Thread: Quadrajet & extreme inclines

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I recently bought a rebuilt Q-jet, as my old one was leaking gas all over the engine. I live in San Francisco, so you can imagine I have to park on extremely steep hills all the time. After installing the new carb on my '61 Impala & park on a steep incline overnight (downhill), gas seeps into the cyclinders and the engine doesn't turn over. I have to drain the gas out of the spark plug ports._ Gas also leaks out of the airhorn seam, this is exactly why I replaced the old carb!_ Everything is tight, it doesn't leak when parked on level ground. Is this normal? When thinking about how carb floats work, how can it work when tilted at almost a 30 degree angle? What could I do? (besides move?)

Any advice would be helpful!

Tech1,

Out of your vast experience would you please make some further comments regarding the Quadrajet? I have a dirty one from a '76 Corvette (assuming that is a Q-jet) and planned to refurbish it for use until I can buy a better new one as either a Holley Avenger or Edelbrock carb. I am expecting to basically just dunk it in carb cleaner and maybe replace a gasket or two. I am joyfully venturing in over my head building my '29 from large pieces, but now realizing that I don't know a lot of the fine details such as where to attach the vacuum for power brakes and how to hookup the kickdown cable to my TH350. After considering your advice for a Streetmaster intake and communication from Edelbrock, I am probably going to play it safe with a Performer intake, but it is my understanding that the Q-jet will bolt on the Performer without problem. While I reserve the right to make my own decisions based mostly on economic considerations, your advice and that of others on this site have already proved to be extremely valuable, so I look forward to a "few good words" regarding the Quadrajet.

Don Shillady
Retired Scientist/teen rodder

A few bits of advice. 1) many times an Edelbrock carb is cheaper than a Rebuilt Rochester. At least in my experiance. 2) many 4X4 companies have custom built Off Road carbs. Always an option. However, your current carb is savable.Just set your float down. That way, it doesnt have as much of a fuel reserve and your car will start in the morning. Just an idea.

Oh, and BTW, there is a trick you may want to try untill you fix the carb. If you put you're foot to the floor when starting, your carb will shut off the jets. You should be able to start it then.

Originally posted by Don Shillady
Tech1,

Out of your vast experience would you please make some further comments regarding the Quadrajet? I have a dirty one from a '76 Corvette (assuming that is a Q-jet) and planned to refurbish it for use until I can buy a better new one as either a Holley Avenger or Edelbrock carb. I am expecting to basically just dunk it in carb cleaner and maybe replace a gasket or two. I am joyfully venturing in over my head building my '29 from large pieces, but now realizing that I don't know a lot of the fine details such as where to attach the vacuum for power brakes and how to hookup the kickdown cable to my TH350. After considering your advice for a Streetmaster intake and communication from Edelbrock, I am probably going to play it safe with a Performer intake, but it is my understanding that the Q-jet will bolt on the Performer without problem. While I reserve the right to make my own decisions based mostly on economic considerations, your advice and that of others on this site have already proved to be extremely valuable, so I look forward to a "few good words" regarding the Quadrajet.

Don Shillady
Retired Scientist/teen rodder

I rebuilt many Q-jets.... It's a very capable carb, and it isn't that hard to trick out.

You can buy a full rebuild kit, which comes with all gaskets, new check-ball, accelerator pump, float, measuring tool and guide. It costs $40 bucks here in Canada, so its probably like $2 USD . Just write down the number on the side of the carb body so they can give you the proper kit.

You'll get an exploded view of the carb with the rebuild kit incase you forget what goes where.... When you dis-assemble the carb, do NOT bend the rods for the accelerator pump to remove it - there is a pin that you can drive out with a small punch, and for most others theres a small clip.

Get the carb hot-tanked after you dis-assemble it, regular carb cleaner stuff (or varsol even), requires a lot of scrubbing to get the carb really clean. Hot tanking comes out looking new

The power brakes will attach to the FAT vacuum outlet on the base-plate. It may be threaded on some carbs.

For the kickdown, you should have the bracket with your carb on the side where the throttle cable clips, if not, head to a wreckers yard and take the brackets off a 70's car with a TH350.

I plug all other outlets that arent being used.


As for modification;
On the primary side, all you do really is change jets/rods for the approriate mixture, modify the accelerator pump, and the power circuit spring to suit your vacuum at idle.

