If the OEM timing set has more than 80K on it it is due for replacement. The intake and exhaust valves are non adjustable on these engines unless you have aftermarket Chevy style wobble rockers installed. Before you start to hop up an engine it is always a good idea to make sure the basic engine is sound.

 

Crane has a shim kit for pedestal mounted rockers but it will only lessen lifter preload. the shim sits in the square recess of the pedestal, under the rocker fulcrum. it's a little delicate but no big deal. as you're tightening the rocker bolt, roll the pushrod back and forth between your fingers. when you feel the pushrod stop turning easy, this is 0 lash. now count the amount of turn(s) it takes to bottom the bolt. that is your preload, 1 turn is .0625", 1/2 a turn is .03125", 5/8 turn is .0390625", 3/4 turn is .046875". that's where i shoot for between 1/2 and 3/4 turn, or about .030" to about .045" of preload.

this is all done one cylinder at a time at TDC of course, start at #1 firing TDC and do both rockers on the #1 cylinder. then turn the crank bolt 90* and do the next cylinder in the firing order which is #3. turn the crank bolt 90* and do the next cylinder in the firing order which is #7, 90* do #2, 90* do #6, 90* do #5, #4, #8.

after a valve job it should be checked because the valve tips may not have been ground to compensate for the seats being cut. too much lifter preload(bottomed out lifter plunger) could cause the issue you're having. could be carb/vacuum leak, or ignition too?

 

So I would do that to gauge the thickness of shims I would need right?

 

Sorry if you already answered this, but are you positive your ignition timing is set correctly? If it were me, I'd adjust it 3 degrees retarded and test, and then 3 degrees advanced, and test, to see if there is any difference. On my recent rebuild startup, I was getting backfire through the carb, and it turns out I had the wrong dampener timing pointer, and the ignition timing was severely retarded (something like 15 degrees ATDC).

 

Ok, I borrowed an ignition module from a different truck, no difference. I bought the rocker shims, when I get some good weather, I will look into those

 

DO check for play in the timing chain. Easy, costs nothing. Best to eliminate the chain as a source of your troubles. Not drawing any conclusions here, tight valves will do it to you also.

 

I talked to one of the guys at my local part store. He has experience with a lot of ford motors and he thinks that my cam is worn down and causing the problem. The engine does have a good amount of miles on it, so i guess it very well could be. Since I will be replacing my timing gears & chain, I suppose I should just buy a cam, liters & pushrods. Any input or cam suggestions guys?