My 1st post in here : carb tuning problem

Hamad

Hamad

Member
Joined
Apr 15, 2009
Messages
14
Location
Doha
Hi all,

This is my 1st post here, but I was reading this forum since it was 1st established. I have a problem setting the A/F mixture screws in my QJET carb, the story goes like that, I got a '71 BB and before I started the engine build, I've sent my carb to Lars for a rebuild, which he did and the carb was perfect for my engine and was running excellent with no adjustments what so ever, but when I re-installed it after a full engine rebuild I feel a little hesitation and I dont feel the power like it was before, so I thought about re-adjusting the mixture screws using a method that I read about a while ago, which is using a vacuum meter and setting the screws for the highest reading, well, I saw no difference at all while adjusting the screws! .. not even idle speed change!, so I just set both of them 2 turns from full in and the car will run OK, no over-heating , just the hesitation and a little choked, no real BB power there! ..

Any suggestions?

BTW, I got a stock LS5, except for a 9:1 comp. and a little bigger cam (Lunati 60202).
 
Take a stethoscope and listen around the carb base, or intake passages....I bet you got one hell of a vacuum leak somehow....

you could try lowering the idle off the adjustment screw, or make sure the throttle is free to close all the way, linkage and all that crap....

I bet you have kind of a high idle too...no??

:bonkers:
 
Any carb that I have built is eligible for return to me for a complete checkout and test at no charge other than return postage.
Lars
 
Hi

I am not a carb spezi, so pls correct me. I thought that this screws you adjust are only for the idle mixture. Nothing to do with power which is regulated by internal needles.
I would take Lars's offer .:nuts:

Rgds. Günther
 
Thanks guys for all the responses, and special thanks to Lars :thumbs:

The problem was the throtle cable position, it was connected to the upper hole (in the throtle linkage) , I just bolted the small ball stud to the lower positon to give a shorter leverage to the accelerator pedal, now I can open the secondries very easily and the performance of the engine is awesome!

Thanks again Lars, I should be proud that my carb was rebuilt and tuned by you!
 
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