TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

Need Help on tbi rebuild adding some power 90% complete need tech guys!

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Old Oct 7, 2009 | 01:04 AM
  #1  
JeepYJv8's Avatar
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Joined: Jun 2009
Posts: 129
Likes: 5
From: PA
Car: 1992 Jeep Wrangler + a few more car
Engine: Gm 5.7 T.B.I with 1227747 ECM
Transmission: 700r4 DIY built
Axle/Gears: Ford 8.8/D30- 4:10 and lockers
Need Help on tbi rebuild adding some power 90% complete need tech guys!

Thanks for reading. this was my first build

Heres what i got:

L05 350 T.B.I was 9.3 comp swirl port heads(no comments on them please i love them

I completed rebuild. compression is at 9.5 molly rings clevette 77 bearings cloyes heavy duty double roller

Comp cam (Very mild cam) #cl12-249-4
206-212*@ .050
249-260* duration
0.434-0,444 lift
lobe is 112* center
Intake is 108 center
also purchased there springs recommended for the cam

QUESTION 1
will it benifit me using roller tip rocker they recommend with the cam? it wont be spinning over 5k maybe not even that? is it worth the extra $200

Question 2
are self align rockers required on 1990 gm 193 casting swirl ports? im thinking so but looking to confirm?

Question 3
e bay has 1.52 steel roller tip rockers 1.52 ratio self align .. is this even worth doing? will i need to replace pushrods for my origional 1.5 rockers cause they are 1.52 ?? (hey i said first build)

Ok before you anwser i figure ill tell you my goals
and the vehical

Useage: offroad (lately been mudbogging at a PBIR race track.
Engine installed in jeep yj
trans art carr 700r4
headman small tube headers and dual super 44's
Gear ratio 4.10
Tire size 36"
actual weight 3460

Last race i placed 4th. i was 3 seconds off the leader in my class. I ran the pit in 4 high but with the 4ft mud 250ft long i was having a hard time keeping the engine moving over 2k. ( though something may have been wet. it sucked some water. so my goal is the low end torque but without using 4 low. so i can gain speed off the line. so this is my delima!! i need 2-3 seconds in a 250 ft span..lol
also ofcourse this is offroad jeep so im not looking to go crazy for something to swim in the mud..lol im 13k deep already.. wait thats before rebuild..:0..

I am cleaning up the heads some and a valve job.
also
i chose a milder cam because i dont want a load of tuning before the race. it is noverber 7th. some im hoping it will be plug and play.. ok that leaves more ?????

Question 4
I know i need to learn to burn chips and such but should this run ok off the stock tune, maybe just throw a bit more fuel at it?

Question 5
should i just buy a pre tune chip for now? dont yell at me!
Question 6

i run win aldl ive read all docs on this forum. one thing i dont get is important. BLM so i know i want to be at 128 but say im 30% petal straight ground and im at lets say 120 BLM .. so is it going rich or lean?

Question 7 and final

wow i cant think of another one rite now.. i know this post is all over the place. im sorry to throw this at you guys like this. but my brain is about to explode...lol any help would be great. and i know this isnt an offroad forum. but i believe this forum has the most inteligent people behind it. and ill have better luck here..

One more thing. i used comp cams software to pick my cam. it is saying predicted power is:
294HP @ 4000 rpm
468TQ @ 2000 rpm
Now i know this isnt even close. how do they get these numbers? maybe i added a 100hp shot of nos and didnt notice it.. lol im kidding.. i dont know just giving you guys all the info i got except my ssn..
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Old Oct 7, 2009 | 02:15 PM
  #2  
ShiftyCapone's Avatar
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From: Cincinnati, OH
Car: '90 RS
Engine: 377 LSX
Transmission: Magnum T56
Re: Need Help on tbi rebuild adding some power 90% complete need tech guys!

The stock heads will use self aligning rockers but you can use non self aligning with guideplates. Rollers, although better than stock, are not needed with your set-up. Save the $200 for tuning equip, that will make 10 fold more power than the rockers. I would check for proper push rod length (cheap tool to check) and run the stock rocker arms. If you wanted more in this area Pro-Form sells some stamped 1.6 rollers for around $100. For your combo, that is the better deal IMO.

I will assume the cam specs are advertised with stock 1.5 rockers? If so a 1.52 ratio would take you to .440I/.450E, which could be the limit for pressed in studs and stock valve guides. If the heads are off might want to spend the $50 or so to have a shop cut the guides for a higher lift cam. You could safetly run the 1.6 rockers then. However, you would then be pushing it with the stock pressed in studs. Might be wise to invest in screw in studs now if you are going to beat on this motor. These motors create a chain reaction with mods.

As for tuning, your combo is just a mild L05 so if you are using an F-body or Caprice ECM you can use the 350 TBI Chip from the LO5 Caprice cars. This won't be optimal but "should" allow the motor to run half way decent. You've acknowledged that tuning is optimal and we can't stress that enough. A stock L03 chip with that combo will leave you at the starting line with a stumbling, surging, undrivable mess.

I am sure Fast355 will chime in, as he is the L05 and 193 head king. He will be glad to tell you how to get the most out of that combo.
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Old Oct 8, 2009 | 08:02 PM
  #3  
JeepYJv8's Avatar
Thread Starter
Member
 
Joined: Jun 2009
Posts: 129
Likes: 5
From: PA
Car: 1992 Jeep Wrangler + a few more car
Engine: Gm 5.7 T.B.I with 1227747 ECM
Transmission: 700r4 DIY built
Axle/Gears: Ford 8.8/D30- 4:10 and lockers
Re: Need Help on tbi rebuild adding some power 90% complete need tech guys!

Thanks for your reply opinions help alot. i think maybe 3 of 5 machine shops asked "are you sure thats the head you want to use" i just really need the low end. i read a book on porting. and dove in there with my die grinder. not so bad.

Im due to deliver the heads to the machine shop tomorrow. but im a bit shy of being done with the porting. I will ask about screw in guides. so far the cleaning, magnaflux, 3 angle and back cut, resurfacing, guides as required, and assemby is running 250. most shops here are between 200 low and 350 high. my middle guy came pretty highly recommended. not a bad price rite?

I agree with the tune. maybe ill just hold off on the heads and concentrate on tuning.i read that artical "come in for free tune like 3 times, i think 3 more times and ill understand it. my ecu is from 1990 gmc jimmy 1227747. do you think its necessary to get at least a base tune before the race? or do you think it will run ok as is? as for the race i just need to be about 2-3 seconds faster. i just need to make it 250 ft in 19.00 seconds.. lol sounds easy huh?

yes the lift is avertised with the stock rockers. maybe ill just get them to install the studs. i really need dependibiliy. i take this baby 3 hours out in the middle of the woods. so maybe mild is good for me?

back to the tune. that sounds good. i was on moates website a few months ago and even seen when i could run 2 programs with a flip of a switch. that would be perfect for me. ok im sold thats next!!!

Thanks for your input!!

Jeff
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