OK, I'm actually chipping away (port work finally) through the heads. Nothing fancy, just small DIY stuff while following the MP W2 porting templates. Compared to a couple of factory iron ('596 castings) that I fully ported in the past, these are a joy, the ports are already fairly large and the templates do not require much material removeal (raltively speaking). It's still messy work and it takes much time regardless...but I love this part of the hobby, so no objections!

The question I have is regarding what to do about the missmatch on the exhaust port.

So I'm tossing the TTI headers on this stroker - 1-7/8" primary pipe (340BEW2-17835C0). The TTIs have large (to me anyways) square openings in the flange and when compared against the W2 ports they are significantly larger.

How large/different you ask?

Here are a few pics:







The markings you see in pics are as follows:

1) THIN black lines are the outlines of the TTI header gasket

2) THICK black lines are the outlines of the Mr.Gasket #5939 gasket

Based on what I understand about exhaust port matching: it is not necessary to match, in fact, some say it is actually better for the head port opening to be smaller (thus creating a lip) than the flange port so as to prevent some of the exhaust reversion from taking place, or at least minimizing it.

The differences between the two gaskets are significant and from a DIY perspective I do not have the means to "hog out" the exhaust port WHILE at the same time understanding the impact of the changes I'm making (no flowbench lol).

So should I just leave it alone and be done with it?

Thanks, as always!

Leave the exhaust port alone. It’s way too big already.

Make sure the header flange openings are larger (1/8 inch +) than the exhaust ports are
The exhaust is under pressure when the valves open, so you do NOT want any interference between the head port and the end of the collector for max power

OK, thanks guys!

I suspected I was already on the bigger side and really didn't want to touch anything else there. Will leave in as-is configuration.

You can go in there and get the throat sized and the short turn cleaned up. Just don’t make it bigger. My next W2 build I’m going to spend some time and see if I can fit a 1.500 valve in there. If I can’t go that small I’ll go as small as I can that isn’t 1.600 as that valve is pretty big too.