All other modification takes place on the secondaries.
The secondaries require two "specialty" drill bits (1/32 and 1/5), grinding bits, brass plugs, homemade "tool" out of aluminum rod, etc etc....

Buy a book called "Rochester Carburetors" by Doug Roe, published by HP Books.... It explains everything very clearly. Its what I started with and its still what I refer to whenever I deal with Q-jets.
http://www.amazon.com/exec/obidos/tg...books&n=507846
Good Luck

Thanks a lot, that is very helpful. What is the name of the rebuild kit? I guess I will try H&M Speed Shop in Richmond and/or the local NAPA shop and ask for a Quadrajet rebuild kit with the correct part number. Yesterday I "ran out of parts" in that I have installed all the parts I have and now await the next shipment of rear coilovers and the rear panhard bar. I hope next to order the power master cylinder and the engine so that by the end of the Summer I will have the drive line and brake lines installed and now is probably a good time to start rebuilding the Quadrajet.

Don Shillady
Retired Scientist/teen rodder

Thanks very much, I wondered about the hot tank treatment. I have worked in metal finishing and most metals are OK in caustic tanks but Aluminum, and to a lesser extent Iron, will be etched away by both acid and basic solutions, so if there are any aluminum bushings or Al content in the white metal, hot tanking will eat that away. I burned valves on a VW due to a pinhole leak in an aftermarket intake, so a vacuum leak will degrade the Power booster and possibly lead to over lean conditions. Maybe I will just use a toothbrush scrup on the whole unit and avoid any etching. What the heck is white metal anyway, Tin, Lead, Cadmium, Antimony? Those four metals should be relatively inactive and not be etched in basic (caustic) solutions like radiator hot tanking (brass radiator). Maybe there is a hot tank solution for aluminum radiators that would be good for carbeurators too?

Don Shillady

Originally posted by Streets
Dang and I thought "Antimony" was what yer ex-wife got from ya after the Dee-vorce..

No No that's Alimony. Antimony is the structure of animals and people.............
No No that Anatomy. Antimony what a rich family member has.....
No No that's Aunties Money. Now I'm confused.

OK so I mispelled CADMIUM (a poisonous metal, although shiny). It is often mispronounced as CADDY-UM, but when you spread it real thin you get CADDY-LAC! Anyway under all the grime the label on the side of the carb says ROCHESTER QUADRAJET, so your comments have been quite helpful AND I used the edit feature to correct the spelling! The list of metals came from an Internet search on "White metal" but they didn't give the percentages. Note that elements 49, 50, 51 are Indium, Tin and Antimony, so if your Aunt-had-the-Money you could plate your tin motorcycle with element 49 (In) and it would be an INDIUM bike!
(I should be doing something better with my/your time??) Thanks again for the tips on the carb rebuild!

Don Shillady
Retired Scientist/teen rodder

Since we are on teh subject of quadrajets here...got 2 of em, both running on 305 chebbys.

gonna replace one of the 305s with a .030 over 350, 10.5:1, alum vortech heads, a cam like a ZZ4...

would like to put EFI on it, but the budget is tight.
was going to put an air gap intake and new 4bbl carb and avoid EFI indefinitley, but this would be a cheap solution...

However, since getting a free working Q-Jet, would it be worthwile to use it (with the stock iron intake or aftermakret?- I assume jetting or other tuning would be required. This would be an temporary solution (for a year, 3000 miles or so).

Worth doing? What are your thoughts?


chris

Originally posted by Don Shillady

(I should be doing something better with my/your time??)
r

Na, It's Sunday night...... what else is there to do........ maybe get ready for Monday morning?

Originally posted by pro70z28
Na, It's Sunday night...... what else is there to do........ maybe get ready for Monday morning?

I hear of this thing called sleep. Anyone else heard of it? is it new?

I've Used Carbs Unlimted several times. They have rebuilt Rochesters, Webers all the way up to monster Edelbrock Thunder series. The have complete Q-Jet rebuild kits, but they sell undividual gaskets, jets & stuff. Free shipping!

All online too:
http://www.carbs.net/

- I buy this stuff online, while my wife is shopping at oldnavy.com

Originally posted by Streets
They are not as fast as the fastest bike in the world tho, that was called the "Kamakaze" the only Japland motorcycle in the world that would do 250 mph and it came standard with NO BRAKES...

Ralph N.'s favorite bike............ He He HE