1970 LT-1 Valve Lash, Idle and Idle Mixture Setting

[Wolf S.]

[Timothy B.]

Re: 1970 LT-1 Valve Lash, Idle and Idle Mixture Setting

The chugging may be a little to much advance, how much vacuum advance is the B-28 providing. You can install a rubber bushing on the end to limit the travel hence less vacuum advance. All looks good though IMO.

[Duke W.]

Re: 1970 LT-1 Valve Lash, Idle and Idle Mixture Setting

Two other things to check are total idle advance and total cruise advance.

With the VAC connected how much advance at idle speed?

Total idle advance = intial, plus full vacuum, plus maybe a couple of degrees of centrigual if it starts below idle speed, but you data say it doesn't if you idle at 900 - should be a about 30-34.

Then with the VAC also connected rev the engine to 3000, which is above where the centrifugal is all in.

Total cruise advance = initial plus full vacuum plus full centrifugal - should be 50-54.

Your data only indicates a total of 22 centrifugal, OE spec is 26.

In what gear and at what RPM is the engine not smooth at constant cruise speed on level ground?

Duke

[Wolf S.]