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Just another Push rod question!!!!

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Old 04-24-2010, 04:01 PM
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Default Just another Push rod question!!!!

I have a torquer V3 cam with PRC LS6 2.5 heads milled to 61cc, engine is stock block so no decking was done. When I used a PR checker it said I needed a 7.375 pr (.075 preload added on) or close to it. I have both 7.400 pr's (TSP recomended) and 7.375 pr's as well. What I have found is when I use the 7.400 pr's. The intake valves go 1 1/4 to 1 1/2 turns to 22 ft/lbs. and the exhaust valves go to 1 3/4 to 2 turns. When I use the 7.375 in both exhaust and intake, the Intake goes 1 turn or so and the exhaust runs down to 1 1/4 to 1 1/2 turns. So what I did was used 7.375 in the exhaust valves and the 7.400 in the intake valves. My question is does the Torquer V3 have two different base circles on the intake verses the exhaust. My guess would be yes based on what I have done here. I would also guess this based on the lift value that the intake is running (.643) verses the exhaust (.598) I assume the lift being higher then (+.600) makes this lobe have a smaller base circle than the exhaust. true?
Thanks in advance
Troy

Last edited by 1NASTYZo6; 04-24-2010 at 08:23 PM.
Old 04-24-2010, 09:22 PM
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Originally Posted by 1NASTYZo6
I have a torquer V3 cam with PRC LS6 2.5 heads milled to 61cc, engine is stock block so no decking was done. When I used a PR checker it said I needed a 7.375 pr (.075 preload added on) or close to it. I have both 7.400 pr's (TSP recomended) and 7.375 pr's as well. What I have found is when I use the 7.400 pr's. The intake valves go 1 1/4 to 1 1/2 turns to 22 ft/lbs. and the exhaust valves go to 1 3/4 to 2 turns. When I use the 7.375 in both exhaust and intake, the Intake goes 1 turn or so and the exhaust runs down to 1 1/4 to 1 1/2 turns. So what I did was used 7.375 in the exhaust valves and the 7.400 in the intake valves. My question is does the Torquer V3 have two different base circles on the intake verses the exhaust. My guess would be yes based on what I have done here. I would also guess this based on the lift value that the intake is running (.643) verses the exhaust (.598) I assume the lift being higher then (+.600) makes this lobe have a smaller base circle than the exhaust. true?
Thanks in advance
Troy
I just went through a cam swap and my setup is fairly close to yours.

I just installed a TSP 233/239 596/605 on a 112 with 5.3L Stage 2.5 heads that were milled .023. We ended up a little less than 1.75 turns to get to full tq. (about 1 2/3). It is nice and quiet with this setup.

My setup used 7.375 pushrods. I tried 7.400 and they ended up with 2.25 turns to full tq. 7.350 would have put me right on 1 full turn. I was told better to be slightly on the high side then on the low side.

I have heard the question about two different sizes being asked before on the board and have only seen one answer so far, 1 size, no need to stagger the lengths.

Worked for me..... Good Luck!!!
Old 04-24-2010, 09:43 PM
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Thanks for the info. I know most use just one lenght. I guess I was more comfortable with the preload being equal on each valve. I guess my question is really coming down to if the torquer V3 has different base circles for intake and exhaust. I guess I will give TSP a call on Monday and find out if I have done this right or not. PS The car runs fine with different lenght PR's. Just has the expected valvetrain noise, not real loud just noticable. I have read on another post about using different lenght PR's as well. I guess its just personal taste.
Troy
Old 04-25-2010, 07:38 AM
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I have seen a number of guys use two different length pushrods. Can't answer the question on the cam, but I seem to remember someone saying the lobes are different. If you have the cam card, you may be able to check Comp's web site for the lobe data.
Old 04-25-2010, 08:19 AM
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Yes it does have two different lobe profiles. I think LSK Intake and XE-R Exhaust if I remember right. This is only going by someone elses comments on here.
Old 04-25-2010, 09:40 AM
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Originally Posted by 1NASTYZo6
Yes it does have two different lobe profiles. I think LSK Intake and XE-R Exhaust if I remember right. This is only going by someone elses comments on here.
^If this is accurate information, then your varying measurments would make sense. If you used 7.4 or 7.375 pushrod on all valves, what would this make your preload for intake/exhaust for each length?

The reason I ask is that (if you're using ls7 lifters) is to mention that the stock style lifters have a very generous range for acceptable preload, as it's somewhere around .050-.080 (give or take). Even with the different lobes for intake/exhaust, you may be within the acceptable preload range for both the intake/exhaust with one given pushrod length.
Old 04-25-2010, 10:11 AM
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Originally Posted by squirts11
^If this is accurate information, then your varying measurments would make sense. If you used 7.4 or 7.375 pushrod on all valves, what would this make your preload for intake/exhaust for each length?

The reason I ask is that (if you're using ls7 lifters) is to mention that the stock style lifters have a very generous range for acceptable preload, as it's somewhere around .050-.080 (give or take). Even with the different lobes for intake/exhaust, you may be within the acceptable preload range for both the intake/exhaust with one given pushrod length.
Good point on the range. I am using Comp Cams OE replacement lifters. From what I understand they have a .060 - .100 range. I have went on to comp cams web site lobe profiles catalog and can not see the base circles listed. It lists journal size as 55mm. I guess I am surprised that others have not asked this question before since this cam has been around for awhile. That or my OCD is getting the best of me worrying about the correct preload on the valvetrain. LOL




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