just spoke to CC tech line about the 220/224 cam

does the base circle of 1.510" sound right??

he said it was "around" 1.500" i asked him if that was exact...then he proceeded to say it's more like 1.510" ......


Anymore know what the base circle is for that cam...exact numbers please


220/224 530/534 on a 112

 

Stock LS1 Base Circle: 1.552” cam base circle = 0.776” centerline to heel distance

TR-220 Base Circle: 1.502” cam base circle = 0.751” centerline to heel distance (.025” less than stock)

Ron,

 

My base circle measured 1.538 diameter on my Comp 218/218. My factory measured 1.552 and on an 01 LS6 cam I had was 1.520.

That LS6 cam with my factory pushrods made more noise.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Larry:
<strong> My base circle measured 1.538 diameter on my Comp 218/218. My factory measured 1.552 and on an 01 LS6 cam I had was 1.520.

That LS6 cam with my factory pushrods made more noise. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Hmmm, interesting...i wonder if Comp Cam tech support gave me the correct numbers?

 

My numbers were not from reading someone elses post. I got the specs from putting a mic on it myself.

Your 220/224 cam should be very close to these numbers. Remember, it's not the base circle thats important. It's the cam's centerline to lobe heal distance. This number is what determines your lifter preload, and is exactly 1/2 the base circle distance. Base circle is just the measurement across the lobe at the points of no lift.

Ron,

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Tin Indian:
<strong> My numbers were not from reading someone elses post. I got the specs from putting a mic on it myself.

Your 220/224 cam should be very close to these numbers. Remember, it's not the base circle thats important. It's the cam's centerline to lobe heal distance. This number is what determines your lifter preload, and is exactly 1/2 the base circle distance. Base circle is just the measurement across the lobe at the points of no lift.

Ron, </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes i understand the logic behind it.....and that it's half the base circle....etc.

my problem is i have not purchased the cam yet, and trying to decide if i will need shorter pushrods, reason being is the heads are milled .035"

if the base circle of the 220/224 cam is 1.510"

which is .021" smaller than stock.
.035" - .021" = .014" preload against the lifter.

if my understanding is correct, anything over .030" is bad.....will .014" be too much preload? i would assume that a 7.350" rod would be too short for my application.

what other options do i have..... how much preload can i get away with....should i consider shimming the rocker base up about .015"?

 

Your heads are milled .035" > that, by itself would take a .035" shorter pushrod to retain your stock lifter preload.

Your cam's centerline to lobe heal distance is .025" less than the stock cam > that, by itself would take a .025" longer pushrod.

Combine the two: We only have a difference of .010" (ten thousands) Actually, you will wind up with .010" more preload than what you started out with if you used the stock 7.40" rods. Make sense?

And I can tell you, 10 thousands is nothing.

BTW, pushrods come in .050" increments. Keep your stock length rods. You have nothing to worry about.. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

And I am telling you the specs I quoted above are correct. I don't care what anyone has told you. I put the damned mic on both cams myself...

Ron,

<small>[ April 15, 2003, 07:52 PM: Message edited by: Tin Indian ]</small>