I have a 1970 455 Stage1 Qjet #7040246, it is the real thing and original, datecoded etc. I am rebuilding the carb for a customer, it is not for sale. I note that the baseplate does NOT have the idle air bypass holes drilled in front of the primary bores. Can someone with one of these carbs please look and tell me if they should be there? I know that the 1970 455 non stage carbs DID have the idle air bypass holes. And that the 1971+ Stage1 carbs did have them. This is the first 70 Stage1 carb I have personally looked at, and I want to be sure if the holes should be there or not. Thanks for any help.
I have looked more closely at the baseplate on this 7040246 Stage 1 carb, and it has part #7038888 in a circle towards the rear pulloff vacuum nipple. I checked a bunch of 1970 7040240s and 7040247s and they also sport the 7038888 designation on the baseplate. Does anyone have a 7040244 350 carb that they could check for this baseplate #? I have attached a pic of the holes locations as indicated by pen and pencil. A few things come to mind 1) factory could have left off the bypass holes on Stg1 carbs in 1970 2) baseplate could have been swapped out for a 350 baseplate - they dont use bypass air holes, and in 1970 could have the same 7038888 baseplate casting# 3) could be a factory "oops" where an operation got skipped I sure would like to confirm one of these as the "right" answer I tend to think that the holes should be there. Any help appreciated.
Ken, there is one of these on ebay now that definitely looks original. Many different shots, take a look you might spot something. I have one (246) on my car now, I have the original carb also. I'll see if I can look it over a bit today.
WOW this is super interesting to a Qjet geek like me. heres the one on ebay I found, thanks Frank http://www.ebay.com/itm/1970-Buick-...Parts_Accessories&hash=item1c39c12ce3&vxp=mtr looks like the real deal with 218th day of 69 datecode and 2nd POE holes below the airflaps I note that it does NOT have the idle air bypass holes. VERY interesting
Hey Ken. I have done several of these, and I keep notes on all of the measured components, but many of these have been modified over the past 40 years. I have one in my shop now, and it does have the idle bypass holes, but I also know for a fact, it was modified and changed up. Does the body itself have the bypass holes? That is one place I always look to make sure the base plate and the body are on the same page. If the body has the holes, then the base plate should also have them. I have a pile of base plates and can check on the numbers later today and see what I can find to help out.
Ken, I have a 7040244 350 carb that Dustin was going to put on my car before the 455 went in it. I just looked at the base plate and the lower side looks just like the pic you posted. I then scrubbed the gunk off and it also has the same numbers in the circular pattern as you are asking about (7038888)this carb has a build date of NA 2779 on the side below the 7040244. It also has a 4 digit number on the bolt flange by the 7038888 number. That number is 38753... If you need pics,I work till 8 pm and could get them then for you. PS, I would sell this carb for a good price..
Ken, I the 71 Stage 1 that I had, that appeared all original did have the idle bypass holes that measured .090. Yea, I know, it wasn't a 70.
Thanks for the input fellas So the 1970 Buick 350 Qjet has the same baseplate number 7038888 without the holes, so that means one "could" have been swapped in. yes the 7040246 air horn and main body have the passages necessary for idle air bypass We now have two very original 246 carbs confirmed without the idle air bypass holes One 246 (modified) with the holes Lets see what Frank turns up with his two 246 carbs....
Ken, it's actually only one 246 I have. When I said the original, I meant a 240, because it's not a Stage 1 car. The 246 is on the car now all hooked up. It's immaculate, all replated and I can't see anything hinky about the stamp. It is NFS, at least for now. I leaned way over + can't see the circular baseplate # well. It does have the B like the ebay carb. I did look down through or by the choke plate but can't see well. Problem is...I don't know if it's a good reference because it was not original to the car, and it's clearly been rebuilt. Also...it's on the car and to see the holes I'd have to take it off the manifold. I have 2 240's that are unmolested down to the white stripe hose I can look at easily, but I know it's the 246 you need the info for. I don't think I'm going to be much help here for you other than the ebay listing. I don't want to keep you hanging when surely someone here has 1/2 dozen of these on their shelf.
I've got a 7040244 and a 7040240 that has the same 7038888 # on the Base Plate and the 240 has the same hole in your picture. The 244's on the motor right now so I can't see the bottom.
When looking at what the factory did to the 7040246 and the 1971 and later 455 Buick carburetors, you have to take into consideration that the 1970 engine still had pretty high compression. This offsets the overlap from the big camshafts that they used, and lessens the need for idle bypass air to make them happy at idle speed. When you take nearly 2 full points of compression out, and still use a pretty "hefty" cam in them, idle bypass air is going to be needed in most cases. It's also extremely rare to find anyone building a completely "stock" engine these days right down to the stock cam, compression ratio, all stock emission devices in place and operational, etc, plus we have to factor in lower quality fuel with ethanol/oxygenated, so in most cases the factory calibrations aren't going to be ideal anyhow......Cliff
bump for any more info on these. Thanks everyone for the info so far. My interest is in the original configuration of these 7040246 carbs. Whether or not they had idle bypass air holes in the baseplate when they came from the factory? It seems kind of oddball that the factory would leave bypass air off these stage1 7040246 carbs when they were adding bypass air to the non stage 7040240 carbs of the same year. Seems like the non stage carbs would need it even less. But I do tend to believe this carb came from the factory without the holes. Anyone who has got one of these carbs feel free to chime in thanks
