After fooling around with Holleys for a couple years I've decieded to try out a Q-jet. I'm just not getting the fuel economy and throttle response I would like with the Holleys(althought they seem to run great open throttle). I know there are tons of different applications and am curious which one is the right for me.

Engine is 355 Ported World S/R Heads 1.94/1.5 203/212@.050 hydraulic cam(.429/.439 lift) Dart Sportsman II dual plane intake, 9.0 Compression With a Tremec TKO 5-speed Manual and 3.42s in the rear.

I would like to use the choke and don't know which one to get-some say the electric choke is a bad idea, others say differently. Just curious as to what type of Q-jet I should be looking for. I'm gonna use an adapter plate with my current intake manifold. Any thoughts? I'm going to either rebuild it myself or send it out to a member of one of my message boards.

PS- Am I going to lose anything at the 1/4 mile from switching? The best 1/4 mile time now is 14.1@98.2 mph with a 2.1 60ft time. Would like for it to stay that way(might even go faster considering the DP Holley gets a nice little bog when I floor it hard).

Get one off a stock motor that is about the same as yours!! Say a '69, 295hp/350..

It should work fine imho..

pdq67

i might be wronge but i thought that qjet where either a 750 or a 850 cfm.. 750 are super easy to find just get one off a car befor 1986 i belive. ( no electrical stuff on it) and after that jsut rebuild it ( pretty easy) and then jsut the jet and hanger changing stuff which im not to familiar with.

Q Jets can be made to work really well if you modify them. Try to find one of the old HP books called Rochester Carburetors. They have excellent information on how to modify them for performance.
Back when I used to play with street small blocks, I modded one up for my 350 and that was simply the best running carb I ever had on the engine. Instant response and good mpg to boot.

One of the problems today is finding tuning parts. 15 years ago folks would give you Qjets for free and at the swap meets they were $5. If a guy collected enough of them, you could come up with a wide variety of jets, rods, hangers etc.

There were 2 sizes of Qjets, 750 and 800cfm. The difference was actually in the primary side. The secondary sizes were all the same. The big ones only came on 455 Buicks and Olds motors I believe. You really don't need one of these.

Personally, I'd try to stick with 1968-1972 models. Once GM started playing the emissions game, they just didn't run as well.

If you have a few and need help deciphering the numbers on the side of the carb, drop me a line and I can tell what it came off of. I somehow managed to get a hold of one of the massive GM Rochester Carb books that lists pretty much everything made through 1975. From the code, you can tell the year make and model of the carb. It also tells what jets, rods and hangers etc that were supposed to be in it from the factory.

I know that you have a nice intake manifold, but you might consider switching to an Edel Performer. That way you could use the original choke setup. Wieand also makes a similar manifold.
I had mine on an mild 350 like yours and it ran 13.0 @ 105....but it was in a Monza....a pretty light car.

Ron

A buddy has a BRAND NEW 1901 Edelbrock Quadrajet with divorced choke. His engine builder bought it for his PONTIAC, unfortunately, its CHEVY only. (choke issues) Email me if your interested.
Greenblud1@aol.com and put "carb" in title so I don't vaporise it. ;)

If the Edel deal falls through, Chris Corwel posted sopme time ago that Holley- reman QJs were available at Autozone. I'm relying on memory here, the 750 cfm version, ( say a 1970 sbc Corvette or Chevelle), and the 850 version ( say a 1970 bbc truck). I bought a Holley reman Q from a local junkyard for $50 and it was mint.

Also, a fella named Tom Toal lives in Webster. Tom was on the orignal QJ design team, he knows more about them than we all will forget. Tom should be back from FLA by now, and can be reached at toalfree@yahoo.com. Tell him I sent you ( if he remembers me!). He may have a core, and most improtantly, even if you source your own QJ, I would stop by Tom's house and get a free education from the QJ designer himself. This guy is a gentleman and, of course, supremely knowledgable. If he ins't super busy, a hour spent with a guy like that is a hour VERY WELL spent. If I was in your shoes, I would hope he 'd 'breathe' on the carb for you AND invite you to the house for the install/initial settings and not charge his typical $150 rebuild fee.


To answer your question, any of the standard 700-750 cfm QJ's will work well. I bet you end up richening the primaries, just a tad to compensate for your better-than-stock air flow.

