Carb change, good and bad. -
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post #1 of 5 Old 07-04-2013, 03:29 PM Thread Starter
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1989 YJ Wrangler 
Join Date: Oct 2011
Location: Stevens Point
Posts: 291
Carb change, good and bad.

My 4.2 YJ is nuttered (pre-smog distributor), HEI ignition, and aftermarket exhaust manifold (not sure on what brand or type).

Last year I took out the computer and carter BBD carb and installed a weber 32/36 because the carter wasn't performing very smoothly. The idle was unstable and I had to clean the venturi cluster a few times when she stopped providing fuel for the idle, yadda yadda yadda.

After the nutter and swapping to the weber the engine performance was all around smoother, BUT, it came with a trade-off. I know the 32/36 is supposed to be a more fuel efficient upgrade, but off the line I feel like the weber has 1/2 as much power as the carter did. The weber seems to work well in the higher rpm ranges of each gear, but is not very powerful down low. Anybody and everybody (except for semis) beats my off the line when the light turns green.

I remember reading on a weber site (after I had already purchased and installed the carb) that for a 4.2 that has had modifications like mine has had the 38 carb is the better choice and it's close to impossible to get the 32/36 to perform to it's full potential. Any thoughts on this? Anybody else have a 32/36 on a 4.2 with upgraded ignition and exhaust manifold?

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post #2 of 5 Old 07-04-2013, 03:40 PM Thread Starter
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1989 YJ Wrangler 
Join Date: Oct 2011
Location: Stevens Point
Posts: 291
I actually just found where I read that a long time ago! Check out #3
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post #3 of 5 Old 07-04-2013, 04:49 PM
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1987 YJ Wrangler 
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Location: west palm beach fl
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heres a thread on tuning the weber. when I had mine it did pretty good, definitely better than the carter.

Do everything with a positive attitude, it won't always work but you'll piss enough people off to make it worthwhile.

the voices aren't real but they sure have good ideas.
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post #4 of 5 Old 07-04-2013, 07:06 PM
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1990 CJ7 
Join Date: Nov 2008
Location: Ga
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Double check the engine for any and all vacuum leaks. They will kill your low end power.

Check especially the intake to head area and retorque the hold down nuts attaching the intake to head.

418 miles on 19 gallons of gas. Can't beat the BBD !
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post #5 of 5 Old 07-05-2013, 03:57 PM Thread Starter
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1989 YJ Wrangler 
Join Date: Oct 2011
Location: Stevens Point
Posts: 291
Don't believe there are any vacuum leaks. The intake and exhaust manifolds got a new gasket just last year, I retorqued just now anyway just in case. The only place I could possibly imagine an air leak would be in the carb mounting, but even that is only a year old and when I installed it I followed the guide word for word.

I have been through tuning it a bagillion times, usually always following the guide, but at times I have swapped jets, changed idle screws just to see if I could get it closer, but I can't. The last time I tuned the carb I followed the weber guide and that is how it is today. Don't get me wrong, she'll start right up and run fine, but somewhere something is lacking. I say this because I remember a noticeable difference in low end power from the carter to the weber. In every other test the weber wins, all except for the low rpm performance.
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