Valve chatter at high rpm’s

Ian Rogers

 
 
Joined
May 5, 2004
Messages
1,399
Location
Mill Valley, CA
So on the way back from surf n turf I was experiencing valve chatter when on the freeway in 4th gear. It would only happen when I would load up the truck i.e. going 55mph and give it more gas. It only seams to happen under load. What could be causing this? I ran a quick go-no go valve clearance check and they were all right on. Intake .010” and Ext .014”. I am running a E-67 135 F motor with the timing bumped to about 10* with a NON-USA distributor

Thanks for the help

Ian
 
Joined
Sep 10, 2004
Messages
950
Location
coastal empire
Just last night I noticed a chatter and thought it was valves at high rpm but discovered that my clutch slave needed a little adjusting. Sound went away with a little pressure.

Just trying to eliminate the obvious (or stupid stuff) first. :)
 

honk

 
Joined
Nov 14, 2004
Messages
3,413
Location
PNW
rogersfj401969 said:
So on the way back from surf n turf I was experiencing valve chatter when on the freeway in 4th gear. It would only happen when I would load up the truck i.e. going 55mph and give it more gas. It only seams to happen under load. What could be causing this? I ran a quick go-no go valve clearance check and they were all right on. Intake .010” and Ext .014”. I am running a E-67 135 F motor with the timing bumped to about 10* with a NON-USA distributor

Thanks for the help

Ian

Sounds like spark knock, preignition, whatever. Low octane gas and/or too much advance under load is the usual culprit.

If you were to keep your foot in it while it's doing that you could find yourself with a hole in a piston, but most of the time if you just back off when you hear it you'll be OK. I wouldn't use the sound as a tachometer - waiting for it before downshifting or letting of the gas. That's a dangerous practice.
 

Pin_Head

 
 
 
Joined
Feb 6, 2002
Messages
14,861
Location
OC, CA
honk said:
Sounds like spark knock, preignition, whatever. Low octane gas and/or too much advance under load is the usual culprit.

.
X3

Sorry I missed it. Sucks having to work.
 
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