Pushrod length and ptv
Thread Starter
Teching In
Joined: May 2020
Posts: 12
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From: Hurley VA
Pushrod length and ptv Ok guys I think I figured out my ptv. I used the pushrod checker and got it to 7.300 and that wasnt at 0 lash. I actually had a little lash on both valves. The intake had .010-.012 and the exhaust had .022-.024. So I added that in with my clay measurements for my ptv and should be .082-.085 intake and .100-.105 exhaust. I think i got that part in good shape.
Ok, now here is where my head is exploding. You are supposed to have around .040-.050 preload on the lifters, right? To get that amount I will need a 7.350 pushrod. Now, my biggest concern is that going to skew my measurements on ptv or will it be ok?
Let me know if I did that right or am I missing something or am I worrying too much. This is my first time doing this. I milled my heads .035 and am using a .045 gasket. The motor has an unknown cam in it (I made another post about that), that to me doesn't seem to be a big duration. I've been trying to take what I've learned on here and do it myself, but keep second guessing myself.
Or do I need to do things differently?
Ok, now here is where my head is exploding. You are supposed to have around .040-.050 preload on the lifters, right? To get that amount I will need a 7.350 pushrod. Now, my biggest concern is that going to skew my measurements on ptv or will it be ok?
Let me know if I did that right or am I missing something or am I worrying too much. This is my first time doing this. I milled my heads .035 and am using a .045 gasket. The motor has an unknown cam in it (I made another post about that), that to me doesn't seem to be a big duration. I've been trying to take what I've learned on here and do it myself, but keep second guessing myself.
Or do I need to do things differently?
Last edited by brmz28; May 19, 2020 at 11:26 PM.
TECH Addict
Joined: Dec 2017
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PTV clearance doesn't change with preload, unless you put in so much that the valves can't close.
THIMK about it... changing the push rod length doesn't change the cam lift, eh?? Well it won't change PTV clearance either.
As long as the PR length is within the range of preload that the lifters can accommodate, the valves move essentially exactly the same.
THIMK about it... changing the push rod length doesn't change the cam lift, eh?? Well it won't change PTV clearance either.
As long as the PR length is within the range of preload that the lifters can accommodate, the valves move essentially exactly the same. Thread Starter
Teching In
Joined: May 2020
Posts: 12
Likes: 1
From: Hurley VA
Yes I thought that after I did. Which I checked at valve tip and rocker and added that clearance to my ptv numbers. I'm still using original ls1 lifters. Thanks
Thread Starter
Teching In
Joined: May 2020
Posts: 12
Likes: 1
From: Hurley VA
PTV clearance doesn't change with preload, unless you put in so much that the valves can't close.
THIMK about it... changing the push rod length doesn't change the cam lift, eh?? Well it won't change PTV clearance either. As long as the PR length is within the range of preload that the lifters can accommodate, the valves move essentially exactly the same.
THIMK about it... changing the push rod length doesn't change the cam lift, eh?? Well it won't change PTV clearance either.
As long as the PR length is within the range of preload that the lifters can accommodate, the valves move essentially exactly the same.
Banned
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From: USA
One whole turn of the rocker bolt is approx .078 preload. 3/4 turn is .058 preload. (not everyone likes this method but it will be close enough for a forum explanation.)
You might see the valve go down, then come back up as the lifter bleeds down.
So you're sure you're on the base circle? Are you sure the lifter is not bled down?
You might see the valve go down, then come back up as the lifter bleeds down.
So you're sure you're on the base circle? Are you sure the lifter is not bled down?
Thread Starter
Teching In
Joined: May 2020
Posts: 12
Likes: 1
From: Hurley VA
One whole turn of the rocker bolt is approx .078 preload. 3/4 turn is .058 preload. (not everyone likes this method but it will be close enough for a forum explanation.)
You might see the valve go down, then come back up as the lifter bleeds down.
So you're sure you're on the base circle? Are you sure the lifter is not bled down?
You might see the valve go down, then come back up as the lifter bleeds down.
So you're sure you're on the base circle? Are you sure the lifter is not bled down?
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Joined: May 2020
Posts: 252
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From: USA
This is what I copied off this site. I verified these once with a dial indicator. I know someone else might come on here and give me hell about this, but if you're not using a dial indicator counting turns is close enough.
Just make sure the lifter cup is all the way up before you start counting turns. It should be solid, not springy if it's pumped up enough.
This is turns VS preload
.50T = .039"
.75T = .058"
1.00T = .078"
1.25T = .098"
1.50T = .117"
1.75T = .137"
2.00T = .156"
Just make sure the lifter cup is all the way up before you start counting turns. It should be solid, not springy if it's pumped up enough.
This is turns VS preload
.50T = .039"
.75T = .058"
1.00T = .078"
1.25T = .098"
1.50T = .117"
1.75T = .137"
2.00T = .156"
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Teching In
Joined: May 2020
Posts: 12
Likes: 1
From: Hurley VA
This is what I copied off this site. I verified these once with a dial indicator. I know someone else might come on here and give me hell about this, but if you're not using a dial indicator counting turns is close enough.
Just make sure the lifter cup is all the way up before you start counting turns. It should be solid, not springy if it's pumped up enough.
This is turns VS preload
.50T = .039"
.75T = .058"
1.00T = .078"
1.25T = .098"
1.50T = .117"
1.75T = .137"
2.00T = .156"
Just make sure the lifter cup is all the way up before you start counting turns. It should be solid, not springy if it's pumped up enough.
This is turns VS preload
.50T = .039"
.75T = .058"
1.00T = .078"
1.25T = .098"
1.50T = .117"
1.75T = .137"
2.00T = .156"