[tjones70]

I recently bought a genuine'70 Judge with the correct YZ engine. When I went over it with a reliable mechanic he said the car lacked the "go" he would expect from a 366hp engine. We noticed the carb is from a '69 400, but ewverything else looks ok. Did the Judge come with a special higher revving Q-Jet? I know the correct number s/b 7040270, but is it functionally different from a 7029262?

[tjones70]

I recently bought a genuine'70 Judge with the correct YZ engine. When I went over it with a reliable mechanic he said the car lacked the "go" he would expect from a 366hp engine. We noticed the carb is from a '69 400, but ewverything else looks ok. Did the Judge come with a special higher revving Q-Jet? I know the correct number s/b 7040270, but is it functionally different from a 7029262?

[Txbobcat]

I dont know the answer to your carb question but I would check the timing and probably advance it some and make sure the vacuum advance is working and plugged into a ported vacuum source.

['ol Pinion head]

Yes,
'68-70 RA carbs are functionally different than non RA carbs of same era. It's a little more than:

jets,
metering rods,
power piston spring,
secondary windup,
choke pulloff hole size/pulloff rate,
& small holes in front butterflys.

Hope further details are not disclosed as too many honest individuals are being duped by the counterfeiters & counterfeiters read these boards

Nearly every other week I get pics of one of these carbs that has been screwed with from someone wanting to buy an original...not good scenario.

'70 automatic RA GTO's & T/A's could come with

#7040270
or
#7040570 (CA cars with EEC)

[Half-Inch Stud]

OPH...agreed. I just unload my extra Q-jet supply. Guess the only bodycore of interest was a 7029268. I think the topplates, baseplates, and parts-features are more telling.

Otherwise, a saucerful of secrets remain for telling an original 73 SD carb, a 70 Ram III, 69 ram III, and a 69 Sprint 4spd carb.

Had 2 68-70 baseplates with factory air-bleeds drilled in-line with the Primary throttle shafts, but on severe angle. Wee regular folk would drill the primary throttle plates to accomplish same.

..just let another one out of the bag.

[tjones70]

What are some reliable sources for the correct carb?

[poncho-mike]

I've noticed that the Pontiac replacement carbs are different from the originals. I had an original 69 Ram III 7029270 and another 7029270 with a 1973 production build (found on a junk yard car, so it wasn't a restamp), and there were definite differences.

One question: I have a 7041268 and a 7041273 carb. I see the differences and both are 800 cfm with one boost ring. I have a 7042273 I got with my dismantled 72 T/A. I expected it to be an 800 cfm, but it isn't. It has two boost rings and the narrower primaries. I thought 72 HO carbs were supposed to be 800 cfm. Carb appears to be tired original, no restamping evident and certainly not rebuilt. In fact, the throttle plates on the base plate are seized up. Can I use a base off a different carb?

Mike

[carbking]

There are some differences in early 7029270 (before April 1969) and later (after April) 7209270 original carbs. There also some differences in both of these to the service dated units.

A few of the 1971 carbs 7041263 (some), 7041267, 7041268, 7041270, and 7041273 had the single booster.

All 1972 Pontiac carbs were small venturi, double booster (750).

The SD only Pontiac carbs starting in 1973 (7043270, and 73) were large venturi, double booster (800). This practice continued in 1974 (7044270, 7044273). The other non-SD 1973 and 1974 carbs were the smaller venturi.

As we stop with the 1974 model year, I cannot add information newer than 1974.

As a general rule, throttle body assemblies differ from RA/HO carbs to non-RA/HO carbs. Check the master parts book by part number to be sure.

Jon.

Good carburetion is fuelish hot air.

[carbking]

Thom - the major difference in the design of the HO/RA carbs was to allow them to perform on the street with the reduced vacuum of the bigger cams.

The 7029262 has the same air flow at WOT as the 7029270, but in stock condition, would not work with the RA cam nearly so well as the 270 under street conditions.

Jon.

Good carburetion is fuelish hot air.

[A1Judge]

JUst curious why the only core of interest was the 7029268? Is it a "good" carb?

I recently purchased one, fully rebuild, bushed and replaced that I am no running on my motor. It does seem to run much better than what I took off, idles smoother and the idler adjustments actually work...

Any, just curious on opinions on the 268 Q-Jet.

Thanks

Don



restored a 70 Judge at: http://home.rochester.rr.com/dchapman