off idle stumble

[TJ's Chevy]

Did you ever check if you mechanical advance was working? If its binding...that will cause hesitation. If you haven't....it only takes a second to check...pull the cap and twist the rotor....one way it won't turn at all...and the other way it will turn a little and you'll feel some spring load....if it doesn't turn either way....that may be your problem. Send the motor to me...I wanna tinker with it. lol

[jdl71]

Yes, the advance is working:

http://www.youtube.com/watch?v=ohppZXCFN64

I also did what you suggested and took the cap off and checked the rotor. I will move clockwise and spring back, and will not move counter clock wise. I also took the points and condensor out of my parts truck and swapped them in, no difference. My next steps are to pull the manifolds off (yet again) and try another new gasket to see if I can seal up the intake and exhaust leaks. I'm considering doubling them up, I just don't understand why they won't seal. The surfaces look flat. If that does not work I'm going to take the distributor, cap, coil, plugs and plug wires out of the parts truck and put them in. If that fails to fix this the engine is coming out and I will either tear it down for a rebuild or tear down my spare engine, see what it needs, and put it in.

[TJ's Chevy]

The intake gasket won't seal? Is it the metal felpro one?

[jdl71]

No. I can spray carb cleaner around the front port and hear the engine rev. Yes it's the fel pro metal one. It also sounds like the gasket between the intake and exhaust manifolds is leaking. I can feel air from that area when the engine is running. I did use the intake gasket last week the first time I tried putting stuff back together when I discovered my old exhaust manifold was junk. I guess it could have blown out in the 2 or 3 minutes of use but it did not look like it. I went to Napa tonight and got another new set. I am now considering doubling them up to see if it will seal.

[TJ's Chevy]

Originally Posted by jdl71

No. I can spray carb cleaner around the front port and hear the engine rev. Yes it's the fel pro metal one.

That's your problem if the gasket is not sealing. I got mine to seal just fine. What pattern to you use to torque your bolts down? There is a sealant out there for these gaskets. Course I forgot the name. Clifford Performance has a Nice gasket they sell for $20.

[jdl71]

I originally started in the middle and worked out towards the ends. I did not see a pattern in the shop manual, so I treated it like a head or intake on a v8. I would think a felpro gasket would be good enough. I even looked at their site to make sure I was installing it correctly, and they recommend smooth side towards the exhaust manifold so it can move as it heats and cools. That is the way I did it. I have went back and tried loosening and re torquing in a different order and didn't see to make any difference. It's not a huge leak but I can definitely tell it's there. Are these gaskets reusable? Being metal I would think just one torquing would not destroy them, but I have a new one so I will try again. What order do you think I should tighten things down? And finally, if the engine is so lean why are my eyes burning after 5 minutes in the shop fooling with this?

[TJ's Chevy]

Originally Posted by jdl71

I originally started in the middle and worked out towards the ends. I did not see a pattern in the shop manual, so I treated it like a head or intake on a v8. I would think a felpro gasket would be good enough. I even looked at their site to make sure I was installing it correctly, and they recommend smooth side towards the exhaust manifold so it can move as it heats and cools. That is the way I did it. I have went back and tried loosening and re torquing in a different order and didn't see to make any difference. It's not a huge leak but I can definitely tell it's there. Are these gaskets reusable? Being metal I would think just one torquing would not destroy them, but I have a new one so I will try again. What order do you think I should tighten things down? And finally, if the engine is so lean why are my eyes burning after 5 minutes in the shop fooling with this?

I believe I put the smooth side towards the head when I did mine....Can't remember anymore. Ya might take your old gasket and put the smooth side towards the head and see if that does it. From the center out is how I did mine...snugged it...then tightened them down till they were tight.

[jdl71]

I took off the front bolt and retainer and re tightened. Now the engine tries to die when I spray carb cleaner around the intake port, just before I did that the engine would speed up. WTH? This should not be this difficult. The gasket should seal. Maybe I'm expecting too much of a carburetor but I grew up with them, and I'm pretty sure it shouldn't do this:

http://www.youtube.com/watch?v=AJaaczDkPzM

[TJ's Chevy]

Originally Posted by jdl71

I took off the front bolt and retainer and re tightened. Now the engine tries to die when I spray carb cleaner around the intake port, just before I did that the engine would speed up. WTH? This should not be this difficult. The gasket should seal. Maybe I'm expecting too much of a carburetor but I grew up with them, and I'm pretty sure it shouldn't do this:

You sure the intake flanges are not slightly warped? Head surface?

[jdl71]

I have not put a straight edge on the head, but the manifolds are not. I would think that the gasket would make up for any slight warpage I couldn't see on the head.

Out of left field here, but what if I was using 5/16 fuel line when it should be 3/8? Would that be enough to cause this?

[TJ's Chevy]

A metal gasket won't seal well with warpage....the one from clifford probably would as it is a super hard gasket made out of the same material as a carb base gasket. If you have a long straight edge that you can put across the ports you might be able to see if there's warpage.

[jdl71]

Okay, so look at this. This is the new manifold and gasket I put on, has about 30 minutes of run time. See how much bluer the rear cylinders are, like they were hotter?



I could feel an exhaust leak from somewhere around the carb mount, but I never could pinpoint it. I wondered if it was the pivot for heat riser leaking:



You can see clearly in this pic the exhaust was not sealing up worth a crap:



I put a straight edge on the head and it does not seem obviously unflat. LIke the manifolds nothing the gasket would not compensate for. I also noticed the studs that hold the intake down were loose, so I am thinking that was part of my leaks. Going to pull them and reinstall with loctite. My question for you though is do you know if it matter which of these hold downs go in what position? When I took it apart, naturally I paid no attention to what went where. Also some on my 63 (which is the intake I am using) were different from my 64. I'm wondering if I'm somehow getting them in the wrong spots and not getting the clamping force I should.

