LT1 Valve Adjustment Procedure Variation.

[Ralph B.]

I have noticed several methods written for valve adjustment that differ. Without question the method that I subrcribe to is the one presented by Duke Williams where starting @ TDC two valves can be adjusted, then two @ each 90 degree interval with a total of (8) rotations required. ------- However I have also seen on several occasions a different concept where only two rotations are required as follows: With #1 at TDC you can set 1,2,5,7 intake and 1,3,4,8 exhaust valves. Rotate the engine one revolution to set the remaining valves.
Is there any merit to the (2) rotation concept or am I misunderstanding both concepts?
Thank you,
Ralph

[Michael B.]

Re: LT1 Valve Adjustment Procedure Variation.

I agree with the two location adjustments. While there may be some exteme duration cams, streetable cams are in the range of 270-320 degrees of crank rotation. That is 135-160 degrees at the cam and 68-80 degrees from the lobe center. Your adjustments are going to be on valves that are 90, 180 or 270 degrees full open.

There are going to be others that insist that you must have the lobes exactly 180 degrees from full open. Just remind them that valves from the same cylinder are never at the same place on the base circle at the same time.

I used to run hydraulic warm and running but not any more. Static adjustments work just fine.

[Bill M.]

Re: LT1 Valve Adjustment Procedure Variation.

Here's Duke's explanation for his procedure:

This procedure should also be used for the LT-1 cam. The exhaust is "on the ramp" at TDC. The inlet is not, but just barely. With the Duntov cam all 16 valves may be adjusted at TDC #1 and TDC #6 as outlined in the 1963 Corvette Shop Manual. The Duntov cam has shorter clearance ramps than the 30-30 or LT-1 cam.