Bob -

403 only or 455 too ??

Steve W
1973 23'
Southern California

Roughly a year ago or slightly more, I was having trouble with the idle circuit on my original carb on my 403. I saw the ad on Ebay linked below. Again, the net allerted me to the horror stories of special GMC carbs, power piston springs and special passages that still have never been clarified other than foklure. I bought it, took it apart and looked at the components with my GM carb engineer and determined it was the real deal and the correct p/n. Some here were horrified that it was just a truck carb and not the right thing to do. I installed it and never even had to set the idle mixture much less the idle speed. There was no core charge so I sold my original as a core. I say all of this because they become available from time to time and I want to attest that they are a correct quality replacement.

http://www.ebay.com/itm/191549358602?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Yeah, its not black magic. Q jets are fairly broad in their appliccations. If you or you can find someone who knows what they are doing, they are fairly adaptable.

But for those not willing to modify a bit, the original is a good bet.

My favorite carb, especially for the street

The early 7043254 has been clarified by me, no worries there.

I am not sure about the newer ones like yours, but a tip is to compare the throttle linkage to the original carb, if it is identical so are you pretty darn close.
But why not rebuild the one you have ?

Bob de Kruyff wrote on Thu, 02 April 2015 06:04

Roughly a year ago or slightly more, I was having trouble with the idle circuit on my original carb on my 403. I saw the ad on Ebay linked below. Again, the net allerted me to the horror stories of special GMC carbs, power piston springs and special passages that still have never been clarified other than foklure. I bought it, took it apart and looked at the components with my GM carb engineer and determined it was the real deal and the correct p/n. Some here were horrified that it was just a truck carb and not the right thing to do. I installed it and never even had to set the idle mixture much less the idle speed. There was no core charge so I sold my original as a core. I say all of this because they become available from time to time and I want to attest that they are a correct quality replacement.

http://www.ebay.com/itm/191549358602?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

To rebuild the one I had was more than buying this one plus I sold my original as a core since I didn't need a core to buy this--I thought it was a good deal and has proven to work very well.