Too Slow/Q-Jet question

[rboyle]

I had as much as 6 tenths difference between my good carb and another name carb that seemed fine but ran slow and after much trial and error found 3 qjets that were from .05 slower to .10 slower even though they made more HP on the dyno. All were set up the same metering rods and hangers. All were known builders.

[JP1738]

Originally Posted by rboyle

I had as much as 6 tenths difference between my good carb and another name carb that seemed fine but ran slow and after much trial and error found 3 qjets that were from .05 slower to .10 slower even though they made more HP on the dyno. All were set up the same metering rods and hangers. All were known builders.

I don't really have the funds to buy a name brand, brand new Q-Jet, but do you know of anyone in the NC/SC area that can at least go through one and tell me what I have? From what I understand and the previous owner of the car, my Q-jet was gone through, rebuilt, and ran well on another combo, but truthfully I do not know enough about it to say if that's true or if it's right for my combination. If there is even tenth to be found in the tune-up, that'd be all I need. I'm already under the index in good air, but as soon as I get to marginal air, I'm in trouble.

[Mike Pearson]

With a 65 jet in the front it must not have primary metering rods. What rod and hanger are in the secondary’s? does it have a fast throttle plate? Have you worked with the speed of the air flap on the secondary?

[JP1738]

Originally Posted by Mike Pearson

With a 65 jet in the front it must not have primary metering rods. What rod and hanger are in the secondary’s? does it have a fast throttle plate? Have you worked with the speed of the air flap on the secondary?

Could not answer any of these question right now. I only had it apart long enough to replace the needle/seat and float. Set the float up best I could based on resources I found online. Is there a good resource on looking at what I have and determining what's in it? I'd be happy to take it apart and measure everything just so I could have a baseline starting point. I just worry about taking it apart so far I can't put it back together. Granted, I suppose that's about the only way to learn how.

What is a "fast" throttle plate? Also have not messed with the air flap but I know that it does open at WOT, just not sure how much or how fast.

[Mark Yacavone]

Where are you? Division 1 ?
Mexico?
If we knew then maybe we could recommend someone that could to help you at the (1/4 mile) track.
Who was the previous owner of your car?
Who built your 350 trans?
Does it have a 2.74 low gear?
What rear gear?
What rear tire?
Where's the other tire and brake?

[JP1738]

Originally Posted by Mark Yacavone

Where are you? Division 1 ?
Mexico?
If we knew then maybe we could recommend someone that could to help you at the (1/4 mile) track.
Who was the previous owner of your car?
Who built your 350 trans?
Does it have a 2.74 low gear?
What rear gear?
What rear tire?
Where's the other tire and brake?

D2, and don't mind the ambiguous profile. I race out of Charlotte, NC and hope to go to the Darlington 1/4 mile test next Saturday.

The car has changed hands multiple times since it last ran, best I can tell it last went down the drag strip in 2015 or so. I do not know who last ran it. No idea on TH350 builder or first gear, but I know it and the converter came out from behind another 305 of similar combo so I'm 90% sure its 2.74 first gear.

5.38 rear gear on a Hoosier 30x9 C06 radial.

If you need any more info please send me a PM, I don't want to hash every minute detail of the car out and make the entire forum listen, but I do genuinely appreciate all the people who have reached out or chimed in!

[Mark Yacavone]

Originally Posted by JP1738

D2, and don't mind the ambiguous profile.
If you need any more info please send me a PM, I don't want to hash every minute detail of the car out and make the entire forum listen, but I do genuinely appreciate all the people who have reached out or chimed in!

My comment here would be that the more info you share here, the more feedback you'll get.
There are many other ways to pick up some ET besides in the Q Jet.
Of course Mark Lewis can help with that ,as can Mike McDonald

[Mike Pearson]

Originally Posted by JP1738

Could not answer any of these question right now. I only had it apart long enough to replace the needle/seat and float. Set the float up best I could based on resources I found online. Is there a good resource on looking at what I have and determining what's in it? I'd be happy to take it apart and measure everything just so I could have a baseline starting point. I just worry about taking it apart so far I can't put it back together. Granted, I suppose that's about the only way to learn how.

What is a "fast" throttle plate? Also have not messed with the air flap but I know that it does open at WOT, just not sure how much or how fast.

If you come to Orlando I will be there. I wound glad to take a look at what you have. I can show you what a fast throttle plate is. And how it works. It is a linkage modification that brings the secondary in faster. You want the secondary and air flap to open as quickly as possible with out getting a bog. Sound like your carb is basically a stock Q jet. Even if you don’t bring the car come out and we can meet and talk

[JP1738]

Originally Posted by Mike Pearson

If you come to Orlando I will be there. I wound glad to take a look at what you have. I can show you what a fast throttle plate is. And how it works. It is a linkage modification that brings the secondary in faster. You want the secondary and air flap to open as quickly as possible with out getting a bog. Sound like your carb is basically a stock Q jet. Even if you don’t bring the car come out and we can meet and talk

As much as I think it is ill-advised, knowing I could get some help or expertise there would make it worth it. I have been planning on coming all winter so I'll probably bring it just to get a grade point and participate. I'll link up with you when I get there. Shoot me a PM if you don't mind.

[Mark Yacavone]

Don't really need to speed up secondary opening if you are two stepping it off the line.
I don't think we know that yet, either.