[pontorquer]

Looks funny, different top maybe ?

[PAUL K]

The vent tube has been cut off....probably the wrong top unless it's a California emissions carb.

[Shiny]

Listing on eBay for this carb says the vent was cut off (not mine but was watching the listing):

https://www.ebay.com/itm/12423001598...p2471758.m4704

"The only issue that I am aware of is the the air horn vent on the top front has been milled down to fit under a low profile air cleaner"

Looks to be a nice carb otherwise...

[Joe's Garage]

In addition to that:

1) Vent tube is machined off (as already noted).
2) Several small holes drilled into the vent tube housing. Front, rear and side holes shown in pics.
3) Tube to connect the charcoal canister to the carb is missing.
4) Wrong choke pull-off (should have two vacuum nipples).

I'd predict that the air bleeds, etc. are different sizes on the two tops, due to the California emissions standards. So the calibration would be off.

The 7040267 number indicates a NON-California carb. The California-emissions carbs usually have a '5' in the fifth digit position (ie: 7040567) vs 7040267.

Here's a link to a picture of a California 7040567 (the pic on the right):
https://www.carburetion.com/CarbNumb...Number=7040567

And one that shows what an un-modified 267 carb top looks like (again, the pic on the right):
https://www.carburetion.com/CarbNumb...Number=7040267

[Navy Horn 16]

Originally Posted by Joe's Garage

In addition to that:

1) Vent tube is machined off (as already noted).
2) Several small holes drilled into the vent tube housing. Front, rear and side holes shown in pics.
3) Tube to connect the charcoal canister to the carb is missing.
4) Wrong choke pull-off (should have two vacuum nipples).

I've got a 70 Q-Jet off a GTO, and it doesn't have the charcoal canister tube, and only one vacuum port up front. The choke pull off is the same as pictured.

[pontorquer]

Thanks everyone, now the question is how hard it would be to find the correct top ...

[77 TRASHCAN]

Drop CLiff an email, if he doesn't have one, he might know of a source...

[Joe's Garage]

Originally Posted by Navy Horn 16

I've got a 70 Q-Jet off a GTO, and it doesn't have the charcoal canister tube, and only one vacuum port up front. The choke pull off is the same as pictured.

That would be a 49-State-emissions carb with a replacement pull-off.

Every State EXCEPT Kommie-fornia got one carb - like yours - while California
got the one with the big vent and charcoal canister one year ahead of everyone else.

The choke pull-off with a single nipple is the aftermarket or replacement style.

Factory quadrajets in 1970 had the metal pull-off with two nipples - one went to the carb vacuum port and the other to a vacuum canister on the passenger's-side inner fender. The carb was calibrated to take into account the extra vacuum when the throttles were opened and the secondary air flaps were pulled open. The pull-off (actually called a 'vacuum break') would slow down the opening and prevent a bog.

Gasoline vapors from the intake manifold and carb would collect in the canister on the passenger's inner fender when the engine was turned off and then enrich the mixture momentarily when the engine was started back up. Less release of un-burned gasoline fumes into the atmosphere, as they would be contained in the air cleaner housing and the canister and then burned and sent off with the exhaust.

In 1971 they added the big tube and charcoal canister on the radiator support with the associated hoses and lines and stuff on 49-State cars. California got it on their cars in 1970.

The dual nipple pull-off was more expensive and has only recently been reproduced.

As far as finding the correct top, hopefully Kenth can chime in with the correct casting number. He has a serious handle on that stuff.

Good luck.

[grandam1979]

I didn’t think qjets had the big tube till 71 ?

[Joe's Garage]

And they changed the 5th digit to a '5' to note it was a 'California emissions' carb.

There are a lot fewer of them than the 49-State carbs, particularly for 1970.

['ol Pinion head]

Airhorn is incorrect. Should have the 49 state 70 Pontiac airhorn, as well as a non '70 RA airhorn. Have boxed & in the shelving a 7040268, several 7040263's, & 7040570 & have rebuilt many more 70 Pontiac application Qjets.

My bet, w/o cking a Rochestor Master Parts book (which is what Kenth is sourcing) is an airhorn off a 70 Pontiac 49 state non RA application Qjet would be what one would be looking for. Will ck later tonight. Thought i had a few 7040262's but have not come across them yet, 262's are usually what I rob small parts off of, ESP screws.

[pontorquer]

No hurry OPH, I don't even know if I'll win the auction ... Thanks

[Greg Reid]

Are you guys having much luck mixing and matching bowls, bases and airhorns from different carbs?
I replaced the airhorn on the last carb I rebuilt because the original had been damaged/slightly melted...and I never could keep the airhorn gasket completely dry when completed. I belt sanded the airhorn as far as I dared with only limited success. It got better but never solved it...Wound up buying a complete core and rebuilding it instead.
It's a shame too because it runs fantastic after using Cliff's recipe and parts.
I just couldn't feel comfy with that fuel seepage going on.

[Cliff R]

It's basically what I call here a "Frankencarb", mixed/matched components and may have been commercially "remanufactured" at some point. I don't think the baseplate is correct either, but can's see enough of it to tell for sure.

In 1969 and 1970 the non Ram Air carbs got an airhorn that used a primary side POE system so those tops are unique to those two years. They are not the same either but will interchange. One has the adjustable airbleed screw as the upper idle airbleed (1969), the 1970 model used that screw to fine tune the upper MAB. CA only in 1970 got the first of the tops with the large vent tube and the nipple to the charcoal canister as mentioned.

The white plastic pull-offs currently being produced don't "dampen" anything, they use the wrong spring and the hole in them is HUGE. I take every one we sell apart and modify them so they work correctly, no one else is doing this that I know of.

1970 non Ram Air also got the pull-off with two nipples on it although it's pretty rare to see one actually being used like it was suppose to, so the plastic pull-off usually gets installed to replace it........Cliff

[Kenth]

The 1970 non-RA Pontiac Quadrajet carbs i´ve taken notes on is 7040264 400 A/T and 7040268 455 A/T.

These two have the exact same cast numbers (and fine stamped numbers.)

On air horn the cast number is inside (Rochester made) #7038736. On Carter made units this cast number can be found on outside of air horn.
On float bowl the cast number is #7038024.
On throttle plate the cast number is #7037174.

There is no reason to believe carb #7040262 would be different than these two regarding the cast number on parts.

[P@blo]

Hello Pascal I hope all is well. Are you specifically looking for that carb number? If not I might be able to help you out as I have a few carbs sitting around collecting dust.