I got home from Downstate last night and decided to brave the cold (and couple inches of snow) today to work on the Camaro. Pulled the top of the carb off and the needles seem to be dropping down from the seats but not immediately. Almost like a short delay and then they dropped down. I took the original needles and swapped them out. These fall down with the floats so I like that better. Put it all back together and it fired right up and ran at 1300 rpm. Like clockwork the #7 header tube started to glow in less than 3 minutes of running. I've discovered (as of now anyway) that it's the #7 AND #8 tubes that are glowing. #8 not as bad as 7 but they're both doing it.


I read that potential culprits for this are a lean situation or vacuum leaks. I also read to check for internal vacuum leaks by putting your hand over the top of the carb while running to see if the engine would bog down/stall as it should without an internal leak. So I did that, couldn't even tell my hand was there. Engine ran just like it always does with/without my hand there. I'm not assuming there's an internal leak but wanted to ask if someone could verify this for me? I had checked for vacuum leaks a while back with carb cleaner and didn't notice any change in idle around the intake, carb, base, etc. and I don't even really know what an internal leak is. Just trying a last ditch attempt at figuring something out, wheel dollies are here, as is the snow and I've got to get the water drained, coolant added and this thing moved over in the garage, this weekend. Any insight is truly appreciated, from anyone.

 

If you sealed up the carb well with your hand to the point where it should have choked the engine, then you have a vacuum leak.
From post #1208:
I know you said there was no block decking or head shaving done. Still doesn't mean you don't have an intake manifold fitment issue though. An internal vacuum leak is where the lower portion of the manifold to head ports aren't sealed tight, you can't see that from the outside. Is your intake a new or old one? Perhaps it's warped? Did you use the rubber valley gaskets (front and rear of block), or RTV? You don't want to use the rubber ones, as that can jack up the manifold and give a poor gasket seal at the ports, or they can eventually squish out and give you an oil leak.

 

I covered up the entire top of the carb with my hand, engine never stuttered. It's a brand new intake and the rubber valley gaskets were not used. So if there is indeed an internal vacuum leak, would it only affect #7 and #8? I remember a while back when there were other header tubes that glowed on the driver side, but those stopped doing that with rocker adjustment. The intake was properly torqued when installed, should I try tightening the bolts in the back where 7 and 8 are?

 

An internal vacuum leak could affect certain ports, if the leak was at those ports, and not others. Some of the import intakes from China have machining issues, and sealing problems. Their engineering is great, as they simply stole technology from companies like Edelbrock and Weiand, but how they cast, fit, and finish the products is the big difference. I've seen import intakes with casting flaws and machining issues that didn't appear obvious under first casual inspection. One I checked with a long straight edge had waves in the machined surface that created leaks in the intake gasket. Another I saw had a porous spot in the casting that popped after the intake was in use for a few months, and the piece was found in the lifter galley when we removed the intake. It allowed the intake runner to leak into the valley area, and created tuning issues that drove the owner nuts. It also sucked oil into that cylinder and fouled the plug.
Prices on these intakes are very appealing, and most have no problems. But unfortunately their processes aren't solid, so every so often a clunker slips through and gets to an end user.

 

There's no way I could say for sure on this, but this intake was sent down to TN for porting work and I know it was checked for straightness/flatness. What seems so odd to me still is that there have been different glowing header tubes throughout the last 2 months. Seems to move around like a ahem... virus. I don't want to get back into a debate about every overseas part ever made being bad even though that would probably be my luck. Should I try and tighten the intake mounting bolts down more? Should I get a new intake gasket and replace it? I don't want to over tighten the bolts but I guess I could go through and check the ones I can with a torque wrench.


I just remembered something after resurrecting thoughts of the whole TN head/intake porting debacle. I sent 2 sets of intake gaskets to the guy for port matching, I was told all along that they would be matched to a 1206 gasket and I had originally sent a 1205 to him. When I bought the new intake I was told to get 1206's and send them with it. When I picked up my stuff down there I only got one set of gaskets back. I was told after all that BS that they were matched to a 1205 after all. I can not honestly say whether or not I got the 1205's or 1206's back! I remember installing the intake and taking pictures of how well the ports lined up and didn't notice any size variances between the ports and the gaskets, but I really don't know. So, with that said, 1205 -1206 intake gaskets, if the bigger gasket was used it's probably safe to say that could cause a vacuum leak? I really don't think I used the bigger gaskets as it was not even a thought when I installed the intake, but I'm not certain as I sit here thinking about it all over again. It's a possibility.


