where to start..

[Big_John]

There a good way to check it on the engine? The coil has spark.

Don't worry about this. You have spark.

 

[Matt Conlan]

Stuck needle and seat or float. Basically it's letting too much gas in.

That would be your problem.

Thanks! But would that cause a shutdown at highway speed? With no warning?

 

[73Coupe]

So you were still able to turn the motor and the distributor rotor turned with it, even though the chain was bad? How did you determine it was the chain?

Yes, the chain just skipped a few teeth. The cam gear is the failure item due to plastic teeth. I checked the rotor position but was too subtle to tell if it was out of position. Then I did a compression check - across the board low numbers which told me it was the timing.

Edit: I had gas burping out the carb too!

 

[Matt Conlan]

Yes, the chain just skipped a few teeth. The cam gear is the failure item due to plastic teeth. I checked the rotor position but was too subtle to tell if it was out of position. Then I did a compression check - across the board low numbers which told me it was the timing.

Thanks. I'll track down this carb issue first, and then I'll do a compression test, too.

 

[Matt Conlan]

Yes, the chain just skipped a few teeth. The cam gear is the failure item due to plastic teeth. I checked the rotor position but was too subtle to tell if it was out of position. Then I did a compression check - across the board low numbers which told me it was the timing.

Edit: I had gas burping out the carb too!

You had good luck replacing the timing chain?

 

[Big_John]

Thanks! But would that cause a shutdown at highway speed? With no warning?

Yes, it could, but I guess we may have to define gas "burping" out.

I assumed (bad me) that you had gas coming up out of the vents of the carb.

What exactly do you mean by "burping"? Do you mean it's backfiring through the carb? Yea, that could mean a bad timing chain.

You are looking at different causes to one problem. There's just one cause.

 

[Matt Conlan]

Yes, it could, but I guess we may have to define gas "burping" out.

I assumed (bad me) that you had gas coming up out of the vents of the carb.

What exactly do you mean by "burping"? Do you mean it's backfiring through the carb? Yea, that could mean a bad timing chain.

You are looking at different causes to one problem. There's just one cause.

I would say backfiring through the carb is right. As the engine shut off, gas spurted up through the carb.

 

[73Coupe]

You had good luck replacing the timing chain?

Check out linked thread in post #14.

 

[Matt Conlan]

Check out linked thread in post #14.

That's a great thread! Thanks! You do nice work. Looks like you left the engine in the car. Did you remove the radiator to get some space?

 

[fury fan]

Thanks guys. Only 78,000 on this engine. I tuned it up earlier this summer and set the timing. It does have a pertronix electronic ignition. The engine actually sounded like it had a timing prob to me when I tried to restart. like a piston was missing, but there was no backfire.

If you have 78k on a nylon-coated gear (which a 1970 would have from factory) you are running on borrowed time.
A Cloyes true-roller is (or used to be) about hte finest chain you could get. Holding one of them vs a factory, or other aftermarket, you can tell the difference.

 

[Matt Conlan]

If you have 78k on a nylon-coated gear (which a 1970 would have from factory) you are running on borrowed time.
A Cloyes true-roller is (or used to be) about hte finest chain you could get. Holding one of them vs a factory, or other aftermarket, you can tell the difference.

That's what it sounds like. Looks like I have my weekend set. Thanks.

 

[73Coupe]

That's a great thread! Thanks! You do nice work. Looks like you left the engine in the car. Did you remove the radiator to get some space?

Thank you sir. Yes the radiator came out...no room otherwise, especially for removing the balancer. While the timing chain is easy to do in the car, the oil pan was a bugger because I did it on the ground and in the driveway. With a lift, it wouldn't be so bad.

 

[Matt Conlan]

Thank you sir. Yes the radiator came out...no room otherwise, especially for removing the balancer. While the timing chain is easy to do in the car, the oil pan was a bugger because I did it on the ground and in the driveway. With a lift, it wouldn't be so bad.

Yeah, it'll be a driveway job for me too. And I just flushed and filled that radiator. Oh well.

 

[fury fan]

FWIW, don't automatically trust the timing gear dots and align to them. Use a dial indicator setup if you can, and verify intake valve opening vs TDC with a long probe to the top of the intake valve's lifter. I did an LA chain many years ago and the marks weren't correct (ether made wrong, or marked for the wrong year of engine). I had to go back into it several times, ultimately moving the cam gear by 2 teeth to get the car to run the way it did prior. Trust but verify!

I would recommend flushing a gallon or so of kerosene or mineral spirits thru the oilpan when you have the timing cover off. There will be an open gap of the front edge of the oilpan there, so it's somewhat simple to do. Or can also funnel it thru the fuelpump slot.

Leave the drainplug in, and put a gallon in the pan and let it sit/soak. Drain that out, and pour some fresh down to get the rest of the sludge out.

