As far as T4 heads go I only offer fully re-manufactured heads. I do not offer partial repairs .
There is a technical and legal distinction between rebuilding and re-manufacturing. A rebuilt component (starters, alternators, cylinder heads etc.) will re-use old parts as well as the O.E. casting.
For the re-manufacturing process only the parts O.E. housing or casting is re-used. All other parts are replaced with new parts. We carry it to an extreme with these heads by restoring the spark plug threads to new condition as I describe below. Only the intake studs are left, and if they’re flaky they’re replaced as well.
BTW, it is illegal for a company to market a rebuilt component as re-manufactured.
Here are the features that go into all of my reman heads.
All new valves, seats, guides, valve springs, retainers, new ground keepers, rocker studs and new exhaust studs.
We always weld the spark plug bores shut and machine new fresh threads, no inserts! During that process if there are any cracks around the plug bosses (usually are on 1.8 & 2.0 914 heads) we weld them up at no extra cost (provided they aren’t excessively bad cracks in which case I’ll have to add a small amount to the cost)
1.7’s and 2.0 914 heads with O.E. rocker chamber vents have the option of welded in replacement tubes (see photo below) or machining for a 3/8″NPT fitting. If the engine will run carbs we recommend plugging the vents. Keep the vents when the factory Fuel Injection is retained.
The oval exhaust gasket counterbores are re-faced (where the copper gasket fits) and if any inserts or flaky work was done to the ex stud bosses they are machined out and new ones welded in and new threads machined, again no inserts!.
The valve seats are machined with Serdi tooling that I have found to flow nicely, yet with a wide enough seat face to draw heat from the valves. Valve stem ht’s are set to factory specs and levelled to within .005″ of each other for consistent rocker geometry.
The heads are wet flycut using diamond dressed tooling and the chambers cc’d.
Stripped M5 & M6 sheet-metal threads are repaired.
With the exception of the seat work all work is perfomed on several Bridgport mills fixtured for specific operations.
When we service a pair of these heads the intent is to restore them to new or better condition. Naturally you will still have old castings, but they will have all new parts and fresh plug threads and freshly machined surfaces, with the exception of the intake manifold surfaces. And we can reface them if it is needed, though it would be due to damage, not from heat induced warpage.
The valve seat, valve guide, and valves are comprised of modern, durable and strong materials designed for long reliable life with unleaded fuels.
These photos illustrate the detail that comes standard with every pair of our re-manufactured heads.