Unusual pushrod length
Thread Starter
Joined: Jun 2005
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From: Oskaloosa, Iowa
Unusual pushrod length Measured my pushrod length and came up with zero lash consistently at 7.4. I trust the measurements since everyone I checked was consistently 12 turns out on the comp cams tool at zero lash. So a 7.475 pushrod will give me 0.075 preload. Setup is ls3 short block, unmilled 241 heads, ls9 gaskets, custom cammotion cam, ls7 lifters and ws6store max effort rockers.
I'm confident enough in the measurements and know that it is what it is even if unusual length so I went ahead and ordered a set of Summit 11/32 .120 wall 7.475 pushrods. I'm just the kind of person that wants to know why? So after thinking a while the only thing I can come up with is the base circle of the cam is possibly smaller?
Progress pics...
I'm confident enough in the measurements and know that it is what it is even if unusual length so I went ahead and ordered a set of Summit 11/32 .120 wall 7.475 pushrods. I'm just the kind of person that wants to know why? So after thinking a while the only thing I can come up with is the base circle of the cam is possibly smaller?
Progress pics...
The base circle of the cam is smaller than what? The stock cam? Yea. The average cam? You're right, it is what it is, as long as you didn't have the lifter plunger pushed down when measuring.
I would suggest not using the LS7 lifters, not even knowing the cam specs, but if you have 11/32 pushrods you must have reason. Those lifters aren't the best choice by far. Sure people have used them but now is the time to think about cheaping out.
I would suggest not using the LS7 lifters, not even knowing the cam specs, but if you have 11/32 pushrods you must have reason. Those lifters aren't the best choice by far. Sure people have used them but now is the time to think about cheaping out.
Thread Starter
Joined: Jun 2005
Posts: 2,265
Likes: 673
From: Oskaloosa, Iowa
The base circle of the cam is smaller than what? The stock cam? Yea. The average cam? You're right, it is what it is, as long as you didn't have the lifter plunger pushed down when measuring.
I would suggest not using the LS7 lifters, not even knowing the cam specs, but if you have 11/32 pushrods you must have reason. Those lifters aren't the best choice by far. Sure people have used them but now is the time to think about cheaping out.
I would suggest not using the LS7 lifters, not even knowing the cam specs, but if you have 11/32 pushrods you must have reason. Those lifters aren't the best choice by far. Sure people have used them but now is the time to think about cheaping out.
I wasn't putting pressure down on the length tool. I would put a pushrod on the exhaust lifter and rotate the crank until it started to push up. Then I would pull it out and put it on the intake lifter to lightly push it down back onto the base circle. Then sit the tool in place and hand tighten the rocker down. Zero lash was always at 7.4. I checked 3 intakes and 1 exhaust on one bank then 2 intakes and one exhaust on the other bank and got the same measurement every time so I called it good.
Slightly thicker head gaskets and slightly smaller base circle ended up in a 0.075 longer pushrod than stock to achieve 0.075 preload. Just curious if my thinking behind why this is the case is correct because I don't build motors regularly and some people on here do. As far as parts selection I don't want to get into that debate. I chose the parts I did based upon budget and everyone I purchased from I trusted what input they gave me. That is why I chose them when I made purchases.
Probably just the combination of stuff. Unmilled heads vs most everyone in here running heads milled 020-030, short base circle, thicker gasket. The rocket cups might be slightly deeper. Every little thing adds up.
I ended up with 7.4 pushrods on LS7 lifter, unmilled 243 heads and a BTR stage 2 cam. I think the head gaskets were GM mls.
Are LS7 lifters noisy? My engine sounds louder than I'd prefer but it runs good.
Are LS7 lifters noisy? My engine sounds louder than I'd prefer but it runs good.
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Situations like yours are why we introduced the HDR . 025 increment pushrods. Simply put, more of our customers are getting better with their measurements and want to set preload on kill to avoid oil aeration and extend rpm.
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Verdad Gallardo Thread Starter
Joined: Jun 2005
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From: Oskaloosa, Iowa
Long block is now done and ready to drop in the car...
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From: Oskaloosa, Iowa
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From: Tasmania Australia
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From: Oskaloosa, Iowa
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They aren't the "best" lifters, but they should be fine for what I'm doing. Even Cammotion themselves said they would be fine for what I'm doing. When I pulled my stock motor apart a found a few pushrods that were bent. I think this was from an over rev when I blew the tires off (650+ rwhp at the time on street tires in cool temps). So I decided if I'm buying any way to go ahead and use 11/32 pushrods.
I wasn't putting pressure down on the length tool. I would put a pushrod on the exhaust lifter and rotate the crank until it started to push up. Then I would pull it out and put it on the intake lifter to lightly push it down back onto the base circle. Then sit the tool in place and hand tighten the rocker down. Zero lash was always at 7.4. I checked 3 intakes and 1 exhaust on one bank then 2 intakes and one exhaust on the other bank and got the same measurement every time so I called it good.
Slightly thicker head gaskets and slightly smaller base circle ended up in a 0.075 longer pushrod than stock to achieve 0.075 preload. Just curious if my thinking behind why this is the case is correct because I don't build motors regularly and some people on here do. As far as parts selection I don't want to get into that debate. I chose the parts I did based upon budget and everyone I purchased from I trusted what input they gave me. That is why I chose them when I made purchases.
I wasn't putting pressure down on the length tool. I would put a pushrod on the exhaust lifter and rotate the crank until it started to push up. Then I would pull it out and put it on the intake lifter to lightly push it down back onto the base circle. Then sit the tool in place and hand tighten the rocker down. Zero lash was always at 7.4. I checked 3 intakes and 1 exhaust on one bank then 2 intakes and one exhaust on the other bank and got the same measurement every time so I called it good.
Slightly thicker head gaskets and slightly smaller base circle ended up in a 0.075 longer pushrod than stock to achieve 0.075 preload. Just curious if my thinking behind why this is the case is correct because I don't build motors regularly and some people on here do. As far as parts selection I don't want to get into that debate. I chose the parts I did based upon budget and everyone I purchased from I trusted what input they gave me. That is why I chose them when I made purchases.
Thread Starter
Joined: Jun 2005
Posts: 2,265
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From: Oskaloosa, Iowa
It's together and in the car now so I'm going to run it. Some people go to .100 and others recommend .050 preload with ls7 lifters. I'm at .075 to .080 so it should be fine.
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Thread Starter
Joined: Jun 2005
Posts: 2,265
Likes: 673
From: Oskaloosa, Iowa
Thank you. This forum and it's members helped me a lot. I read books on tuning and building LS engines along with lots of reading/asking questions here and that is how I learned everything. I'm going to change the oil today and dust her off then start breaking her in and street tuning.
