Evinrude 31.8ci Mod Advice

[Emustard]

Where would you find a non rev limiter powerpack for this engine? Because I think your right, that it won't rev past 6200.
We did not get a base line reading before, might have to get a stock tuner to test with. If we have a chance we will test blocking the relief holes in the tuner. I think we might buy a jack plate in the next week or two. And as you were saying we want a speed prop with one person in the boat so maybe are best bet is the 16pitch over hub cleaver from Ron Hill what do you think? Are his props good? Is there any body else that makes a prop like that? We are running pump has premium and 50-1 oil ratio.

[smitherik33]

Has anyone on here ever fabricated a V block reed set-up for the 31.8ci?

[JohnsonM50]

Has anyone on here ever fabricated a V block reed set-up for the 31.8ci?

I have had a V block in one hand & a crank case in the other, looking at the possibilities & intend to do it. I know serious gain can be found there from a failed reed experiment. bending the dampers out too far will result in a broken reed however till then I had the best result I've seen since putting a gear case & prop on. It's there for the taking but the shapes don't cooperate. I think the answer lies in an extended intake but that will increase crank case volume which could result in loss velocity -defeating the purpose.

[Arltralite111]

Here are a couple of heads I have. The top heade is from a 1982 30hp. The bottom is from a 1988 30hp.
When I started with the 1982 head, I got 115psi compression. The other head had 120psi compression. After planing the 1982 head and making room for the piston, I got 165psi. I got 155psi out of the 1988 head. Another mod I did to the 1988 head was blocking the water off from going on to the exhaust. The epoxy can be seen in the lower water passage.
I put 4 tubes in the water jacket cover to dump the water overboard.

[smitherik33]

Good evening. I have recently acquired a 1982 head as well. I'm wondering if I'll gain any compression just by simply by bolting it on. Did you use a certain head gasket? I've heard of a thinner version but can't find one.