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 Intake / Carb and Fuel Delivery Tech
 Best aftermarket Quadrajet on market?
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 14 May 2017 :  5:34:33 PM  Show Profile  Reply with Quote
And would it be a problem mounting it on a Edelbrock performer intake? I'm running a Holley 600 cfm on it now. It's a 400 crate, 6x heads, don't know the cam but it does thump a little. After a lot of reading about carbs my head is spinning, but I'm getting sold on the Quadrajet. I thank you for any thoughts or just plain comments. Oh... reason.... car feels great off the stoplight but seems to want a bit more fuel down the stretch. I just installed new stainless 3/8 line from tank to pump also.

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cortcomp
Coyote

USA
5335 Posts

Posted - 14 May 2017 :  7:10:48 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
IIRC the edlebrock performer and performer RPM take both square and spread bore carbs without an adapter. If you look, there should be 2 holes in each corner to mount the carb (8 holes total, 4 sets of 2 holes next to each other.)

If that's the case, with the right gasket, should bolt right on.
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 14 May 2017 :  11:26:21 PM  Show Profile  Reply with Quote
Thank you,
Also my block is a 75, and I have headers and flowmaster 50s.
Looking at the JET Q jets in stage 2, DO you feel the 750 or 800 would be a good fit?
Thanks,
AL

What is the S, in Custom S ?
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 15 May 2017 :  10:55:48 AM  Show Profile  Reply with Quote
On the q-jet the 50 cfm difference is slightly larger primary venturi's, by like 1/32" IIRC. The smaller carb is said to give more control over the idle circuit.

The newer q-jets 1976-77 (800 cfm's) have distinct advantages in float geometry and well plug sealing. Also the front fuel inlet, pontiac, olds, and buick carbs are more user friendly because of pontiac fuel pump location.

I prefer the un-molested greasy grimy take-off carbs. Then clean and install one of Mr. Cliffs carb kits. Or let Mr, Cliff build it to your application. There are not that many parts inside a q-jet if your feeling frisky..

-- http://cliffshighperformance.com/ --

Cliff's Q-jet book is an excellent reference. It includes what to look for when selecting a carb, history, techniques, and modifications.

--





Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 15 May 2017 11:41:54 AM
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 16 May 2017 :  07:10:53 AM  Show Profile  Reply with Quote
Carbs and mudding drywall are best left to professionals , some things I'm just not good at......

What is the S, in Custom S ?
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cortcomp
Coyote

USA
5335 Posts

Posted - 16 May 2017 :  09:42:10 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I haven't seen a qjet rebuild larger company that didn't cut corners or mismatch things. Of course, i don't find out until later because i don't know what i'm doing that it's crap.

I see you're in Ohio by Cle! I'm over north of ytown. You have two choices if you don't want to do it: send it to cliff out by you, or send it to benchwick's in youngstown. Harry at benchwick's is a little cheaper but i've never had a carb done wrong by him. Any time i get an old car, its carb is going to benchwicks whether it needs it or not, cheap insurance. The cliff carb i had was worth it as well, and IMHO, when you see a pontiac for sale in the pontiac circles, having cliffs carb on it makes it a little bit better deal.
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67drake
Sitting Duck

Azerbaijan
1501 Posts

Posted - 16 May 2017 :  11:03:00 AM  Show Profile  Reply with Quote
quote:
Originally posted by AlsCustomS

Carbs and mudding drywall are best left to professionals , some things I'm just not good at......




From what I hear,aftermarket Q-jets are inferior to a good old rebuilt one. Never bought a "new one",just going by what I read on this.
But, Problem is,as Blued noted,you want an old unmolested one to start with. Getting harder to find these days,but they're out there. i.e. I bought a '73 Firebird Q-jet off of a local guy for $20. It was supposedly the original from his '73 Bird. When I tore it down for a rebuild it was a mess inside. I sent pics to Cliff and he said it looked like it was soaked in some strong solvent that the "crank em' out" rebuilders use. The top of the accelerator pump well and the top of the power piston retainer area was eaten away. It's a parts carb now. I bought a whole box full of carb cores years back for $25 from a Craigslist ad. 5 Q-jets and 2 Holleys. I found an unmolested '76 Buick Q-jet with APT in the box,that's what I ended up using.

