I have the stock pushrods in my 5.3 now, but will be swapping heads soon. The new heads are milled .020, and I may mill them another .010-.020. What if any loss will I see? Also I will try and get a bigger cam before the TR shoot out. Not sure if that will change any thing, but I want to go with a 216/220. Thanks

 

valvetrain geometry is a **** and can cause problems. If I had to do it again I would buy a pushrod length checker the accurate one not the really cheap one comp sells both or you can make ur own if you really want to get into it from a stock pushrod, someone told me how a while back im sure it in a post.

then start reading on how to adjust and measure valve spring preload, I have a good how to from crane if you want it.

The reason my engine and alot of others sound like sewing machines and have noisy valves after cam swaps and headwork is people dont check geometry or bother to adjust preload (this include your truely) when I did it I flew by the seat of my pants and now I have a noisy valvetrain and could possibly have uneven wear on the valve stems. So dont be like me buy a pushrod length checker and adjust your preload

 

Generally speeking, milling the heads will require a shorter pushrod while larger cams warrant a longer pushrod due to their smaller base circles. I will venture to say with a set of .030-.040 milled heads and the small cam you are running, a 7.35 pushrod would be needed.

 

well ill be changing my cam out soon along with new hardened push rods and 918 springs. do i need to do any of this measuring and setting the preload that yall are talking about?

 

Thanks for the info. That how to would be great. If I get the geometry correct will it sound like a chevy again instead of a singer??

 

yes
whats your email?

 

mwbrown03@***.net
Thanks

 

sent the info

This is my take on things

The base circle of many aftermarket cams is alot smaller than the stock cam so though you might mill .050 off your heads this amount is nothing compared to the base circle of your new cam that has taken away around .100 numbers can vary even between identical cams from the same manufacturer.

so with the use of very forgiveing(thank god) stock hydraulic lifters we are able to half *** cam swaps and milled heads because the lifters have around .100 to .120 leway in them taking up the slack for less cam base. But at the same time When you install a setup with too little preload you are getting all that hydraulic force traveling through the lifter jaring the pushrod and making valve train noise (hence sewing machine) plus it cant be good for the lifters.
For extended use I have probably cut 25k miles of the total life of my engine because of this but I still could get to 120k on it in the end who really knows.

I do know when I get around to building my stroked 6.0 that thing is gonna run like a watch and its gonna be quite as a mouse.

 

Its usually a good idea to get a 7.43 rod when you do a cam to make up for the BC. Some just get the 7.4's and call it good. I put Comp 7.43's in mine and its quiet. Did the same in my new motor.

 

Thanks, I guess I'll be checking into what length I really need.

02 The attatchments wouldn't open Think you could re send? Thanks