I took my '72 out for a 'spirited' drive on Saturday afternoon when I ran into a problem. I was cruising along and the car started to lurch/chug. It's like the power was pulsating almost as though the clutch was losing it's grip, then gripping, then losing, etc. At first it was a little shudder, now it’s full-on jack-hammer effect.

At first I thought it was a fuel problem as I had removed a phenolic spacer when the carb was rebuilt earlier this year, it was pretty hot outside and I had been driving her pretty hard. So I put the spacer back. I took her out on Monday night, much cooler out, and she was acting up right away with the engine cold. The engine runs like a champ as long as it’s not in gear. Pretty sure it’s not fuel.

The transmission shifts fine (except a little grind when going into reverse if I don’t hold the clutch down for several seconds) and there are no weird noises otherwise. I have noticed that when the revs are low it’s ok, but as soon as I get into the gas, even a little bit, it acts up. The pulsating was slight at first but is getting progressively worse. She’s basically undriveable at this point.

This is my first manual car, and I’ve had it about a year so I don’t have much experience with clutches :o so I’m looking for some advice as to what could be causing this? Seems to me if the clutch linings were worn that it wouldn’t grip the flywheel so well. And I figure that if it started to slip a little it would deteriorate rather quickly. Does this sound right?

It figures that this happens one day after I fixed the spongy brakes with a new M/C. Before, she would go like hell but not stop so good, now the brakes will stand me on my head...if I could just get her to go!

Thanks in advance for any guidance you can provide.

 

Sounds more like a bad plug wire to me. Misfiring under a load.

 

Have you checked timing and fuel supply? Fuel pump or filter?

 

Get it in 4th gear/cruising speed. Mash the throttle to the floor. If the tach. (rpm's) don't shoot up, the clutch is not slipping.

 

sounds more like you got misfiring cylinders, fuel or spark likely culprits, check your air filter too and make sure its not clogged or anything.

 

Clutch won't cause the problem you describe.

 

[QUOTE=
The transmission shifts fine (except a little grind when going into reverse if I don’t hold the clutch down for several seconds) and there are no weird noises otherwise.
QUOTE]

To stop the grind going ito reverse, select first or second gear just before selecting reverse while you hold the clutch pedal all the way down. That will stop the gears from spinning....and no crunch


Joe

 

Thanks everyone. I'm glad it's not the clutch.

I put a multimeter on the plug wires tonight and recorded the resistance but I can't find anywhere to tell me what an acceptable reading is. The wires are 8mm and they say "Hi-Temp Super Stock Radio Suppresion" on them, not sure what brand they are. Here are the readings I recorded:

Cyl / Reading

1 / 16.9
2 / 14.0
3 / 12.2
4 / 14.7
5 / 7.5
6 / 8.9
7 / 7.9
8 / 8.5

I took it out for a short drive and it ran ok for a while, but after about 10 minutes it barely ran. Would the resistance in the wires increase with heat?

Again, I really appreciate the help.

 

It's going to be pretty hard to diagnose a wire that's breaking down under a load. I would just swap them out. My guess is that's the problem. Don't try to complicate things. Sometimes the most obvious is the culprit.

 

I'm wondering if you've got a leak from your fuel bowls. Once it heats up it might start to leak, drip in and surge a bit eventually flooding it . You were in there removing the spacer so I would take the carb off and clean it right out first. Also too, check your pinion bushing, if this bushing is bad the car will also surge.

 

What would the issue be with the pinion bushing causing this type of problem. Unless I am mistaken about what pinion bushing you are referring to.

kdf

 

Once your car starts jerking because of the motor issue, having this bushing worn would compound or add to the jerking. I hope I'm not misunderstanding the motor issue this guy has.

 

the gears in the dist for the cable drive tach can cause similar symptoms as they destroy themselves.