i have another topic on here that relates to my cam selection but i want to know some of your opinions on the combo i am looking at. the engine is as follows

99 454 "vortec" low hour block and heads from a mpi non mag motor
carter/edelbrock 750 carb
edelbrock performer intake
gil/merc stainless exhaust
crane 731 cam
maybe add roller rockers?
adding new screw in studs to make valvetrain adjustable
springs if i need them
thunderbolt igntion but upgrading to a msd or similar later

i know my engine is not forged but after dumping as much into the boat this year i have to work with what i got here and i am not going for a 80mph boat or anything, i want something decent though. anyone have thoughts on a top speed maybe with this combo in a 89 baja 250 es running a 23 pitch prop? is there anything that i have chose that might not fit the combo? i am thinking a different carb might be coming later also.

That looks similar to what a lot of guys here run. Exept for the internals on that engine are cast not forged. You could bore & stroke it to a 489 or 496 with forged crank, rods and pistons. Those heads should be large ovals with small chambers (good for flat top pistons). However the heads do have small valves. I did a port job and installed larger 2.19/1.88 valves in my large oval heads. Call RMbuilder for your cam, lifter, spring setup. Good Luck!!

65 to 68 mph

i would be happy to be in he mid to upper 60s! so does everyone agree that this will be a decent setp to run for awhile. i think i will swap out the internals to forged next spring and maybe do some head work. i am not sure how many people have been paying attention to what i have been doing but between transom, stringers, floors, all ne interior, wiing and a new motor funds are running low lol. i have everything besides the stuff for the heads right now. thanks for the replies

Dont get your hopes up to high. When I started I had a stock 330HP with 21P prop at 55MPH. Every time I chaged somthing I only gained a couple MPH. If you leave it a 454 and just do the cam, exhaust, manifold and carb. That cam you are looking at will need forged internals to reach peak RPM. You might be looking at 61/62 GPS. Of course on the "Drunk Guy" speedo that would be 70. Take your speedo that reads 3 mph too fast then add a few more for fun.

Your intake manifold will be a problem. You need to flow alot to get the vortec heads working. I'm not a big fan of the Carter Edelbrock carb either for flow (cfm). Too much turbulence. I run the same motor, 0.060" over with fly cut dome tops, cut heads to match, slight port and flow work with a Victor Jnr manifold. I was going to run a Performer RPM Air Gap, but I found the Victor first! I also run a BG Demon.

With your exhaust (Gil / Risers) you really need to work on steady flow. A better intake manifold (high rise dual plane) would help and you can't beat the RPM Air Gap apparently. You'll also need a good electric pump, I wouldn't run one of those combo fuel / raw water jobbies if you paid me. Try an Aeromotive SS Marine or the Holley Blue pump and a Holley or BG Regulator (for either pump) and you'll be fine.

The 731 cam is good for your combo, RMBuilder could do better of course, but if you're looking for a simple no bull solution now, stick with the 731. Change the intake and upgrade the carb, make sure you use the 4 hole 1 inch (min) spacer on top too!

Oh and for what it's worth, I would also avoid the MSD 6M if you could. The TB IV is good enough if you upgrade the coil to a Blaster 3 or similar with good (MSD 8.5mm) wires. Your motor will be bullet proof!

Good luck mate, let us know how you go!

thats good that you mantion the intake now, thats one of the things i have not ordered yet. i didnt metion it but i am also gettting the holley blue fue pump and regulator. i agree that the carter wont vut it for long but i got a super deal on it rebuilt and it will do me alright until the wallet recovers from all of the other stuff. this makes me feel pretty confident about the combo, it works with what i have and i think it will leave from for improvements over time.

1. You are going to upgrade and thinking of not doing roller rockers.

2. I really do not see a problem with not having a forged bottom in this application, you are going to be well under 500 HP and their were quite allot of builds done on 454's that have cast bottoms that are under 500 HP if you do a search. (I am no expert just an opinion)

3. Speed prediction......a true 63mph GPS

- I like you cam selection
- Intake I like the Weiand Stealth
- Electric fuel pump as stated earlier
- Do not know much about your heads

JMO

I have a great deal on the perfect cam for what you have. here ar the spec's
MERCRUISER 454 502 MAGNUM ROLLER
MERCRUISER # 431-850478 / GM#12551622
.004 300*/ 300*
.006 288*/288*
.050” 224*/224*
.200” 125*/125*
Lift .483”/. 483”
ICL 109*
LSA 115.5*

http://cgi.ebay.com/ebaymotors/454-5...1%7C240%3A1318

Good cam, not as much lift as the 731 with a bit more LSA and less duration.

With the smaller valves on the Vortec's you need lift ( ~ .530 - .600") so I'd stick with the 731 if you want the best power for your combo.

Not trying to cut you off Rock, just my 2 cents (for what little it's worth with the exchange rate and all...)