Thread: 4.2l stroker crank into 3.9l?

Hmm, dunno if I know what I'm on about, but the people I've gathered all my info from seem too.

I've no idea what the comp ratio will be, but it would have to be higher than stock with the machined heads for one. Is the comp ratio difference in the engines purely due to different pistons? Regarding the heads, now you've got me nervous - I had a few sets of heads, and I know one set were ERC0216, though I can't remember which ones are getting reco'd! I hope it was that set.

Loanrangie - I wasn't sure about the effectiveness of the Edelbrock manifold with gas anyway, so was just gonna see how it went. It's a 4 barrel and I was going to fabricate an adapter by cutting off the upper part of a stock carby manifold and welding it to some plate aluminium. I've heard the gas rings work well with carbs and haven't come up with any other bright ideas, though what you suggested definitely makes sense. Maybe it's better to just use a stock manifold? Would certainly be simpler.

Thanks for the info guys, it's incredibly helpful and I feel a lot more confident in the direction I'm going with the whole rebuild.

BUT all 4.0, 4.6 short motors are backward compatable.
Ie you can hang your 3.5, 3.9 heads, rockers, oil pump, timing chest, oil pickup, flywheel, sump, etc etc on it and it will go.
Only needs a small spacer on the longer crank. Oh and a dowel ground off the back of the crankshaft
Just thought I would clear that up.
regards Philip A