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Discussion Starter · #1 ·
I have a problem and cant figure it out.bbc in 72 chevelle when cruising car runs great when i mash throttle i get a popping thru carb for about 3-4 seconds and then it takes off.timing is at 36 deg.at 3000 rpms.edel.carb 800cfm.i jetted up rich 4 % on chart both prim. and secondary.dont no what else to do.got a 1 inch spacer between carb n manifold rpm air gap.th400,3000 stall tci,3.73 gears.good it need more timing?thanks.
 

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too many toys,not enough money
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Try the lighter 3hg first, if it helps great. If it gets worse, go to the stiff 8hg spring see if that does anything for you.


Also you may be lean on the power mode. Think outside the gride. You say you have a 800 cfm Edelbrock, so I'm guessing you have a 1812 or 1813 carb, if you jetted up 4% from #1 on the chart, you'd be at #7, so try the #3 spot on the chart. It will lean up the cruise mode, but will richen the power mode.

I just went through this on mine. I had the same, low end '' bog " or pop through the carb when I put the petal to it, from a low rpm. I'm at 4,500 ft and am at # 3 on the 1407 chart and thinking I need to richen the power mode another notch. You may need to go richer yet than #3 on the 1813 chart, on the power mode.
 

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My pipes are my music
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Somehow, it's going lean when you mash it. Have you tried changing the linkage to the accelerator pump arm? It should have 3 holes. The one closest to the fulcrum will give you a biger shot and may cover the bog.
 

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More for Less Racer
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I feel opposite of MT71c-10, you need to go to a stiffer spring. You have a lean hole in the fuel curve under WOT, the stiffer spring will lift the metering rod out of the jet sooner.

Sqzbox is correct about the accelerator pump arm, you may need a bigger shot and the pump arm would be what to do first, then the metering change if needed.
 

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too many toys,not enough money
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It just takes some playing around ( unless you can get an air fuel meter ) you will go backwards some but you will figure it out. Edelbrocks are easy to rejet, all it takes is time. Good luck and repost if you need any help.
 

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too many toys,not enough money
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97 Posts
I did forget about the accelerator shot. As sqzbox said, the top hole is the richest shot, but the nozzle is probably a 35, you may need a 45 to get it right. I had a 45 in mine, changed it back to the 35 and it would barley move without a lot of throttle playing, changed it back after rejetting richer and it helped a ton.


As for springs it just depends on what your engine wants. Try the stiff first if you want, it does'nt matter, either way I would try both just to see what works for you.
 

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Discussion Starter · #11 ·
i changed to the silver springs,and at first it was the same then i drove all weekend and it seem to get better.i still might try a bigger shot like a 43 i will pull the 35 out.thanks for asking.like you said it takes time to fiddle with it.
 
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