of Team G intakes would be desirable too.