Hi, I am new to the board. I am building a 383 and I am trying to set up my heads with 26918 beehive springs. I need to cut my valve seats down .060(in) to get my installed height right. I have GMPP LT4 heads. Does anyone know if they can be safely cut .060 deeper? The machine shop I am using is not sure since they don't see to many LT heads.

 

Don't think .060 is safe.Get .100 longer valves or get .050 up retainers or locks or both.The springs may not be right pressure after that.Watch for rocker contact with retainer and ya are going to need pushrods if ya go .100.

 

I've got the same springs, and use the +0.050" keeps like the other poster suggested. Considerably easier/cheaper than having your heads machined!

 

My machine shop did use the +.050 locks but I purchased self aligining roller rockers that need the valve stem shoulder to align on and the alignment tabs hit the retainers before the rollers hit the valve stems.... Anyone need a set of self aligining 1.6 roller rockers.