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Checked again and called TSP back....
EOIC with TSP PR 7.400 at 0 lash gives me 5/8 turn to tight cylinder #1 and 2
TDC with PR ck tool at now 12.5 turns 0 lash gives me 5/8 turn to tight cylinder #1 which is 7.425 without any lifter preload calculated in.
TSP is thinking only one size up to 7.425
thoughts?
7.425" will be fine ... 25 thousands longer ... okie dokie
There is a pretty big travel distance in the stock lifter internal bore ... you will be fine
The other thing to consider is that with a good, much more rigid aftermarket pushrod, you won’t have that pole-vault bending effect of the stock pushrod, which effectively shortens the pushrod as the lifter accelerates up the lobe of the cam. I’ll bet if you could view a set of stock pushrods in slo-mo at high rpms, you would be shocked at how much they flex.
05 LS2
OEM lifters
OEM heads
TSP dual valve springs
TSP 228/232 112 LSA
I’m using pushrod length check tool. On base circle intake I get 11.5 turns ZERO lash hand tight.
11.5 x .050 = .575 + 6.80 = 7.375
So now I add .070 for OEM lifter preload giving me a total pushrod length of 7.445??
If yes do I use a 7.450 pushrod which will give me .075 preload?
thanks
If you have the Comp 7702 PR length checker your calculations is correct. Just make sure it’s the ”real” zero lash
Last edited by joystick; May 30, 2020 at 04:55 PM.
Ok found digital calipers...
-all zero lash measurements taken on base circle
EOIC
-TSP PR 7.400 on cylinders #1,5,2,6 both intake and exhaust I get 3/4 turn to 22 lb ft torque.
-PR length ck tool taped and set at 12.5 turns equals 7.425 on cylinders #1,5,2,6 both intake and exhaust I get 7/8 turn to 22 lb ft torque.
TDC
-cylinder #1 same results as above.
I will note that on cylinder #1 I did feel some slight lifter plunger preload and was careful.
I’m pretty sure at this point I should use 7.425 PR.
Thoughts are welcomed..
thanks!
Here is a few pics of PR using calipers and of course they are not exact.
I’m pretty sure at this point I should use 7.425 PR.
Thoughts are welcomed.
You know, that makes sense ..... As I stated before, these aftermarket cams have a slightly smaller base circle than the OEM cam, so if anything, would require a slightly longer pushrod ... the next size longer than the 7.40" stock rod would be a 7.425"
Either way ... a 7.40" or a 7.425" rod would be fine.
But, like you said; the stock rod is actually slightly shorter than 7.40" ..... The more I think about it, I would just buy a set of hardened 7.40" rods that are actually a verified 7.40" long.
Not trying to beat this to death but....
my stock LS2 cam base circle is 1.522
TSP verified new cam base circle is 1.432
So 1.522 - 1.432 = 0.09
0.09/2 = 0.045
Stock PR 7.385 + 0.045 = 7.430
So I’m at 7.425 PR length again 😁
Last edited by rc51racer; Jun 2, 2020 at 09:29 PM.
Still patiently waiting on new 7.425 PR from TSP. Ordered them early Tuesday morning and are in stock. Still haven’t shipped. Apparently they get in no hurry to ship. 👎🏼
Still patiently waiting on new 7.425 PR from TSP. Ordered them early Tuesday morning and are in stock. Still haven’t shipped. Apparently they get in no hurry to ship. 👎🏼
That figures ..... If it's not one thing, it's something else
Finally got 7.425 PRs from TSP and installed them last night. From 0 lash base circle I got 1 1/8 turns on all rocker bolts when torqued to 22 lb. ft.
Measured the 7.425 PRs with calipers and of course they came out a little longer. I know I’m splitting hairs. Just wanting this to be done correctly.
[QUOTE=rc51racer;1601672123]Finally got 7.425 PRs from TSP and installed them last night. From 0 lash base circle I got 1 1/8 turns on all rocker bolts when torqued to 22 lb. ft.
Measured the 7.425 PRs with calipers and of course they came out a little longer. I know I’m splitting hairs. Just wanting this to be done correctly.
That’s probably as close to perfect as you can get. Don’t worry so much about what they actually measure out to, as long as you get the right amount of preload on the lifter.
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