I have a Q jet on a 1974, LS 4, 454.

The number on the carb ends in 5 which means it should have been for a manual, but my car is an automatic. I am absolutely positive this is original to the car.

I read where there were numerous exceptions to the odd/even numbering rule for the Q jet.

Does anyone know what the exceptions are?

Why would an auto 454 have a carb numbered as Manual?


BTW, the car is running fine. And has been for decades now. I am just really curious.

 

What's the full number? This list shows carb applications ending in "5" for both manual and automatic. But I wouldn't blindly trust a list of carb numbers that wasn't emailed to me by @lars.

https://corvettec3.ca/carb.htm

HP Application Manufacturer Model Number
195 THM Rochester MV4 7044206
195 4-Speed Rochester MV4 7044207
250 THM Rochester MV4 7044210
250 4-Speed Rochester MV4 7044211
250 THM (Cal) Rochester MV4 7044506
250 4-Speed (Cal) Rochester MV4 7044507
270 THM Rochester MV4 7044225
270 4-Speed Rochester MV4 7044221
270 4-Speed (Cal) Rochester MV4 7044505

And throw this into the mix. Perhaps your car wasn't always an automatic. It's never too late to fix that! What does the engine suffix say?

https://corvettec3.ca/engines.htm

 

(Although Gordon didn't post his carb number in his post above, I have the advantage of knowing his carb number....It's frightening the things that I know...):

Gordon -
Carb number 7044225 is for a 1974 454 non-California Vette with an automatic. The non-California manual 454 Vette was 7044221. California automatic 454 Vettes were 7044505.

Often, the only difference between an automatic carb and a manual carb was that the auto trans carbs had a provision on a lower extension of the throttle lever for the automatic transmission kickdown cable attach fitting. The manual transmission carbs often had this lower throttle lever extension cut off. For this reason, it is often impossible to run a manual trans carb on an automatic car with a TH350 tranny.

Since the 454 automatic cars all came with a TH400, which does not have a kickdown cable, and since all big block carbs have to have the lower part of the throttle lever cut off to clear the low-rise intake manifold, it would be logical that the automatic carbs would have the "odd" number to signal the "manual trans" version of the throttle lever to be installed.

Here is a '74 small block auto trans car lever:


Here is a '74 small block manual trans or big block (auto or manual) carb lever (your carb). You can see where the lower part of the inside lower lever has been cut off. This was done by Rochester on small block manual carbs and all big block carbs with TH400 auto trans or manual trans, and would be reason to give the carb the "odd number" designator:




Lars

 

I will tell you that is awesome information.

YOU are the Q Jet Maestro!!!

thanks!!!

 

I shake up an awesome Martini, too.

Lars