One must be aware of what to ask when buying heads. All of the offshore stuff is coming in with a basic 3 angle valve job and guides that are reamed to a certain number. The valve job and guide clearance is based on some valve sample that was sent with the heads but not all valves are created equal.

When buying heads ask these questions?

Do you tool form the seats with a cutter?
This process when done properly takes the valve being used and its seat location and properly cuts it into the existing seat in both the correct area and correct width. Along with the seat cut other angles are cut into the seat to enhance flow.

Do you vacuum test the valve job?
Do they test for leaks using a vacuum pump?

Do you lap the valves?
Using a lapping compound the valve seat is lap finished to the seat.

Are the guide honed to size? If so what is the clearance?
Just because a valve will drop in the guide doesn't mean is to correct. You need to know what kind of clearance they are using.

Are you measuring all the valve heights and shimming to with in .010" accross the board?
Spring pressures are critical. Measuring one valve height and assuming you have the same across the head is easy. Measuring each stem and shimming each valve takes time.

If one is just assembling heads using the provided mating surfaces and tolerances from overseas a set of heads can be assembled in about 20 minutes. At a wage of $15 an hour the labor in the heads is $5 a pair.

If one is tool forming the seats with a $50K machine, lapping the valves, leak testing the valve job and then assembling the heads, but a machinest making around $30 an hour. One has about 4 hours in labor and overhead to pay for that would be around $$30 an hour also.

Ask questions and know what you are paying for.

 

I purchased "offshore" heads, but I had them professionally assembled by a particularly ****-retentive engine builder.

I totally agree that purchasing offshore heads then building them "out of the box" with little or no experience in what pitfalls to watch out for can be problematic.

That also doesn't mean that all "offshore" castings are complete junk. As with anything, you need to be careful with them.

Good post and good heads up.

 

PM sent

 

When I'm ready for heads and cam I'll be contacting you but for now I have other issues to deal with...

 

I just hung up with Chris after about a 30 minute conversation. He is a wealth of information, helped me to weed through a lot of the facts and opinions that are out there. And he has a very good price on the Patriot heads.

Thanks