Clutch chatter at different RPMs??

[sharkskinman]

It seems that whenever I have my throttle down but let's say three quarters of the way slightly accelerating I can hear it feel almost as if the clutch is chattering not sure what it is but it definitely seems something's afoot
It can happen in first or second gear usually about middle of the RPM range

[C10 - C90 Bill]

I never heard of a clutch chattering while you are driving it, only when starting off, but I believe I would be looking under the truck for anything loose or worn in the driveline.

Could be the Driveshaft.

[geezer#99]

It's pinging!!
Adjust your timing!!

[padresag]

Originally Posted by sharkskinman

It seems that whenever I have my throttle down but let's say three quarters of the way slightly accelerating I can hear it feel almost as if the clutch is chattering not sure what it is but it definitely seems something's afoot
It can happen in first or second gear usually about middle of the RPM range

check your centre support in the d/shaft. or engine mounting
your clutch can only produce a chatter at release otherwise it will just be slipping
ron

[sharkskinman]

Now that I'm trying to kind of keep track of it almost seems like when I'm driving at just maintaining speed and I were to let my gas off a little bit it starts doing it...
I'm going to check my dwelling and I think my dwells around 30-32 and my timing just straight-up 8*.. regular 250 regular distributor I'll check a couple things in that aspect but I timed it and talk to it and it seemed fine but I'm going to have to check again maybe I'll lower or raise the timing a little bit and make sure that my points are gapped proper well it's supposed to be 32-34? I'm in the process of doing a couple things as well as getting an HEI distributor I'm just trying to figure out if I want to get a stock replacement from a slightly newer truck or if I just want to buy one off of eBay

[TJ's Chevy]

Originally Posted by sharkskinman

Now that I'm trying to kind of keep track of it almost seems like when I'm driving at just maintaining speed and I were to let my gas off a little bit it starts doing it...
I'm going to check my dwelling and I think my dwells around 30-32 and my timing just straight-up 8*.. regular 250 regular distributor I'll check a couple things in that aspect but I timed it and talk to it and it seemed fine but I'm going to have to check again maybe I'll lower or raise the timing a little bit and make sure that my points are gapped proper well it's supposed to be 32-34? I'm in the process of doing a couple things as well as getting an HEI distributor I'm just trying to figure out if I want to get a stock replacement from a slightly newer truck or if I just want to buy one off of eBay

8 degrees initial is only 2 degrees advanced over stock. Unless your running 5 year old fuel I see now reason for it to detonate or ping. I ran my 292 at 10-12 initial with a 65K hei and it was fine.

Clutch chatter is the clutch slipping and grabbing. If there is oil on the discs it could do like you are describing. Does it chatter while letting the clutch out in 2nd? If you accelerate Hard does if feel like it's grabbing and slipping and grabbing?

How long have you been running the 250? It won't just all of a sudden start detonating or pinging out of no where. You'll notice other issues 1st.

[jtrichard]

How old are the U-joints?

[padresag]

I think that if you guys looked at the symptoms that he describes you would realize that it is not ignition. an engine doesn't ping under deceleration.
you will notice an engine pinging more in high gear under load than you will in 1st and 2nd
ron

[geezer#99]

Originally Posted by padresag

I think that if you guys looked at the symptoms that he describes you would realize that it is not ignition. an engine doesn't ping under deceleration.
you will notice an engine pinging more in high gear under load than you will in 1st and 2nd
ron

It's easy to eliminate as a possibility.. Plug off the vac advance.
Fwiw I had detonation in a bigblock like that. When I backed off the throttle, the vacuum increased and so did the vac advance. You could hear it rattling.

[sharkskinman]

The 250 has not even 1500 miles on it probably.. I will pay super close attention to it tonight when going home from work..
Driving in 2-3 with light throttle.. If I let up a little where I'm not accelerating or decelerating.. That's where it is..

[TJ's Chevy]

Originally Posted by sharkskinman

The 250 has not even 1500 miles on it probably.. I will pay super close attention to it tonight when going home from work..
Driving in 2-3 with light throttle.. If I let up a little where I'm not accelerating or decelerating.. That's where it is..

Something simple to check would be flat spots or unbalanced tires. They can create a strange ride.

[luvbowties]

Originally Posted by sharkskinman

The 250 has not even 1500 miles on it probably.. I will pay super close attention to it tonight when going home from work..
Driving in 2-3 with light throttle.. If I let up a little where I'm not accelerating or decelerating.. That's where it is..

Adjust the clutch, paying attn. that the spring tension is keeping linkages tight. Also check motor support--esp. the one on the driver's side.
Sam

[shp4man]

What transmission do you have?

[sharkskinman]

I'll try plugging vac

3 speed tree non syncro

[sharkskinman]

Plugged vac advance.. Seems 90% better

What reason would it have to catch vacuum at right under throttle
Felt today and 2-3 at fhalf to full speed if I let up on throttle a little I would feel it..

Two nights ago I turned out the fuel another probably quarter to a half an inch and it seemed like it got rid of it is it possible that I just need to clean my damn carburetor

[sharkskinman]

Sitting still in N

Reved up to 1800-2000 RPM
It starts to stutter
If I'm on the road at speed 2-3rd gear I let the throttle up slightly so I'm not accelerating not slowing down it happens
With adjustable timing gun seems it goes up to 50* of advance??
Is there a vac advance STOP? So it only advances so far??
It happens with or without canister plugged up

[sharkskinman]

Bump?
Any ideas?

[luvbowties]

Originally Posted by sharkskinman

Bump?
Any ideas?

Loose bolts from the bell housing to the engine can cause these precise symptoms. Sorry I left thread so soon 'back then'. PLEASE let us know what you find here.
Thanks,
Sam

[geezer#99]

Put an hei in it!

[rvrfoot]

Well from timing to flat spots on tires. Its been about a year did you find out anything?