I know i had it, but i lost it.

Can someone post a link to the current SWCDUKE doc on setting solid lifters?

 

Intake closing set the exhaust, exhaust opening set the intake.

 

Below is a cut/paste from the original. Where in Naperville are you? I live in Oswego just up 34 from you. Have a red '62



"30-30" AND OTHER OEM SB SOLID LIFTER CAM VALVE ADJUSTMENT

By John Hinckley and Duke Williams


The traditional method of adjusting valves one or more cylinders at a time with each cylinder at TDC is fine for hydraulics and for most solid-lifter cams, but NOT for the factory "30-30" solid-lifter cam used in '64-'65 L-76 365 HP and L-84 375 HP (FI) Corvette engines (and in '67-'69 Camaro 302/290 Z/28 engines); this cam has VERY long clearance ramps that are .020" high, and at TDC for any cylinder, both the intake and exhaust valve for that cylinder are still on their ramps, NOT on the cam's base circle, which is why the Service Manual for all cars so equipped says specifically to set them "hot and running".

There is, however, a better way to adjust the valves with a "30-30" - you can set them "cold and not running" by setting the intakes at 90 degrees ATDC and the exhausts at 90 degrees BTDC - so the lifters are on the base circle, not on the ramps. This has been confirmed with cam lift/crank-angle diagrams, and I've done mine this way - results in a nice mechanical "singing" sound, no "clacking", it runs better, sounds better, idle is more stable, and throttle response is improved. Several other Z/28 owners have followed this procedure as well since we developed it, and all of them have seen the same positive results.

Set them cold at .026"/.026" (or .008/.016 for Duntov equiped FI cars). The actual measured (stamped rocker arm) ratio at the lash points is actually about 1.37:1 (not the design 1.5:1, which is a “theoretical” number), so the clearance ramp, which is exactly .020" high on the lobe, is all taken up at .0274" clearance; .030" clearance with the valve closed is too loose - the ramp ends/begins before the .030"clearance is taken up, resulting in the valve being lifted off and returned to the seat at greater than ramp velocity. This will contribute to valve seat recession, and can cause valve bounce at the seats at high revs - it will also be noisy.

You can adjust two valves at each 90-degree rotation point, starting at #1 TDC, turning the crank 90 degrees at a time seven times (measure and mark your balancer first at 90-degree intervals from TDC). Removing the plugs simplifies rotating the crank, but you were going to change them anyway, right? Proceed as follows:

TDC #1 - 8E, 2I
90 deg. - 4E, 1I
180 deg. - 3E, 8I
270 deg. - 6E, 4I
0 - 5E, 3I
90 deg. - 7E, 6I
180 deg. - 2E, 5I
270 deg. - 1E, 7I

Start at TDC #1, then rotate 90 degrees at a time, setting at .026" cold. If you like, you can then go back after you're done to each cylinder's TDC position and check clearance on that cylinder's two valves, and you'll find that they've closed up to .024", indicating that both valves are still on the ramps at TDC, as I pointed out in the beginning.

Trivia - the point of max inlet lift on the "30-30" cam is at 112 degrees, with a lobe separation angle of 114 degrees (angle between points of max lift, not the geometric center of the lobe - the lobes on the "30-30" cam are asymmetrical).





Addendum (May 19, 2003)

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 this indexing procedure may be used, or both valves may be set with the cylinder at TDC of the compression stroke, or 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 ramps than the 30-30 or LT-1 cam.

This indexing procedure on page 1 may be used with ANY cam to assure that the lobe is on the base circle, and MUST be used for cams with very long ramps.

The following inlet/exhaust valve clearances are recommended with the engine cold and not running. The difference between “hot” (engine idle speed) and cold clearance on a cast iron pushrod engine is negligible, so clearances can be set cold, which is more convenient. These clearances are computed by “factoring” the OEM recommended clearances by the ratio 1.37/1.5 to compensate for the actual rocker ratio of 1.37 at the lash point. The computed number is then rounded down. The factory clearances are derived from multiplying the maximum height of the ramp above the base circle by 1.5. When running hard, such as sustained WOT, the exhaust valve head will heat up considerably. About 80 percent of exhaust valve cooling is through the seat, but the stem temperature will increase, which will cause the stem to grow and decrease running clearance. This is why exhaust ramps are typically higher than inlet ramps – to allow for more stem growth and maintain some running clearance to ensure the valves fully seat. Since the inlet valve is cooled with every fresh intake charge, its temperature and clearance will remain more consistent over the entire engine operating spectrum.

The rocker arm nut should be tightened until a light drag is felt on the feeler of the same thickness as the recommended clearance. Then the clearance may be verified by inserting a .001” larger gage, and if it does not go the clearance is between the two gages, which is just right. Note that the inlet clearance specification for the 1963 Corvette was tightened to .008” to give a bit more effective duration. This does not need to be “factored” anymore. We recommend this tighter clearance for all 327s, and it is optional for 283s for a little more top end power though the effect may not be noticeable. Normal engine service will usually result in slight loosening of the clearance, and Chevrolet service recommendations from the sixties recommend a lash check every 12,000 miles as part of a normal tuneup.

Duntov cam (283) .010”/.015”
Duntov cam (327) .008”/.016”
30-30 cam .026”/.026”
LT-1 cam .021”/.026”

Note: Clearances are listed inlet/exhaust.

 

Thanks Joel.

I'm in south Nap, almost Plainfield.

I'm a midyear guy. blk 65 coupe and red 65 conv. I do see a red 62 tooling around where i live though every now and then.

Getting ready to put an LT1 cam in early next month.

 

Duke revised some of the numbers a while ago. I searched around and came up with his latest:

"My current recommendation is .016"/.023" for the LT-1 cam, .023"/.023" for the 30-30 cam, and .010"/.016" for the Duntov except 327s, which should have .008 inlet valve clearance, and this is also "optional" on 283s.

My initial recommendations were based on clearance ramp height measured with a dial indicator.

The new recommendations are based on the actual lobe data from the engineering drawings and my dynamic analysis. The engineering lobe height data are listed to five decimal places every cam degree - MUCH more accurate than dial indicator readings on a production cam, and my dynamic analysis allowed me to pick out the exact top of the constant velocity clearance ramps, which mulitplyed by the 1.37 lash point rocker ratio that I measured yields the cold setting clearance."

Duke

Doing my adjustment this weekend (if I don't freeze).

 

The latest revision was just this past December (some of which is reflected above), and I don't anticipate any more changes. After obtaining the design lobe data from Santa Claus and crunching the numbers to determine the complete lift, velocity, acceleration, and jerk profiles I was able to precisely determine the tops of the clearance ramps above the base circles, so it's a done deal including the added interesting, and heretofore generally unknown, historical information/revelations about the lobe designs.

All the OE SB mechanical lifter cams from the Duntov up are covered. I have all the lobe data and analysis for the BB SHP mechanical lifter cams, but don't yet have a reliable data set to determine BB rocker ratio behavior. At the present time my best estimate is 1.55:1 at the lash point and 1.63:1 at maximum lift, but this awaits confirmation with some actual measurements that can be deemed reliable

If you have an aftermarket cam, the best you can do is "factor" the specified clearance by 1.37/1.50 for SBs and 1.55/1.70 for BBs if you can reliably assume that the specfied clearance was determined by multiplying the clearance ramp height dimension times the "design" rocker ratio of 1.5 or 1.7:1.

If you want a copy of the latest revision, e-mail me, and I suggest that you print and save it in a safe place.

I've had a lot of: I had a head crash and can't recover your Word document about valve lash...

Duke

 

point taken, i left u my email ina PM.

Thanks Duke.