1968 Pontiac GTO carb question - Team Camaro Tech
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post #1 of 18 (permalink) Old Apr 7th, 08, 12:28 PM Thread Starter
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Talking 1968 Pontiac GTO carb question

I am working in a shop that normally handles European sports cars, but we have gotten in a 1968 GTO Convertible to do some work on.

The car is completely restored and absolutley beautiful, but it runs terribly.

The carb on the car is a late model quadrajet, which I have no experience with.

I talked to a guy who rebuilds these things and he said that the carb on the car, being intended for a smog vehicle, will never run right.

So, now here's the problem. What would be the best way to solve this problem. He's running the original intake, so it would take an adapter plate to get a square bore carb on there.

I have found a rebuilt period correct quadrajet carb for about 800 bucks.

The owner is not set on having the original carb on there, he just wants it to run right.

So, would you put the adapter plate on and bolt on another carb, or buy a rebuilt quadrajet that was original to these cars and put that on.

Mike

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post #2 of 18 (permalink) Old Apr 7th, 08, 12:43 PM
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Re: 1968 Pontiac GTO carb question

I don't buy the carb rebuilders opinion on the carb. It may not get the performance level of other carbs but it surely can be tuned to run properly unless it's just worn out. If there is room for a spacer and square bore carb the Holley Avenger series are very streetable and will provide performance too. If you want to keep more in line with the orig carb look at Edelbrock carbs. I don't know whar the Edelbrocks cost but an Avenger should be in the $325 - $350 range new.

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post #3 of 18 (permalink) Old Apr 7th, 08, 12:59 PM Thread Starter
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Re: 1968 Pontiac GTO carb question

Thanks Dennis, I'm going to check the spacing in the morning. I think he'll want to go with the edelbrock. I've been trying to call them to match one up, but they have a huge wait time on the tech line. This quadrajet is about an 800 cfm carb if the guy gave me the right info.


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Mike

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post #4 of 18 (permalink) Old Apr 7th, 08, 02:21 PM
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Re: 1968 Pontiac GTO carb question

I would for sure stick with a q-jet on that car.

Brian Lewis has posted about a shop that makes performance q-jets?





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post #5 of 18 (permalink) Old Apr 7th, 08, 03:03 PM Thread Starter
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Question Re: 1968 Pontiac GTO carb question

I would like to see the guy give us the time to put the right carb on this thing, but I know he wants to take it to a show and may want a 'quick fix'. I'd like to wring the guy's neck who put this carb on here.

Anyone else want to chime in on this?

Mike

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post #6 of 18 (permalink) Old Apr 7th, 08, 04:03 PM
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Re: 1968 Pontiac GTO carb question

i have the same engine (400) on in my 'bird and the e-brock 1406 works great right out of the box. i can't see a q-jet doing much better, except costing more...
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post #7 of 18 (permalink) Old Apr 7th, 08, 05:03 PM Thread Starter
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Talking Re: 1968 Pontiac GTO carb question

Excellent John, that's the same part number that I got from Edelbrock on the phone just a little while ago.

Thanks!

Mike

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post #8 of 18 (permalink) Old Apr 7th, 08, 06:26 PM
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Re: 1968 Pontiac GTO carb question

I grew up around all the early Poncho's most being 389-421. I found the Q -jet on many but I also found guys switching over to an AVS type carb (because of the large rear bbls) and this carb is a cousin to old Carter AFB's which also has faded away. But, the Edlebrock(,much like the Afb) , like the 1405, 1406 or 1407 would work well on an aftermarket manifold. But it sounds like you wish to retain orginality so , I would locate someone that knows how to tweak these Q-jets and can outperform many other carbs. Choice is yours. I am a Holley fan but just don't see many Holleys on a Poncho, unless its running Prostock.

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post #9 of 18 (permalink) Old Apr 8th, 08, 05:06 AM
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Re: 1968 Pontiac GTO carb question

Many of the smog Q-jets have different calibrated APT circuits and different metering rod/jet calibration as compared to period correct Q-jet.

I'd stick with Q-jet for the Pontiac because of the ease of operation, maybe get a rebuilt unit for the period of year. Might try Jet Performance. Hedstrom is another.

A correct Q-jet is hard to beat. Try RockAuto?

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post #10 of 18 (permalink) Old Apr 8th, 08, 06:55 AM Thread Starter
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Re: 1968 Pontiac GTO carb question

Haven't tried those yet, I found a guy off of e-bay that has quite a few. It's really the customers call, so we'll see what happens, I sure do appreciate the help though, beleive me, it helps as usual!

Thanks guys, Mike

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post #11 of 18 (permalink) Old Apr 8th, 08, 04:01 PM Thread Starter
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Talking Re: 1968 Pontiac GTO carb question

Ok, got him to go for a rebuilt period correct quadrajet. Now I gotta go find one

Mike

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post #12 of 18 (permalink) Old Apr 8th, 08, 09:20 PM
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Re: 1968 Pontiac GTO carb question

I personally wouldn't run the Quadrajet unless the customer insists on having a numbers matching.

I would run a Holley 4011. Looks like there aren't any 800s right now though. Here is a 650 in bad condition http://cgi.ebay.com/ebaymotors/Holle...QQcmdZViewItem

The 4010/4011 are nice carbs that will set up nice and give and maintain a good all around tune.
-They have annular boosters.
-The powervalves and jets are on the bottom of the bowls so they don't get uncovered.
-They have a one piece top with the gasket above fuel level.
-If you need to change their tune everything is in a booster/mains cluster.
-They have 2 circuit emulsion on the idle circuits.

Holley went real conservative on the pump shot though. Drill the primary squirter to at least .033"-.035".
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post #13 of 18 (permalink) Old Apr 9th, 08, 04:27 AM
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Re: 1968 Pontiac GTO carb question

Quote:
Originally Posted by 1NAST69 View Post
Ok, got him to go for a rebuilt period correct quadrajet. Now I gotta go find one Mike
Jack Podell, he's listed in Hemmings as the carb guru under Services and in the ads of individual makes.

And Hedworth vs. Hedstrom as I suggested earlier.

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post #14 of 18 (permalink) Old Apr 9th, 08, 05:10 AM Thread Starter
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Talking Re: 1968 Pontiac GTO carb question

OK, I'll check those out. I was checking Hedstrom like crazy last night, got everything but carbs

Thanks, Mike

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post #15 of 18 (permalink) Old Apr 9th, 08, 03:39 PM Thread Starter
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Talking Re: 1968 Pontiac GTO carb question

Found a carb, rebuilt and ready to go. Still isn't a 1968 carb, but is a factory replacement unit, built in 75, but to replace the 68 carb. Now he wants an original air cleaner and alternator. Back to the search

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