Hi,

There is a fella selling rebuilt Q Jets not far from where I live.
Is there any major difference in these carbs (aside from the 2 styles)
that CAN NOT be discerned from the outside?
He gave #'s that are stamped on the bodys:
part # 7042208 QC 2801. Another available with part # 17057213 AWP 1647

Says they are 750's. Will they work in my 472?
Can I swap Jets/Rods to make them work?

Thanks,

Paul

bump.

I Said BUMP !

I used to know those Quadrajet numbers but can't remember lately. I'm positive if you google quadrajet numbers you will figure it out quite easily. I would look for an original Cadillac carb to be sure it would work perfectly. They should come up on Ebay once in a while. If you try an unknown carb, just make sure the fuel inlet is the same, the choke linkage is similar and the throttle linkage (rod/cable) is compatible. Whenever I am looking up what carb has what jets, I use google to find spec charts. Good luck dude.

Just a follow-up...
I rebuilt the carb myself, first one I did in 15 years and it was pretty simple.
I'd tell someone with the slightest experience to go ahead and rebuild it themselves.
Car runs exactly the same as it did before, falls flat on its face @ open of secondaries and backfires thru the carb, which has me concerned about the cam positioning..
Base timing is at ~14deg. Steadiest firing I have ever seen in a motor...
Engine has had lifter noise since I bought it, and if I didn't already know I was nuts, I'd say it got a little worse. Maybe..
I am going to put the secondary baffles on direct manifold vacuum and see if it helps with the hesitation.
Plus the heater core just gave-out:banghead:

Can you watch the secondaries opening? Are they flopping open too fast? If you push the secondaries open with your finger, can you see the rods raising? (I had one once where that cam broke and wouldn't raise the rods) Are the mechanical and vacuum advance working? Is the engine making good vacuum?

Ya know, this reminds me of a Camaro I was working on a couple years ago. I took the carb apart to change jets without test driving it first, then it would fall flat on it's face when secondaries kicked in and popped too. I thought I messed up the carb and took it apart a few more times; couldn't fix it, left it running on primaries. A few weeks later the fuel pump died. The new fuel pump cured the lack of power on the secondaries. You might want to check the fuel pressure too. How many miles on this engine? Keep us posted and I hope you figure it out.

Hi again,
Can you watch the secondaries opening?
Yes.

Are they flopping open too fast?
Maybe, I aint for sure..

If you push the secondaries open with your finger, can you see the rods raising?
Yes, the rods are connected and the little plastic cam is in one piece and seems to be functioning properly(moves them up and down as-proper?)

Are the mechanical and vacuum advance working?
Mechanical I don't know, but the Vac advance works, seems to be ok, motor was detonating with vac can hooked to the manofold, plugged it back to carb and the detonation went away mostly.

Is the engine making good vacuum?
Define 'good'. It seems off, actually.... It is not pulling as hard as it seems it should. how many inches is it supposed to be? Too lazy to check right now.. I'll put a guage on it over next couple days.

I highly suspect a skipped timing gear set and damaged valves. I am not an expert, but if the vac is low like I think it is, that means camshaft timing/valve/and maybe piston issues.. Whole top of motor is going to get done over as soon as I never get the $ to buy the parts. :nono:
175k?
New fuel Pump is a good idea period.
Thanks,

Paul

It sounds like the basic operation of the carb is working as it should. Since the engine pinged with manifold vacuum and ported vacuum at the carb cured it, that tells me the timing is pretty much spot on. The vacuum should be 18-20 like any engine. If it isn't, then you should verify compression in all cylinders. If it has a burnt valve it will run doggy but shouldn't fall flat on it's face. It probably is a weak fuel pump. Are you still running the points ignition?

HEI is in there now new plugs/wires and correct boots on dist cap too.
I was never sure if this car came with it or if it was added.
There are fuel pumps for BB Caddys on ebay right now that are cheap cheap cheap advertised as 'without AC'--is there a difference?
What's the range of years I'm looking for?
On a side note, The car has not started well since the carb rebuild, when its cold it takes FOREVER to start to fire.
When its warm it starts immediately. I assumed this was because i removed the factory carb fuel filter and put an in-line one down by the fuel pump.
The origional filter looked like it had some type of check-valve in it....

How hard are the heads to clean up myself with basic instructions?
If I take them to my usual shop I'm going to get violated....

Another available with part # 17057213 AWP 1647 Says they are 750's. Will they work in my 472? Can I swap Jets/Rods to make them work?Paul

the 7213 p/n seems close to mine (7230 or 7231...) for a 1977 425. You can google it for sure...