push rod length after heads milled .021
Thread Starter
Teching In
Joined: Dec 2015
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push rod length after heads milled .021 Turbo 5.3 cam specs
will it be advised to get push rods made or stock be acceptable. Running PAC 1218 springs
Compression raito squeaks in at 9.1
- Lift: 0.585"/0.585"
- Duration @ 0.050": 228°/230°
- Advertised Duration: 283°/286°
will it be advised to get push rods made or stock be acceptable. Running PAC 1218 springs
Compression raito squeaks in at 9.1
Maybe this will help. I have an 04 5.7 motor. The heads were ported last year and milled .0020 ths. The OE specs are 7.4 on an unmilled head and using a .0051 compressed multilayered OE gasket and OE rockers. Technically, the pushrods should be reduced by .0020 to say 7.380 or so. After discussing the matter with Howards, it instructed the OE length rods would work OK.
I took the advice and the motor runs great on the OE rods. Another benefit after reading many posts on the issue here, is that the LS7 lifter operates better with more preload. I believe but I am not certain that the 5.7 OE preload is set at about .0040 from the factory. The preferred preload, or at least what many members here suggest for an LS7 lifter, should be about .070 or so. So, my preload is now set at about .060 and the motor runs well.
I do not know what the best preload should be for the 5.3. But, I guess the OE sticks will work well for you. But, check it out.
I took the advice and the motor runs great on the OE rods. Another benefit after reading many posts on the issue here, is that the LS7 lifter operates better with more preload. I believe but I am not certain that the 5.7 OE preload is set at about .0040 from the factory. The preferred preload, or at least what many members here suggest for an LS7 lifter, should be about .070 or so. So, my preload is now set at about .060 and the motor runs well.
I do not know what the best preload should be for the 5.3. But, I guess the OE sticks will work well for you. But, check it out.
All good info but all of this goes out the window when an aftermarket cam is installed (which it sounds like the OP has). Cams can have different base circles and that WILL affect valvetrain geometry and required pushrod length.
The best way to proceed is to measure what length pushrods YOUR engine needs.
The best way to proceed is to measure what length pushrods YOUR engine needs.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
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From: Central Cal.
I noticed you don't see base circles noted in aftermarket cams. You don't know if they are different or not. I think such info would be VERY beneficial, especially when trying to figure if new pushrods are needed or not. If you KNOW the base circle is as stock, AND the heads have NOT been milled, one could very likely run stock pushrods. Of course, checking is still a good idea...
Bottom line, cam grinders should list the base circles of all cams, IF not stock.
Bottom line, cam grinders should list the base circles of all cams, IF not stock.
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You also need to know your lifter preload when selecting a push rod as it is crucial on a hydraulic lifter. If you are running LS7 lifters and the cam is indeed a stock base circle then you will be fine on stock length push rods.
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Verdad Gallardo All the above is correct. Thats why I called Howards to make sure the sticks would work in my motor. I suggest The OP find out the type of cam he has and call the manufacturer. BTW my cam is 226 232, 578 587, 115.