74VETTE

I had gotten Lars' paper on the quadrajets and was able to look up what application the one on my car came from. I have a 1974 Corvette with 454 engine and auto trans. The correct carb for my year is code 7044225. Somewhere along the way my original carb must have gotten swapped. The Qjet on my car now has code 7043201 which is from a 1973 truck with a 454 and manual trans. Does anyone know the difference between these two? Should I stick with what I have or replace it? What is the difference in a carb built for a manual vs. a carb built for automatic?

mar

How does it run? If it runs good I'd leave it alone. My 74' SBC 4-spd has a truck Q-jet carb on it too. It runs unbelievalby great. Starts right up, hot or cold, no hiccups or anything. Very likely that the truck carb was not mated to a manual tranny. Experience has shown me that certain things on old cars should not be tinkered with if they are ok. Consider yourself blessed if it runs good.

74VETTE

It runs OK. It stumbles a bit until it warms up. Starts up usually on the 2nd try after pumping the gas about 5 to 6 times.

PAmotorman

7043201, 77 jet, 48 pri rod ,DA secondary rod. 7044225, 75 jet, 41 pri rod, DH secondary rod

74VETTE

So would there be any material benefit in taking it to the 7044225 specs?

73, Dark Blue 454

7043201 was also used on the Corvette in 73 that were equipped with a 454 and a 4-speed. I don't know if it was used on trucks as well. Seems trucks received their own stampings.

The specs that PA posted above are correct for the 201.

I'd go with it. It's built for a 454 Vette. I'd also run a kit through it, and make sure the rods and jets are correct, and make sure there aren't any hidden issues with the carb (warped air horn, wrong parts, stuck parts, etc)

The hard-starting could be fuel that's evaporating from the fuel bowl. How often do you drive her?

The "stumbles a bit" during warm-up could be several things, but could be a mechanical problem with the choke. Are you running the thermal spring set-up to the little choke stove on the intake?

74VETTE

I usually drive it on weekends. After about 5 minutes it clears up and will start up just fine the rest of the day and even the next day. I've got the divorced choke attached to the intake.

So sounds like I'm best off sticking with what I got then and leaving things alone.

PAmotorman

trucks have enclosed air filters and corvettes have a open air filter so the carbs are jetted differently

Jeff_Keryk

My guess is, if you have to change anything, richen the primaries by 2 sizes and leave the secondaries alone. If possible, tune with an O2 sensor...

Rich's'78

I am not sure there was much difference betweeen auto vs. manual, but I would expect a truck carb to be set up richer to prevent engine damage from being too lean under heavy load (which a vette doesn't see, much lighter vehicle, not used for towing).

trw

The 7043201 is the same carb that is on my stock 73.

I would just dump it and send it to me.

Should be a good carb for you. I think the autos were a little richer on the primary side.

Terry

mar

Starting 73' Vettes' had enclosed air filters...

73, Dark Blue 454

Starting in 73, Vettes received cowl induction intake system which includes a dual snorkel air cleaner.

Q-Jets for manual tranny cars were typically slightly richer, all else equal. For instance, the counterpart to the 7043201 was the 7043200 used for automatic tranny equipped 454's in 73.

The only difference was with the primary rods which were 50-B for the 200 vs. 48-B for the 201. Obvioulsy smaller rods = richer mix.

FWIW

LS4 PILOT

very enlighting thread , always wondered about the carb differences . Between manuel and auto carbs . I believe the auto might have a special kickdown linkage off the carb.

my 7044221 is worn bad , the shaft wobbles , vacuum leaks , it needs a full restoration at this point not a rebuild.