Jeep Strokers

Hi guys, i'm new to the site. I'm currently piecing together a stroker, since my last motor bit the dust due to an oil pump seizing.
It's going to be going into my 91 xj, which is currently on 1 ton axles with 5.38's, 37's, doubler, ax15, etc. So there is a fair bit of weight to push around.

I'm starting with a 92 4.0 block, 12 weight 4.2 crank, 4.2 rods, and my head from my 91.

The list of parts i ordered are:
comp cams 232 camshaft
silvolite cast pistons (i believe that's the brand, i ordered everything from a respected engine builder and member of this site), std bore
new moly rings
new lifters
new melling oil pump
new felpro gasket set
new timing set
brass freeze plugs
new bearings

I had planned on tinkering with the head to see if i could port it some. I have a machine shop, so i had intended on decking the block myself and dishing the pistons if needed. I have a cnc mill so it shouldnt be an issue.
Right now i'm trying to do my homework. From what i read, it seems a zero deck height would be ideal. I've been having a hard time finding solid data as to what i should machine off for some reason, but it looks like about .03-.035". I'm not certain if i should deck it more since i'm able to play with the dish in the pistons.
Also, the push rods will take some homework to see what length i'll need after decking the head. I'm on a tight budget so i don't want to spring for adjustables if i can avoid it.

Lastly, ive been looking into valve spring options. I had been looking at stock springs for the Ford 3.8, 3.9, and 4.2's. Here's the specs:
http://www.sbi-e-catalog.com/PartDetail ... %20Springs

I found some retainers (late 90's buick 3.8 retainers) that seem to work with both the springs and stock jeep keepers, however the head will need to be machined to work with them since the retainer's spring seat sits lower on the valve than the jeep retainers. Any thoughts on these? I just want to avoid coil bind.

Thanks for all the awesome info on this site!

The springs look interesting, but are they going to have enough seat load for the cam? You could shim them up a bit before coil bind (or not depending the instal height with the retainers), but it may be tight. What is the degree on the retainers?

7* on the retainers i believe. the spring seat on the retainer is about .1" lower on the valve than the stock 4.0 retainer, so the spring seat on the head would have to be machined down .1" or so in order to use the combo. Other retainers might be an option, but i'd be concerned about there being enough meat on the retainer that high up on the taper to not shear off under spring load. the wall thickness would be rather thin. IMO, machining the spring seat on the head is the only option. But the wire is oval, so it's similar in pressure and height as the stock 4.0 spring, other than the wire is wider and shorter so coil bind will be less of an issue.

Here's my 6 month old oil pump that caused me to have to do something with my motor.


Here's the rig it's going in.



Still waiting on parts, but i got my head off the old motor so i can work it a little, and the new block is cleaned, decked, and painted. Went with a zero deck height.

Now to figure out how much to dish the pistons, if any.

so i played around with porting the head a little. Anyone have some input on what ive done so far?
I havent really tried to gasket match anything, i was just trying to smooth it out and get rid of any constrictions or tight turns. I've only done one cyl so far, so any input is appreciated.

danimal wrote:I havent really tried to gasket match anything, i was just trying to smooth it out and get rid of any constrictions or tight turns.

Thats the idea. Looking good so far. Leave the intake rough and polish the combustion chamber and exhaust port as much as possible. Throw a head gasket on the head and see if you can unshoud the valves a bit. Looks you don't have much room there though. I recommend protecting the head surface with a few layers of duct tape as well as protecting the valve seats with modified valves. Grind down the head area to provide better access to around the valve seats. Best way is to put them in a drill press and grind them while rotating. Remove the margin and cut them as close as possible.

thanks! yea i actually turned down a couple valves in the lathe so i could protect the seats. tape on the head gasket surface is a good idea!

so i started dishing my pistons today.

Ok i got the stroker in the jeep, but i cant get it started. there is spark, however there wasnt fuel at first. it was just flowing out the return line for some reason, so i replaced the regulator. now it is building up some pressure in the rail, but i'm not sure it's enough. I suppose it's possible that the distributor is in wrong as well, but i'm pretty sure i did it right. I'm going to rent a pressure gauge tomorrow to check it out. Anyone have any other ideas?
this pic is right after i dropped it in.