[PonchoV8]

Timing and carb adjustments?
It's in my 78 TA 400 automatic car. Reportedly rebuilt as a .060 block and looking like it probably was freshened at least, at low speeds around town it's fine. When you get it on the interstate for 12-15 minutes it starts faltering. And I don't drive over 55 mph on the interstate either. First you hear a noise like a ticking, then it gets more pronounced. Then it starts loosing some power and if you try to accelerate, it wants to cough thru the carb. When I pull off the highway, it starts running fine again.
So Quick Silver gave me some ideas to start with that might cause this. Lean running issues and timing issues I want to sort out if I can. Something I've never bothered learning is the different timing adjustments. All I've ever worried about is that a car doesn't ping under full throttle. Other than checking the timing with a light, what sets my total timing and how do I check that? Other than swapping the carb to see if another runs better, how would I go about troubleshooting it? Left up for me to decide, I'd just close the mixture adjustments in the base and bring them out a turn and a quarter to start with then go by driving feel from there. This carb has the mixtures screws accessible on it.

What would you start with or suggest? Oh YEAH! The previous owner sealed off the EGR stuff on this engine. It's all missing now. See the red RTV where the valve used to be? Since I moved, I can't even think of where my timing light is.

[David Jones]

How quickly does it come back to normal operation after you get off the freeway?

[PonchoV8]

Very quckly it seems--but I drive this car very little. So there aren't that many times that I've experienced it. When I bought it, I drove it over an hour on the interstate and didn't notice the issue. But it was a cool rainy day. Now I'm finding the issue on warmer days--but it's still coolish up here. It was only in the mid 60s yesterday and it did it. It seems to be getting a little more frequent and pronounced. The temp gauge is jacked up too, so I can't monitor that right now. I'm working on fixing that though.

[69birdboy]

It's possible you have a clogged fuel filter, or a worn out fuel pump, or some kind of restriction in the fuel system.

[PonchoV8]

I'll start with those since they're the easier items.

[Overkillphil]

Originally Posted by PonchoV8

The temp gauge is jacked up too, so I can't monitor that right now. I'm working on fixing that though.

OK, can you explain this a little better? By "jacked up" do you mean the gauge is running high in temperature? Or jacked up meaning it is not functioning properly?

Or is it the literal defination where the gauge is currently out of the car and residing on an a pumped up floor jack?

[sleepy]

Is that just RTV stuffed into the open EGR hole?

[David Jones]

Bad lifters.

[PonchoV8]

Originally Posted by sleepy

Is that just RTV stuffed into the open EGR hole?

I'm afraid to test it. I think it's plated off and gooped up. I can't imagine it's jsut RTV.

The temp gauge is jacked up too, so I can't monitor that right now.

Lifters are a possible too. I'll look at the fuel delivery first--since it's easier.

[Geoff]

If it drives ok for 12-15 minutes, then it is not a lean mixture. My guess is the fuel vent is plugged. Not sure where it is on your TA. The air needs to enter the tank & fill the space left by the depleting fuel volume. The vent does this, & can cause fuel delivery problems if it is plugged.

[PonchoV8]

That sounds easy to check too--I hope.

["QUICK-SILVER"]

Originally Posted by PonchoV8

That sounds easy to check too--I hope.

Just loosen the gas cap.

[Overkillphil]

Yes, we realize you cannot monitor it now, but why? What do you mean by "jacked up"?

[69birdboy]

My guess is the fuel vent is plugged

I've had this happen before, and it didn't take 15 minutes to become a problem. It was noticeable at lower speeds as well.

[PonchoV8]

The car is starving for gas--no doubt.

[getmygoat]

It seems the lifter tick you are experiencing should lead you in that direction before chasing fuel/timing issues. Lifters shouldn't start ticking after highway driving.

There is another thread in this forum with a similar issue... i.e. sustained high speed running causes lifter tick and then engine performance problems.

If a lifter is sticking badly due to lack of oil flow, it will definitely effect how well the engine runs.

Do you have enough oil in the engine? High speed running with low oil level will starve the valve train of lube and cause lifters to stick. How worn is your oil pump? How good is your oil pressure?

[Lemans64]

Have seen issues as u describe, runs great when cool or short trips, extended trip it will start to sound like noisey lifter then develope into an engine miss, and after some cool down or some idle time problem will dissappear. Carboned up exhuast valves, carbon builds up on the valve stem and gets past the carbon relief on the valve which causes the valve to stick in the valve guide when hot, causing lifter noise and engine miss, after cool down problem goes away. There are some injector flush chemicals u can spray down the intake to try and loosen up, but permanent fix is to remove heads and clean valves and guides or have valve grind done. Just my opinion though, u should have a professional drive it and give their opinon.

Rick

[PonchoV8]

It's a recent rebuild though. I don't think there's more than 3-5 thousand miles on the build. Regarding the oil pressure, I still have to correct the pegged needle issue. It's grounded. Someone hacked in the cluster with an aftermarket unit that also pegged hard--I just installed the correct one and it pegs hard as soon as the ignition is turned to ON--without starting.
Soooooo, I believe there is enough oil, but I have a bastardized dipstick and tube I'll have to check on too. It's still got the 4 row radiator.

Too many gremlins and Chevyguy mods right now to even know what I'm getting in feedback from the car.
This car only likes 40 mph and under.
TO DO LIST:
(1) fuel filter
(2) correct oil pressure gage
(3) correct water temp gage
(4) oil tube and dipstick
(5) fuel vent

[sts]

I can't imagine it's jsut RTV.

And why not? I plugged a crossover mismatch with only a glob of silicone. Held tight and didn't leak a drop for 22 years. It never failed; I tore it down, and used felpro 1233 to put it together.