Head tools

[dweymer]

I was wondering what tools people are using to perform the following work on a set of heads:

Grind valves and seats
Install new guides
Port/polish
Dual plug mod

Just curious how it's done, and with what.

TIA

[asphaltgambler]

The valve/seat grinding work is performed (oddly enough) with a valve grinding machine. Very expensive so only most auto machine shops have them, not something the average home mechanic would have. Also the best machine is nothing w/o an experienced operator. I've seen some real messes even though the shop had very nice equipment.

Guide install /modification is with basic hand tools coupled with a simple tool that finds instant center for the guide. Depending on the type they also may use a small press and or heat to smoothly assist in removal or install.

Port/polishing has been done in the past with high-rpm small hand-held grinders with either carbide cutting bits or stones depending on the material and the amount removed. Very similar to a dentists' drill. Very labor intensive and time consuming. One mistake could ruin the part.


The newer method for porting /polishing is extrude-hone. Basically a machine forces a toothpaste-like metal compound with force through the opening to make it more uniform, larger and with a certain finish. Much faster and precise but it has limitations.

Dual plugging is usually performed on a mill. Basically a large, very precise low-speed drill press. Again these are very expensive so not every shop will have one.

[ChrisBennet]

To clean up the head sealing surface you use a jig to hold the head in a lathe an turn the whole head. This jig and the "setup" for doing the twin plug mod is something a machine shop who does Porsche heads will have.
-Chris

[john walker's workshop]

any of these procedures require plenty of experience, or all can be lost. a talented amateur could probably get thru it if they asked enough questions though. i do them here, but most shops actually farm them out.

[Jubbie]

The best tool I have used here is the telephone.

[dweymer]

Agreed that an amateur(me) could do more damage than good.

JW-Where would one go to learn the specs? Do the factory manuals have the valve grind specs in them? I have them, but have not read them completly. I have a set of 2.0 heads to play with before I would do my 2.7's. I am (to my own financial detriment no doubt) a DIY'er; not to save $$, but to learn. What is the specific tool to find instant center for the guide? Sorry if these are goofy questions, but I'm here to learn. Also, I'm shopping for a mill/lathe, any recomendations on brand/size or combo machine as opposed to 2 seperates.

[john walker's workshop]

they show a cross-section of a seat, with the different angles and seat widths, and the guide replacement procedure, but not how to grind the seat or what tools to use. the 45° part of the seat needs to be fitted to the valve face, so the face just overlaps the top edge of the 45. if the 45 is wider than the valve face, the seat is narrowed from the top with a 15° stone. then the width of the seat is adjusted by grinding or cutting a 60° angle from the bottom. this is just the bare basics in a perfect scenario. there is a lot more that experience will teach you. search the web for how to do a valve grind for some more info. not all of it will relate to a 911 head, but you will get the idea.

[dweymer]

Thanks JW, like everything in life there is always a learning curve. That's what makes it fun. I wish you were here, I would work a few hours a day for free just to soak up some of your knowledge/experience.