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CJ7 4.2L Stroker Question

Posted: May 4th, 2025, 7:34 pm
by oldjeepguy
I just found this board. I'm interested in turning my 4.2L in my 1979 CJ7 into a stroker for more torque and horsepower. Can someone point me to a place where I can get started gathering information? I'm mainly interested in torque/HP for various configs, sample parts list, etc. Just trying to assess the magnitude of such a project right now.
I have experience rebuilding engines, albeit older ones such as Model A, mini-truck, etc.
thanks for any help!

Re: CJ7 4.2L Stroker Question

Posted: May 5th, 2025, 5:10 am
by amcinstaller
For these strokers, you would tear down your 4.2, save the crank, and use it in a newer 4.0 to make a 4.5-5.0, depending on budget. Build threads here or Dino's site in the faq section will have some base info for you

Re: CJ7 4.2L Stroker Question

Posted: May 5th, 2025, 5:40 am
by oldjeepguy
Looking at the Golen site, it looks like they make a stroker from the 4.2 block. Is that something that anyone here has done?

Re: CJ7 4.2L Stroker Question

Posted: May 5th, 2025, 4:18 pm
by amcinstaller
I'm not aware of any *stock jeep/amc* crankshafts with a longer stroke than the 4.2? A 4.0 head swap to the 4.2 block is also fairly common, but your bores will still be small.

I'm also not familiar with the off the shelf kits. They could be selling a custom crank

Re: CJ7 4.2L Stroker Question

Posted: May 5th, 2025, 9:04 pm
by Cheromaniac
There used to be a stroker kit for the 4.2 but I don't know if it still exists. It's much more preferable to start with the larger 3.875" cylinder bore of a 4.0 block, and there's no shortage of those in junkyards since the engine enjoyed a 20-year production run.