(haven't made it out to Leicester so far. Summer's been way too busy with a house move pending now - hope to see you out there some day).

how big is the holley you've been using???
shane

Originally posted by AllGoNoShow:

Engine is 355 Ported World S/R Heads 1.94/1.5 203/212@.050 hydraulic cam(.429/.439 lift) Dart Sportsman II dual plane intake, 9.0 Compression With a Tremec TKO 5-speed Manual and 3.42s in the rear.

I would like to use the choke and don't know which one to get-some say the electric choke is a bad idea, others say differently. Just curious as to what type of Q-jet I should be looking for. I'm gonna use an adapter plate with my current intake manifold. Any thoughts? I'm going to either rebuild it myself or send it out to a member of one of my message boards.

Electric choke and divorced choke Quadrajets each have advantages. Electric works with any manifold, is very adjustable, but won't work with a stock air cleaner. (The integral choke tends to hit the air cleaner base.)

Divorced choke carbs will work with the stock air cleaner, and may deliver better performance AND fuel economy out of the box. They also tend to have more generous idle passageways.

Whichever route you take, try the stock primary rod/jet combo first. If you have a modified engine, go with a set of "CV" or richer secondary rods.

Mike

What exactly is a divorced choke?

Does anyone sell aftermarket hangers and such or do you have to go used to find em?

427L88- Thanks for the email. I may have to drop him a line. Who knows I might even tackle a rebuild myself(but that autozone idea sounds good too!). Def. come out to lecister. I'm usually there weds. nights brackets, sometimes fridays for test and tune. Trying to break in the 13s currently so not looking to go many rounds(my car is a manual so its hard to get consistency), just looking to run the numbers! Hopefully my poor broke college ass can squeeze together some extra money and stick a cam in it and get a 12.99 if I'm lucky. Who knows!

Originally posted by AllGoNoShow:
What exactly is a divorced choke?

Does anyone sell aftermarket hangers and such or do you have to go used to find em?

A "divorced" choke means that some of the choke components are seperated from the carb. That is another way of saying that it uses a choke coil monted on the intake with a rod that connects it to the carb. An "integral" choke means that the choke coil is physically attached to the carb.

Edelbrock sells hangers/rods. FWIW when replacing primary rods, I prefer GM parts.

Mike

Originally posted by Unclepennybags:
</font><blockquote>quote:</font><hr />Originally posted by AllGoNoShow:
What exactly is a divorced choke?

Does anyone sell aftermarket hangers and such or do you have to go used to find em?

A "divorced" choke means that some of the choke components are seperated from the carb. That is another way of saying that it uses a choke coil monted on the intake with a rod that connects it to the carb. An "integral" choke means that the choke coil is physically attached to the carb.

Edelbrock sells hangers/rods. FWIW when replacing primary rods, I prefer GM parts.

Mike </font>[/QUOTE]Thanks for clearing that up. So do you need a special manifold to run the divorced choke design? I have a Dart Sportsman II dual plane intake that is emissions legal I believe, but I'm not sure if it would have whats needed to run the divorced choke. I know there is a hole now in the back of the manifold(its plugged), would that be where it hooks up?

AGNS,

A divorced choke manifold will have a small "well" on the passenger side at the base of the plenum - roughly mid way between the front and back of the carb. This well will be about 1" wide by 1.5" long - or there abouts. No mistaking it. It should also have a small hole right next to it that will accept a small screw that's used to secure the bi-metal spring cover.

Dan

Originally posted by AllGoNoShow:
Would like for it to stay that way(might even go faster considering the DP Holley gets a nice little bog when I floor it hard). If that's the case, why not find out why you have a bog before you go to all the trouble of swapping carbs? If set up right you should NEVER have a bog. What size Holley are we talking about? Vacuum or mechanical secondaries? Single or double pumper?

I like Q-jets too for their reliability and relative simplicity but a properly tuned Holley would likely perform better at the track and seat of the pants.

Would a divorced choke carb be easily replaced with a different kind of choke? Manual or electric? Any convertions needed?

Are you talking about a Holley or a Q-Jet? If it's a Holley there is likely a conversion kit available to change to the kind of choke you want, check their web site. I know there are electric choke conversion kits for Q-Jets that have an intergal choke already, don't know about conversion kits for the other way around.