'69 430 troubles

[Guest]

I recently had the 430 in my '69 Riviera GS completely rebuilt. Initial run-in was fine; however, it now has a slight roughness to it off-idle and up - I can't seem to get rid of.<P>Here is what I have done:<BR>a.)Original carb professionally rebuilt.<BR>b.)Electronic ignition/conversion.<BR>c.)Installed 2nd new set of wires and 3rd set of plugs.<BR>d.)PCV valve O.K.<BR>e.)Vaccum +/- 1/2lb @ idle.<BR>f.)Scoped it and revealed good spark dist.<BR>g.)Cranking compression 150 - 165lbs.<BR>h.)Propane in carb to check for lean condition - none apparent.<BR>i.)Valve train - quiet... although, emmissions sniffer indicated high HC's...<BR> <BR>Suspecting a mechanical (valve train)problem, I removed the valve covers and rocker shafts, I placed a machinists' straight-edge across the valve stems and measured to the spring bosses with a dial caliper.<BR>I found that the stem height varies from 2.105 - 2.155. My '69 Service Manual indicates that they should be at 2.275. I questioned the machinist that performed teh rebuild and he indicated that the hydraulic lifters should more than compensate for that amount and that I am looking in the wrong place. I got a second opinion from another machinist and he says "no way, that's your problem." <P>So now I am confused. Does anyone know what the correct valve stem height should be for the '69 430? And, can anyone tell me if they think that the variance I found in the stem height could be causing my general roughness (not a dead hole... just appears to be a slight miss from more than one cylinder). If anything, my stem height is [lower] than it should be... strange.<P>Any help or input at this point would be greatly appreciated!!!<P>Thanks for taking the time to read this.<P>Dino<P>

[The Old Guy]

I believe that if the distance is shorter and you don't have any lifter noise then the valves are not the problem.If the distance is shorter, that means the lifter will toward the top of its travel shouldn't cause a problem. I would try changing the timing a little and checking to see if maybe the new ignition isn't causing the stumble.