Podguy

After visiting my local machine shop and getting a quote of over $1000 for the two heads on my 86, I figure I can buy the proper tools and rebuild them myself. I read through the manual and the process is not much different than the VW heads that I have rebuilt many. I suspect air cooled VW heads are more difficult.

There are a couple tools I can not source. The first are the tools to remove and then reinstall the valve seals. The manual seems to indicate the valve seals can be reused. At $1.95 each this does not seem to be such a good idea, but then there are 32 of them.

There are some special tools for setting up the two cams. Does anyone have a source for them or can they be made.

My first step it to take out the valves inspect the seats and check the valve guides for excess wear. I found a valve spring compressor for $52. Also the manual mentioned shims for the 16 valve engine but did not mention them for the 32 valve engine.

Thanks.

SeanR

Call Roger when he gets back.

I had him source the Porsche tools for the majority of it and they were pretty reasonably priced. The ones you can't find, just use e-bay. I think I've got less than $400.00 in to all the proper tools to do the job. Now saying that, I gave it a go a few times and said to hell with it, and send them off and let the pro's do it, not worth my time or aggravation.

dr bob

I don't know about the 16V engines, but the valve guides on the 32V look like they are very short, and therefore subject to a lot of wear. So your cylinder head toolkit should have the arbors, a fixture for holding the head, and a press, to be able to replace the guides. From there, seat cutters and grinder, and a valve grinder. Sounds like a bit of change unless you don't mind used stuff.

The seals should be replaced. At $2 each, a relative bargain.

I know that Rob Edwards has displayed some of the cam timing tools. IIRC, somebody had posted images of a set that could be used to make your own if the factory pieces are out of reach.

davek9

You can get a proper Valve Spring Compressor tool from a local Sears Approx $25.00

The seals are not re-usable, and the valves must be installed FIRST before the new seals are pressed on.
you also need to buy a few Valve Seal Condoms to protect the seals when the Valve stems go through (an additional ~5 bucks).
If you don't need new guides (and that is where I would take it to a shop) it is easy to lap the valve seats install the valves and new seals, but it takes time do do all 32 (16 would be quicker

edit: you don't need the cam tool, use the marks on the chain & cam's and get a porken32valver tool

I'll look for a pic of the home made tools I used, but if you do a search here you will find them.

good luck you and will be happy you did the work yourself

Dave

fbarnhill

Dan, I manged to get my cam timing perfect without any special tools. I just used the marks on the cams, followed the writeup I had and used Porken's bumpstick and his 32v timing kit. That was the job I feared most but it turned out to be quite simple compared to finding a solution to the nostart issue.

Good luck with your rebuild. Are you thinking about a writeup? If so, I may make an attempt on my old heads to have a spare set.

Thanks,

Podguy

I found a used valve grinder for about $100. Still need to negotiate with the guy a bit. I am waiting on a quote for the cutters. Only a 45 and I think a 60 degree are needed. I have the numbers. I have cut many seats by hand. It is a technique but the reality is to do less than more. I found a guy in England who makes a lapper that connects to a drill. It reverses direction. Neat idea. I always lapped valves. I know that is old fashion but I have found it gives the best seal.

One thing I read in the manual is to replace the valve chains if the timing belt breaks. I looked at the cam chains and cannot see anything wrong with them. Any one have experience with this?

Yes a write up would be part of the deal, but I preface that perhaps it should not be so detailed as to encourage someone with little experience to attempt the job. I have worked as a machinist and owned a machine shop rebuilding VW engines. That experience accounts for something. I do notice the tendency here on this list to replace rather than inspect. Often the manual can be excessively detailed when other times there are certain things that are a given just because the engine is together or things cannot be changed.

Thanks for the input.

GlenL

I don't find $1000 for a pair to be expensive because I don't have the desire to assemble the tools or rebuild the engine to fix my beginner's mistakes. