Engine 360 Pistons and Rods

[M1redskin]

Hello Guys,
I am looking to swap in a 360 on my 304 74 - CJ5. Mostly because I was able to purchase a profesionally machined block for cheap on a 360 and my 304 is about shot. The block was machined .030" over, deck was machined .012" but the crank journals were within spec so the line bore was left untouched. So I am not sure 100% sure on the combination of pistons and rods that would work. I understand that I would need new pistons since the bore is .30 over. The heads have not been reworked yet and I am going to assume for the moment they will not require resurfacing. I was able to find the specs on the heads from the casting number. I am OK with a bit higher compression if reasonable. I would plan on running rec (92/93) fuel since it will be mostly a trail rig. I currently have headers on the 304 that I would reuse and would plan on an Edelborck intake. Thanks and any help would be appreciated.

View attachment 4231001

 

[CJ]

Sorry for my late reply. I believe your asking if 304 and 360 rods are interchangeable.
Yes
Same length, pin and bearing diameters.
You have to use a 360 dampener and flywheel though.

 

[M1redskin]

Sorry for my late reply. I believe your asking if 304 and 360 rods are interchangeable.
Yes
Same length, pin and bearing diameters.
You have to use a 360 dampener and flywheel though.

Yep - that I knew but was just asking since my deck was machined .012" if stock rods would still work or my compression would then be too high or create any interference issues. Another guy thought that it shouldn't affect compression any appreciable amount. Thanks though.

 

[CJ]

Yep - that I knew but was just asking since my deck was machined .012" if stock rods would still work or my compression would then be too high or create any interference issues. Another guy thought that it shouldn't affect compression any appreciable amount. Thanks though.

Ahh... .012 is only the thickness of two average pieces of paper. Might rais compression about .02 which is a non issue. Valve to piston clearance is much greater stock unless you up your compression. Intake gaskets should easily compensate for the lowered heads as you roughly only have about .0085 to compensate for (90 deg engine / 2 = 45 deg. Sin of 45 deg = .7071 * .012 - intake manifold angle works out to about .0085)
Sorry for the math lesson, I got carried away...

 

[M1redskin]

No worries and thanks also. I’m not quite that smart to know how to figure that out but I do understand it. Just an FYI that I wasn’t planning on changing gasket thickness but it appears that’s not needed anyways.

 

[CJ]

Keep us up to date with your build. My friend and our member @shooby just swapped in a 360 for his 304 due to washed out cylinders because of a fuel injection pressure issue and he loves it. Swapped everything from his 304 to the 360 except for heads, dampener and fly wheel.
This is what his 304 looked like that he had to replace.

Engine - Got a friend with a dead 304

Build or crate a 360? I say build, control parts and tolerances. Clevite 77, Speed Pro, he has a new cam made for his intake. I say no brainer... He wants to keep it AMC. Thoughts?

jeep-cj.com

 

[M1redskin]

Keep us up to date with your build. My friend and our member @shooby just swapped in a 360 for his 304 due to washed out cylinders because of a fuel injection pressure issue and he loves it. Swapped everything from his 304 to the 360 except for heads, dampener and fly wheel.
This is what his 304 looked like that he had to replace.

Engine - Got a friend with a dead 304

Build or crate a 360? I say build, control parts and tolerances. Clevite 77, Speed Pro, he has a new cam made for his intake. I say no brainer... He wants to keep it AMC. Thoughts?

jeep-cj.com

Yea - I’ll be sure to do that. It’ll be a few months but I’ll let everyone know how it goes. Thanks again!

 

[Armyvet25]

no clearance issues, if it actually raises the compression enough to cause pinging(detonation) then maybe a thicker gasket or higher octane fuel. but like said previously, should not be a significant difference.