4.0/4.6 swap in a CJ7

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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Posts: 2
Joined: February 17th, 2019, 4:55 pm
Stroker Displacement: 4.6
Vehicle Year: 1985
Vehicle Make: Jeep
Vehicle Model: Cj7

4.0/4.6 swap in a CJ7

Post by McSyd »

New member here. Glad I found this site.

Long story short, I was going to do a 4.0 head on a 4.2 but decided to do a stroker. I have the crank from the 4.2 and 2 sets of rods. Also have a full set of 4.0 rods. I pretty much had 2 complete 4.2’s and one complete 4.0 to scavenge parts from. The machinist is top notch and seems to know exactly what to do for the actual build. But I have a few questions on the swap for an 85 CJ7. The head is a 7120 and has been magnafluxed, it’s good to go.

A little background: The stroker outta be around 200+hp when all said and done. Planning on a comp cams 4x extreme cam, 8.8:1 compression. The cam might change depending on the exhaust I go with. Have to see what the guys computer says. Planning to keep the stock 3.31 gears and hopefully will run 32’s or 33’s. This Jeep is 100% road and highway. Won’t see any dirt at all.

Which rods should I plan to use? The 4.0 or 4.2?

Which intake should I use on the 4.0 block/head if I plan to stick with a carburetor?

Any recommendations for brand/model of a 500cfm carb that’ll fit either the manifold?

I’m keeping the t4 trans for now. The 4.0 came from an auto XJ. Will everything swap directly over? Throw out bearing, bell housing, clutch, etc?

I want bare minimum wiring for the engine. Won’t need any efi stuff and I’ll be doing the nutter bypass if needed. What for wiring will I HAVE to do to make it run?

Will I need an electric fuel pump?

Which motor mounts should I use? The original CJ7/4.2 or the newer 4.0?

What will I need for a water pump? I read something about a reverse rotation pump for the cj swap. So should I find a YJ 4.0 pump or??

For valve springs, should I just use whatever is recommended for whatever cam I go with or something else?

Any advantage to using head studs and oil pan studs vs regular bolts?

Any recommendations for a clutch? Will a cj7 style clutch fit the 4.0?

Which fan should plan to use? The smaller XJ fan or the original, larger CJ fan?

Does anyone have a completely assembled motor photos either in or out of a cj7 I could use for references?

Any hints/tips or things to triple check when I assemble the engine?

Any other little odds and ends I’m missing on dropping the 4.0 stroker into the cj? It’s a bare chassis at the moment and I plan to leave it that way until the drivetrains total done and installed.
Thanks a bunch
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