1970 Trans Am No Start

H

Houston77056

New member
Joined
Jun 29, 2020
Messages
6
Reaction score
0
Points
1
I have a beautiful Lucerne Blue 400/auto paperweight . . . The engine was redone before I bought the car and is as clean as a whistle inside. I was worried about having jumped timing, but it has compression of 175-190 all around.

I can get it to sputter and cough some but not run. I have confirmed TDC with a wire through the spark plug hole and the balancer seems correct. Timing set at what looks to be 9 before, although I have tried it multiple ways. I have 7 v at the + side of the coil while "on" and 12v while cranking. I get spark with a spark tester in place of the plug. The carb has a good spray with the acc pump and ether doesn't help . . It has gas.

Appears to have a parts store rebuilt distributor, and I have gone through the usual litany of new parts including points, condenser, cap, rotor, coil, wires. Tried another carb I had. No help. What am I missing?

Many thanks!

John
 
Did you use a dwell meter to set the point gap?
Have you done a fuel pressure test?
When you open the gas cap, any sounds?
 
melsg5 said:
Did you use a dwell meter to set the point gap?
Have you done a fuel pressure test?
When you open the gas cap, any sounds?
Click to expand...
Thanks for your thoughts. I couldn't get it running to use a dwell meter, so .016 feeler gauge. Not easy to get in there but I think I did a good job. Fuel pressure looked plenty high, although not sure I really trust my gauge. It filled a peanut butter jay in short order, though. (You won't find that test in the manual). I took the gas cap off and bumped the car and heard gas sloshing. I also blew out the line a bit ago to make sure the sock was clear. . .. until the bumper was baptized with gas. It won't run on ether, either. . .

Thanks for your thoughts!

John
 
Just cranking the engine should give a dwell reading.
What pressure did you get, at least 5 psi?
In changing all those parts, is the distributor cap firing order correct?
Did you open the air horn of either carburetor?
Did you check the fuel filter in the inlet of the carburetor?
______________________________
 
I didn't know that about dwell. I'll double check where it is timed now that I moved it around in a fruitless effort . . . well, never mind, and then check dwell. I think pressure was at 7 psi at the carb inlet. I have checked firing order a bunch of times, but will again. It is easy enough . I have not opened either carb yet. I had enough problems! The filter was clean as new when I checked the pump pressure. I don't have much hair left to pull out. Thanks for teaching me something!
 
Dwell has to be adjusted first since it changes timing.
Did you remove the carburetor inlet, I'm assuming you have a Quadrajet, the filter is inside the inlet. Be careful you dont strip the threads on the inlet fitting.
Is the choke working?
Does the choke pull off work, small diaphragm on the passenger side of carburetor, has a single vacuum line and a rod that cracks the choke open once the engine starts?
 
melsg5 said:
Dwell has to be adjusted first since it changes timing.
Did you remove the carburetor inlet, I'm assuming you have a Quadrajet, the filter is inside the inlet. Be careful you dont strip the threads on the inlet fitting.
Is the choke working?
Does the choke pull off work, small diaphragm on the passenger side of carburetor, has a single vacuum line and a rod that cracks the choke open once the engine starts?
Click to expand...

I knew there was a chicken and egg deal about dwell and timing. Now I don't have to look it up! Thanks.

Yes, I took the filter out of the Q-jet inlet and made it back without stripping (lesson hard learned when my father did that years ago with a chevy one- fortunately the aftermarket responded with a compression fitting just for that! He evidently wasn't the only one.) Choke is closed, but not like a bank vault. It can be manipulated, and I think it will respond the next time it gets some vacuum, etc. Thanks for your thoughts. I'll tinker with dwell.
 
An update . . . First, I can’t thank you enough for all of the helpful suggestions and support. I had been futzing around with this thing for weeks and it was really, really getting under my skin. I haven’t had one this hard to figure out in decades . . .BUT, as I often tell my friend after a day in the garage: we have made a lot of progress today, some of it even forward.

I went back yesterday evening and started rechecking everything, soup to nuts. Like my GT500s, the distributor still rotates backwards, but the real problem was the point lead, at the distributor grommet. I was getting unreliable spark, which led me to check that wire for continuity, which varied as I jiggled it. On further inspection with my old eyes, under the installed distributor with a mirror (!), it had been crimped or kinked there. I pulled that out enough to cut, solder and shrink wrap it, and that got me steady spark. I would start ranting about the quality of replacement parts, even those in AC Delco boxes, but you’ve tolerated enough so I’ll save that for another day . . .

Also, a plug wire was not fully seated in the cap, so shoving that in didn’t hurt, either (8 is better than 7). Finally, I checked the dwell, and, although my .016 was close, I was only at 25 degrees of dwell, so I adjusted that up to 30. (And, from the above, learned that the car does not have to be running to do it, just cranking . . Go figure.)

So . . . it is still hard to start and requires too much cranking and pumping to come alive. It also wants too much initial advance. But, hopefully with some carb adjustment (moving fast idle up and dropping advance back, as well as idle mixture) I can work on that. Most importantly, it runs!

Thanks again for your help and indulgence.

jpd
______________________________
 
It's the small things that always get you.
While you were in the distributor did you notice if the advance weights move freely back and forth?
Going on memory, are you setting initial to 9 degrees with vacuum disconnected?
When you start the car from completely cold do you pump the gas pedal completely to floor 3 times before cranking?
 
Advance weights are moving nicely. Oddly, the old rotor seemed to catch and not allow them to. Now they are very smooth.

9 degrees is the plan, but it doesn't want to keep running until, and I don't know the number, but a significant twist of the distributor is added. My suspicion is that the fast idle has never really been set, so I'll start there, and see if I can get by with less advance. We will see.

It takes way more than 3 times. Like the fast idle, I am sure the idle mixture screws could use some attention. I got it running last night and it was time to eat ;)
 
You must log in or register to reply here.

Share this page

Back
Top