Author Topic: Two Q-jets opinions on set up  (Read 2091 times)

Offline montez27

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Two Q-jets opinions on set up
« on: October 01, 2015, 08:11:22 AM »
My main question is what effect the main air bleed has on the jet/rod combo and can recommendations be made for certain size main air bleed (I am using the single main in the air horn). My combo is a ZZ4 with TFS heads and a Smokey ram SY1 cross ram. The lid is modified for the Q-jet. No adapter being used just a correct 4 hole spacer.

First carb is a 17088041 (big block truck carb with unique rear sec venting. They are plugged and the SEC main well tubes are at .035) I know it isn't the first choice but it was a very clean solid  core.
I'm running a 76/54m combo. DR/K sec combo.
The main air bleed is .0875.
   The idle circuit is set up very nice and it idles very nice with control from the mixture screws. (i have idle tubes purchased from Cliffs)
   Carb runs very well with a slight lean cruise. (should I use a 52m rod or go up on the jet/rod combo)?

Second carb I have is not built yet but it is a 17080298.
Main air bleed on this one is at .050.
   I have run a 74/52k, sec DR/I hanger in this carb but it was years ago.
   Again I am not concerned with the idle circuit as I can get it set up no problem.

My main question is what to do about the main air bleed sizes if anything and to have a general understanding of what to use jet/rod combo depending on the air bleed size.
   Thank you for any insight on the matter. I know you are busy and I appreciate that Cliffs can provide the small parts I need in order to get these Q-jets up and running. They always perform better than any Holley I have tweaked.
    Thanks again
   Monte

Offline Cliff Ruggles

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Re: Two Q-jets opinions on set up
« Reply #1 on: October 16, 2015, 05:19:54 AM »
If you are working with single main airbleed carburetors leave the main airbleeds at the stock sizes.  They are "indirect" bleeds.  A few numbers difference in jet size makes up the difference.

The "M" series rods were used with those carburetors with .036" tips.  If you use smaller tipped metering rods, you will need to reduce the jet size some or they will be rich at heavy/full throttle.

52K is a very poor choice for one of those carburetors, as it only provides .005" of tuning room on the upper section.....Cliff