The soaking will break up any sludge and the rinsing gets any loose nylon and the rest of the solution out.
Then do an 'early' oilchange afterward (maybe couple hundred miles) to get the 'fresh' rinse out.
Or if this is an engine you've owned for awhile and has had good oilchanges, the rinse might be sufficient.

On engines that I have done this on, I find that the oil stays cleaner far longer between oil changes.

 

[Matt Conlan]

FWIW, don't automatically trust the timing gear dots and align to them. Use a dial indicator setup if you can, and verify intake valve opening vs TDC with a long probe to the top of the intake valve's lifter. I did an LA chain many years ago and the marks weren't correct (ether made wrong, or marked for the wrong year of engine). I had to go back into it several times, ultimately moving the cam gear by 2 teeth to get the car to run the way it did prior. Trust but verify!

I would recommend flushing a gallon or so of kerosene or mineral spirits thru the oilpan when you have the timing cover off. There will be an open gap of the front edge of the oilpan there, so it's somewhat simple to do. Or can also funnel it thru the fuelpump slot.

Leave the drainplug in, and put a gallon in the pan and let it sit/soak. Drain that out, and pour some fresh down to get the rest of the sludge out.

The soaking will break up any sludge and the rinsing gets any loose nylon and the rest of the solution out.
Then do an 'early' oilchange afterward (maybe couple hundred miles) to get the 'fresh' rinse out.
Or if this is an engine you've owned for awhile and has had good oilchanges, the rinse might be sufficient.

On engines that I have done this on, I find that the oil stays cleaner far longer between oil changes.

that all makes sense. good tips! thanks

 

[73Coupe]

FWIW, don't automatically trust the timing gear dots and align to them. Use a dial indicator setup if you can, and verify intake valve opening vs TDC with a long probe to the top of the intake valve's lifter. I did an LA chain many years ago and the marks weren't correct (ether made wrong, or marked for the wrong year of engine). I had to go back into it several times, ultimately moving the cam gear by 2 teeth to get the car to run the way it did prior. Trust but verify!

I would recommend flushing a gallon or so of kerosene or mineral spirits thru the oilpan when you have the timing cover off. There will be an open gap of the front edge of the oilpan there, so it's somewhat simple to do. Or can also funnel it thru the fuelpump slot.

Leave the drainplug in, and put a gallon in the pan and let it sit/soak. Drain that out, and pour some fresh down to get the rest of the sludge out.

The soaking will break up any sludge and the rinsing gets any loose nylon and the rest of the solution out.
Then do an 'early' oilchange afterward (maybe couple hundred miles) to get the 'fresh' rinse out.
Or if this is an engine you've owned for awhile and has had good oilchanges, the rinse might be sufficient.

On engines that I have done this on, I find that the oil stays cleaner far longer between oil changes.

I initially flushed the pan with it installed, just as you described, because I didn't want to remove it. But then I checked with a flashlight and still saw many bits o' nylon down deep that flushing couldn't remove. But more importantly, the pump pickup screen will need to be cleaned too. Mine was packed with nylon and causing pressure problems. I pulled the oil pump too, and flushed out the passages. That plastic gets everywhere in the crankcase.
After I reassembled everything and got it running, a few days later I came to a hard stop and the oil pressure dropped again and wouldn't resolve itself. So I pulled the oil pump again, and found a tiny bit of nylon wedged along the pressure relief valve holding it open. No problems since....

 

[Matt Conlan]

I initially flushed the pan with it installed, just as you described, because I didn't want to remove it. But then I checked with a flashlight and still saw many bits o' nylon down deep that flushing couldn't remove. But more importantly, the pump pickup screen will need to be cleaned too. Mine was packed with nylon and causing pressure problems. I pulled the oil pump too, and flushed out the passages. That plastic gets everywhere in the crankcase.
After I reassembled everything and got it running, a few days later I came to a hard stop and the oil pressure dropped again and wouldn't resolve itself. So I pulled the oil pump again, and found a tiny bit of nylon wedged along the pressure relief valve holding it open. No problems since....

Yeah, Ill drop the pan. AFAIK, it's never been done. Once one[s down there, might as well do it all. Thanks for the tip! Ill report back how it goes.

 

[fury fan]

I initially flushed the pan with it installed, just as you described, because I didn't want to remove it. ....

Good point. I never pulled a pan off, but the only chain I had jump was nowhere as bad as yours, and never saw OP problems either. After my first chain-jump that became a new preventive repair for any new car I got.
Probably a good use of a cheapo borescope on teh smartphone, to determine if pulling the pan is/is not justified.

 

[Matt Conlan]

Update. Replaced the timing set, fuel and water pumps. Didn't see any damage to the original sprockets, but the chain seemed to be really loose.

Anyway, just went to start it up, and the motor turned well, but didn't start. I figured it was because I changed the fuel pump, so I went to get the starting fluid. Trying again, all the dash lights come on, but turn to ignition and, click, it all shuts off. So I don't know how it worked yet. Gotta fix this new problem.