To much timing, not enough octane, 7psi of boost = blown head gasket, damaged block and head between cyl 4&6. All my fault
and now it's time to move on

I currently have an all forged 383 short block under construction. I used up most of my budget on the 4 bolt block, Eagle rotating assy w\JE pistons. Can you guys recommend some cyl head options? I will be keeping the Vortec intake with the MPI. I'm not sure if I will be changing the cam yet but would like some opinions there also.

My 22.5' Crownline ran just over 70 gps before my mistake and I'm not looking for a lot more speed. But what self respecting hp junkie wouldn't take this opportunity to pick up a mph or 5

Tom,
I have wondered the same thing, what heads could be swapped in and still use the factiory MPI. Keep me posted what you find. I am on my second season so far with the twin 350 mpi pro-charger setep, however I am running 5 psi and stock timing. I have the set and forget it setup and it "seems" bulletproof at this point. Did you make the crownline run at cumberland a couple weeks ago or were your already broke?


You may want to contact Steve ([email protected]) I think he built a couple 383's and used the stock injection as well. Mark at Percision did the dyno work and programmed his ecm's.

Brian

That's where I broke it (Cumberland Crownline Rally). I bumped the timing up for the radar run and forgot to bring it back. Got gas the next day, asked to $100 of premium. After cleaning up the boat I when back to the pump to find he wasn't pumping premium. I stopped him at $60 and finished with the good stuff. I would have been fine if I had brought the timing back down but....BRAIN FART. Anyway I did get about 130 hours out of that set up so I'm not to . I would have preferred this to happen at the end of the season though.

I may just put a set of stock Vortec heads back on for now until I can spring for some good aluminum ones. Anyone have any?

How much more timing were you running? Were you ok with 7psi with stock timing? I still have the original 5 psi pulley on mine. Is that what are motors have now, Vortec heads?

I had bumped the base timing to 10* (my ecu takes out 1*of timing for every # of boost), stock is 8. I had run the 7psi pulley for about 20 hrs with no problem. I do drive the boat very hard. The 350 Mag MPI does have Vortec heads.

Looks like there are two choices in Aluminum, GM performance parts and Edlebrock makes a set as well. GM performance also has a cheap set of cast irons that may even work better then what we have.

Go with aluminum heads to lower combustion temps. Don't bother with any port work on the intake side. Make sure to open up the exhaust side huge so that you have around 80% intake to exhaust ratio. Then you will make some power as long as you have a good exhaust system.

The GM Fast Burns (aluminum)should surely add much more muscle to these engines.

GM also makes a small port and large port Bowtie Vortec cast iron head.

So........there are good choices/alternatives out there. Just make sure to get it reprogrammed when making these changes. Live (vs phone) is always better !

GM. Fastburn heads are angled plugs, may be an issue with your exhaust. The Edelbrock E-tech heads are straight plug, but are 64cc just like the Fastburn heads. What JE pistons are you using?

I'm not sure exactly what piston my builder is using he just recommended the JE for my combo. I'm sure they are dished, just not sure how much. I have the Revolution Marine manifolds.