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The vacuum port just to the right of the fuel filter housing in the main casting is the distributor port.  It is ported vacuum and will work fine for the vacuum advance.

What is the application and engine specs?  Most engines are fine with a good ported vacuum source designed for the distributor.......Cliff
Quadrajet Parts and Numbers / Re: Throttle Plate ID for a 7040273
« Last post by Kenth on April 17, 2021, 11:55:39 PM »
I would say yours is correct, comparing it to my original 7040270 plate.
Your spare shaft is from another carb obviously.

Quadrajet Parts and Numbers / Throttle Plate ID for a 7040273
« Last post by lintmann on April 17, 2021, 06:33:12 PM »
Hey Guys I was wondering if someone could help me ID this throttle body assy and the levers. I'm pretty sure it is original to my 7040273 carb but just wanted to be sure.

The casting is 7037174 which I think is correct however it was also used on other quadrajets of the era so that is only a clue. Hopefully it will have some other features that someone could use to confirm it's the correct throttle body assy.

My other question was about the primary throttle shaft/levers. Which one would be correct for this carb, the one that is in the body or the one beside it)? The one that is installed is the one that I believe to be correct. If you look closely at the small levers on the choke side, you will see that it is more pointed that the one that is not installed. Also, the radius of this one where the plates attach in the bore is quite sharp where as the one (green one) that is not installed has an obvious radius. Not that this radius should matter but it might help to ID the correct shaft.

Any help is appreciated as I'm about to rebuild this carb and want to have it as correct as possible.
Diagnose a Quadrajet carburetor problem / No Vacuum at Carb Ports
« Last post by Chevynation on April 17, 2021, 08:03:11 AM »
Hello, I had a carb rebuilt (7042220) and I don’t have vacuum at any of the ports. The choke pull off does have vacuum there but I’m trying to get full manifold vacuum for my distributor vacuum advance. So I can’t adjust the idle mixture screws since my gauge doesn’t read anything. I’ve tried seeing if my gauge was malfunctioning but the ports are clearly not sucking when I uncap them. The gasket is on correctly but what seems to be the issue? Could they have been blocked during rebuild?
For Sale / Wanted / No.s matching 1970 q-jet airhorn pontiac
« Last post by Mr.Pontiac on April 17, 2021, 07:26:50 AM »
Completely redone, 50.00$ pictures upon request
For Sale / Wanted / Re: Pair of 66-7 BUICK throttle shafts nicest in the country
« Last post by Mr.Pontiac on April 17, 2021, 07:17:41 AM »
Quadrajet Carb Talk and Tips / Re: #7044270 Secondary POE Restrictions
« Last post by Cliff Ruggles on April 16, 2021, 03:02:32 AM »
I've lost count of how many times I went to test carbs that used CC rods in them and the engine "puked" all over itself going quickly to full throttle.  A quick bend on the hanger with a pair of pliers to get them out of the jet holes and problem solved. 

Instead of bending hangers or looking for higher ones I just replace them and all the issues go away with no other tuning needed.

This is also interesting Kenth and something you need to know.  We were on the dyno with a 455 and making pulls on it.  A/F was showing a tad lean with a set of CV rods so I tossed in a set of CC's.  Going from .052" down to .030" should have fattened it up some correct?

Next pull it showed even leaner with the CC's in it!   Those rods don't have nearly as smooth of a transition to the skinny tips as other rods and fat section right above the skinny tips, so unless you get them up pretty high you can actually go leaner even though they have really small tips. 

I've repeated that testing several times and did some track testing with them as well.  This was early in my learning curve and I decided to custom machine a complete set of rods from the same cores.  I very carefully machined those rods from the same cores with the same tip length and included angle leading to the tips starting at .030" and going all the way to .060".  Next time I went up on the dyno metering changes were spot on and very predictable.

I still have those custom machined rods today and use them when tuning at the track.  I've also machined quite a few sets for dedicated drag racers who run in various classes, Pure Stock, FAST, SA and Super Stock.  It eliminates the need to "juggle" hangers around with different profile and tip size secondary rods and makes things a LOT easier when you tune.  Once you find a hanger that makes the grade for perfect transition you just change metering rods based on the weather, Density-Altitude, etc.......FWIW.....Cliff
Quadrajet Carb Talk and Tips / Re: #7044270 Secondary POE Restrictions
« Last post by Kenth on April 15, 2021, 10:46:04 AM »
We left the restrictions at .077", which are the largest to be found in any Quadrajet and common in Pontiac high performance carbs.
Also, we found the initial discharge was improved going to the cut-out air valves making the CC rods actually worked as intended.
High numerical rear end gears and high stall converter may have helped jetting with CC rods in this 455 SD engine some.
Respond at WOT was instant w/o hesitation of any kind.
Quadrajet Carb Talk and Tips / Re: #7044270 Secondary POE Restrictions
« Last post by Brian B. on April 15, 2021, 05:55:41 AM »
Thank you gentlemen.

Kenth.....did your friend leave the Secondary Restrictions stock or were they enlarged. you prefer rods along the order of AX or DA?
Quadrajet Carb Talk and Tips / Re: #7044270 Secondary POE Restrictions
« Last post by Cliff Ruggles on April 15, 2021, 05:04:47 AM »
CC secondary rods are HORRIBLE, too fat up top and too small on the bottom.  I refuse to use them for tuning as they need a pretty tall hanger to get them up out of the jets holes quite a bit to get a clean transition going to WOT.

I've actually had better success removing the notched Pontiac flaps and installing solid ones that the other way around IF the holes were under the flaps or directly in line with them with a large opening exposing some of the entrance under the flaps. 

Another neat trick when tuning the secondaries is to leave a very slight amount of slack in the linkage so it can "tip" back just a tad exposing the POE holes to the underside of the flaps and fuel from the holes directly to the intake........Cliff
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