35THSSLE

Have 2002 Camaro LS1. Am getting CNC LS6 bare heads that are milled .030 and will be running the B1 cam (221/221 .558/.558 114) <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> . What length pushrods should I be getting? I was thinking I need slightly shorter ones, 7.350. Anyone know? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Thanks in advance...Alex

Tin Indian

I understand the B1 cams are now manufactured by Comp Cams. Most of the Comp Cams in the area of .550" to .575" lift have between a .025" to .030" smaller base circle (cam centerline to lobe heal distance) than stock.

With that in mind, if you mill .030" or so off the heads, your stock length 7.40" rods would be needed to get you very close to the factory spec lifter preload.

Ron,

Tin Indian

I was thinking I need slightly shorter ones, 7.350. Anyone know?

You would need shorter ones [if] you just milled the heads, but again, you now have a new cam with a smaller base circle (which is about equal to the amount you are milling from the heads)

See, that was easy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

35THSSLE

Ron,

Thanks that is helpful. Only thing is I am getting the B1 used off of this board. Not sure how long ago it was cut, it might be a Lunati grind. Is it just the newer comp cams that have a smaller base circle? Plus, Aren't the Ls6 stock pushrods (used with the Ls6 heads) shorter than an Ls1's from the factory. Is it because the stock Z06 cam has a smaller base circle too? Thanks for the help <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<small>[ October 26, 2002, 07:10 PM: Message edited by: 35THSSLE ]</small>

Taspeed

iTrader: (1)

mkay....let me toss this at you. I was unaware of the smaller base cirlce on the comp grinds. I just ordered a .591/569 230/226 112lsa cam yesterday. I am running .010 milled 5.3 heads. So with this new info I wouldn't want to run 7.35 PR would I? I'm thinking the math .030 smaller BC + .010 milled heads is only .040. BUT...if I use a .050 shorter PR + .030 BC - .010 mill =.070 difference in stock valve symetry. This could adversly affect the performance of the camshaft...Please confirm this one as I just royally confused myself <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

35THSSLE

Taspeed-

Using the the logic above, you would be -.10 (milling) + .30 BC. Your difference from stock is + .20 If your BC is .30 smaller (might want to confirm this), then it appears you should stick with the 7.4 PR's

Now, does anyone have thoughts regarding my question??? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Tin Indian

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 35THSSLE:
<strong>Ron,

Thanks that is helpful. Only thing is I am getting the B1 used off of this board. Not sure how long ago it was cut, it might be a Lunati grind. Is it just the newer comp cams that have a smaller base circle? Plus, Aren't the Ls6 stock pushrods (used with the Ls6 heads) shorter than an Ls1's from the factory. Is it because the stock Z06 cam has a smaller base circle too? Thanks for the help <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The 2002 LS6 engine's cam has a base circle of 19mm (.748")
The stock LS1 cams base circle is 19.7mm (.776")

That means the 2002 LS6 has a .028" smaller base circle than the LS1. They both use the standard 7.40" pushrods. However, the 2002 LS6 uses lightwieght sodium filled valves that are .7mm (.028") longer than the LS1 to make up the difference.

Tin Indian

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Taspeed:
<strong>mkay....let me toss this at you. I was unaware of the smaller base cirlce on the comp grinds. I just ordered a .591/569 230/226 112lsa cam yesterday. I am running .010 milled 5.3 heads. So with this new info I wouldn't want to run 7.35 PR would I? I'm thinking the math .030 smaller BC + .010 milled heads is only .040. BUT...if I use a .050 shorter PR + .030 BC - .010 mill =.070 difference in stock valve symetry. This could adversly affect the performance of the camshaft...Please confirm this one as I just royally confused myself <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">To be very accurate, you would need to measure your Comp Cams base circle (cam centerline to lobe heal), however, it will be about .030" (smaller/shorter distance) than stock with that new cam. With that in mind, you would need .030" [longer] pushrods to achieve the exact spec lifter preload as you had stock.

You milled .010" off the heads. That alone would require a .010" [shorter] pushrod.

Combine the two, and to be exact, you would need a .020" longer pushrod.

PRs come in increments of .050" (50 thousands), so in your case, the stock 7.40" rod would get you closest to the factory spec preload.

Remember, hyd lifters have a variance + - and don't have to be exact. Your .020" is well within this variance.

Ron,

35THSSLE

Thanks Ron <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Getting the stock measurements was most helpful

<img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />