push rod question

[NorCalChris]

How much can you machine off the head of a stock Renix 4.0 before you need to buy pushrods?
What about stock 91+ 4.0?

[NorCalChris]

Ok, spec on Alldata is 9.640 - 9.660 in. I checked on a 89 XJ, 92 xj, and a 99 xj. Thats a .020 difference. I replaced a headgasket with the victor reinz mls style gasket, then the machine shop took .008 off the head. So thats .016 total removed, is that too much?

[SilverXJ]

You should be okay. IIRC max stock preload is around .060". What is your preload now?

[NorCalChris]

Not sure, I need to measure it tonight.

[gradon]

I'm inclined to say you are OK but always measure. Mine are probably on the short side and whenever I have to take the head off, I'll install the .010" thinner HG.

[gonridnu]

As stated, a little off the head (.016") isn't going to make a difference.

What might make a difference is aftermarket cams are not always ground on the same base circle as a stock cam which can really change your pushrod length. If it is a total stocker you will be fine. If it is not, you need to check.

[NorCalChris]

It is a complete stocker POS engine. I litterally pulled chunks of grime out of the lifter valley of this engine. The cylinder head is the nicest thing about this engine. I didnt think .016 would be a problem. I have a misfire or two (or three) right now. I found one dead hole last night. Started pulling injector wires one at aq time . Cylinder three didnt change. swapped in a different injector, same problem. Pulled the spark plug, theres spark. So I compression tested it. 130 psi. I'd like to do a leak down test, but I dont have a leak down tester. I'm going to compression test the whole engine, then put the old injector back in, but in a different hole and see if the misfire moves. I'm using Ford design 3 yellow injectors. I have three extras that have been in my tool box for two years now. So they might be stuck too..... Im going to measure egts with an IR gun and then pull the valve cover and inspect the valve train.
**EDIT** When I pulled the injector harness on cyl 3, I used a noid light. It lit up so I'm fine there.