[ryankopecki]

Well, it seems I have a problem with my 4.2 in 81 cj8. I'm thinkin it needs some valve train work. So I can get a 95 4.0 complete engine with 60K on it. What I'm wantin to do is make sure the 4.0's head is good (rebuild if needed) and put it on my 4.2 block (that's simple enough). But I also want to use the cam, lifters, and pushrods out of the 4.0. Will these work?

 

[1985]

I wish I knew, and you probably have looked, but try this:

head swap

Grab the computer and harness and Inject that 4.2!

Cecil

 

[Guest]

If you have the 4.0..then I would put in the whole engine and hook up the fuel injection as well. You can make the 4.0 head work on the 4.2 block....but...why? Especially when you already have the whole engine.

The fuel injection will give you much better performance than the ol' carb.

 

[1101]

In reply to:

You can make the 4.0 head work on the 4.2 block....but...why?

[/ QUOTE ]
Admittedly, a complete 4.0 swap is probably going to be quite a bit simpler, and somewhere between a little and a lot cheaper. BUT...

The 258 does have a longer stroke, thus one of the reasons the 4.0 head swap became popular is that you get the stroke of the 258 with the flow of the 4.0 head. I was also under the impression that the 258 short block was a little stronger - but I'm not really going on anything of authority here.

I don't know whether or not the 4.0's cam and lifters would work, but I wouldn't recommend putting a used cam and especially lifters in if you are going through the trouble of pulling it apart. I would get a fresh cam and set of lifters. Use the 258's pushrods. Not sure if there is a difference or not, but I know that the 258's pushrods work with a 4.0 head.

In reply to:

I can get a 95 4.0 complete engine with 60K on it

[/ QUOTE ]
"Complete" is a term that can have a WIDE range of interpretations. I would not start a 4.0 injection conversion (short block or not) unless I had continued easy (read: back yard) access to the donor vehicle. There is a TON of little tiny crap that you are going to need, and unless you really know what you are doing, it is going to be very hard to get all of that stuff in one or even a few trips.

 

[ryankopecki]

"The 258 does have a longer stroke, thus one of the reasons the 4.0 head swap became popular is that you get the stroke of the 258 with the flow of the 4.0 head."

Yep, that's why I want to keep the 258 short block. Lower rpm power band to go with the 4.10s and 36s.

"I would get a fresh cam and set of lifters."

You underestimate my cheapness.

"'Complete' is a term that can have a WIDE range of interpretations."

In this case complete means the whole thing including intake and exhaust manifolds, injectors, wireing harness, and no computer. I do not plan on injecting at this time and when I do it will most likely be megasquirt. The megasquirt should be much easier to install, cheaper, and its fully tuneable for when I get around to mixing more parts to make a 4.6 stroker.

The 4.0 head swap is trivial. All I'm worried about is the cam, lifters, and pushrods.

 

[1101]

In reply to:

You underestimate my cheapness.

[/ QUOTE ]

Okay then... just be SURE that you VERY CAREFULLY mark or somehow indicate which lifter came from which hole. The lifters mate to the cam in the break-in process. Improper break-in will wipe a lobe or even the entire cam, and I would guess that swapping lifters around could easily do the same.

As for the pushrods... is there something wrong with the 258's? I don't know if there is any difference, but I would lean toward staying with the 258's just in case there was any difference in height. If you really want to go with the 4.0's, at least put one side by side with the 258's and see if you can notice any difference. Since it is a hydraulic train, I doubt that a difference smaller than the human eye could detect would matter. It's going to build up "x" amount of hydraulic pressure in the lifters anyway. Like I said, I KNOW from personal experience that the 258's pushrods work fine with a 258 short block and a 4.0 head.

Haven't played any with the Megasquirt. It may be fully tuneable, but that doesn't make figuring out what to tune it to any easier. I'd do some hefty research here. Of course a lot depends on your own mechanical prowess and resources as well. I found out the hard way that tuning an engine is a complex formula of timing, throttle, mixture, combustion chamber shape (which you are changing), and atmospheric conditions. Wound up doing a fair amount of fiddling with my carb and distributor to get things as good as they are - which still may not be perfect, but is pretty durn good.

 

[445]

I'm a super cheep ex hack job (well trying to change my ways) and i even sprung for new lifters and push rods when i did my head gasket. I just did lifters, push rods, feel pro top end gaskets, rocker arm bridges (suposed to be the most common source of amc valve train noise), and an aluminum valve cover and got if from ultimate 4 wheel drive www.ultimate4.com for $197, i think the valve cover was around $75. So you should be albe to get your parts for less than $200 since i also got a valve cover, dan is a great guy to deal with and knows jeep stuff and swap stuff, tell him andy sent ya. Don't cheep on these parts it's not worth it. You will all ready have your motor torn down to the point to replace those parts. This isn't something to cheep out on. Swapping the whole 4.0 in is much more costly so i see why he's not doing that, it's also a lot more work.

BarrelRoll

 

[elusive]

you are begging for a stroker!
use the 258 crank and rods in the 4.0.. you'll get the longer stroke you desire and the 4.0 head and all newer parts.
yes, the 258 cam and lifters are interchangeable with the 4.0 stuff. not sure about the pushrods...
I even have a super secret way to keep it from spark knocking now...
my stroker has 12000 very very hard miles on it now.. still purrrrrs

 

[ryankopecki]

Yes I'll have a stroker some day. Just not now. The 258 can burn 36s running on 5 cylinders so I don't need the extra power yet. It's further toward the end of my planed mods, actually, it is the last one.

I think I have the problem fixed now and it should be running on all cylinders by tomorrow night. A push rod kept junping out before. Nobody would approve of my fix so I'll just let yall know it is creative and will work according to myself.

 

[ryankopecki]

You also underestimate my cheapness.

 

[1101]

In reply to:

super secret

[/ QUOTE ]
Yer a butthead!!

Share the love! Whatterya doin?

 

[ryankopecki]

Yes dammit.