My carb #17059216 has #10 rods w/ type M hanger, my other one 17059222 has CH rods w/ type O hanger, which is better and what's the difference. Thanks for help!

 

without the list of #s I can't say which is which.
basically the cam/hangar determine how fast and far the rods open the jets
the rods determine how much the jets can flow.

these adjustments tune the secondary for best power
things like weight of car and gearing and vacuum from cam.

 

I don't know what kind of rods you have in the first carb (Q-jet secondary rods are designated by two letters, not "10"), but both came with CH rods from Rochester. Both carbs are about the same and could easily be interchanged.

God bless, Sensei

P.S. Hangers don't matter. You can bend any hanger to get what you need.

 

The hangers drop the rods further into the jets .005 as the letters increase. M is .575 & O is .585 so there's not much difference & you will probably not be able to tell the diff. w/o good measuring equip. The M is probably better for perf. assuming basically stock 350 w/ CH which is a normal 350 rod.

No 10, should be 2 letters.

 

Thanks to all and I'll take notes. I just love learning the different things about our older cars.

 

Well I pulled the M hanger w/the #10 rods in question, and they are CH rods.

Must have been the 10 drinks I had and not wearing my glasses!

See, another lesson learned, but it was fun..............

Thanks again

 

If you're looking to increase performance,
try: www.73-87.com/7387garage/drivetrain/damon.htm for how to tune the secondaries and what rods are the best.

 

The author, Damon has called himself something like Last remaining QJet tuner on planet Earth & is well known w/ Camaro/Malibu guys.
The tuning in above link is for 350s.
Not for high power 383 & BB.

 

Thanks for the url.....Great info. .

 

Thanks again to all!!!!!!!!!!!

 

I'm going to go out on a limb here and contradict the "Last remaining Quadrajet tuner on planet Earth". I read his post from the above link and :

1. Don't take out your secondary air valve shaft and replace it with one from a junk yard! You don't need to do this and you could cause serious problems if you don't know what you are doing. I have been doing performance Quadrajet builds for racers/ hot rodders for years and have never found one that needed this to get full air valve opening.

2. Don't waste money on secondary rod hangers. The only difference in one hanger to another is how high or low the holes on the hanger's arms are. The arms are easily bent to put the holes at the desired height.

God bless, Sensei

 

I agree, here's a link to Lars papers http://www.florida4x4.com/tech/quadrajet/qtune.pdf PG.

 

I don't agree with much anything from the link above (Performance Tuning the Q-Jet by Dmnon Nichols).

1) Removing the little screws that hold the air-valves (and throttle blades) is tricky; not a '2 on a scale of 1 to 10 on the difficulty scale'. The ends of the screws are pressed and fattened to limit thier backing out and falling into the intake. It takes a careful touch to remove them without hogging out the screws holes and ruining the shafts. Some grind off the ends of the screws so they can be more easily removed. You'll likely need new screws to replace them (use some red lock-tight).

There were some Q-Jet equipped cars that limited the opening of the air-valves but our Corvettes aren't one of them. Some 6-cylinder Panchos limited the AV opening.

2) The tension spring which controls the rate of the air-valve opening is more sophisticated than the writer believes. It's not that easily installed and a generic setting of 1/2 to 3/4 is good start but you'll need to adjust it for your engine's demands. An L-36 (q-jet equipped 427, 390hp) will want a quicker opening than an L-48.

2a) The writer believes ill-suited secondary rods is what leads to the infamous "quadra-bog". I disagree. An improperly set tension spring is usually the culpret. The bog usually occurs because the air-valves open too quickly.

3) The best place, in my opinion, to purchase q-jet parts is here:

http://www.carburetion.com/quadrajet.asp

...where rods are much less than $25 each.

4) I can't believe his secondary rod choices (DR, CP, and BA) for a performance car. All have a .0570 tip. Since a q-jet's secondary jets are static, the A/F ratio is solely controlled by the tip at WOT. The smaller the tip, the richer the mix. I run CE in colder weather (.0410 tip) or DA (.0443) in warmer weather. These selections are track tested on 69 Camaro with a healthy 406. Your engine may want a fraction richer or leaner rod than this, but it sure won't like anything with a .0570 tip; way to lean.

5) Lastly, I assume we'e talking about a street carb and if so, there are a few other things to consider for performance, like pump shot, and a larger needle and seat to compensate for the small fuel bowl.

FWIW

 

The 79 L48 is stock and at this time, trying to keep it close. Consistancey with a small mod here and there, so the M hanger I have is a little better than O???

Man what knowledge this forum has, happy to have a Corvette(my younger dream) and joined this forum........So helpfull, thanks ED

 

 

Thanks for the web site tip!

 

I think what a1sensei is trying to say is, don't get carried away with which hanger to use. You're not going to find any HP there. For performance (WOT) most any hanger will do so use whatever you have. Make sure the the holes in the hanger for hanging the rods are round and not oval-shaped (worn out).

 

Funny you should mention oval shaped because I now remember that the rods were a little sloppier in O hanger holes, will double check it.

Thanks again ED