If I'm going from stock 98 heads and cam, to a pair of 5.7l s1 heads milled .040 and a TR 224 112 cam, would I use the stock 7.4" pushrod or a 7.35"? What is the base circle size on the TR cams?

 

ttt
I'd like to figure this out this weekend to take advantage of tbyrne's free shipping. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<small>[ April 06, 2002, 07:27 AM: Message edited by: AzzHauler ]</small>

 

Why don't you call Thunder Racing and ask. Then report back here. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I am sure there are a lot of people wondering what the base cirlce of that cam is. I am one of them. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Maybe someone will jump in but I would call Thunder and ask them directly.

ERic

 

Or, do a search. I came up with this thread. jmX measured his diameter at 1.493".

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by jmX:
<strong>My TR224 came in at 1.493 I beleive.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I measured my Hammer cam to be 1.462". Close enough. My heads were milled 0.030" and the base cirlce was 0.060" smaller diameter or 0.030" smaller radius speaking) so I went with a 7.4 pushrod length since the heads were lowered the same as the decrease in radius. Hope this helps you some. Still, call TR and see what they say.

Eric

PS Here's the link to the thread. https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=003413

<small>[ April 06, 2002, 07:48 AM: Message edited by: wizkid ]</small>

 

Thanks man! Where would my head be if it wasn't attached. <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> I'm gonna give thunder a call when they open, hope I'm still awake (night shift is great! <img border="0" alt="[barf]" title="" src="graemlins/gr_barf.gif" /> ). And I can't believe I forgot the search too.

 

They didn't have the exact size handy, but he said it was "just a tad smaller than stock".

 

I ordered GTP S2 heads (5.3L heads) and TR224 112 LSA. I called and they said 7.350" is the right lenght. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
It has been 6 weeks now. I hope they have everything done by the end of next week. GTP+TR <img border="0" alt="[hail]" title="" src="graemlins/gr_hail.gif" />

<small>[ April 06, 2002, 01:34 PM: Message edited by: MuscleCar ]</small>

 

So whats the verdict????

7.4 or 7.35??

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MuscleCar:
<strong>I ordered GTP S2 heads (5.3L heads) and TR224 112 LSA. I called and they said 7.350" is the right lenght. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
It has been 6 weeks now. I hope they have everything done by the end of next week. GTP+TR <img border="0" alt="[hail]" title="" src="graemlins/gr_hail.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Good post...you answered my question before I even asked it. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by msce2b-dustin:
<strong>So whats the verdict????

7.4 or 7.35??</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well with the base circle being almost the same, and .040 milled off my 5.7L heads, they told me 7.350 also.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by AzzHauler:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by msce2b-dustin:
<strong>So whats the verdict????

7.4 or 7.35??</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well with the base circle being almost the same, and .040 milled off my 5.7L heads, they told me 7.350 also.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If you heads were milled 0.040" and the base cirlce is what is stated above by JMX from an earlier post, I would think you would need 7.400" pushrods.

I think the 7.35" would be too short as well.

Eric

 

I have been thinking on this some too. If the stock is ~1.551 base circle and jmx's was 1.493, then that's .058 difference, or .029 difference on the radius. So that would seem that the 7.4" rods would be the better fit with the lifter compensating for the .011 extra. However, Thunder said to use the 7.350" rods. I think I'm goning to see if I can get my order changed to the 7.4" rods, and if the cam is bigger when I get it I can sell them.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MuscleCar:
<strong>I ordered GTP S2 heads (5.3L heads) and TR224 112 LSA. I called and they said 7.350" is the right lenght. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
It has been 6 weeks now. I hope they have everything done by the end of next week. GTP+TR <img border="0" alt="[hail]" title="" src="graemlins/gr_hail.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I thought that GTP didnt mill their heads at all. If they dont, then 7.350 is too short.

Brad

 

Don't forget that there is alot of preload on the lifters in a stock configuration so going with a 7.350" pushrod isn't necessarily going to be too short.

Tim

 

Well, assuming those base circle measurments are correct, in my application with 7.4" rods, I'll be adding .011" worth of preload to the valvetrain. With 7.35" rods I'll lose .039" worth of preload. I'm not sure what those actually amount to, but since adding the .011 is closer to stock then loosing the .039, I figured on using the 7.4". Is that a good/bad idea?