JCCRAZY

I AM WORKING ON A 385 HP 454 / FORMERLY KNOWN AS A 7.4 MAG MPI I BELIEVE. USING THIS LONG BLOCK, 8.6 COMPRESSION AND STOCK HEADS I HAVE ADDED A 750 CFM CARB, EMI EXHAUST, WEIAND STEALTH MANIFOLD AND THE INFAMOUS CRANE "731" CAMSHAFT. I AM PLANNING ON DOING SOME GASKET MATCH PORTING TO THE HEADS AND UNFORTUNATELY AM OUT OF CASH TO DYNO THE RESULTS AND TWEEK THE PROJECT. I SEEK TO GET SOMEWHERE IN THE 450 HP NEIGHBORHOOD AND CRANE TELLS ME I SHOULD SEE THAT WITH THE COMBO. IF SOMEONE COULD RUN THE #'S ON THE DESK TOP OR IF YOU HAVE A SIMILAR COMBO WHAT HAVE YOU SEEN AS A RESULT. ANY INPUT IS APPRECIATED.

rpm

Don't have the program, but experience says 400 to 425 HP Max @ 5400 and if you don't have the long SS risers for those manifolds its going to suck water.

Rod

JCCRAZY

I UNDERSTAND WATER INVERSION IS CAUSED BY VALVE SCAVENGING OR VALVE OVERLAP; THE 713 CAM HAS A 112 LOBE SEPERATION, THE SAME AS THE FACTORY OR CLOSE SO WHY WOULD SUCH OVERLAP BE A CAUSE FOR INVERSION. I GUESS I CAN CALL BACK EMI AND FIND OUT WHAT THEY HAVE TO SAY.

seahawk

if you don't have stainless risers EMI will revert water.
it happened to now i got CMI no water reversion

JCCRAZY

I CALLED EMI AND YOU ARE CORRECT, THEY NOW TELL ME ANYTHING OVER A 230 DURATION MAY HAVE A PROBLEM. GREAT NEWS AFTER THE FACT --- SO I GUESS THAT'S MORE MONEY TO THE PROJECT FOR THE STAINLESS RISERS. I DON'T THINK THE IMPROVEMENTS ARE GOING TO BE EFFECTIVE WITH A CAM WITH THAT SHORT OF DURATION.

JCCRAZY

I CALLED EMI AND YOU ARE CORRECT, THEY NOW TELL ME ANYTHING OVER A 230 DURATION MAY HAVE A PROBLEM. GREAT NEWS AFTER THE FACT --- SO I GUESS THAT'S MORE MONEY TO THE PROJECT FOR THE STAINLESS RISERS. I DON'T THINK THE IMPROVEMENTS ARE GOING TO BE EFFECTIVE WITH A CAM WITH THAT SHORT OF DURATION.

olysan

Please stop yelling.

Griff

Boost your compression ratio up to 9-9.25 to add some more HP. Sounds pretty low for N/A. Stock is 8.75. You could mill the heads .030 and get it up to 8.9. or better yet leave the CR alone and supercharge it.

seahawk

sell the EMI $800.00 each and buy CMI from Jones Marine for $1750.00 each its only a $100.00 or so more and much better.

By the time you fix those EMI thay will have cost the same as CMI and you will still have the problam of the gaskets between riser and manifold.

$800.00 + $900.00 = $100.00 = $1800.00 = CMI no gaskets more HP

$1150.00 + $900.00 = $2050.00 = EMI w/ gaskets

Keith

Typing in all CAPS indicates yelling, and it's hard to read.

Good luck with the project.