I'm in the process of installing a '86 carbed 350 into my Formula F-18. I am running the engine on a pallet outside to make sure everything with the engine is ok. when I run the engine with a garden hose hooked up to the raw water inlet hose, the plugs on the even bank are coming out wet. I thought it was bad riser gaskets and replaced those. I did leak down and got about 18% on all the cylinders. To my knowledge the engine was never rebuilt, but it does have a edelbrock intake and carb on it and I can see someone was under the valve covers, so I think the cam was changed. I played around with throttling the garden hose volume and when there is just trickle coming out of the exhaust pipes the even side plugs come out dry. if I turn up the water volume, the even side plugs come out wet. If I turn up the water volume all the way the a couple of the odd side plugs come out wet. I am thinking that the camshaft is causing reversion on the odd side. Has anyone experienced this situation? Short of changing the camshaft (which I don't want to do, I'm putting the boat back together to sell) is there a solution to this?

[ATTACH=CONFIG]526688[/ATTACH]

if you are getting reversion on the garden hose it will be a lot worse in the boat with the sea pump.you have 2 choices,change to a dry exhaust or change the camshaft.

Depending on the grind, advancing the cam could eliminate reversion as well. The first step is figuring out exactly what is in there. If it has a lot of overlap and a tight LSA, it needs to go.

i agree with the cam advance theory but if he has reversion on the garden hose il bet the cam needs to go.

Pressure check the exhaust manifolds first. That may be the problem. There may be a slight crack that is not seen the the naked eye.

A tight LSA is not necessarily the cause of reversion. It is the combination of several valve train timing events. Merc small blocks came with a 109 LSA cam for many configurations without reversion.

That's why I gave it the overlap caveat...

I agree with trash. just cuz you changed riser gaskets doesn't mean manifolds are good. take them off. stand upright. fill manifolds with hose thru bottom hose on manifold till water runs out the risers. look in exhaust ports. see that water dripping down?

i just assumed that the manifolds were pressure checked,i guess i should have not made that assumption.

I vote for exhaust issues.

But, we aren't the ones physically checking it out so...it's up to the person on hand.

Update: I just pressure checked the manifolds with a garden hose (about 40 psi) and did not see any water leaks. I did not pressure check the risers. Is there a way to do that?