[TJ's Chevy]

The smaller clamps would be used in the smaller spots and larger ones where they would be able to fit. That's all I remember. lol

[jdl71]

Yeah, the only problem is they will both fit in any spot if turned 90 degress, lol. Off Topic here, but I just watched an inline 6 video on YouTube, and I didn't see you comment on it! lol

https://www.youtube.com/watch?v=_AhBFAC4m9s

[TJ's Chevy]

Yep I have seen that one many times. LOL. Course at least 3/4 of the I6 videos I've watched I haven't commented on. haha

[jdl71]

Out of the 5 or 6 that autoplayed after I watched the one you linked to in another thread earlier, this was the only one I didn't see Military Chevy on.

[T and S]

Just brain storming here - I would try leaving the bolts / studs loose that join the intake / exhaust together. Then I would torque the intake / exhaust bolts to the head to the proper torque, then tighten up the bolts that hold the intake / exhaust together. Just something to try I guess.

[jdl71]

Originally Posted by T and S

Just brain storming here - I would try leaving the bolts / studs loose that join the intake / exhaust together. Then I would torque the intake / exhaust bolts to the head to the proper torque, then tighten up the bolts that hold the intake / exhaust together. Just something to try I guess.

That is how I did it. I read it somewhere, I believe the factory service manual. I got yet another gasket to assemble the spare engine I am using. It is also Fel Pro from the same parts store, yet seems to be thicker and will only line up and go on one way unlike the other. Since I am also putting these manifolds on while it's on an engine stand I should be able to tell which retainers fit in which places the best and I can see if it is sealing up. I also found the bolt that goes in from the bottom that holds the intake and exhaust together had bunged up threads and was not clamping the pieces together even though it seemed tight.

[Dans1960SWB]

I would pull that hole motor out and toss it in the junk yard. Im not a big fan of those sixes....But that being said I would start it up and spray some starting fluid around the intake. Those manifolds warp very easy. You could still have a vacum leak and I don't care how big of a shot that carb squirts it won't run rich enough with a big leak...Those carbs are very basic. I don't think you will have a problem getting it back together. When im working on something like that I snap some pictures of it with my phone. That way I can look back later as a reference.

I guess I should have read the hole thread...lol

[63ChevC10]

There are some great suggestions in this thread. It looks like you might have a couple of things going on here, but I was having similar troubles with my 63. It has an I6 (with points) and it was getting so bad that I had to leave the choke out some just to drive it. It would backfire through the carb, hesitate, and it was even starting to backfire through the exhaust. I made sure (as best I could) the carb was ok and that there weren't any leaks with the carb or intake gaskets. I finally broke down about bought an HEI distributor off of eBay, and wow! I can't begin to tell you how much that helped it out. Like Dan said above, I was about to pull it out and put my 327 in its place. The distributor changed my mind. Just a thought.

Jerry

[jdl71]

Originally Posted by 63ChevC10

There are some great suggestions in this thread. It looks like you might have a couple of things going on here, but I was having similar troubles with my 63. It has an I6 (with points) and it was getting so bad that I had to leave the choke out some just to drive it. It would backfire through the carb, hesitate, and it was even starting to backfire through the exhaust. I made sure (as best I could) the carb was ok and that there weren't any leaks with the carb or intake gaskets. I finally broke down about bought an HEI distributor off of eBay, and wow! I can't begin to tell you how much that helped it out. Like Dan said above, I was about to pull it out and put my 327 in its place. The distributor changed my mind. Just a thought.

Jerry

Both of these ideas have crossed my mind. But I want this engine to run and run right and I'm not going to take the easy way out and throw a small block in it. I am feeling a lot better about the way things are going back together this time. I also found this on the Stovebolt forum and even though I think it was referencing headers, I have done this:

To check your work, run a light across the bottom side of the exhaust as you check across the top. Look for light at the mating surfaces. If you see light, then loosen that side and repeat. If you don't see any light then you're almost home!! Use a sheet of plain typing/printer paper for one final test. Place the paper flat against the block and try to slide the paper between the head and the intake and exhaust. If the paper won't penetrate the mating surfaces then you've done all you can do. Your leak problem should be resolved. If the paper slides behind the intake or exhaust then loosen things up and repeat this process.

[vince1]

I`d swap out the coil if you have a spare and is it OK to spray the gaskets with a can of that copper coat stuff?

[jdl71]

I don't know about the copper coat, not sure if it would burn off or what.

[jdl71]

Originally Posted by Dans1960SWB

I would pull that hole motor out and toss it in the junk yard. Im not a big fan of those sixes....

I'm about to take your suggestion. This is a new (different) engine, new exhaust manifold, different intake manifold, and all new gaskets:

http://www.youtube.com/watch?v=zLArHyUOw2U

As you can hear the exhaust sealed real well, huh? This is ridiculous. There is no reason it should be this difficult. Not to mentinon, the lean bog and popping that started all this followed me to this engine.

[TJ's Chevy]

Mine always sealed up fine...All of mine in fact. Like said, you may need to ditch that metal gasket. Clifford has a softer one they sell that seals up WAY better.

http://www.shop.cliffordperformance....et-62-0096.htm