Curious about crankshaft how are made and getting strokers.

[Jonroberts]

I have read a forum with modular engines and different strokes , having 3.543 stroke a 3.650 stroke and 3.661 , 3.650 , 3.750 and 3.800. To make strokers ? What I really want would be a 3.661 stroke with a 3.629 bore .. In a bore / stroke calculator it comes to the best beeing 302 point Something cant really remember right off my head. Compared to the others on Wikipedia/ modular engines and bores / strokes listing...? Are these crankshafts milled to the spec?

 

[01yellercobra]

That was kind of a tough read. But I think I know what you're asking.

The stock crank has a 3.55" stroke. In the early days companies would offset grind the rod journal to increase the stroke. That's how the one I have was done. It's a 3.75" stroke. But it requires a different set of rods. In my case it's a Chevy small block rod with a 2" journal. They all require different rods as the rod length changes from stock. But that's what I ended up with.

Nowadays the cranks are cast or forged to the needed stroke. So something like a Manley crank is forged to the 3.80" stroke.

You're not going to find a stock mod motor with a 3.66" bore. Not without sleeves at least. The big bore blocks are 3.75". The same goes for the crank. Unless you get something custom, but that's $$$$.

There are a couple ways to get a 302. You can run a stroker crank in a stock block and get there. Or find a big bore block and run a stock stroke crank.

My personal preference is a big bore block with a stroker crank for 323-326 cubic inches.