Best 40hp big bore kit?

[Connorwaddell]

My original 63 40hp has barely any compression because of worn out rings and I was thinking of just going to a big bore kit but I’m not sure which kit to get. What kit have you all had luck with? Thanks!

[anthracitedub]

I think there is some discussion over in the vintage speed section... most people are going with the AA offerings. Like most parts, always check fitment... people have found minor clearance issues with the piston skirts.

Also, I would recommend reconditioning the cylinder heads while you have it tore down... it’s likely they need refreshed.

[Eric&Barb]

If the main bearings are well worn, most likely they will give out all too soon when you put the extra pressure of new P&Cs in.
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In Stereo, Where Available!

[KTPhil]

If you are rebuilding, consider adding a doghouse fan/shroud/cooler kit. Original parts are best. I did this on my 1200/1384 conversion, and it really made a huge difference in cooling, and general running when warmed up. It is pretty much a bolt-in setup if you have all the pieces. Otherwise a 1384 can run too hot in traffic or on the freeway.