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Discussion Starter · #1 ·
1990 jeep yj manual trans cawler

81-85 4.2 block .60 over and 10:1 pistons
4.0 ho head with 2.02 intake and 1.64 exhaust valves
comp cams K 68-239-4 262/270 491/512
harland sharp roller rockers, studs and guid plates
mopar high volume oil pump
gmb high volume water pump

this is what i have right now still looking for intake/header/carb set up
was thinking of the clifford intake and header with a holy 470 cfm truck avenger
or may be tbi injection. realy im aiming for 200hp / 300tq trying to spin some 37's with 4.88's.
 

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IMO trying to get the horsepower and torque that you want out of the motor that you got is going to be troublesome. a 4.2L is designed for low end, not really anything in the mid range, which is what cam is in it. The .60 over helps, but then you have to factor in the major heat build up. Maybe a new 4 or 5 core radiator and electric fan?

As far as the intake and exhaust, I have an Offenhauser on my 4.2 with a Holley 390cfm. I am still running a stock exhaust manifold with a custom 2.75" exhaust mainly because of the clearance issues with a header. It sticks down too far and comes in contact with the front driveshaft under full compression of the front suspension.

Trying to spin 37's? I hope you have already changed the running gear to a set of 1 ton axles. The pic shows it still has 5 bolt wheels. Tsk tsk, the 1/4 ton axles in a stock YJ will not last very long under torque trying to spin 37" tires.
 

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the clifford manifold and the holley TA would be a good choice. with the work done to the motor it can handle the 470 cfm. you should be real close to your HP numbers.
is the comp cam a carb or FI cam?
 

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Discussion Starter · #4 ·
0III0forlife-theres a ford 8.8 and a ford 3/4 ton high pinion 44 under the frunt with yukon gear axels i think they will be fine.

thanks for your advice roadyrob and ya compcams says its for a carb motor and not recomended for efi. but i found a video on you tube with a cherokee running this cam on you tube though and it sounds lumpy;) but he is using efi.

jeep cherokee xj with comp cams ( cammed ) - YouTube
 

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That's nice! What axles are you running and what type of suspension kit is that? I want to do a similar set up later on but dont know where to buy.
 

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Discussion Starter · #10 ·



well got the engine together.. what a project..

1986 4.2 block and crank with a ballanced rotating and recipracating assembly and used a mellings high pressure / high valume oil pump.

forged flat fender racing 9-1 pistons .060 over

1994 4.0 ho cylinder head with 2.02 intake and a 1.75 exhaust 5 angle valve job with some mild porting to the diameter of the valve seats;)
comp cams springs and harland sharp roller rockers!:happyyes:

comp cams 68-235-4 there 4x4 extreme line. so far i like it not to lumpy but revs quick! real quick. kinda ridiculous:whacky:

clifford's 4brl intake and header for the conversion! kinda spendy but nice and clean!

gmb high flow water pump working with the champion 3 row aluminum radiator.

chevy v6 hei 1 wire distributer 65,000 volts uh! was the best fitting of all the modifactions droped in and work first try. cheapest to ebay on that one like 80 bucks.


and put a holley lighly used holley 470 4brl (truck avenger series)

also installed a full set of gauges just because i couldnt break in that motor with half of my factory gauges not working.

so far i have put around a hunderd miles on her its freaking fun ill tell ya that much. i thought that holley would be to much fuel for her but its working out very well. used to have it to put the peddle to the floor to do 55 now 1/4 throttle does it just fine even had her up to 70 in 4th with lots of throttle left. milage has yet to be determend lol.
 

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very nice!! do you plan on dynoing it? would love to see what numbers your getting. I'd bet you passed your 200 hp, 300 torgue target.
 

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What RPM range do you plan on running?
 

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very nice!! do you plan on dynoing it? would love to see what numbers your getting. I'd bet you passed your 200 hp, 300 torgue target.
It is very nice, really nice actually. I would bet that he is in the upper 200's closer to 300HP.

Mine has half as much work done to it and in Dec. it was on the dyno at 235HP at the rear wheels. Which is a lot better over the 140 (flywheel rated) that the motor has stock.
 

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Discussion Starter · #16 ·
thanks guys

ya im woundering my self how shell do on the dyno.. the cam is in the range of 1000-5000
but she doesnt like to idle much lower than 850-900, loads up a bit:) any lower than that:).
off idle power is pritty nasty compared to the old tired 4.2 it was. ill get some vids for ya of the engine;)

done some beach rides now, and tore the hell outa the trails on my property pritty fun stuff. my kids are as pumped as me to have her going again:)

hoping to take it out to the alaska4X4network meetngreet comp and trail events this summer! that shits ganna be fun fun right there!!

im curently working on my atlas 4 speed looking at replacing the tail section of it to ocomidate a speedometer and e brake. theres another grand probably, but those are the last of the fixes
 

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I have my idle set at 850-900 as well. It doesn't run well below that. The Holley 390 loads up on me, it just wants to breathe. I also went with a low restriction K&N filter in my snorkel and it seemed to help somewhat.

What you have done so far looks great, I have a super running 4.2L and I am envious of yours.
 

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NICE!!! I'd love to get my rig to even half way where yours is. I've only had it a year and it's a SLOWWW work in progress (plus it's my DD). The last 4x I had was a K5 Blazer with a 355 pushing 400hp at the rear wheels... I miss the power off road but these 4.2's are torque filled little six's and that does me good for now on the trails.
 

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Discussion Starter · #19 ·

hears a vid i took on day two of heat cycling mostly checking for leaks and what not.:beerme:
 

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What did you jet the TA to. I have the clifford intake and headers, and actually a very similar setup to yours. I still had to jet mine way back to 44s on the primary (8.5 pv) and 46 on the secondary, still working with the spring on that though. It seems to have a lot of power here. However I also live at 6,000 feet so had to jet back for that.
 
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