Topic: tbi to carb

[warpedredneck]

i have a 87 mj comanche 2.5 4 cyl,
5spd 2wd,
im looking at converting it to carb and doing away with the tbi
i have the ign system figured out,
does anyone know the cfm rating of the throttle body?
ive been looking for this info so i can figure out what carb to look for?
im thinking the motorcraft 2100 is too big?
thanks folks

[chardrc]

the 2.5l had a carb in the cj7's so you could look up the stock carb and see what cmf it was rated for...

[pioneer4x4]

I know clifford performance has gotten a bad rep. latlely, but they make an intake that would fit more carbs, than yours would, if yours would match up any anyway? just be very carful dealing with clifford, oh yea you would have to get their headers also, but be ware, because on my XJ i had to do some beating to get them to fit, also someone else with an MJ also had fitting problems with their header also. but the intake looks like it would be awsome. why dont you like the TBI? I have recently drilled through my fuel regulator to make it adjustable, the factory put in a plug on bottom so you couldnt adjust it, but drill it out, tap it, and you got an adjustable regulator to fatten it up. I have also thought of going to carb also, let us know how it goes.

[Mr_Random]

I'm moving up to MPI rather than down to carb... but MAN is it just more trouble than it's worth... I should have saved money and bought a better jeep, now I'm rebuilding an engine on top of the MPI cost... AH...

[Jeffy]

I'm moving up to MPI rather than down to carb... but MAN is it just more trouble than it's worth... I should have saved money and bought a better jeep, now I'm rebuilding an engine on top of the MPI cost... AH...

Have you considered just buying a low mileage MPFI 2.5L and dropping it in?

[warpedredneck]

the jeep is an awesome little runner, however the computer and wiring related to the computer are starting to go for a crap(green corrosion,ghost glitches/driveability issues)
the block has provisions for a mechanical fuel pump
the ign is no prob
if i put a carb on i'm done/ good to go!
the places i go picking up parts are 50mile from nowhere and i need to be able to rely on it again
thats why i'm going tbi to carb

[Mr_Random]

Have you considered just buying a low mileage MPFI 2.5L and dropping it in?

At this point I'm neck deep in it, just need to figure out if the bulkhead connector is directly compatible, rewire if it isn't, then swap the crap in (including new engine). I'm struggling on the bulkhead (fuse panel), so I hope I can find something new to help...

Anyways, to warpedredneck; sounds like you have a good idea of what to do, maybe the clifford intake would be the best idea; I think it can work with a 4bbl carb. Good luck!

[warpedredneck]

holleys website carb calculator doesnt work with a 151ci engine
however if you plug in a 302/max rpm of 5000 it comes up with 500cfm
if i divide it in half 302/2= 151 - 250cfm?
found a motorcraft 2 barrel thats listed as a 240 cfm
going to the u pull right now to see if i can find it
**
what bulkhead probs are you having?

[Mr_Random]

I hate terminology, I wish one thing was always one thing. For some reason the fuse panel connector is also called the fuse bung, bulkhead connector, and some various other names that I don't remember. Anyways, I'm trying to plug a 94 yj engine harness into my 86 fuse panel (on the inside of the engine compartment, of course). The connectors are the same, and will mate right up, but I don't know whether the voltage (or ground I suppose) to each pin is the same, so I'm expecting some rewiring. The hardest part is that there is ZERO information on either of the pinouts, especially my 86... ugh.

ha, I like how you figured the cfm, I know little to nothing about carbs, so that was pretty fitting to use the 301 as a guide.

[chardrc]

when looking nup tbi injector sizes i found that the injectors for a chevy 5l tbi (has 2 injectors) have slightly higher flow rate than the stock (1) injector for the jeep 2.5l tbi.. so your 301/2=151 should be close enough... maybe

[Matt vs YJ]

IMHO, you'd be much better off just trying to find another wiring harness (from an XJ maybe?) on ebay or someplace.

Painless recently came out with a replacement harness for the 87-90 YJ, but it's a bit expensive! (~$800)

[warpedredneck]

800?
i have a msd ign(6al)
i have a msd blaster coil and timing controler box(from a previous victim)
2 barrel carb cost 25$ rebuild kit with float was 29$
carb adapter was on the shelf (needed to redrill the holes)
fuel pump was 37$
it a far cry from 800$

[Matt vs YJ]

it a far cry from 800$

That's why I said look for a used harness. Nevermind... you've made up you're mind already.

Maybe I'm just having a brain fart... but how are you planning to trigger the ignition? Did you find another distributor with a pickup or points in it?

[Matt vs YJ]

Also, make sure your camshaft has the extra lobe to run the fuel pump. The block may have the spot to mount it, but that doesn't mean the internals are there. (I speak from experience  )

[warpedredneck]

cam has the lobe(was down that road once before too)
that was a lesson not soon forgoten
pick-up coil in the dist used for a trigger
central ontario is a harsh environment- used harness's or anything used on a 21 year old jeep is pretty much useless