Draw through carbs

7

79bird

Member
Joined
Oct 31, 2002
Does anyone know how a draw through carb would work on a NA motor, carb #170592430 0419 CKD. The motor is a 4.1 with bigger valves, 2" intake I think, and the cam is two steps above stock. The guy I got the motor from hasn't given me the specs. on the cam yet. And would I want to use headers or stock manifolds. I'm just worried that the carb will be too big for the motor. Thanks for any help.
Chuck
 
ok, while the info would be helpfull, and I thank you, for a NA to turbo conversion. I'm looking to put a Draw Through Carb onto an NA motor. What I don't have is access to the non-turbo carb that came with the motor from the factory. Hence the question, would a draw through carb work on an NA motor or would there be too much airflow for a nice crisp throttle response? Or should I say the heck with it and go with the Edelbrock that was recomended over the Q-jet at the parts store?
Anybody??
 
Sorry, When I hear draw thru the first thing I think of is a draw thru turbo setup.

Are you using a Computer controled Carb and Disp?
Or is it a NonCC setup, Vac advance Disp?
Are you looking at using the carb intake from a turbo setup?
Jim
 
Originally posted by 79bird
#170592430
Click to expand...

That's a '79 Turbo V6 carb. It's a non-CCC carb. The CFM won't be an issue. It's a just a little bigger in the primaries than most q-jets. A turbo motor uses the same CFM as a NA motor.

The only difference compared to a NA carb is that the power valve is externally plumb to the intake. Look at this vacuum diagram for a '79 turbo motor. http://home.flash.net/~rjgeorge/images/vac79abfed.JPG The line going to the PEVR needs to see manifold vacuum, otherwise the power valve will be open all the time.
 
So the carb will be ok, that's good. When you say the primarys will be a little big I'm assuming you mean the jets. So going down one or two sizes will do what I want for the NA motor. Or am I wrong and you mean the primary side of the carb? That would be ok too I guess because of the motor it's going on. I copied the diagram to look at after I'm offline. Thanks for the help here. Another question is if this motor would benefit from headers or stock manifolds, I'm not planning to do any racing or high RPM driving with it. I do want to go with a dual exhaust setup, The drivers side crossing under the eng. and going down the pass. side.
 
Most Quadrajets are 750 CFM when the secondaries are fully open. The one you have is 800 CFM. The extra 50 is found in the larger bore of the primaries.

I don't know much about NA headers for these cars. I would try and find 79/80 stock V6 manifolds, they are bigger than later years (but still single).
 
Draw thru

The carb I'm looking for was a 4.1 specific Q-Jet made for the motor. Wether the secondaries were restricted down for around 500 or so CFM I don't know. I think that was the case, But the number is, 17080244 M4ME. If there's any more numbers I don't know.
 
Re: Draw thru

Originally posted by 79bird
The carb I'm looking for was a 4.1 specific Q-Jet made for the motor. Wether the secondaries were restricted down for around 500 or so CFM I don't know. I think that was the case, But the number is, 17080244 M4ME. If there's any more numbers I don't know.
Click to expand...

That's enough numbers that is needed to identify the carb.
You can restict the CFM by adjusting the opening of the secoundaries. There is a tab on the right side of the upper butterflies that resticts it's opening.
Freddies Buick had some good info on the NA carb setup, but I cann't seem to find his web site...I think he forgot to add it to his profile....Freddie are you reading this?????? ADD YOUR WEB SITE
Jim
 
draw thru

According to a site I visited about 30 clicks ago, it said I need 390 to 600 cfm for the 4.1. Edelbrock has a 600 with elec. choke they say works better than a Q-jet. But if I can go with a good Q-jet that'll be just as good and save me some money.
Thanks Jim
 
draw thru

But wouldn't that be max cfm at wot, seems to me that if a '79 Turbo Regal has a 850 cfm draw thru carb, that a 600 would be fine for an NA. My .02!
 
341 cfm at 5500 for a 252 ci. motor. And I don't anticipate hardly ever see'ing 5500 rpm. Actually make that never. The motor does have the performance cam and head rework, probably bigger valves and some porting, springs to match the cam. Cam is supposed to two steps above stock. Still have to find out. So that turbo carb. would be too big. I want to step on it and go, not wait for things to wake up and ask if it's time to work! :rolleyes:
 
I'll try again.

ALL Quadrajets (even the 4.1's) are either 750 or 800 cfm IF the secondaries are open fully. They are not. The Turbo V6 does NOT use 800 cfm, just as the 4.1 does not use 750 cfm. They at set up for much less.


Turbo engines need the same cfm rating as the NA. So the 3.8 Turbo's Q-jet might be the a little less total cfm than the 4.1's Q-jet. I bet it's too close to be a problem. Plus it's easy to adjust the secondary air valves.
 
Any references or pics on how far to set the secondaries so they don't open too far?
Thanks for clearing things up.
 
Re: Re: Draw thru

Originally posted by Ttype83
Freddies Buick had some good info on the NA carb setup, but I cann't seem to find his web site...I think he forgot to add it to his profile....Freddie are you reading this?????? ADD YOUR WEB SITE
Jim
Click to expand...
Sadly,

Back in December I lost everything. First my DSL company went belly up. Second my home network blew a hub. Third and final nail in the coffin, a bug infected my host computer and I lost everything in it......(ie: Website and all my images). :eek:

My core writing was saved but the images are history. For those of us in cyberspace.....image is everything. I dedicated alot to the assistance of our members. It hurts knowing the effort helped some but could not remain to help more. :( :(
 
draw thru

would have been back sooner but I crashed my pc, HARD! Oh well, I have the Q-jet book by Doug Roe. It should tell me what I need to know. A few words you may be tired of hearing by now, Anti-virus Protection. I hope the future is better for you than the recent past.
Chuck
 
draw thru carbs

would the person I was going back and forth with about the turbo carbs please e-mail me. I lost my archive mail and our messages. I'm still interested in buying one of those carbs. Thanks, Chuck
 
Carb Jets and Primary Rods

Does anyone know the Jet sizes that were in the 4.1 NA carbs along with the rod numbers? This being for the primary side of course.
 
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