3000 rpm issue - JeepForum.com
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post #1 of 4 Old 08-29-2019, 04:50 PM Thread Starter
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1987 YJ Wrangler 
Join Date: Aug 2009
Location: Granby, CT
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3000 rpm issue

Currently, when I rev my Jeep to 3000 rpm it acts like it is hitting a rev limiter. Any suggestions?

The Jeep is an 87 with the 4.2l 258 straight 6. The motor is running a Weber carb. I have performed the nutter bypass and team rush upgrade.

I have replaced all vacuum lines and the vacuum advance on the distributor.

Jeep starts great, idles great, and runs great up to 3000 rpm. Once I get to 3000, it’s like a light switch with it acting up.

I’m going to replace the ignition module to see if that helps. Any other thoughts?

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post #2 of 4 Old 08-29-2019, 07:04 PM
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1995 YJ Wrangler 
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Location: Near Whacko
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Check timing, check fuel, check air.

Honestly though, do you ever need to rev it higher than 3k?
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post #3 of 4 Old 08-30-2019, 01:06 PM
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Originally Posted by clogee View Post
Currently, when I have performed the nutter bypass and team rush upgrade.

I have replaced all vacuum lines and the vacuum advance on the distributor.

Once I get to 3000, it’s like a light switch with it acting up.

Any other thoughts?
I don't know what this problem is...
Although, these distributors have a limited mechanical/centrifugal advance, this is emissions timing and adjusted by the ECM under the dash. (Nutter by-passed)

The pictures (I hope) will show a peep hole to check what advance head you have. I have flipped the advance head/slot from the 13R around to the 18R advance slot. This works very well with the Motorcraft distributor. You may have the 6.75 or 7.75 advance head and would probably need to "hawg" it out, or replace the distributor.

Many others like to buy from the Chinese company CRT, their HEI distributor for $125.00 and be done with all of the Duraspark/emissions distributor stuff.

Check out what you have and see if you want to pull the distributor and take it apart and flip the head around. It sounds harder than it is.


Edit: A reasonable total timing that I use is 32-34 degree's total advance at 2800-3000 RPM, no towing, no pinging
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post #4 of 4 Old 08-30-2019, 04:03 PM
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1990 YJ Wrangler 
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Location: Grass Valley
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I guess my question would be why are you revving over 3K?

I have the 4.2 with Howell fuel injection and HEI distributor and run 5.13 gears on 37's and rarely hit 3K.

I'd guess it's a timing issue as well though.

Originally Posted by George Orwell
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