1967 carb/HO exhaust manifold question - Pontiac GTO Forum
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post #1 of 11 (permalink) Old 03-17-2013, 01:36 PM Thread Starter
 
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1967 carb/HO exhaust manifold question

1967 HO has the exhaust manifold with the flapper. When I had the engine rebuilt we took off the flapper and welded the holes on the exhaust manifold. Does the carb choke have any connection to the exhaust manifold. Would the exhaust manifold flapper door have any connection to the carb idle-choke? The reason I ask, I have 2 carbs, a rebuilt qjet with electric choke that is on the car now and the original one(manual choke) that I was told wasn't any good. I'm thinking the right carb guy could rebuild it. It was on the car originally before but the idle had to be set so high or it would stall and until it was warmed up it would just die out and I had to keep pumping the gas peddle to keep it from stalling out at a stop light. In fact I had to put it in nuetral at every light just so I wouln't stall out. The mechanic could not get the carb adjusted so I think he just gave up and said get a new one by default and I listened to him. So I got the rebuilt qjet one that would bolt right on with the original linkage and minimal down time and an electric choke. But this carb has issues too, the idle has to be set so high to keep it running at a stop light. The car runs fantastic in all other respects. Great acceleration, high way cruising speed and kick down. Its just the idle speed. The original carb is numbers matching date code correct carb! So now after a long winter here in Minnesota and having plenty of time to think about this, I'm thinking of rebuilding the original carb. The mechanic says bring the (rebuilt ) to the shop you bought it at, I did and he said find a competent mechanic. Help!
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post #2 of 11 (permalink) Old 03-17-2013, 02:08 PM
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No '67 GTO's came with a manual choke. It is known as a divorced choke, and works off of a spring that is mounted in a steel box on the intake manifold. Exhaust heat operates the spring. The heat riser valve in the exhaust is important for proper choke operation and cold weather drivability, especially in you neck of the woods. It helps exhaust heat on a stone cold engine heat up the intake and improves cold drivability a bunch. My advice would be to re-install the heat riser valve, and check out Cliff Ruggles's book on quadrajet carbs. Cliff also rebuilds them. Q-jets, are one of the best carbs out there, but you need the proper knowledge and skills to rebuild them and calibrate them. Once done, they are bulletproof. My advise would further be to have the original carb rebuilt by Cliff or another expert, (or yourself if you have the book and are feeling up to the task) and install it on the car with the original choke configuration. I'm running the original Q-jet on my '67, and it performs flawlessly. Good luck.
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post #3 of 11 (permalink) Old 03-17-2013, 03:51 PM
 
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Originally Posted by geeteeohguy View Post
No '67 GTO's came with a manual choke. It is known as a divorced choke, and works off of a spring that is mounted in a steel box on the intake manifold. Exhaust heat operates the spring. The heat riser valve in the exhaust is important for proper choke operation and cold weather drivability, especially in you neck of the woods. It helps exhaust heat on a stone cold engine heat up the intake and improves cold drivability a bunch. My advice would be to re-install the heat riser valve, and check out Cliff Ruggles's book on quadrajet carbs. Cliff also rebuilds them. Q-jets, are one of the best carbs out there, but you need the proper knowledge and skills to rebuild them and calibrate them. Once done, they are bulletproof. My advise would further be to have the original carb rebuilt by Cliff or another expert, (or yourself if you have the book and are feeling up to the task) and install it on the car with the original choke configuration. I'm running the original Q-jet on my '67, and it performs flawlessly. Good luck.

What he said! LOL! The technical term for the part is either an exhaust dampner or some manufactures call it a heat riser valve like like geeteehoguy stated and he is 100% spot on. If you want the car to run properly on a cold weather start up you need to have one installed. Do not be surprised if when you do find one it is a bit pricey too.
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post #4 of 11 (permalink) Old 03-18-2013, 06:20 AM Thread Starter
 
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Thanks GTO guy, so you think the mechanical choke would be better than the electric choke? I don't think there is any going back to change the exhaust heat riser now. Also, I meant mechanical choke not manual choke on the earlier post.
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post #5 of 11 (permalink) Old 03-18-2013, 10:14 AM
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Gotcha. I prefer the mechanical choke to the electric, but the electric will work. Just go easy the first few miles when cold. Without a heat riser, the intake will still see enough exhaust heat to use the original mechanical choke. Your choice. I have no heat riser on my '65 (Has tubing headers) and it has it's original choke.....works fine. A bit more cold blooded than my stock '67, but workable.
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post #6 of 11 (permalink) Old 03-18-2013, 08:53 PM Thread Starter
 
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GTO Guy, I saw one of your responses from 10/5/2011 regarding the gaskets between carb and intake. I meet with the carb guy today and I'm going to have the original carb rebuilt (1967 HO with air) this is a numbers correct carb and the car has the PHS documentation. My question or to confirm the 67 only has a total of 3 gaskets with the metal one sandwiched between the two. Ames said i need two? Since you have the original set up I just want to confirm. Also, I will not be replacing the heat riser. Thanks,
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post #7 of 11 (permalink) Old 03-19-2013, 01:13 PM
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67, technically, there is just one gasket and one steel plate. I personally prefer 2 gaskets, with the steel plate sandwiched in the middle. I believe it seals better, and I know it insulates engine heat better. Works for me. Be advised that '67 carbs are a one-year carb, highly sought after and pretty rare. A rebuildable core can go for upwards of $1000. Glad you're having the original carb rebuilt and going to use it! That's what I'd do.
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post #8 of 11 (permalink) Old 03-19-2013, 03:04 PM
 
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I remember when there were still a decent number of the Pontiac V-8 motors on the road and I can remember that intake manifold leaks were pretty common due to the design of using the plate to seal the intake. I have never tried using a gasket along with it but it sounds like a good idea. It might make the tendancy for the intake pan to cause intake leaks later on a lot less.

I am just learning the ins and outs of the GTO being mostly a Corvette and 67-69 Camaro guy.
I had no idea that the 67 Q-Jets for the GTO where that rare. I am still sorting through the pile of parts that came with my 67 GTO but I do know in the stash of stuff are two Q-jets! One has been remanufatured and I have matched up the numbers on it and it is for a 67 GTO automatic. The other looks to be in need of a rebuild but I have no grabbed the number off of it yet.
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post #9 of 11 (permalink) Old 03-19-2013, 04:59 PM Thread Starter
 
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Guys, thanks for your comments. I think its great we are having a discussion from coast to coast and I'm in the midwest waiting for spring so I and the car can come out of hibernation.
All the problems started with what I believe is a carb and maybe a choke problem when its cold, but even in the summer it would be difficult to idle smoothly so we set the idle way up to compensate for the car stalling out all the time. Then if we set the idle down, when I would pull up to a stop light, it would just stall out.
But, we only had one gasket between the carb and manifold. So, when I get the original carb rebuilt, and I want to confirm it takes two gaskets, one being metal. But, you use 3, Is that correct? I see I can order the gasket from ames.
Thanks,
Greg
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post #10 of 11 (permalink) Old 03-19-2013, 10:12 PM Thread Starter
 
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One more question. What is the sequence for placing these gaskets between the intake and carb?
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