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 Building Q-jet for mild 350 in daily driver 
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 113
novadude wrote:
Is a 72 primary jet too big for .046 MABs? I've observed that many OE 350 ci Chevy carbs that used small 0.046" MABs seemed to have ~67 jets and 39 primary rods.

Building one for the Nova or something else? What carb is it?


Tue Oct 25, 2016 10:54 am
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Joined: Tue May 06, 2014 5:34 pm
Posts: 45
novadude wrote:
Is a 72 primary jet too big for .046 MABs? I've observed that many OE 350 ci Chevy carbs that used small 0.046" MABs seemed to have ~67 jets and 39 primary rods.


I've done quite a few Qjets with .046 dual main air bleeds (from .120") with 72 main jets along with Cliff Ruggle's .044 full tapered custom rods. On stock engines, heavy load always ends up around 12.5 on a wideband, and at light load (cruise) I can pretty much chose where I want to be, from let's say 14 all the way to 17, thanks to the APT. And I can confirm that cruising at 17 is no problem. I also always set-up my idle circuit the Tuner way and it works wonders.

This is my usual starting point on the primary side. Hope this helps, Frank.


Tue Oct 25, 2016 12:38 pm
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Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
I just bought a my kit and a 72 jet with a 44 rod from Cliff. Not sure if it is a full taper rod but it is a K style with the .026 end, haven't actually had time to put a mic on it.


Tue Oct 25, 2016 1:54 pm
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 113
Any of the of the K rods I've seen didn't have a taper.
You could try what I did & use bigger jets & the M rods they go up to 54 or 56 I think.


Last edited by 77cruiser on Tue Oct 25, 2016 5:05 pm, edited 1 time in total.



Tue Oct 25, 2016 4:26 pm
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Joined: Fri Oct 23, 2015 8:43 am
Posts: 33
77cruiser wrote:
novadude wrote:
Is a 72 primary jet too big for .046 MABs? I've observed that many OE 350 ci Chevy carbs that used small 0.046" MABs seemed to have ~67 jets and 39 primary rods.

Building one for the Nova or something else? What carb is it?


Thinking of trying some things with a 2-air-bleed 1980 Chevy carb to see if I can get a more optimal part throttle fuel curve (running a SMAB unit now that doesn't seem as "tuneable. Seems like the Single air bleed card isn't as easy to tune for all Rpms / loads.


Tue Oct 25, 2016 5:04 pm
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Joined: Tue May 06, 2014 5:34 pm
Posts: 45
Hey Novadude, if you go with a dual .120" main air bleeds, you'll absolutely love it. Try one and let us know how it ends up. Those are my favorite style by far.

Frank.


Tue Oct 25, 2016 8:22 pm
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Joined: Wed Oct 23, 2013 8:01 am
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The one I converted from SMB to DMB, best running carb I've had. Starts cold with a touch of the key AFR runs 12.5 till choke comes off then it idles 13-13.5 steady cruise I'm at 14.5 -15 get into a bit & it's up to 15.5. Now if I could keep it full at WOT I'd call it Rochester FI. :w00t:


Wed Oct 26, 2016 8:34 pm
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Joined: Fri Oct 23, 2015 8:43 am
Posts: 33
77cruiser wrote:
The one I converted from SMB to DMB, best running carb I've had. Starts cold with a touch of the key AFR runs 12.5 till choke comes off then it idles 13-13.5 steady cruise I'm at 14.5 -15 get into a bit & it's up to 15.5. Now if I could keep it full at WOT I'd call it Rochester FI. :w00t:


Did you use small .046" bleeds, or the large .120 bleeds?


Wed Oct 26, 2016 9:40 pm
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 113
.046


Thu Oct 27, 2016 7:17 am
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