Cast or aluminum heads......?

Heys guys,

So heres what i got, stock 350 chevy with edelbrock manifold and carb in a heavy ass schiada( i know a small block in a schiada! :eek ) with a outdrive. Im looking to do some upgrades to the motor to get some more juice out of it. Nothing crazy but im thinking heads, and cam. so my question is would i really benifit from aluminum heads or should i stay with cast? I found a set of reworked stock heads with 64cc chambers, big valves and 170cc runners, whats your thoughts? how does runner size benefit performance? Also what are some cam recomandations. I will be running stock center rise thru transom exhaust. Is it possible to get 350hp out of a stock bottom end with just bolt ons? :rolleyes

Thanks for the help
Dan

dano214 said:

Heys guys,

So heres what i got, stock 350 chevy with edelbrock manifold and carb in a heavy ass schiada( i know a small block in a schiada! :eek ) with a outdrive. Im looking to do some upgrades to the motor to get some more juice out of it. Nothing crazy but im thinking heads, and cam. so my question is would i really benifit from aluminum heads or should i stay with cast? I found a set of reworked stock heads with 64cc chambers, big valves and 170cc runners, whats your thoughts? how does runner size benefit performance? Also what are some cam recomandations. I will be running stock center rise thru transom exhaust. Is it possible to get 350hp out of a stock bottom end with just bolt ons? :rolleyes

Thanks for the help
Dan

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What RPM are you currently able to run? Next question is which drive is on the boat? With the heavy boat and small engine, you end up needing to match power to prop.

There is probably no real advantage to aluminum head on your current bottom end. Besides the obvious weight advantage offered by aluminum heads, they are easier to repair if damaged, and may give a little more "cushion" against detonation if you are running something with more performance. Larger runner is usually necessary for higher RPM. An example is a dirt track racing engine that I build for a guy may use a 200 cc runner, since it needs to turn 7000 RPM.

Just changing the heads may not net much change, but will probably increase compression, depending on what's on there now. It would probably be beneficial to upgrade the cam at the same time.

Barry,
currently its spining a custom Ron Hill 4 blade 14 1/2 X 21 to about 45-4600 max and is running about 47-48mph on gps. It has a volvo 280 drive on it, which i hate but just don't have 10k to do the up grade. Im just trying to get it to run in the mid 50's if possible for now and then im going to save my pennys and hopefully upgrade it later to a big block and a bravo drive. Ive toy'd with selling it and buy something else but i really like the boat it just not fast enough. I plan on doing a cam and rockers at the same time. Do you have any suggestion on a cam?

Thanks

dano214 said:

Do you have any suggestion on a cam?

Thanks

Click to expand...

Yes, I can have my guy grind something up for you, PM for phone number. His custom grinds don't cost any more than one off the shelf.

dano214 said:

Heys guys,

So heres what i got, stock 350 chevy with edelbrock manifold and carb in a heavy ass schiada( i know a small block in a schiada! :eek ) with a outdrive. Im looking to do some upgrades to the motor to get some more juice out of it. Nothing crazy but im thinking heads, and cam. so my question is would i really benifit from aluminum heads or should i stay with cast? I found a set of reworked stock heads with 64cc chambers, big valves and 170cc runners, whats your thoughts? how does runner size benefit performance? Also what are some cam recomandations. I will be running stock center rise thru transom exhaust. Is it possible to get 350hp out of a stock bottom end with just bolt ons? :rolleyes

Thanks for the help
Dan

Click to expand...

I believe you can get into the 55+ mph range with cam and heads. Stroking would help a lot, but that is more invasive. If you are upping the compression the aluminum will buy you perhaps 1.0 point of tolerance. I'd keep it iron in you situation.

When you say you have some stock reworked heads, which heads are you referring too? Vortec or something else? If it is a Vortec head it has a different intake bolt pattern than the previous generation heads so you may have to change the intake manifold. If it is not a Vortec head and the previous generation stock head I'd either get a Vortec head or a quality cast aftermarket head. Dart and AFR in my opinion are good products, but AFR is predominately aluminum.

What do you mean by big valves? The traditional 2.02 / 1/60 or ??? Make sure the bigger valves aren't shrouded in the chamber.

170-190 cc runners will work good for a 350 cid class motor. Like Barry said, if you spin a lot of rpm and/or have a 400" plus small block bigger runners might be of use. Too big a runner can soften bottom end response due to slower intake charge and less cylinder filling. Typically torque is down a little, which is NOT what you want in our typical marine engine.

There are lots of cam choices. It can be overwhelming. I am a big, big fan of hydraulic rollers. They can achieve much more in ramp rates and profiles that traditional cams in my estimation. Lunati, Crower, Comp Cams etc. have good choices. As Barry also states getting a custom grind is not any costlier should you decide to go that route. Bob Madera at Marine Kinetics is real sharp on marine cams and heads. He's worth talking too.

Your stock exhaust, preferably with through hull will be fine with up to moderately aggressive cams. If you plan on running the exhaust through the prop your breathing, and hence cam selection, will be limited.

I've got a block, oil pan, crank and Vortec heads lying around if you are interested. Shameless spam, I know......

Trash,
The stock heads I found were a stock casting non-vortch head, not sure on the casting numbers but they were rebuilt 170cc runners with 2.02in and 1.60ex. They weren't camel hump heads I'm thinking they had them opened up. I've also looked at the pro comp aluminums, I've heard goods and bads on them but the price is good. I've been eye balling the stuff you have for sale, pm your bottom price for it all.

As for cam i don't need to get all radical with it i just want it to perform well and sound good.
Thanks for all your guys help
Dan

dano214 said:

Trash,
The stock heads I found were a stock casting non-vortch head, not sure on the casting numbers but they were rebuilt 170cc runners with 2.02in and 1.60ex. They weren't camel hump heads I'm thinking they had them opened up. I've also looked at the pro comp aluminums, I've heard goods and bads on them but the price is good. I've been eye balling the stuff you have for sale, pm your bottom price for it all.

As for cam i don't need to get all radical with it i just want it to perform well and sound good.
Thanks for all your guys help
Dan

Click to expand...

PM in progress.