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Timing advancing too much... solution?

89 YJ I6, bored .30 over, RV cam, Weber 38DGES

Since I put the Weber on my 89 I've had this problem - set the initial timing just right, and when the vacuum advance is re-connected , it will advance too much at low speed under 4lo load causing piston-killing detonation. I've tried retarding the initial timing and that takes care of it to an extent, but then the idle is crap. Is there a way to retard the vacuum advance? I think the entire problem is the monstrous vacuum coming off the Weber. Any help/advice would be greatly appreciated.

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89 YJ 6 Low input, High output 95 YJ 4 High input, Low output 03 Rubicon - High Payment
Reply to
Jeepaholic
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I had the same problem. My set up is 90YJ 258, headers, Weber carb, HEI distributor. You need to get a bigger idle jet from Weber. Your problem is that you have to open your throttle plate too much to get the idle you need, this exposes the "ported vacuum" for your advance. If you get a bigger jet you can close your throttle and only get vacuum when you hit the gas. The way to get around it is to set your timing with the advance connected, you will have a flat spot when accelerating but your idle and low end will be there. I had to go from a .70 to a .80 jet because of my headers.

Scott

90YJ

Reply to
Foot Loose

Makesense - I have a bunch of jets here.

Reply to
Jeepaholic

The springs inside can wear out too.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Jeepaholic wrote:

Reply to
Mike Romain

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