Installing brand new stainless steel valves

[GSXRolla]

I'm rebuilding my engine, and the time has come to tackle the head. I decided when I started this to upgrade the cams, valves, and install new 3g lifters. So here's the question...

The valves I bought were standard size, and the valve seats look decent. Do standard size valves usually just lap in? Or will I most likely need to have the seats ground for them to fit perfectly? The head has 130k miles on it, but I never really hear about any body asking this question.

Also, I was told by a guy at the machine shop that by 130k that the exhaust guides are usually on their way out, and should be replaced. Sound true?

 

[sonicnofadz]

Your valve guides need to be checked for excess play by a machine shop and should replaced if neccessary. At 130k they definitely may be in need of replacement. You COULD just lap the valves in, (i've done this before to other cars) but the end result won't be as good if you had just brought the head in for a proper valve job by a machine shop. The valve seats need to be cut and reshaped by a machine shop. If you just lap the valves, then your compression may be very poor (especially if you aren't experienced lapping valves) and the compression that you do obtain probably won't last too long. I've seen some guys lap their own valves have perfect compression afterwards, and retain the compression for a very long time, but this is usually NOT the case. Lapping the valves is ALOT of work, and I would just recommend taking the head and valves to a reputable machine shop.

 

[TSIfreek]

Yea you need to get those valve gides replaced with new bronze guides, new valve seals and get a 3 angle valve job done buy a DSM engine/head builder so he knows what works and doesnt for seat angles. To your question NO you cannot just lap them in the seats need to be reground for the valve to seal properly.