350 SBC head question
 

OK, working on deciding what I want to do with my small blocks and I have a couple of different options available. Basic blocks with flat pistons with valve reliefs. stock exhaust for now at least.

One, do I go with the standard mercruiser center bolt heads from the early 90's with a edelbrock performer intake and cam package (flat tappet cam) or

Do I spend extra and get the vortec heads, a roller cam (maybe lt4 or similar) and the performer intake for the vortec heads?

Planning on having my stock carbs checked into by someone recommended on the board here if they will be enough cfm. Any thoughts.

So, how much power do people think each package will produce? Wondering if the extra coin is worth it on the vortec and roller cam package. Really curious what the different power levels might be.

Thank you,
brian

The Vortec heads are a nice upgrade for the money. Since you're buying an intake manifold anyways, just order one for Vortec heads. I would suggest a roller cam if you have the correct block. There are a few good roller cams for marine 350 SBC engines that work well in thier respective RPM ranges. The LT4 Hotcam seems to work well, the TPIS ZZ9 also works good on a 114 LSA. I've used both several times. I have been trying to use Roller Cams as much as possible since the oil offered off the self doesn't have any Zinc/phosphate additive package for flat tappet cams. A 350 with 9:1 compression and Vortec heads, Edelbrock intake, LT4 Hot Cam will make 330 HP and 365 ft lbs through the marine manifolds. The ZZ9 on a 114 Will generally make the same HP number but have a higher average torque number ( more torque from 2500-4000 RPM) Vortec heads are relatively cheap and you can probably find a roller block for $200-$350 as a basis for the build. A roller cam will also keep oil temps lower, make a little more power, benefit from better cam lobe designs, and no worries about correct break-in period.

yeah what he said vortecs great bang for the buck but also remember you need an electric choke on the carb no exhaust cross over

Brian,
One thing to keep in mind with the Vortec heads is that they are going to bump the compression ratio up to around 9.5 to 1 if you have true flat top pistons with 4 valve reliefs. That is going to require 93 octane fuel.

I would second the roller cams if you have the right blocks.

If the carbs are Quadrajets, they will have plenty of airflow capacity, but they will need to be rejetted and have different secondary metering rods for the additional power.

Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md