Here's the pics at assembly, you can see the gasket in the pics but I don't know what a 1205 would look like compared to a 1206 really. I know it's a difference in the size of the port opening/height.

 

I know your working on other issues but in regards to the car stalling out when you put it in gear, jack it up and set the diff on jack stands and try to put it in gear. You can do this and let the trans run through the gears. What i am thinking is this would be a good way to tell if your transmission and TC are working properly and that it is indeed the engine stalling out under load. Want to make sure that the TC isnt trying to hookup at an idle.

 

The more stuff you describe, the more it's sounding like an intake manifold leak. What a pain, but you'll want to pop that thing off and see if you can see what's going on with the gaskets.
Once it's off, you might as well check the intake to head angle match too. To do that, find some washers that are the same thickness as the gaskets, and silicone them to the head over the 4 corner mounting holes, don't need to put washers at all of the bolt holes. Then make some tiny wads of clay that are thicker than the gaskets, and stick them onto the intake manifold, one above and one below every port. Smear a little oil on the heads around the ports so the clay doesn't stick. Gently lower the manifold onto the heads and install the 4 bolts where the washers are. Crank the bolts so they're just snug, then remove them and lift off the intake. Cut the clay in half with a razor blade and measure the thickness to see if there's a difference between top and bottom. If say the bottoms are noticeably thicker, then your gasket would have gaps (leaks) at the bottom of the ports.

 

http://vid1298.photobucket.com/album...psr4mjjvmy.mp4


http://vid1298.photobucket.com/album...pszqplgupu.mp4


http://vid1298.photobucket.com/album...psdfwfd1ls.mp4






My handy new vacuum gauge indicates that there might not be an intake leak after all? I was surprised to see that much of a reading actually with that cam. I advanced the distributor a little more since it indicated late timing and the needle was flickering between 18-20 on the gauge but the engine didn't want to turn over very well when I did that. From what I know (read) the flickering is common with a big cam due to the overlap on the valves. Also, here's a clip showing the first start today and when I put my hand over the carb (fully) the engine died. I did it again on the second clip but you can clearly see that I didn't have my hand fully covering the carb and didn't leave it there very long. So, not sure what to think now? Any thoughts after seeing the vacuum gauge?


Sudstoy - Are you saying that the TC might be trying to engage while not in gear? I've actually had the rear of the car up on jack stands this whole time. The trans engages well when shifted into gear, it's idling too high and dropping down too low when I shift into gear and causing it to stall. Haven't been able to set the initial timing as I can't get it to idle lower than 13-1400 rpm and most likely had the throttle plate opened too far on the carb. Been trying to deal with this glowing header tube issue lately and haven't focused on getting the curve set. Chasing my tail basically. Appreciate the suggestion sir.

 

In your attempts to get the engine running right, you've gotten a little sidetracked with various suggestions we've all made to try and help out. I'm almost afraid to make a suggestion now, as it seems to send you in a different direction immediately. I think it might be best to start from point A and work your way through each component to ensure everything is OK. I know it's frustrating, and if you find out somewhere along the way that a step was OK, you'll feel you did that step for nothing. But you really need to not get sidetracked at this point, so you wont be doing things multiple times.
I'd start by pulling the intake, and check the gasket for proper match. Then do the test that Chuck described with clay. If that checks out good, then replace the intake and move on to the carburetor, and ensure it's 100%. Then the distributor, and timing.
Jumping around from one thing to another, and back again, isn't going to help you find out what's really wrong. Too many wild goose chases.

 

Watching the video, I noticed the time it stalled out you had the carb well sealed with your hand. The 2nd time you had plenty of gaps to allow air around your hand, to allow it to still suck enough air at idle. Need to seal it with your hand, not almost seal it.