Chevy Nova Forum banner

1 - 15 of 15 Posts

·
Premium Member
Joined
·
1,342 Posts
Discussion Starter #1
I have a buddy who loaned me 4 carbs to take home decode and get info on!! 2 are Rochester quadrajets 2 Holley!

Rochester number 1 Has electric choke and vacuum secondary's! (im not sure on the 2ndary part)

The numbers on it goes as following 17080504 2709 CKH





Rochester Number 2 Has vacuum choke the numbers are 17080213 3143 CPX



Holley Number 3 Has vacuum choke and vacuum secondary's the numbers are
2419 List 4440-1 (on the top of the carb 6R 3167 B)


Holley number 4 has NO choke. (this is really more of a parts carb!)


the numbers are 741 ECZ AD
List - 1273-1




I would like to know which one will be easiest to hook up and is best for my 307 set up

I don't care about mileage!

thank you for your advice and time!
 

·
Premium Member
Joined
·
2,106 Posts
Ok, the 1273-1 Holley is a 600cfm Vacuum secondary. I beleive the other is as well, but I'm not sure. i couldn't find it in my quick search. Both Q-jets are from 1980. The first is from a 1980 California Corvette with the 305, and I beleive the second is from a 1980 truck with a 454. The Corvette carb is a computer controlled carb, so stay away from that one. Now the other Q-jet or the 1273 Holley, both could be rebuilt and perform really well on your 307. I prefer the Q-jet, but you'll need a rebuild and probably need to bush the throttle shafts, plus calibrate it for your engine. The Holley will be a little easier to tune and rebuild, but it has no choke. I don't know how important that is to you. Oh, and the choke on the Q-JET isn't vacuum, it's a heat riser. Heat from the intake is fed into it thru a small metal tube to open the choke.Holley #3 has a manual choke on it. The vacuum canister is the choke pull off. If you find it's number, and it's a 600-650 carb, then use that one.
 

·
Premium Member
Joined
·
1,342 Posts
Discussion Starter #5
Ok, the 1273-1 Holley is a 600cfm Vacuum secondary. I beleive the other is as well, but I'm not sure. i couldn't find it in my quick search. Both Q-jets are from 1980. The first is from a 1980 California Corvette with the 305, and I beleive the second is from a 1980 truck with a 454. The Corvette carb is a computer controlled carb, so stay away from that one. Now the other Q-jet or the 1273 Holley, both could be rebuilt and perform really well on your 307. I prefer the Q-jet, but you'll need a rebuild and probably need to bush the throttle shafts, plus calibrate it for your engine. The Holley will be a little easier to tune and rebuild, but it has no choke. I don't know how important that is to you. Oh, and the choke on the Q-JET isn't vacuum, it's a heat riser. Heat from the intake is fed into it thru a small metal tube to open the choke.Holley #3 has a manual choke on it. The vacuum canister is the choke pull off. If you find it's number, and it's a 600-650 carb, then use that one.
so by looking at them you cant tell the cfm?

where would those numbers be at (if there are any?)
 

·
Premium Member
Joined
·
2,106 Posts
No, I googled the Holley list numbers. The q-jets are 750's though. They made 3 different Q-jet sizes, but only 2 came on V-8 cars. The 750 and 800 Q-jets. Almost all (including these two ) are 750 carbs. The 800's came on certain Pontiac and other large engines in the late 70's (like Buick, Olds, and Cadillac). I don't remember Chevy using an 800, and Chevy's use the side inlet Q-jets.
 

·
Premium Member
Joined
·
1,342 Posts
Discussion Starter #7
No, I googled the Holley list numbers. The q-jets are 750's though. They made 3 different Q-jet sizes, but only 2 came on V-8 cars. The 750 and 800 Q-jets. Almost all (including these two ) are 750 carbs. The 800's came on certain Pontiac and other large engines in the late 70's (like Buick, Olds, and Cadillac). I don't remember Chevy using an 800, and Chevy's use the side inlet Q-jets.
ok so the q jets = too big

I need to find out wether that other holley is a 600 or not (the mostly complete one)
 

·
Premium Member
Joined
·
2,106 Posts
No, the Q-jet's are not too big. The primary's are smaller than the Holley's, so off idle and part throttle driveability will be better, and the secondarys are air flow operated. They will only flow as much as the engine needs, but have the capability to flow big air if the engine needs it. The Q-jet is simply the best street/strip carb you can put on an engine if you learn how to tune one properly. It will work on everything from a 265 to a 454. Pontiac even put them on their overhead cam inline 6 cylinder Sprint engines.
 

·
Registered
Joined
·
1,989 Posts
#1 is junk #2 is ok, i believe the 80's Q-jets are 795cfm #3 would be nice to use, #4 parts like you said. I have a 750 Q-jet for sale in good rebuidable shape with a good trottle base and extra parts, its from the 70's and you can hook up a manual choke using a cable and a bracket, asking $30+sh.
 

·
Premium Member
Joined
·
8,405 Posts
The same 2 basic Q-Jets were used on everything from 230" Pontiac OHC 6's to 500" Caddy's. Just ignore the CFM rating.
I agree. I've used them on 283-305 size engines. that's the beauty of the Q-jet design. If the vacuum secondaries are dialed in, it won't suck more air than the engine wants. If the flapper spring breaks or the set screw loosens you get the "Quadrabog" effect. Most inexperienced people are befuddled by that, but it's easily fixable.

The small primaries give better driveability and economy than the Holley will. The Q-jets are cheap but might be hard to set up if you don't have any experience. Then again if you haven't dialed in a Holley it's going to be a steep learning curve also.
You can get electric choke conversions for the hot air choke from Edelbrock along with jet kits and metering rods, but they aren't the only source.
I've made it a habit to pull rods and jets and other essential parts whenever I get a cheap or free Q-jet and add it to my tuning kit.

There are plenty of 10 second cars with Quadrajets. Get Doug Roes book and read it thoroughly before selecting a carb. I prefer the '76-1979 Q-jets myself, but that's probably because I was a GM dealership tech back then and know them inside and out. I wouldn't use the electronic Q-jet for your project but it might have some parts you could use for the other.
Don't pay too much for a rebuildable core.
 

·
Registered
Joined
·
2,146 Posts
I would have to agree Qjets are a very good carb. Once you get to know them and understand how to tune then they kick ***. I had one on my truck and it worked great. I also like holleys too. Not a fan of the single inlet 1850 but can be done right to work.
 

·
Premium Member
Joined
·
11,072 Posts
I've made it a habit to pull rods and jets and other essential parts whenever I get a cheap or free Q-jet and add it to my tuning kit.
I had a ton of Q-Jet parts back in my street racing days (nothing better than a Q-Jet on a Performer to sucker some dummy!) I loaned my best carb to a friend, and he sold his car with my carb still attached--forgot all about it.
I gave my supply of stuff to the guy that builds my transmissions--he races Stock Eliminator with a Q-Jet. I think I had every hanger and most metering rods--spent a lot of time at U-Pick type junkyards!
 
1 - 15 of 15 Posts
Top