Machining the head - question on pushrods and lifters

[timdog]

So, I grabbed a spare 1980 head from the junk yard for the 200 in my '66 Mustang. I adapted it for a 2 barrel Weber 32/36 and sent it off to the machine shop for a hot tank, valve job, and to mill .075" off the surface (I measured just about 62 cc's in each cylinder, right about what the handbook suggested I would find).

Question 1
What do people do about the pushrods when machining a head with non-adjustable rocker arms? The handbook is pretty vague on the topic... I did find pushrods that are 1/16th (.0625") shorter than stock and put in an order for those from NAPA... probably a good idea at only $2.50 each. Think that will be sufficient? I mic'd the head gasket I pulled out and it was right around .055", probably the same thickness as the new Felpro I'll put in. Kind of concerned about just putting things together and seeing what will happen... but not sure what else I can do without adjustable rocker arms...

Question 2
Since I have things apart, I also decided to go for a new set of hydraulic lifters... I had no problem with the old ones, but didn't want to find one go bad in a few years after all the effort to put a new gasket, etc., in... again, at $4.00 each, it sounded like good insurance. Advice? The camshaft lobes looked good, no abnormal wear. Anything special I should do when I install them, other than just some assembly grease?

I also got some .060" thick washers to go under the head bolts and account for the change in head thickness.

I figure I'll put it all together, get it running and get the timing, then change the oil after a few trips around the block. (I know I got some coolant and other minor crud in the engine during the process).

Anything else I'm missing? I feel like I'm forgetting something or making a basic mistake here...

 

[CZLN6]

Howdy Tim:

Q#1. The stock OEM head gasket was .025" thick. The new gaskets are in the .050" thick range. That added .025" clearance. When you milled your head .075" you lost that in clearances but add back the .025" for the head gasket difference. That leaves a difference of only .050". The hydraulic lifters had a tolerance of about .125" plus or minus. That range easily covers the .050" you are dealing with. Adjustable rocker arms are a good idea though, even with hydraulic lifters, to maximize cam function as well as to avoid lifter pump up at high rpms.

Q#2- Typically, the lifters and cam should be changed together, but with a cam in good shape, along with good oil pressure, lifters can be changed. If the existing lifters are in good shape, I'd pass on changing them. It is not easy to remove lifters out the top of the block, but it can be done. be sure to use a quality assembly lube. "Not easy", for several reasons; the access holes in the top of the block are not bid enough to extract some lifters. The lifters are not easy to grab and hold while lifting. FoMoCo had a special tool to aid the job. Those tools are scarce. If you do happen to drop a lifter, you'll most likely have to open the pan to retrieve it.

I hope that helps.

Adios, David

 

[rbohm]

one thing that is always an option with push rods is to pick up a couple of adjustable push rods from any of the cam manufacturers, as well as a couple of solid lifters, and in the mock up stage use these on one cylinder to get the valve train geometry right, then send off the adjustable push rods to your favorite cam manufacturer and have them build you a custom set of push rods that fit your particular combination. they are not much more than off the shelf rods these days.