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Lars, got a question, why is there any difference between a Qjet for a Poncho 455 and a Chebby 454/427/etc......I can understand they block off the secondaries from full opening for say a 350 engine.....but why would the carbs be any different between types/brands of engines.....SIZE I can understand, but what was the reasoning on the most important points???
GENE, olde tyme Poncho hotrodder, my first car was a '60 vette in '66, paid 1000 bux for it....been a while....
My papers outline all the sources for the various rods. Only a few select rods are available, and almost none of the 1975+ M4M passenger car primary rods are available. I try to update the sources and availability in my papers as time permits, so the listing is fairly current and accurate. The rods that are not available can only be obtained by stripping down used parts carbs.
As a reminder, don't use any of my papers you find posted around on the Internet - I don't post my papers, and those posted by others are always obsolete and often altered. E-mail me a request for current copies.
That's a great vintage picture!. Lars is that really you in your avatar? Hilarious.
Here are some pics of carb stamps that show the same smaller font that I believe are real. The first is of a 7029202 dated 0379. You will see it has the same font as the 215 in your pic.
Her are some pics of 215's dated 0379 and 0569 with the same font.
Do you have any preference for vendors for there rebuild kits? What should we look for in these kits beside gaskets?
I have been using the NAPA/Echlin parts for 40 years with generally good success.
Originally Posted by mrvette
Lars, got a question, why is there any difference between a Qjet for a Poncho 455 and a Chebby 454/427/etc......I can understand they block off the secondaries from full opening for say a 350 engine.....but why would the carbs be any different between types/brands of engines.....SIZE I can understand, but what was the reasoning on the most important points???
There is no difference in size on the Q-Jets. They are all 750 cfm, except a few carbs that were 800 (Pontiac and Buick had some 800 cfm 4MV carbs, and Chevy had some 800's in the M4M configuration).
You don't want to just lock out the secondaries when cold on a 350. Any engine will suffer engine damage if pushed into the secondaries when cold, regardless of size.
The differences are in the linkages, fuel inlet configuration, air bleeds, fuel bleeds and jetting. As noted, Pontiac chose to do cold engine secondary lockout by locking the airvalve, whereas Chevy chose to lock out the secondary throttle shaft. The parts required to do those operations differently are completely different from one manufacturer to another. Vacuum connections on the carbs are also completely different from one manufacturer to another: For instance, Pontiac carbs do not have a front PCV hose connection, because the PCV attached to a special fitting on the manifold in front of the carb. Throttle levers are completely different from one manufacturer to another, as are fuel inlet locations due to Pontiac and Buick having the fuel pump on the driver's side of the engine block. Due to all these differences, I do not recommend swapping Q-Jets or Q-Jet parts between GM makes - it can make setup a real mess.
I have been using the NAPA/Echlin parts for 40 years with generally good success.
There is no difference in size on the Q-Jets. They are all 750 cfm, except a few carbs that were 800 (Pontiac and Buick had some 800 cfm 4MV carbs, and Chevy had some 800's in the M4M configuration).
You don't want to just lock out the secondaries when cold on a 350. Any engine will suffer engine damage if pushed into the secondaries when cold, regardless of size.
The differences are in the linkages, fuel inlet configuration, air bleeds, fuel bleeds and jetting. As noted, Pontiac chose to do cold engine secondary lockout by locking the airvalve, whereas Chevy chose to lock out the secondary throttle shaft. The parts required to do those operations differently are completely different from one manufacturer to another. Vacuum connections on the carbs are also completely different from one manufacturer to another: For instance, Pontiac carbs do not have a front PCV hose connection, because the PCV attached to a special fitting on the manifold in front of the carb. Throttle levers are completely different from one manufacturer to another, as are fuel inlet locations due to Pontiac and Buick having the fuel pump on the driver's side of the engine block. Due to all these differences, I do not recommend swapping Q-Jets or Q-Jet parts between GM makes - it can make setup a real mess.
