i have a 87 efi 4.0 out of a comanche i want to put it in my 91 yj... i was wondering if there was a direct bolt on intake manifold without haveing change my exhaust manifold of if there is a adapter plate to put my carb on my efi manifold...and also what is the best carb for my stock 4.0..

bump

Well... just google up what it takes to swap a 4.0 head onto a 258 (4.2) and just use the intake information.

Essentially, you will grind 2 small notches under the dowel holes on the 258 intake. Those notches will rest on top of the dowels in the 4.0 head.

peace
Dave

what carb would u people suggest?

Maybe I am missing something because I am not much of an engine guy, and this is non hardcore but, how are you putting a carb on a EFI engine? I have a 4.0 and I don't have a carb.

if u have a 4.2 people always put the 4.0 engine on them.. useing the carb manifold on the 4.0 head on the 4.2 block... well i got a 4.0 and i am getting a 4.2 manifold for it... so i can have it carb then. i was just wondering if a 4 barrel would be a good idea with a aftermarket four barrel exhaust manifold or is that over kill?

I am having trouble following you here.
You have a 4.0 efi motor from an 87 MJ
(this is a non HO motor and not really worth the effort to swap, IMHO)
You want to put it in a 91 YJ that came FI but..
You have some carb, not sure what one, you want to reuse or you are looking for a carb
(What was/is in the YJ and what carb do you have?)
You are looking for an aftermarked four barrel exhaust manifold
I assume you mean a performance header vs stock as exhaust manifolds are not "four barrel" Can't help you here, I just used the stock type on my 4.0 head.

If the non-HO 4.0 head can take the 4.2 intake (not sure as I have only put one on a HO head) then run a MC2100 2bbl on it. If you want to go to an aftermarket 4bbl intake then get a small 4bbl, like a 390 cfm or so. You will need the whole ignition system from a 4.2, dizzy, module, coil, etc.. if you convert from FI to carb. You will also need a fuel pump for a carb (I am not sure if you can fit a 4.0 with a mechanical pump, so you might be looking at an electric intended for use with a carb). I have read that "dry" intakes like the MPFI 4.0's are not good to use "wet" where the fuel air air has to travel through the intake vs. dry where the fuel is added at the injector location.

If you have a 4cly in the 91 now you may also need to get a different trans and xfer case.

alright sorry for makeing it confusing. i have a 91 yj that had the 2.5 with the ax5 and the 231... i am taking that all out... since the motor blew up.... and putting a 87 mj 4.0 in it that runs strong... and a 90 xj ax15 behind it.. i want to take the 4.0 and convert it to carb by changing the intake manifold off a 4.2... i was just wondering if a 4 barrel intake manifold would be worth it for a stock 4.O? or would a stock two barrel be good enough... and would carb would i run i heard the stock 4.2 carbs are junk... i dont have any carb at the moment so that is y when i get one i am getting a good one and just wondering what was a good one...

I am following you now.

I am just not sure if the 4.2 goes on the pre HO heads. Maybe you could go to your local parts store and ask to see an intake gasket for each. Should tell you pretty quick if all the ports line up. Allignment dowels and clamping the intake to the head can all be worked around.

For a carb I would just use the MC2100 with the 1.08 venturies (sp?). Google it and you'll find all you will need to know on that. It is a large bore 2bbl that will bolt on to the later model 4.2 small bore 2bbl intake with a standard adapter. I don't think the 4bbl is needed for a stock 87 4.0.

You'll need the 4.2's ignition system. You'll need to make some slight modifications to the wiring for it. Google and read up on "Nutter bypass".

Good luck.

Shameless plug time, a propane carb of course:smokin:

You'll need the 4.2's ignition system. You'll need to make some slight modifications to the wiring for it. Google and read up on "Nutter bypass".

Good luck.
i was just going to get a HEI distrutar from DUI one wire hook up then

That will work.