Topic: Time to build it! Got a few questions

[bigal389]

Ok here goes. I'm planning to build the engine in my 87 Yj over the winter and have a few questions. I tried searching and found nothing solid for an answer. So here go the details, port and polish the head, deck the block to be sure it's flat, new pistons 10:1 hopefully if I can find any, gasket the intake and exhaust and a Clifford cam. Now for the questions, has anyone ran a Clifford cam with tbi and if so how did it do? What was done to add fuel? I contacted Clifford and they told me their cam didn't do well with fuel injection and that I should run a carb. I have no problem with this but I would like to know how it performs with tbi before I sink a bunch of $ to loose my tbi. Has anyone upgraded the tbi in any way? I'm sure I'll have more ? As the build gets closer.
Thanks, Al

[sharpxmen]

you'll need a 91+ head and pistons, i think the block is the same.I'd also look into getting MPFI installed instead of TBI

[bigal389]

Just curious, why 91 and up head and pistons?
Thanks, Al

[sharpxmen]

Just curious, why 91 and up head and pistons?
Thanks, Al

+ intake also. The TBI is probably pushed to the max with the 117HP output, the MPFI Wrangler is actually tuned down (same engine in XJ has more power).

head has better flow, the pre 91 pistons are flat head (if I'm not mistaking) and better efficiency overall, the a/m cam would work better with the newer head and pistons.  If you go 10:1 you'll probably need to up the octane, so something to consider as in cost in the long run (might be a wash since would probably be using less gas but that's TBD).

[oldjeep]

Just curious, why 91 and up head and pistons?
Thanks, Al

91 is when they switched to the HO 4.0L

[chardrc]

thanks to sharp i had a bored out TB on my 1990 tbi before i sold it. it livened up the engine nicely especially at higher rpms. The fuel regulator is very similar to those on chevy tbi s and if your adventurous enough i think you can adjust it. you have to drill out a metal plug in the bottom of the regulator bowl to access the adjusting screw if i remember correctly. I didn't do any cams or headers so i cant speak for tbis response to bigger upgrades. you can also use larger injectors from chevy tbi engines. I have a thread on here somewhere comparing flow rates. i think the chevy 5.0l injectors are slightly bigger than stock 2.5l...

[bigal389]

Ok so I need a 91 or newer head and pistons to get the cam to work well. I had thought  about doing the mpfi swap but there aren't many jeeps around here to salvage the parts from. Are there any throttle bodies that will work with the jeep intake or am I just waisting time trying to make tbi that's on it better?
Thanks, Al

[chardrc]

There are no other throttle bodies that will fit on the TBI intake that are bigger than the stock one. I wouldn't be so down on the TBI. The number of TBI 2.5s on this forum is very low so not a lot is known about their ability to adjust for cams and what not. If i still had my jeep I would have been doing a simular build with stock heads but I bought a rubi instead because of frame root. No garenties though.

[bigal389]

I do have a spare tbi intake I may do some experimenting and set what I can come up with.

[sharpxmen]

actually i was wrong, 87 has the same piston, so scratch what i said (i looked up the part numbers and they're the same).

[bigal389]

Ok thanks, I'm going to research a bit and see what  I can find out on the tbi to mpfi. If I remember correct some Dakotas had our 2.5 in so I may be able to get the parts needed there. I'm still going to play with the tbi some aas well in the mean time to see if I can do any mods to help it any.
Thanks, Al

[bigal389]

Sharp, can you give me some info on the bored out throttle body? This is something that I want to try along with some other mods.
Thanks, Al

[sharpxmen]

Sharp, can you give me some info on the bored out throttle body? This is something that I want to try along with some other mods.
Thanks, Al

i took the t/b apart and bored out to whatever the max diameter i could get out of it, there's some pics in the garage sale
nothing special really

[chardrc]

i still have the tb spacer on my desk if you want it (or if sharp wants it back). does me no good without a tbi jeep to put it on....

http://4bangerjp.com/forums/index.php/topic,8142.0.html
http://4bangerjp.com/forums/index.php/topic,10049.0.html

[bigal389]

I am defiantly interested in the spacer, I plan to bore the throttle body as so I can find a spare.