Head milling and Pushrod length
Head milling and Pushrod length I think the norm for head milling is .030. I'm having mine ported, polished and milled .030. my cam has a .563 lift. If I use stock length pushrods that makes it .593 (that is a little too much I think. If get 7.35" pushrods then I loose .020 " of lift. Are those my only option.
TECH Junkie
Joined: Nov 2001
Posts: 3,604
Likes: 0
From: Los Angeles
Re: Head milling and Pushrod length The pushrod is not going to give you more lift. The lifter should up the extra length.
Also, its important to note that new cam's dont have TALLER lobes for more lift, they actually take away material from the low part of the lobe to make the high part seem higher. Basically they lower the valley instead of raising the peak, if that makes sense. What it means to you is that the higher lift cam will cancel out a lot of the effects of the milled heads as far as lifter preload is concerned.
Anyway, the bottom line is your setup will be fine and that you should have about the same valve lift with a 7.35 or a 7.40 due to the way lifters work.
Also, its important to note that new cam's dont have TALLER lobes for more lift, they actually take away material from the low part of the lobe to make the high part seem higher. Basically they lower the valley instead of raising the peak, if that makes sense. What it means to you is that the higher lift cam will cancel out a lot of the effects of the milled heads as far as lifter preload is concerned.
Anyway, the bottom line is your setup will be fine and that you should have about the same valve lift with a 7.35 or a 7.40 due to the way lifters work.
Re: Head milling and Pushrod length OK. So, I already have a set of new 7.4" pushrods. Should I stick with them or get a set of 7.35'. No big deal either way. they are still new in the box. If it make no difference why do you different length pushrods? Does it make difference with solid lifters instead of hydraulic?
TECH Veteran
Joined: Aug 2002
Posts: 4,055
Likes: 1
From: Hartsdale, NY
Re: Head milling and Pushrod length I have ls6 heads milled .055 and a 220/220 564/564 112 cam with with a slightly smaller base circle. The CHANGE in the cam base circle (the new base cicle Vs. the old base cicle on the stock cam) and the amount milled from the heads is used to determine the proper push-rod length...
Mine are 7.35 in lenght. To make sure, ask the cam manufacturor or head manufacturor....
Mine are 7.35 in lenght. To make sure, ask the cam manufacturor or head manufacturor....
