help with valve grinding issue

[jimtash]

I've done a search here pertaining to valve work on a head and some people say that the valve stem shouldn't be ground down when the valve job is done and that the shims will make-up for any clearance issues. All I want to know is will I need wider or thinner shims to make up for any problems and how much material is typically removed when grinding down the valves? Or would my best bet be to let the machine shop grind down the stems to get the original clearance? Thanks.

BTW, the average shim size that I took out was in the 2400 to 2450 range.

 

[93rev2sev]

My machine shop charges a lot more to shim the heads...in the end, it should be done AFTER the heads are installed, anyway.

Have the machine shop do whatever is needed to the valves and seats to get a good seal, then install the cams and shim them yourself after they are on the engine.
Or install the cams and shim them yourself on the bench...but check each and every one after the head is on and torqued to spec.

To answer your question, the valves gets "longer" when they are ground, you will need smaller shims. No need to grind the stem.

 

[St Louis SHO]

grinding the stem restores close to original shim height, as the 2300 series are hard to come across. So I myself would have them cut the stems, but I agree, shim it when they're torqued down, it may or not make a difference, just more peace of mind that way. Just my .02

James

 

[jimtash]

Thanks. So I'll probably be looking at shims in the 2200-2300 range to get the proper clearance, right?

 

[jimtash]

grinding the stem restores close to original shim height, as the 2300 series are hard to come across. So I myself would have them cut the stems, but I agree, shim it when they're torqued down, it may or not make a difference, just more peace of mind that way. Just my .02

James

Luckily it's a spare engine, so I can wait to find the right shims.

 

[93rev2sev]

Depends on how much the machinist needs to take off. If they look pretty good, a light polish might be all thats needed.

Let us know.

 

[jimtash]

I will and thanks.

 

[K-Dawg]

Why grind the valves? Usually all that is needed is a light lapping.

 

[jimtash]

I spoke with the machine shop guy and he said that he'll basically skim over them so I guessing he'll more than likely just give them a light lapping and that'll be it.

 

[AREA 91]

I have only "lapped" the valves by hand myself. No machine shop work.