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Discussion Starter · #1 ·
My 88 YJ I did the HEI distributor swap as well as the GRonk 2150 carb swap kit . Everything correct as far as vacuum lines and timing set . My problem is not constant but I can get it to hesitate on acceleration and when you feel the automatic trans shift I get a hesitation . Iam leaning more to a bog . I have adjusted timing from 10 degrees to 6 and dropped the accelerator rod down one hole after Mike Gronks suggestion still have issue .Anybody have an idea on what to try . New fuel pump mechanical and filter installed
 

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I assume you gapped your plugs to .045" - .050".

If so, try timing to 12* BTDC.

Is your timing flash consistent? Does Gronk have any other suggestions?

How did it run with the Carter? If it ran OK with the Carter, why not put it back on to see if the problem is in the carb or the distributor (timing).

Good luck, L.M.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Did you go with the electric choke, The flat spot in the acceleration is enhanced when not set correctly. You can loosen the three screws holding the and adjust the tension on the choke plate. I had to play with mine a bit to get it set just right.
Also when you did the HEI did you replace the plugs? If so what kind. The high end plugs won't run well for long. Make sure to go with copper core plugs
 
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Discussion Starter · #4 ·
frustrated

Gronk suggested drop accelerator rod to second hole and adjust timing 6 to 8 in gear vac line to dizzy plugged while adjusting timing . Didn't work Iam using champion copper core plugs gapped 45 . I have read in other posts his carbs if they sit for a while its recommended to replace accelerator pump diafram ,others say jet change . Don't know what else to try and frustrated
 

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Do you still have the original Carter BBD carb?

Good Luck, L.M.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Did you go with the electric choke, The flat spot in the acceleration is enhanced when not set correctly. You can loosen the three screws holding the and adjust the tension on the choke plate. I had to play with mine a bit to get it set just right.
Also when you did the HEI did you replace the plugs? If so what kind. The high end plugs won't run well for long. Make sure to go with copper core plugs
Here's a pic of where my choke coil ended up in order to get rid of the stumble when engine is cold. The red mark was straight up on the Center mark above the coil. your adjustment, if necessary, may be different depending on your starting point, I had to adjust mine again a couple months after install due to the 30* temp increase in summer.
 

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Reset timing at 12 hesitation problems gone
FYI, even at 12*, I had hesitation. I discovered that I had the vacuum advance connected to the wrong port. Once I connected the vacuum to the correct port, the hesitation is gone and acceleration is better.

Several weeks ago there was a thread on this forum about where to connect the vacuum advance. It was that thread that described the proper port to draw distributor vacuum from.
I don't remember the thread being for a specific carburetor. What I did was locate the highest port on the carb body and use that one. The difference was noticeable.

Good Luck, L.M.
 

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Discussion Starter · #9 ·
well that didnt cure it 100%

at 12 seems gone except now that temperature getting cooler outside its still there before engines reaches temp then you still feel it slightly.
 

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Here's a pic of where my choke coil ended up in order to get rid of the stumble when engine is cold. The red mark was straight up on the Center mark above the coil. your adjustment, if necessary, may be different depending on your starting point, I had to adjust mine again a couple months after install due to the 30* temp increase in summer.
at 12 seems gone except now that temperature getting cooler outside its still there before engines reaches temp then you still feel it slightly.
You may need to adjust your choke as the seasons change.

Good Luck, L.M.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Glad that worked out for you. You may have to adjust again seasonally if you have a big change in the weather temp and or humidity,
 

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Discussion Starter · #13 ·
Finally issue resolved After trying 12 degrees I had pinging . I then realized that since I no longer have any emission equipment I was pulling wrong vacuumfrom a ported fitting .I set timing initial to 8 degrees with vacuum plugged off then attached distributor vacuum to manifold vacuum . Wow its fixed It has balls and no hesitation any where and no pinging . 0 to 70mph no issues .
 
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