Engine 4.2l kinda stroker not rotating I think I used some Incorrect valve train parts.

[mattam208]

So I have built this engine for my jeep using parts I have collected and I think I need to make an adjustment someplace. Its Kinda A stroker I Built the rotating assembly and all was well built the top end and timed it and now It acts like valve to piston interference. I hope somebody can tell me where I'm messed up at. Here is what I used to build it. 1984 Jeep AMC 258 i6 / 4.2l Block, Crankshaft, Pistons and rods bored .030". 4.0 head casting 0630, comp cam 68-AMC 232 i6 -4 cam, comp 822-12 4.0 lifters,1984 4.2L push rods , 1984 4.2L rockers. am I running the wrong lifters or push tubes or Rockers for that head maybe I just assumed lengths were the same between 4,0 and 4,2 and I know better than to assume that kind of thing. Anyone with info helps. I plan to pull it down and start taking measurements and see where I have an issue such switch to 4,0l push rods or rockers or something maybe.

 

[grimmjeeper]

I was under the impression that a stroker needed a AMC 258 i6 / 4.2l crank in a 4.0 block. Just changing the head doesn't give you any more bore diameter. So all you're getting is the 0.030 overbore. The 4.0 block has much bigger diameter pistons with a short crank. The 258 crank bumps the 4.0 up to 4.5-4.6 depending on the overbore on the block.

I would check the timing on the camshaft. I don't think it's an interference design but it could be a valve hitting a piston.

I think the 4.0 valves fit inside the bore of the 258 so that's probably not a problem.

 

[CJ]

So much info and so much to talk about. Your engine is a non interference assembly. It will take a boat load of change to have piston and valve hitting.
Let's talk the simple thing. Playdo or clay. It's going to suck but pull the had off, put the after mention on the piston an after you rotate the assembly. Yes you have to put all back. Is there a squish or a gap? You don't have to torque or anything, just need to setup the correct valve train.

 

[mattam208]

Yeah thats why I called it Kinda. It’s actually just a AMC 258 i6 / 4.2l with 4.0 head i didnt know if using the 4.2 overhead with 4.0 lifters could be causing an overlift issue. My research showed that cam was good for either engine.

 

[CJ]

Yep, a crazy monster. 4.0 and AMC 258 i6 / 4.2l are serious trouble depending on how they interact. AMC made a cluster

 

[grimmjeeper]

So much info and so much to talk about. Your engine is a non interference assembly. It will take a boat load of change to have piston and valve hitting.
Let's talk the simple thing. Playdo or clay. It's going to suck but pull the had off, put the after mention on the piston an after you rotate the assembly. Yes you have to put all back. Is there a squish or a gap? You don't have to torque or anything, just need to setup the correct valve train.

This would probably be my next step. See what's actually hitting.

 

[mattam208]

Yeah that’s hind of my plan was pull rockers and then see if it rotates. If so then I either need shorter push tubes or lifters or the rockers. I’ll have to start checking and comparing specs. I should have done that to start