m42racer

Steve,

Lots of choices here. Just thought I'd add the most important part to consider. Not so much who you pick, but what they do or DON"T.

There is a big difference between production type of work or precision. All of the performance you should expect from your engine comes from the Head. Done right it will perform. Done basically, you can expect lower performance. Remember the performance you want is what this engine is supposed to produce. Ask if the following procedures are done.

Crack checked
Guides measured
Valve stems measured.
Valve guides pin fitted to valves. Guides need to be sized with used valves. Porsche Valves have the clearance in the stem when new, but with wear, this clearance needs to be added back into the guide. Most times guides need to be replaced. Factory guides are very soft. A good repair shop will fit a guide made from a better material.
Correct clearances checked
Valves cut and margins held.
Valve seat heights held. Not just recut so low that the flow is compromised.
All seats cut to same heights. All seats vacuum tested for sealing.
All Valve stems cut to same length, and proper length. This holds proper rocker geometry.
All springs checked for correct rates etc.
Retainer heights measured.
Correct Installed heights held with shimming calculated. This ensures the correct seat pressures. Distance to Coil bind measured.
All head heights measured and sealing surfaces recut and head heights all equalled.

This is just a short list of what should be done. Most shops disassemble, clean, cut the seats, cut the valves, put the valves into the guides and wiggle them for clearance check, slap a couple of shims under the springs and ship them. This is why it costs less at these places. Its not because they are cheaper, its because they don't do the work. Is it worth having it done correctly and all the stepps done, absolutely. The difference maybe a few Hundred $, but these can be the best spent $ you can spend. I'd ask if they do these steps and do they supply a spec sheet with all the measurements recorded.

Steve Weiner-Rennsport Systems

Good information from m42racer,.......this is just SOP at any competant and experienced 911 racing enterprise.

I'd just add that there are several businesses around the USA (not just ours) that does ALL those things, (and more) and no one particular shop has the exclusive "franchise" on doing these operations correctly.

m42racer

Then why don't they do it? I have had machine work done by 2 listed here. Waited 6 weeks and got very basic machine work. As for the "franchise" of doing things correctly, again, there are those who choose to do it correctly and there are those who choose to do the very least and once assembled, know that we will never know. This work is NOT at available at "any" competant Porsche 911 racing shop. Its available at very few. Most still do the very least and do not know what really needs to be done. I know this to be true. Compare the work, ask them what they do and see for yourself. I'm not trying to **** anyone off here, just trying to educate those who have sent work to some of those listed here. In most cases, when the seats are so low, the seats are still cut and the chamber is cut to level out the surfaces. This kills flow, but makes for short work. Most customers do not know any better and these places know this. Yes the Heads look clean and rebuilt, but not even close to been right. I've talked to those who say, "this is not a race engine" or "you can never tell the difference", well for those who wish to know, yes you can.

Steve Weiner-Rennsport Systems

I will not answer your rhetorical questions but,...I would simply caution you not to paint EVERYONE with the same brush by making wide generalizations.

I do agree that this Forum is an excellent place to educate people that not every vendor & service provider of any kind, is the same.

m42racer

I agree. But I still feel that machine work for Porsche's has always been something that most do based upon cost not quality, "brush or no brush".

steveL

thanks for all the input. case and heads got shipped to Ollie's today. they said the turn around time for this work is about 3 weeks, which doesn't sound to bad. thanks again.