Valve Lash Adjustment: running or not?

[bitfactr]

Rob, Rick,
Thanks for the input. No complaints with the cam being different than the original LS6 [I think I can suffer with only 475 hp ]. I just wanted to be sure that such a different lash setting was correct.

I followed the EOIC method and have the driver side done. Most were in the .012-.013 range, though a few were more loose than that. The adjustment went well and pretty quick and I double checked them. The hardest part was getting the bump-switch connected to the starter when the engine is hot. Taking it back out now to warm it up again for the other side.

Thanks again,
Dennis

[Chevy454]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SS427</div><div class="ubbcode-body"><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.</div></div>

Just curious Rick, headers or exhaust manifolds? Would you mind sharing where it peaked??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bitfactr</div><div class="ubbcode-body">Rob, Rick,
Thanks for the input. No complaints with the cam being different than the original LS6 [I think I can suffer with only 475 hp ]. I just wanted to be sure that such a different lash setting was correct.

I followed the EOIC method and have the driver side done. Most were in the .012-.013 range, though a few were more loose than that. The adjustment went well and pretty quick and I double checked them. The hardest part was getting the bump-switch connected to the starter when the engine is hot. Taking it back out now to warm it up again for the other side.

Thanks again,
Dennis</div></div>
Cool...I actually snag the wire on the firewall, where it's covered by the wire gutter. I betcha before long you'll be able to do it in your sleep!

[bitfactr]

All done. The EOIC method that VintageMuscleCar first mentioned worked great and I can't imagine doing this without the bump-switch. The passenger side had more loose ones. I put them all at 0.12. It's quieter and smoother now, yet still has that lump in the idle that Rob mentioned. In fact, it got lumpier and the engine idle dropped about 150. Had to readjust back up to 750. Runs and sounds great. Yes Rick, I actually drove it. Not just up and down the driveway, but actually on the street [img]<<GRAEMLIN_URL>>/smile.gif[/img]

Rob, I think it was dyno'ed with headers, but Rick would know for sure. I have the output chart (somewhere). I'll locate it later this evening and post the numbers.

Thanks again everyone.
Dennis

[SS427]

Rob,
Dennis' motor was run with manifolds not headers. The next LS6 motor they did for me was assembled identically but used headers instead and it was 492 hp if I recall correctly. So far we have built three of these and all were between 475 and 492 hp. The builder still owes me a case of beer as he said this engine would never break 450 hp with manifolds (and I said it would) and he has done it three times now.

Peak horsepower was 475.1 at 6100 rpm and torque was 482.9 at 3700. Average was 462.4 hp, 393.8 trq at 4500 rpm. They made a total of 7 pulls.

For anyone with access to a dyno, it is one of the better things I have done. They set the carb, timing, valves, etc, make an average of 7 pulls after breaking in the engine and carry it live on the internet so guys like Mark Mitchell could watch his engine dyno run live from California. All this for $250!!!! All I have to do is drop it in and run with it.

Dennis..................YOU DID WHAT???????????? Just kidding, they were meant to be driven. Besides, if I know you, you drove it for 1/2 hour and will clean it for 4 hours! [img]<<GRAEMLIN_URL>>/wink.gif[/img]

[Chevy454]

Interesting that there was only a 17hp difference. Also interesting that the hp peak was so high...my LS6 peaked around 5700 I believe, but that was with the Crane blueprint cam...the Comp piece listed above would certainly move the peak higher.

Ditto on the dyno...I see it as cheap insurance.

[bitfactr]

Thanks for posting the numbers Rick. Saves me searching for them tonight.

Some of the more loose rockers were probably around .015, maybe more. After reading your earlier post, I thought perhaps I should have set them all in the .014-.015 range, since the engine really never gets out of the low end. But the quieter engine, yet better sound, resulting from .012 is nice.

Though driveability felt like it needed a tune-up again, other than just resetting the idle. I'm guessing this isn't uncommon after valve adjustment.

Rob mentioned the tighter lash cam being more finicky. I'm wondering about the margin of error I have in the adjustment. I tried to set it where the .013 would not slide in, .012 would with drag, and .011 easily. So, in theory, my settings should all roughly be between .0115 and .0125.

At would point would a &quot;too tight&quot; adjustment be a problem (i.e. if a valve was set at .010 or tighter, what, if any, damage could occur?)

And, no, I'm not done cleaning it yet [img]<<GRAEMLIN_URL>>/smile.gif[/img]

[Belair62]

This is easier to write down
#1 Cylinder TDC then adjust
Intake - 1,3,4,8 Exhaust - 1,2,5,7

Rotate 360 degrees to TDC #6 cyl firing position and adjust
Intake 2,5,6,7 Exhaust 3,4,6,8

Put valve covers back on. Wash hands. Go for a ride

[Mr70]

Do we really have to wash our hands?

[Chevy454]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bitfactr</div><div class="ubbcode-body">Thanks for posting the numbers Rick. Saves me searching for them tonight.

Some of the more loose rockers were probably around .015, maybe more. After reading your earlier post, I thought perhaps I should have set them all in the .014-.015 range, since the engine really never gets out of the low end. But the quieter engine, yet better sound, resulting from .012 is nice.

Though driveability felt like it needed a tune-up again, other than just resetting the idle. I'm guessing this isn't uncommon after valve adjustment.

Rob mentioned the tighter lash cam being more finicky. I'm wondering about the margin of error I have in the adjustment. I tried to set it where the .013 would not slide in, .012 would with drag, and .011 easily. So, in theory, my settings should all roughly be between .0115 and .0125.

At would point would a &quot;too tight&quot; adjustment be a problem (i.e. if a valve was set at .010 or tighter, what, if any, damage could occur?)

And, no, I'm not done cleaning it yet [img]<<GRAEMLIN_URL>>/smile.gif[/img]

</div></div>
Comp could tell you the exact tolerance number for that lobe, but .004&quot; +/- won't hurt a thing. We've played with lash a lot in our Pure Stock class, and although it's a different lobe, we've gone from .020 to .030+, and COPO Pete has deviated more than that on his ZL1...we're stuck with the stock cams, but that's not always the perfect cam, so you have to try and work around it.

[69Tom]

Guys, what valve lash measuring tool would you recommend?

This has been an interesting thread. Very informative.

Dennis, glad to see you're out exercising the car after all that work!