Onthewater_

Hey guys I have a 96 advantage 21srbr with stepped hall 350 mag that I've been doing some upgrades to i'm trying to figure out if this is a pretty good set up or if there's anything I should change so far I put a new cam in the boat and it really woke it up it's the compcam x4270hr The next thing I was going to buy or promax 180cc 64cc combustion chamber aluminum heads with the Edelbrock performer intake manifold and Edelbrock carburetor 600cfm and GLM exhaust The only thing I'm not sure about is to use 1.5 rocker arms or 1.6 I ran the set up on comp cams Cam quest and it is projecting 500 hp @ 6000 RPMs and 480tq @ 4500 rpm's

What do you guys think
Don't really want to go to the big block

SB

iTrader: (1)

To spit out 500hp on that build that program is about 125hp high. Seriously.
Must be a west coast dyno program.
Edelbrock RPM or Air Gap RPM intake
Consider a 650 or so Holley. But, what ever is easier to tune for you.
If you meant to type XM270HR, that has worked real well.

The above has been a favorite for many SBC I/O users.

SB

iTrader: (1)

Oh wait. Your current engine already has vortec heads on it right ? And what do you currently have for induction ?

Onthewater_

The current engine is completely stock except for the cam. Edelbrock carburetor 600cfm
The cams that I put in is the xtreme 4x4 270 HR
1500 to 5500
Duration intake 270 exh 274
Duration @.050 intake 220 exh 224
Valve lift intake .474 exh .474
Lobe separation 111

Current heads stock
Current intake manifold Stock 350 mag intake
Current exhaust stock

dereknkathy

OK, the GLM exhaust is a little better than the stock merc exhaust, but extending the rises with that cam might be a good idea. You are flirting with water reversion with that cam and stock style exhaust. Or upgrade the exhaust. Stock mercs run out of breath at 350 to 400 hp max.

Trash

GLMs might help a little, but I doubt it would be noticeable. Having said that I run those manifolds.

I would only use 1.6 rockers IF the heads flow better at the higher lift AND piston to valve is not an issue.

Are you running Vortec heads? I know SB queried in that regard but you merely answered stock.

I will back SB in that there is not way that combo will be anywhere near 500 hp.

Onthewater_

The heads I plan on buying are
AFR eliminator heads180cc 64cc $1475 or
promaxx 183cc 64cc for the price $875 a pair
Both are vortec style aluminum heads

NHGuy

I'd recommend the AFR or some Dart heads. Also since you plan to rev it way up, get more CFM in your carb, like 750. And port match the intake.
If you can spend the time and money, replace the pistons with something that will give you correct quench. The oe pistons have a poor shape for it.
Compression ratio should not go too high either. Try to stay 9.6 or 9.9 and you won't be as likely to detonate it.