post #1 of Old 05-14-2010, 08:11 AM Thread Starter
hubb6666
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1990 Wrangler 4.2L Timing Help

I just purchased a 1990 Jeep Wrangler with the 4.2L 258 engine. It has the Offenhauser Intake Manifold with the Holley 390CFM 4 barrel carburetor and headers. I also noticed that the "Nutter" bypass has also been done. My problem is the jeep runs terrible and had to tow it from the persons house that I bought it from. I tried checking the timing but either my timing light is reading wrong or maybe the timing chain is off. I disconnected the vacuum advance and plug it. When I take a reading my timing light is not showing the mark at all. I have to advance my timing light to 45 degrees to see mark at 0 degrees. I tried contacting the guy that sold me the jeep to see if it has ever run after he put all this stuff on and to see if he has messed with the timing chain but no luck. I looked at the timing chain cover and there is a new gasket on it. Can anyone lead me in the right direction on what steps to take next? Thanks

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post #2 of Old 05-14-2010, 08:19 AM
Burnerman
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He may have the distributor gear off by a few teeth. I'd try and get that correct and time it at 10* and see how it runs. That carb maybe a tad big also.

96 ZJ.
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post #3 of Old 05-14-2010, 08:26 AM Thread Starter
hubb6666
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I set the #1 cylinder to TDC at the compression stroke. Distributor is dead on. I just put plugs in yesterday and looked at them this morning and they are black as the ace of spades. I also think the carb is a tad big. I ordered the Webber conversion kit (WK551-34) and should be here today but this timing thing really has me confused.
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post #4 of Old 05-14-2010, 08:48 AM Thread Starter
hubb6666
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Another thing I noticed is my manifold vacuum is 10.
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post #5 of Old 05-14-2010, 09:43 AM
dimatrod
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Try doing the Team Rush mod as well. I had done the nutter bypass and timed it with a timing light and it was missfiring a lot. Just yesterday I did this mod and it's a whole other beast. Carb may be a factor as well, but it goes in hand with the Team Rush. Seriously do this mod and add a hotter coil and you'll be golden, it's just $70 if you look around carefully

Last edited by dimatrod; 05-14-2010 at 09:44 AM. Reason: confused spanish terms with english
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post #6 of Old 05-14-2010, 10:19 AM
wanabejeeper
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Thats a nice rig if you can get it running right... Do the rush mod and see where that gets you.

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My build thread http://www.jeepforum.com/forum/f12/n...thread-867043/
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post #7 of Old 05-14-2010, 10:20 AM Thread Starter
hubb6666
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The Team Rush mod has also been done on this jeep.
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post #8 of Old 05-14-2010, 10:21 AM Thread Starter
hubb6666
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I just received the Webber 34 Conversion Kit so I'm going to go install it and see what happens.
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post #9 of Old 05-14-2010, 10:24 AM
Fernando
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Would be worth inspecting the timing chain, the carb is definitely too big and you won't be able to tune it properly unless you have a different cam. 300 CFM is around the area for a 4.2 engine, 390 seems too much for me...

Make sure you find TDC and check the marks, I know you said you already did but make sure you are on the compression stroke.


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post #10 of Old 05-14-2010, 10:39 AM Thread Starter
hubb6666
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Offenhauser is off!
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post #11 of Old 05-14-2010, 10:41 AM Thread Starter
hubb6666
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Quote:
Originally Posted by Fernando View Post
Would be worth inspecting the timing chain, the carb is definitely too big and you won't be able to tune it properly unless you have a different cam. 300 CFM is around the area for a 4.2 engine, 390 seems too much for me...

Make sure you find TDC and check the marks, I know you said you already did but make sure you are on the compression stroke.
Do you think the Webber 34 is to much for it?
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post #12 of Old 05-14-2010, 10:42 AM
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Quote:
Originally Posted by hubb6666 View Post
Do you think the Webber 34 is to much for it?
not at all, there are plenty of folks on here running the same.

First Jeep was an 1989 YJ, 6 cylinder 4.2L , 258. Nuttered and TeamRushed, Weber 38 DGES, Now, I'm venturing into the world of Grand Cherokees
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post #13 of Old 05-14-2010, 10:45 AM Thread Starter
hubb6666
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What should I do with the EGR port on the stock intake manifold? Also the stock intake manifold has a connection for crap load of vacuum lines.
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post #14 of Old 05-14-2010, 10:57 AM
monkeyhouse
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as long as you don't have emissions worries, you're okay. The CTO, I have mine connected. You can use the gasket for the egr to fabricate a cover, or you can hook it back up.

sorry, forgot to post this link:

http://www.jeepforum.com/forum/f12/v...needed-537650/

First Jeep was an 1989 YJ, 6 cylinder 4.2L , 258. Nuttered and TeamRushed, Weber 38 DGES, Now, I'm venturing into the world of Grand Cherokees

Last edited by monkeyhouse; 05-14-2010 at 11:15 AM.
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post #15 of Old 05-14-2010, 11:04 AM
timatoe
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Look at this site... Coolant Temperature Override Valve (CTO)

That'll tell you what the ports on the CTO valve are. Any of the ports that aren't used can just be capped off with vacuum caps. You could also just plate off the EGR, although if it's still there, I'd go ahead and run it.

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