[pontiaclady]

Appreciate all of your prior suggestions and there has been improvements. However still having issues. Here is what it is still doing:
It seems to be a little too cold natured - takes it a while to warm up and to stay running.

After driving it awhile - at least 15 minutes, when idling at a light, can hear it start to have a very slight stumble, doesnt feel it like it is missing, but can hear the change in the engine sound. if I put it in neutral, it smooths out and there is no problem when under power. It continues to get worse as drive and if do not shift into neutral, it will stall. (I noticed that the vacumn gauge shows in the yellow around 8, very close to the power orange portion. When in neutral, the vacumn goes to the green around 12-16). After it stalls, when turn key, does not start unless give it more gas. Then it will start....anyway he issue is it is still stalling when it gets hot.

Car is 421 tripower, cam is one level up from stock, power brakes, a/c, fuel system recently redone from tank to tripower, new coil, wires.

Background from early post- items done since then:
-timing is fine
-replaced vacumn lines in engine compartment (were some hard ones)
-replaced brake booster line as it was pinching closed
-had solenoid kickdown installed - cold starting is better than before
- new distributor cap, coil, points
- exhaust looks ok, not white
- replaced some of the vacumn lines under the dash for the heaters. the others seems ok, but could not follow all of them.
- The guy that rebuilt my motor prior found that the tripower manifold had a hairline crack under the center carb and on the side, that would open when hot. Replaced with a spare manifold that was ok.

Shouldn't the vacumn at idle be higher? Shouldnt it be in the green at idle and move to the power when accelerating etc.?? I really thought the cracked manifold was the problem. I think there were a lot of issues and it does run a lot better, but still not quite right.

Any suggestions?

[stevep]

Is fuel entering the front/rear carbs when it isn't supposed to? If so, disconnect the fuel lines from the front/rear carbs and see if this helps. I had what seems to be the exact same problem with one of my 3x2 cars and it was fuel entering the secondary carbs when it wasn't supposed to enter.

If the car is running properly, you should have 15-18" of vacuum at an idle if you have a somewhat stock motor.

[LASJayhawk]

I'm thinking in line with stevep. you can pull the air cleaner(s) off after it has died and look for or stick your finger down the end carbs and see if one is wet.

If you even think the vacuum modulator is leaking on the transmission, change it. Should cost about $10 and about a pint of ATF when you change it. Make sure the old o ring comes out, they like to stay in the case.

[61-63]

Originally Posted by LASJayhawk

I'm thinking in line with stevep. you can pull the air cleaner(s) off after it has died and look for or stick your finger down the end carbs and see if one is wet.

If you even think the vacuum modulator is leaking on the transmission, change it. Should cost about $10 and about a pint of ATF when you change it. Make sure the old o ring comes out, they like to stay in the case.

I would vote with this also if you haven't put a new vacuum modulator on the transmission yet try that. From what you are saying it has something to do with the transmission if it idles fine in neutral but the engine dies when you put it in gear. This assuming idle speed is adequate and from what you describe it is. And it sounds like it has to do with something other than the load the transmission puts on it if it happens when things have warmed up but doesn't do it until then as the load stopped and in gear would be the same cold or hot.

[pontiaclady]

"pull the air cleaner(s) off after it has died and look for or stick your finger down the end carbs and see if one is wet.
If you even think the vacuum modulator is leaking on the transmission, change it. Should cost about $10 and about a pint of ATF when you change it. Make sure the old o ring comes out, they like to stay in the case"

Had a "fun" afternoon. Long story short, did not seem to have wet end carbs, actually the center was not all that wet either. Maybe not enough gas from the fuel pump?? What is the fuel pump model number that should be used on 421 Tripower? Changed out the vacumn modulator. The vacumn seemed to bump up a bit, but after it got hot (approx 15 min), when put it in drive with foot on brake and sat there for awhile (like at a long light) - it would start to stumble a bit, noticed a drop from 10-12 HG to 10-8, then it would go back up again to 10-12, after a bit, it did a big stumble under 8 hg and died.

Story of the afternoon - started off good, Had two projects to work on, the suggestions for the GP and flushing the fuel lines on the 2+2 and getting the carbs off to "61-63". Got the 2+2 carbs off and drained so they could be shipped. Next the GP -struggled getting the bolt off the modulator, but finally got it off. Did not have the drain pan positioned just right and the first blast of tranny fluid went on the floor instead. got the modulator off and took to 3 part houses. Autozone not in computer, not in their warehouse, they dont order...Fine...NAPA - not in computer, trouble finding in book, not sure if they have in warehouse. They suggest trying to find one in a junkyard. WHAT??? Guess lots of 66's lying around in yards. Might as well get my air cleaners there too. Finally O'Reilly had some...back to the house, put it back on and test drove the car- looked promising for a while, then after it warmed up...result noted above When cleaning up, pulled the drain pan from under the car and somehow managed to get my hair in the tranny fluid - lovely.
Then back to the 2+2, unhooked gas line at the tank, the rubber hose was cemented to the line - took forever to get it loose, then of course the gas runs all down arm and onto shirt. Unhook the gas line at the fuel pump after fighting with hose clamps that are positioned so only a contortionist can reach with a screwdriver/nutdriver. More gas running down the arms. Blew out the line to the tank, ran gas thru the fuel pump to flush it out and got everything back together. Did not notice any crap in the fuel - so the carb crud must be old. Sending the carbs out tomorrow. I now smell much better after cleaning up and don't recommend tranny fluid and gasoline for your hair or skin treatments

If anyone has any other ideas for the GP stalling problems, let me know and will try that next weekend...

[Blackcat]

I'd also check/clean/replace the PCV hose and valve. Also, the pan grommet cracks and gets hard/brittle and leaks lots of air into the engine.

[Deadhead]

Check out the adjustable kind of modulator for the TH400. I have found those are pretty available. Plus, fun to tinker with. Great with the street/strip kits. Sorry a little late with that, but they were all I could find, so I figured that is what you would end up with.

Last time I fiddled with my trans I realized there was slightly too much fluid in there. I had put a drain plug in, so it will be easy to adjust right? Well, thought I had let it cool down enough, but got the crap scalded out of me and near the usual ATF bath even with the drain plug! So... I feel your pain.

[LASJayhawk]

pontiaclady. Next time I make a suggestion like that I'll include part numbers. NAPA should have had a TM15 or maybe an ATP17499. Autozone I want to say is a 1-401 I'll have to look at work tomorrow. Last time I got one for my 65 I think I had to tell them it was a 71 to get the dang thing.

LASJayhawk walks into a Autozone. "Hi, i need a pilot bearing for a 65 Pontiac catalina with a 421 and a 4 speed."

AZ clerk: (looks at computer) "we dont have that"

LAS: "Ok I need a pilot bearing for a 68 Pontiac GTO with a 400 and a 4 speed."

AZ clerk: (looks at computer) "It's $24.95"

LAS: "Amazing since it's the same freaking part."

[mviker]

pontiaclady,

Haven't you ever noticed how car people have the healthiest complexions? It's due to all those years of grease and dirt acting as an exfolient on the skin. That oil and trans fluid is like a sealer, keeping all your moisture in! We all have that youthful glow and we all owe it to working on our cars!

Your satisfaction meter is going to go off the hook when this gets worked out too. Guaranteed to make the frustration all worth it.

[mike nixon]

I didn't read the whole thread but have you checked the dwell?

[6T5 Cat]

Haved you checked the vacuum lines that run to the heater/AC controls under the dash? I had an issue like yours once and it turned out to be a vacuum line under the dash that I accidentally knocked loose while changing some dash lights.