383 stroker valve size ?

[powerplay230]

I had the guide tops and spring pockets machined and new springs installed .I also had the intake and heads gasket matched. What sucks is if i have the valves done i will have damm near as much in these heads as a set of alum heads. Has anybody gone from the smaller valves to the bigger ones and if so what kind of gains did you get

[MOP]

I did the whole thing at once, 383 and big valves! I have great torque through all ranges, a 383 likes to breath. I am running a fairly mild cam, I make a tad over 375hp and about 400lbs torque. Run a 650 for good all around power and 750 for a tiny improvement at WOT.

Phil

[aj1101]

Phil,

Can you share a little information on your setup? I have an 86 Scarb 22' with a 300 horse vortec 5.7 liter crate motor. We have to pull the motor because we are having an oil pressure problem. I am thinking about stroking the engine while it is out but dont know if simply stroking the engine, putting in the bigger valves in the vortec heads and running the factory wet exhaust will be workable/worth the money in terms of the hp/tq gains I might get. If I need to replace the heads and exhaust I dont think I would want to drop that kind of coin on this boat.

Couple of questions:

What kind of exhaust are you running?

Did you replace the heads or the valves and springs?

Could you share some of the specs for your build?

Thanks.

[yikes]

Like AJ says "Can you share a little information on your set up?" What cam are you using? Is it internal or external balanced?
My motors rusted from the outside in so I will be starting from scratch. Planning 4 bolt blocks with aluminum heads and exhaust. Air gap manifold with a holley and MSD.
It's a rare old school boat and I would love to add another 230 HP. It was runnning in the low 60s with prop exhaust and i hope a jump from 520hp to 750hp would put me well into the 70s.
Thanks

[powerplay230]

My block is bored 40 over. Im running a scatt crank and scatt 6'' rods. U get a little more dwell at tdc with the 6'' rods versus the 5.7'' which i was told will make alittle more power plus theres less side force pushing on the pistons which in this build are forged SRP. Im also running summit racing vortec heads 1.94in 1.50ex, vortec rpm air gap intake,edelbrock750 carb , glm alum manifolds and risers,thunderbolt iv ignition and comps xm276hr cam. C/R is 9.35 to 1. I have found out though that this cam is to big for this ex. which is basicly stock as far as were the water enters im getting reversion. I have since talked to crower cams ,told them my problem, they asked questions about my motor and exhaust and are grinding me a cam specifly for my motor and told me if it didnt perform to my liking to send it back and they would fix the problem which i thought was pretty cool

[motorz]

The new Merc 383 400HP SB is using High-Flow Iron heads with 2.08in 1.60ex . The 383 350HP SB is using Gen+ Iron heads with 1.94in 1.50ex.