Lars
To ME, what is the diff about vacuum fittings?? it's either full mani vac or ported vac, why bother about changes between engines?? 455 is 455 wether chebby/poncho/olds/caddy,even buick....or a 440 mopar....and as for secondary opening, isn't that a factor of the RPM/suck/air demand of the engine?? the flapper up top always seemed to be too loose to me, as I recall....I always had the spring on the right/pass side on full snugged up then tighten the set screw....flapper could still fully open of course....
My carb says Rochester 4 barrel but no number on it . Had it rebuilt twice and the second time he used a kit i found out was for a two barrel carb That kit was auto-tune a Napa product. My question is what is the most important item that should be completed on a rebuild.?
My carb says Rochester 4 barrel but no number on it . Had it rebuilt twice and the second time he used a kit i found out was for a two barrel carb That kit was auto-tune a Napa product. My question is what is the most important item that should be completed on a rebuild.?
There is no way a 2-barrel kit could be used to rebuild a Q-Jet. Not a single part, component or gasket in that kit could be used on a Q-Jet. Not possible... The most important part of a rebuild is to fix all the errors made by previous builders, replace the incorrect parts, and set it up to spec.
I have saved every item on my 77 since i bought it including these rebuild kits and this is what i gave this carb shop for the rebuild. Being retired i have more time to go through my 30 years of parts and this what i found. The kit was bought from Napa 5-01-97 . This was a carb shop in hartford Ct The other kit a Hygrade was the first kit used for the rebuild which was correct but car never ran like my previous two 75. . What is a good kit and who sells it now? Napa has no kits i can find for my rocking Rochester.
Napa has no kits i can find for my rocking Rochester.
That's not correct. NAPA carries all the kits.
If your carb is a 1977 Q-Jet for a Vette, the part number for the kit is 2-5795A.
All 1977 Q-Jets are stamped with the carb number, and they are not stamped with anything that says "Rochester 4 Barrel." They have a cast logo that says "Rochester QuadraJet." Has someone switched your correct Q-Jet for a Rochester 4-Jet?
This is a correct 1977 Corvette Q-Jet. Does your carb look exactly like this?
Does not say "4 Barrel." Q-Jet is marked with "QuadraJet" logo:
This what i have carb # 17058204 . Shows to b a looking at the no 8 digit a 78 production number a 7 would be a 77 production number.There are two stampings Rochester Quadrajet made in usa
This what i have carb # 17058204 . Shows to b a looking at the no 8 digit a 78 production number a 7 would be a 77 production number.There are two stampings Rochester Quadrajet made in usa
Your carb is a '78 Vette 350 Federal emissions, for air conditioned car with auto trans. It takes carb kit 2-5798A, which is a common kit carried by NAPA.
Originally Posted by fake
There is a circle with a different number 170598 the rest of the last two numbers i can not make out is this normal ?
That's a casting number, which is irrelevant. All of the castings on the carb have a casting number. Common core castings were used to create multiple different end usage part numbers.
Be aware that the carb you have pictured above is a commercially rebuilt carb that has been sandblasted and stripped of all original finishes. Cheap commercial outfits that sandblast carbs also commit a slew of other atrocities to the carbs, so the carb shown will have a ton of problems...
Its never been to a company shop. Local guy had it. Whoever cleaned it used something like awesome or simple green i think....it takes all the color away. And for guy who needs it...all they want is the main body number. Everything else can be found to make it 99% correct.
Be aware that the carb you have pictured above is a commercially rebuilt carb that has been sandblasted and stripped of all original finishes. Cheap commercial outfits that sandblast carbs also commit a slew of other atrocities to the carbs, so the carb shown will have a ton of problems...
Lars
Hey Lars, thanks for your very helpful posts. I have a 68 pontiac q jet that I have had since 1979. I bought a set of heads and intake from the 68 and never did use the carb. It had a "delco reman " sticker on it with a part # so am wondering if delco actually rebuilt it or did they farm them out to another rebuilder? Thanks!
03-03-2019, 04:19 PM
