Too Slow/Q-Jet question

[JP1738]

As many know, I’m trying to put a stocker together in time to make Orlando. Went and tested today and everything went great! Car seemed happy, suspension was locked in, and the car was very consistent. Only issue is it’s too slow. Only managed an 8.20 off the NSA 8.26 index in pretty solid air after draining a quart of oil. I think it might be ok in Orlando but I know the car will lose time in the 1/4 vs the index in the 1/8th. I’m looking for more ways to speed it up, even if only a little bit. I’m told I could look into an M200 trans instead of my TH350 which I’m open to. Any input there would be great. Additionally, if there is anybody out there with a similar combo (‘80 305 Chevrolet) what are you guys running for jet size? My carb seems to have already been gone through and loved on as it idles great, launches well, and never misfires or stumbles. Honestly the plugs look good too but I’d still like to double check against why others are running. Mine currently has two 65 mains at 6.5 psi fuel pressure, I’m curious if that’s close to what others are running. Any helpful input would be welcomed, I really wanna go in 2 weeks but if I can’t go 13.00 I there’s really no point.

[Bobby Lundholm]

Originally Posted by JP1738

As many know, I’m trying to put a stocker together in time to make Orlando. Went and tested today and everything went great! Car seemed happy, suspension was locked in, and the car was very consistent. Only issue is it’s too slow. Only managed an 8.20 off the NSA 8.26 index in pretty solid air after draining a quart of oil. I think it might be ok in Orlando but I know the car will lose time in the 1/4 vs the index in the 1/8th. I’m looking for more ways to speed it up, even if only a little bit. I’m told I could look into an M200 trans instead of my TH350 which I’m open to. Any input there would be great. Additionally, if there is anybody out there with a similar combo (‘80 305 Chevrolet) what are you guys running for jet size? My carb seems to have already been gone through and loved on as it idles great, launches well, and never misfires or stumbles. Honestly the plugs look good too but I’d still like to double check against why others are running. Mine currently has two 65 mains at 6.5 psi fuel pressure, I’m curious if that’s close to what others are running. Any helpful input would be welcomed, I really wanna go in 2 weeks but if I can’t go 13.00 I there’s really no point.

I have a metric 200 that was originally built by Turbo Action that Leon Miranian is rebuilding it right now if you are interested. $2,800. Check to see what your converter is flashing to.

[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.

[Henrys Toy]

Originally Posted by JP1738

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.

Good morning to all,
I have walked through your shoes and spent many years learning to go fast.
I made a lot of mistakes as did many others on this forum. That said, you might be able to answer a good many questions by going to a dyno, put the engine on it and run it! You will spend a few dollars here - but what you will learn in one eight hour day will help more then you now know. Yes - I know the cost is substantial , but when someone ( like a Mfg. ) asks you a question, you can answer them and produce HP & Torque numbers and that's what people need to see in order to help you.
If you're guessing , then thats about all they can do too.
You might think that is extreme but you'll find out information it would take a whole season to find out.
Just my 2 cents from over here on a little Rock off the coast.

Respectfully,
Henry Kunz 1534 H/SA

[JP1738]

Originally Posted by Bobby Lundholm

I have a metric 200 that was originally built by Turbo Action that Leon Miranian is rebuilding it right now if you are interested. $2,800. Check to see what your converter is flashing to.

Tough to say what it flashes at on the hit as first gear is so short, but it falls back to around 5100 on the gear changes. Might be in touch about the trans though, thank you for the heads up. Will the converter and shifter work for that transmission swap as well?

[Bobby Lundholm]

Originally Posted by JP1738

Tough to say what it flashes at on the hit as first gear is so short, but it falls back to around 5100 on the gear changes. Might be in touch about the trans though, thank you for the heads up. Will the converter and shifter work for that transmission swap as well?

Your shifter should work depending on what you have. Converter will not work as the trans is set up for a metric input. Get ahold of Leon Miranian on the carb as well. He does all of my stuff.

[Doug Hoven]

Q-jets aren't really "cut and dry" across the board. Some carbs are good with a little work, and others are slow no matter how much effort is thrown at them. If the money isn't there to send a carb out to be built by one of the "gurus," then I would suggest buying the Quadrajet book by Cliff Ruggles. I surprised myself with how much I was able to accomplish with some basic mods to a bone stock Q-Jet. I believe what was meant by a "fast throttle plate" means the linkage was made to open the primaries and secondaries at the same time, unlike the stock progressive linkage that opens the primaries a decent amount first before opening the secondaries. The 1-1 linkage carbs tend to not drive around as well, but some swear by them being faster. As far as tuning goes, the car will tell you what it likes and doesn't like. MSDs can cause plugs to look good even when things aren't so good. I would suggest taking some "swings" at jetting, rods, and trying a few different hangers if you have some. Even if what you already have ends up being the best, at least you'll learn something.