i just totaly washed my ''330 on roids'' motor out this weekend and threw a rod. now i am getting a 454 385 mag reman long block. my question is can i use my holley 800cfm on the mag motor. i know i have to lean it out alot b/c it was way to rich and killed my 330hp 454. also what would be a intake to use with this carb. i had a air gap on my 330hp and it was pretty good. but i read in books and on here that a 800cfm should only be used on a single plane?

Actually, the bigger carb usually requires more jet because the signal is reduced. How do you know it was rich and thats what hurt your engine?

there was alot of fuel in the engine oil before and after the rod flew apart. i was told the oil was so waterd down with fuel it took out a crank bearing due to poor lubracation and threw the crank out of alignment and broke the rod. this is what i was told. i just want to use my carb b/c with the block going, i really dont have the money for a new carb.

Ok, I hear ya. an 800 can work with a 454, it just needs to be set up right, float level, jetting, idle circuit, PV. if you had that much fuel in the oil and the fuel pump didnt have a blown diaphram, there is something very wrong with the carb

I have a deal for ya, I have a 750CMF marien Q jet that needs nothing, off a 454/ 330hp Mag motor that is to small for my 500 hp 502. I was looking for a 800 or a 850 CMF. Want work something out? E-mail [email protected]

I think it was the fuel pump that dumped the gas in the crankcase. A marine fuel pump isn't supposed to vent to the crankcase. I can't see a carb doing that from being too rich.

An 800 will work fine. I used one off an hp500 on my slightly hopped up 454mag. As was said, it will need more jetting because of the weaker signal. I was about 3-6 jet sizes higher than the stock hp500 jetting. I used a stock magnum intake with a 1" open spacer.

Griff, what did you end up with in jet size.? I have a similar motor i work with right now and need jetting in. I start with pri 74 sek 87 and 6.5 power valve. Factory jet was 72, 87
My idle vaccum is 11-12 hg

the fuel pump is brand new so i never really thought it would be dumping the fuel in there. also after taking the motor apart a piston broke so i think it was more the fact of reving cast internals than fuel. but fuel was def. a prob. my new set up is going to be a really fresh merc 420 bottom end with merlin oval heads. and edelbrock air gap intake with my 800 holley on it. that should work right?

Broken piston did a valve hit a cast piston check the oil several times after you start and run a new engine the 800 is not to big the factory Qjet is 750. Check the float levels power valves guessing start out around 76 & 80 with 5.5 power valves that much fuel sounds like a pump problem the cast internals can go 5000 rpm and 500 or so hp just not long WFO runs.