-
Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.
rebild 4.0L
- Thread starter jimbow912
- Start date
stumpXJ
NAXJA Forum User
- Location
- Atlanta, Georgia
Let me see if I can help you here...
I am rebuilding a 4.0L and I wanted to know what you guys think. A few of my thoughts are; larger pistons/boring cylinders, and/or shaving the head for higher compression in hopes of getting a little more power.
Any help is appreciated, and if possible, please provide any links that may have more info on these processes.
Thank you.
Not to be the grammar police..... but sentence structure, spelling, and punctuation goes a long way.
88 Wagonman
NAXJA Forum User
- Location
- Boise, ID
That was a helpful answer to the OP's question!
To the OP: Have you thought about doing a stroker? I Think that you would gain a lot more usable HP and torque for the $$.
Clean Racing
NAXJA Forum User
- Location
- Bellingham, Wa
You should go no more than .030" overbore on the pistons to keep the cooling issues to a minimum. Have the machine shop mock up the piston & rod with the crank in the block and have them zero deck the block to the pistons. That is about all you want to do on the lower end. Look for compression gains by milling the head a few thousands.. I hope this helps..
I was going to stroke it but i don't have the money and i was going to the 4.2L crank and rods but there's a lot more crap to do i had the guy that is doing the motor look that up and hes said that there is a lot to do and i need a motor because my low end is ticking and my head is cracked unfortunately i have the crappy cast head so I'm just rebuilding the motor as a 4.0 and just want to know if there is any thing i can do to get more power while the motor is being built. i don't appreciate the wise remarks :looser:
Last edited by a moderator:
Russ Pottenger
NAXJA Forum User
- Location
- West Covina, California
My advise would to try and find a running 4.0 for a few hundred bucks.
Throw in in.
That said, start saving your bucks and start gathering parts 258 crank, pistons, rings, bearings, and so on.
My point is if your spending any money on machine work.. Put it towards your stroker.
Just My .02
Good Luck on your project.
Throw in in.
That said, start saving your bucks and start gathering parts 258 crank, pistons, rings, bearings, and so on.
My point is if your spending any money on machine work.. Put it towards your stroker.
Just My .02
Good Luck on your project.
chrslefty
NAXJA Forum User
- Location
- centeral phx az
ive heard that u can get a little bit from a cam if ur not wanting 2 stroke it .
wolfpackjeeper
NAXJA Forum User
- Location
- 500' and 500KCAS, RAF lakenheath
So have you ever looked at the cylinder walls on a 4.0? I went .060 over on my stroker with no problems whatsoever, Runs at least as cool as the stock motor, and It does not even have a fan clutch. If you are worried about cylinder wall to water jacket clearance there is tons of room.
OP: just search Jeep Stroker either here or on google, it will provide all the links you need.
wolfpackjeeper
NAXJA Forum User
- Location
- 500' and 500KCAS, RAF lakenheath
Seriously though, you can build a stroker for just about the same cost as you would need to rebuild a normal 4.0.
also, I would really consider using at least some punctuation; and proof read a little bit. The complete run on sentence with lots of misspellings is harder to read, and It leads people to assume things about your intelligence.
also, I would really consider using at least some punctuation; and proof read a little bit. The complete run on sentence with lots of misspellings is harder to read, and It leads people to assume things about your intelligence.
Sherman_thetank
Keep it pinned!
- Location
- omaha, NE
When i rebuilt mine, i bored it .020 over with forged pistons, and stock parts from good aftermarket companies. You will be amazed with that, and a little grinding on the bench with the intake and head the difference it will make. And like most have said for the money you can build a stroke for just about the same, you just need to do your homework before you start.
when I was rebuilding my gm 2.8 the machine shop told me the same thing about going to a 3.1... I think that most machine shops just get worried when talk about stroking anything other then a 350 chev. When my 4.0 goes out I will do everything I can to stroke it. Rebuild it right the first time so you dont take it for the first ride and start thinking of how much faster it could be.
Last edited by a moderator:
bcmaxx
NAXJA Forum User
- Location
- The West Kootenays,B.C. Canada
x2 on .060 over and no probs!
Clean Racing
NAXJA Forum User
- Location
- Bellingham, Wa
How many days over 100*F do you really see in FLA?? Take in consideration a stroker is going to run cooler in cooler ambient air temp too.. Try wheeling in 117*f and see how cool your .060 runs.. Different regions require different thinking for such things.. Thats all I am saying..
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
I have never heard of a overbore of .060" giving any sort of over heating problem on and stroker/jeep forum I have been on.
OP: If you are rebuilding you are only a crank, bearings and a set of rods away from doing a stroker.
If yuo are dead set on just a rebuild I would suggest this. Have a machine shop inspect the bores to see how much they would need to be bored just to clean up. Get pistons for that with new rings. Replace the bearings (crank, rod, cam), maybe you could get away with a simple polish on the crank, maybe it has to be turned. Use a new oil pump. Replace the freeze plugs. Have the head checked and consider a 3 angle valve job. Reuse the stock cam if it is good with a new set of lifters.
OP: If you are rebuilding you are only a crank, bearings and a set of rods away from doing a stroker.
If yuo are dead set on just a rebuild I would suggest this. Have a machine shop inspect the bores to see how much they would need to be bored just to clean up. Get pistons for that with new rings. Replace the bearings (crank, rod, cam), maybe you could get away with a simple polish on the crank, maybe it has to be turned. Use a new oil pump. Replace the freeze plugs. Have the head checked and consider a 3 angle valve job. Reuse the stock cam if it is good with a new set of lifters.
wolfpackjeeper
NAXJA Forum User
- Location
- 500' and 500KCAS, RAF lakenheath
lived in Raleigh, NC for the first year or so after it was built. In the summer that place spends quite a bit of time around 100 or just above. It is not 117, but still pretty warm.
On a side note I love P-cola. the warmest day here was about 98, and with the nice sea breeze that felt great. I bet the average was about 94 or so. Unfortunately the stroker is still in Raleigh, I did not have the extra driver to get it here when I moved. Ill fly up and bring it down later.
5-90
NAXJA Forum User
- Location
- Hammerspace
That would be because the 2.8L V6 is little more than a leaky boat anchor (I had one in a FWD,) and the 3.1L is a better engine in just about every respect (had one of those in FWD as well. Car had a higher kerb weight by 200#, and had about twice the punch to boot! Granted, the 2.8L was TBI, and the 3.1L was MPFI...)
Most machinists just don't think "stroker" with anything beyond the SBC - the most common being the 383ci version (350ci +.030" 400ci crankshaft.)
Big_Al
NAXJA Forum User
- Location
- Gaston Co. NC
I think the big difference you felt was the MPFI. I built a 2.8 mpfi in a Camaro and used a small computer cam and was really suprised. With that being said I throw something in related to the original post:
.
.
.
There's no substatute for cubic inches...Stroke it! But bore the minimum to save your block for your next rebuild :spin1:Al
Last edited:
5-90
NAXJA Forum User
- Location
- Hammerspace
There was also the issue that, no matter how much I tried, I could not for the oil leaks at the rear of the cylinder heads (both of them.) I didn't even have to change oil - I changed the filter every three months, topped it up, and the oil changed itself over that time anyhow...
The 3.1L - tight as a drum.
What, you expect to rebuild it AGAIN after ANOTHER 200k? :laugh:
Bore it out according to cost and reliability. If you wear out the block buy another for $1-200.
