Valve Lash Adjustment: running or not?

[VintageMusclecar]

Once break-in has been completed, you shouldn't have to check the valves any more than maybe once a year, esp. with an OE cam.

[69Tom]

Excellent. I like the idea of a yearly adjustment. Perhaps I should get one of those too. [img]<<GRAEMLIN_URL>>/burnout.gif[/img]

[bitfactr]

Thanks to everyone who responded.

The engine I'll be adjusting the valves on is an LS6, stock rebuild, using a CompCams regrid of the original LS6 cam. (I have the cam card and can provide the numbers if it would be helpful, but the card is at home.)

If I understand the info given by napa68 about the adjustment for a &quot;30-30&quot; cam, the procedure will also work with my engine. I'm guessing the LS6 cam does not fall in the &quot;30-30&quot; category (please correct me if I'm wrong), and shouldn't require the &quot;30-30&quot; procedure, even though it would work.

I was going to follow EOIC method described by VintageMusclecar. It sounds like it would accomplish the same result (providing the LS6 cam isn't like the &quot;30-30&quot. It seems a bit more friendly for those less experienced.

Thanks,
Dennis

[napa68]

Speaking for myself, I like adjusting on a cold engine. I have found the specs they give for a cold engine hits the spec just right for a hot one ( I checked one of mine before and after)
Best of luck.

Tim

[69 Post Sedan]

The first time I set my valve lash, I do it when the engine is hot. Once it has cooled down, I check them and write it down. My Nova was about .002 difference when it was cold.

[bitfactr]

Great ideas and advice all around. Thanks.

I was all set the do the adjustment tomorrow morning. I just looked at the specs for my cam. It is a CompCams, Part # 11-671-4, Engine: CB Nostalgia LS-6+, Valve Adjustment: Intake .012, Exhaust .012. Again, the engine was rebuilt to as close to original specs as possible, and this cam was selected as being the closest.

The 70's era manuals I have, while not listing the valve adjustment for the 70' LS6 specifically, lists the other solid cam big blocks (ex. L78 from multiple years, the '71 LS6 from the Vette, etc.) with lash in the range of .024 - .028.

I didn't expect such a drastic difference in the lash on the contemporary CompCams regrid; it seems to be about half of the original. Should I be concerned about this?????

I don't have the specs on the original LS6 cam, so I don't know how different the CompCams regrid is, but I included the rest of the CompCams specs here:
Valve Adjustment: Intake .012, Exhaust .012.
Gross Vale Lift: Intake .544 Exhaust .539
Duration @ .015 Tappet Lift: Intake 276 Exhaust 283
Valve Timing @ .015: Open: Int 29 BTDC Exh 76 BBDC
Valve Timing @ .015: Close: Int 67 ABDC Exh 27 ATDC
Duration @ .050: Intake 239 Exhaust 246
Lobe Lift: Intake .3200 Exhaust .3170
Lobe Separation 112.0
Specs for cam installed @ 108.0 intake center line

Lastly, I read in another thread that it would be a good idea to disconnect the &quot;power&quot; wire from the distrubutor when using a bump-switch from underhood to crank the engine to be absolutely sure the engine doesn't start. Would simply disconnecting the coil wire from the distributor do the trick?

Thanks again,
Dennis

[firstgenaddict]

I just pull the coil wire.

[bitfactr]

Thanks for the confirmation on cutting the power firstgenaddict. Just tested my bump-switch and all is well. I'm taking it out now to warm it up.

[Chevy454]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bitfactr</div><div class="ubbcode-body">Great ideas and advice all around. Thanks.

I was all set the do the adjustment tomorrow morning. I just looked at the specs for my cam. It is a CompCams, Part # 11-671-4, Engine: CB Nostalgia LS-6+, Valve Adjustment: Intake .012, Exhaust .012. Again, the engine was rebuilt to as close to original specs as possible, <span style="color: #FF0000">and this cam was selected as being the closest.</span>

The 70's era manuals I have, while not listing the valve adjustment for the 70' LS6 specifically, lists the other solid cam big blocks (ex. L78 from multiple years, the '71 LS6 from the Vette, etc.) with lash in the range of .024 - .028.

I didn't expect such a drastic difference in the lash on the contemporary CompCams regrid; it seems to be about half of the original. Should I be concerned about this?????

I don't have the specs on the original LS6 cam, so I don't know how different the CompCams regrid is, but I included the rest of the CompCams specs here:
Valve Adjustment: Intake .012, Exhaust .012.
Gross Vale Lift: Intake .544 Exhaust .539
Duration @ .015 Tappet Lift: Intake 276 Exhaust 283
Valve Timing @ .015: Open: Int 29 BTDC Exh 76 BBDC
Valve Timing @ .015: Close: Int 67 ABDC Exh 27 ATDC
Duration @ .050: Intake 239 Exhaust 246
Lobe Lift: Intake .3200 Exhaust .3170
Lobe Separation 112.0
Specs for cam installed @ 108.0 intake center line

Lastly, I read in another thread that it would be a good idea to disconnect the &quot;power&quot; wire from the distrubutor when using a bump-switch from underhood to crank the engine to be absolutely sure the engine doesn't start. Would simply disconnecting the coil wire from the distributor do the trick?

Thanks again,
Dennis </div></div>
Well, you got some bad info on the cam...the cam you have is a tight lash cam, hence the 12/12 setting, whereas the original was 24/28 like you posted...not only are the cam specs themselves different than the original 143 cam, but the different lash characteristics will change how the engine sees the camshaft as well...I also see that it has a 112 LSA, whereas the original was a 114, which means a tad lumpier idle as well as a bit less vacuum...it's imperitive that you set the lash to the cam card, though, because tight lash cams are a bit more finicky due to their lobe designs.

With that said, your Comp camshaft will still work fine...

[SS427]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chevy454</div><div class="ubbcode-body">With that said, your Comp camshaft will still work fine...
</div></div>

When the engine was rebuilt, this was the closest cam to original specs that could be found according to Total Engine in Bloomington, MN. Can't be all bad as in stock configuration other than a bore increase, distributor recurve and carb magic by Eric it produced 475 horse and 483 ft lbs of torque. I called them and asked them about these settings. He suggested warming the engine and checking all the clearances the way they were set currently. Make sure they are all consistant with each other and none were way off which could point to a lobe issue. He also suggested setting them at .012-015 saying that you will increase low end power at .015 but lose some on the top end. I am not sure it really matters on this engine as it is not driven much anyway.