P & R Engine Rebuilders Inc.
Greensburg, PA

Cylinder Heads

 Cylinder Head Services: 
  • All cleaning and crack/leak detection from previous page applies


  • 3-angle, carbide single point valve seat machining
  • Integral or press fit guide installation or replacement. IDs are reamed close to size and honed with diamonds to finish size, bronze or iron
  • Integral or OEM press fit valve seat installation or replacement
  • Valve spring checking or replacement
  • Surfacing
  • Complete head assembly abilities, OHC installation, valve lash setting etc
  • NOTE: We have access to multiple lines of very competitively priced cylinder head internal components such as valves, seats, guides, springs, seals, rotators, lifters, rockers, pushrods and camshafts. Also, if your head or block failed the crack or leak inspection stage and is deemed unusable, we have access to a few reputable re manufacturing facilities that offer good casting cores or complete assemblies as well as some good local salvage yards you can try your luck at.


  • Multi-angle or radius valve seat machining and bowl hog setup.
  • Valve guide replacement and bull nosing for airflow, using material that is required, ie hardened iron guides, brass or bronze, all honed-finish ID
  • Oversize valve installation and throat enlarging to match
  • Combustion chamber cc-ing and surfacing to raise static compression ratio, as well as angle milling manifold sides for fitment.
  • Combustion chamber stock removal, polishing and cc-ing to lower static compression ratio for forced induction setups and nitrous.
  • Over-size severe duty material or press fit valve seat installation for pulling trucks/tractors, the head is heated and valve seat is shrunk in liquid nitrogen
  • Cylinder head o-ringing or fire ringing
  • Machining spring seats for larger springs
  • Cutting of integral guides for positive seals or high lift cam clearance
  • Screw in rocker stud installation and machining


    Here is a brief explanation of porting and flow measurement using a flow bench.
When a cylinder head is brought to us for performance modification, all above standard services are performed first, ie cleaning, crack checking, and a basic valve job is performed to seal everything up. From this point a dummy (light pressure) valve spring is installed on both the inlet and exhaust valves that are to be used. Then a cam lift simulator (valve opener to check flow at various cam lifts) and a plate with the actual finished bore of your engine is installed. The ports are then measured for flow, usually at .050 valve lift increments, and the results are recorded giving us a baseline. Port, seat and valve modification is then performed, usually on one cylinder's ports with periodic rechecking to determine gains. Once adequate gain is attained all other ports are then modified in a similar fashion until all are equal in both poured volume and flow numbers and finished results are recorded. Head(s) are then cleaned and reassembled final flow numbers are supplied to customer upon pickup.

The largest limitation of a flow bench is the tooling needed, all that must be made not bought, to open the valves and simulate cylinder bores. We have an extensive amount of tooling for this already made, however there are heads we are not yet "tooled up for". Here is what we currently are..

  • Nearly all gasoline domestic 2 valve per cylinder heads: GM, Ford, Chrysler, Harley Davidson
  • Domestic 4 valve Diesel: Cat, Cummins, John Deere, Allis Chalmers, International, Detroit 
  • Imported Gasoline 4 and 5 valve OHC: Mitsubishi, Subaru, Honda, Volkswagen/Audi

NOTE: If you are serious about performance and in need of porting and your head is not above "tooled for" list, bear in mind as we've tried to demonstrate throughout this site, we are willing to make nearly any adaptation to our tooling to meet demands. Simply call with your head make and we will discuss options. Please understand however, there is literally dozens of hours spent to make the tooling we already have that we do not bill customers for because we keep it, so please have a serious inquiry.