Author Topic: 7041264  (Read 3634 times)

Offline bober

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7041264
« on: November 06, 2016, 06:45:16 AM »
7041264 Q/jet anything popular or hard to find ? This is from a 72 running 400 /auto. Thanks

Offline Ethan1

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Re: 7041264
« Reply #1 on: November 06, 2016, 08:07:51 AM »
7041264 Q/jet anything popular or hard to find ? This is from a 72 running 400 /auto. Thanks

 http://newagemetal.com/pages/Pontiac/70-74/pages/70-79Pontiac0023_jpg.htm

 I would say it is neither popular or hard to find to be honest. Sometimes you find them, sometimes you don't.
Ethan

1972 Chevelle

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Offline bober

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Re: 7041264
« Reply #2 on: November 06, 2016, 07:55:01 PM »
Thanks Ethan , I have a great running 400 w/this carb on it so I thought I should check on it . Not sure yet if I'll use this for myself yet or not . Appreciate the info  !!!

Offline Ethan1

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Re: 7041264
« Reply #3 on: November 07, 2016, 12:58:43 AM »
 Not a problem, bud. Glad I could help! 8)
Ethan

1972 Chevelle

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Offline unruhjonny

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Re: 7041264
« Reply #4 on: August 30, 2017, 09:58:04 PM »
7041264 Q/jet anything popular or hard to find ? This is from a 72 running 400 /auto. Thanks
I realise this is nearly a year old question, but I feel my opinion is merited;

7041264 = 1971 Pontiac 400/auto

Considering this is now nearly a fifty year old carburetor, I'd say that good ones ARE getting rather rare to come by.

In the last approximate twenty years, I have come across only two of these units, and after earnestly trying, I had to give up on the first one I had, because it seemed warped beyond my ability to fix it...

Also, the 7041264, and it's stablemate 7041262 (455/auto), in my opinion are both grossly overlooked castings.

To the best of my recollection all other 1971 Pontiac 400 & 455 carbs were the single booster ring units, and are becoming exceedingly rare to come by, and with that cones a hefty price tag - something not all people can afford to pay.

It should be of interest to some, that I have read that it wasn't uncommon for original owners of 1971 Pontiacs which came equipped with the single booster ring casting carburetors to complain about off idle throttle responce (because of the diminished signal which is directly attributed to the single booster ring design), and that often a 7041264 (400ci), or 7041262 (455ci) carburetor was installed to remedy the issue.

For the 1972 model year, Pontiac went back to the dual booster ring castings - that should say sonething in and of itself.

It is my opinion that these 1971 core carbs are ideal replacements for owners of 1971 model year Pontiac 400/455 cars which are missing the correct single booster ring carb - and that when set up properly (via the likes of Cliff) that these should run just as good as the OEM carbs.

The 1971 750cfm (dual booster ring) Pontiac carbs are essentially carry overs from 1970, but with different airhorns which attempted to prevent fuel vapor from entering the atmosphere;
All 1970 & prior 'Ram Air' carbs used the dual booster ring 750cfm casting, so I don't see why these overlooked carbs shouldn't be saved when ever possible.

When comparing the 1971 dual booster ring castings to the 1972 castings, they are essentially the same thing, with the sole exception being that for 1972 the base plate (aka: throttle body) was changed to have a fixed throttle arm...

Offline Cliff Ruggles

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Re: 7041264
« Reply #5 on: August 31, 2017, 03:25:54 AM »
The single booster ring models are excellent, but every tightening emission standards in that time period simply would not allow them to be used past 1971.  As you mentioned lacking the outer rings hurt efficiency right off idle/low throttle angles and that's where the EPA wanted them to be the cleanest. 

They are excellent units and with a very slight recalibration work flawlessly on the big 455 ho engines.  They have several advantages over the standard castings.  One is that they flow 828cfm instead of 750.  They also delivery considerably more cfm on the primary side you can achieve more power and speed w/o the secondaries.

I've drag strip tested the 71 ho carburetors and they will outrun the 750 castings without much trouble and that's probably why NHRA banned them in stock and super stock classes unless you have a vehicle/engine combo that originally used one.

In 1973 Pontiac answered the problem with the 455 Super Duty carburetors which were the larger castings typically dubbed "800" cfm.  They actually flow closer to 850 same as the "famous" Edelbrock 1910 units, but they are much better carburetors than the 1910's, at least in stock form....imho.....Cliff

Offline unruhjonny

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Re: 7041264
« Reply #6 on: August 31, 2017, 12:37:38 PM »
Thanks for chiming in Cliff!

my comments were not in any meant to diminish the performance or potential of the '71 single booster ring Pontiac Quadrajets, but was meant only to try to point out that the '71 dual booster ring quadrajets are (undeservedly) often overlooked - and good candidates as replacements for a 1971 Pontiac which has a wrong year/application carb to begin with.

I do believe that the advertised net horsepower ratings of the 1971 455HO matched the 1972 455HO - in spite of the different carburetors;
I am pretty certain the same can be said for 1971 vs 1972 400 net horsepower ratings.

Offline Cliff Ruggles

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Re: 7041264
« Reply #7 on: September 01, 2017, 02:59:56 AM »
The 455 HO engines didn't have big enough cams in them to fully see the potential of the head flow, so there wouldn't really be any advantage to have a 1971 single booster carb on one vs the standard unit.

I've actually dyno tested those carburetors back to back on 455's at the 500hp mark, and they make equal power to about 4500rpms.  From there on up the larger carb will make more power. 

In terms of vehicle performance the difference isn't much because the engine will spend very little time above 4500rpms on a full throttle run. 

In terms of smoothness of idle, engine efficiency and MPG's, the standard version is going to win in all those categories. 

Couldn't comment on folks overlooking early Pontiac units, we like all of them here, and they are not getting any easier to obtain.  There still seems to be plenty of later units, 73-74's are in good supply, and there is little demand for them unless it's a Super Duty model.......Cliff