As Cortcomp noted,they're not too hard to rebuild using Cliff's book and parts. If I can do it....


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 16 May 2017 11:08:05 AM
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 16 May 2017 :  9:46:51 PM  Show Profile  Reply with Quote
I don't have a core, the car had the Holley on it when purchased. And after all the reading....how can you trust your going to get a good one?? I was hoping to hear something good from aftermarket Q-jets

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tjs44
Cochise

USA
412 Posts

Posted - 19 May 2017 :  09:27:37 AM  Show Profile  Reply with Quote
Give Sean at SMI a call.He builds great carbs and actually owns and drives a pontiac.He does all my QJs and Holleys.Tom
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phil400
Cochise

Canada
456 Posts

Posted - 21 May 2017 :  5:50:08 PM  Show Profile  Reply with Quote
I just picked a complete "greasy grimy" q-jet like B&P mentioned for 25$ at spring Carlisle, off an 80 Buick. A kit from cliffs and I'll be into for a little over 100$ and have a good carb that I rebuilt.

I'd never pay big money for one that I can rebuild myself.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 22 May 2017 :  12:53:25 AM  Show Profile  Reply with Quote
Hope it goes well. Keep us informed.
What year did they start with the electronic metering rods.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 25 May 2017 :  12:29:53 PM  Show Profile  Reply with Quote
Thanks for the response I'm scouring Cleveland Craigslist and other things. Might as well give it a try.

What is the S, in Custom S ?
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cortcomp
Coyote

USA
5335 Posts

Posted - 25 May 2017 :  12:51:14 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I don't know why i didn't think of this before now. I HAVE a rebuilt quadrajet on the shelf, about 5 years old now. I was running it while waiting for my cliff carb. It's front inlet, shelf dusty now. It ran great BUT it had a slight whistle at idle, going into the feed for the idle air bypass, IIRC. I had a thread somewhere, i'll see if i can find it. It didn't affect operation at all. IMHO, likely an idle air passage that needs cleaned or the orifice is malformed and would need peened and drilled to make round. I didn't chase it down. I have a bit of change in it, i'd sell it for $100 and you're fairly close. If you're interested i'll get the numbers off it.

Link: Ignore rough idle, wasn't related to carb.

http://psp.aquacomp.net/topic.asp?TOPIC_ID=4139
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Phil
The Great White Buffalo

USA
7219 Posts

Posted - 25 May 2017 :  4:30:30 PM  Show Profile  Reply with Quote
Al, what max. rpm are you shifting that 400? I've had decent results with the 600 Holley VS carbs on 350's but it can be a bit of a stretch on a 400 depending upon the rpm your taking it to.

Qjet no problem on either of your intakes and you can also lose the squarebore adaptor plate in the process.

My first choice for Qjet work is Cliff as I have dealt with him over the years for parts as well as a few Qjets he built for me in the earlier days, all of which were flawless and are still in operation. SMI has a good rep too and may be quicker if you're pressed for time but check on their backlog as well.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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AlsCustomS
Tribal Scout

USA
38 Posts

Posted - 31 Oct 2017 :  8:04:28 PM  Show Profile  Reply with Quote
Hello,
hope you all had a great summer and fall !
So I settled on the Street Demon 625 cfm with the poly body.
Before starting I installed a Holley pressure regulator and Holley inline 10 micron filter.
Found out I was at 6.5 to 7 psi from the pump, so glad I put it in as the demon likes 5 to 6 psi Started by setting low idle at 650 but it got a big flat spot at WOT burn out, set it at 750 better but flat with a backfire, tighten the spring pressure on the goggle valve a quarter turn and this car really runs,
went with it because of the primary bore is at 1-3/8 "and it really responds moving 3,700lbs secondary goggle valve is like having a 3barrel.{secondary bores are connected in the middle and looks like a pair of goggles with a flap}
I thank you all for your help it got me reading and learning about carbs and would recommend this carb for those who are looking . Oh pretty simple to work on except getting to the high idle screw

What is the S, in Custom S ?
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cortcomp
Coyote

USA
5335 Posts

Posted - 31 Oct 2017 :  8:15:33 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Glad to hear a report on these. They seem like they'd make a decent street carb, i liked the design when i saw one of them at summit. Thanks for following back up!
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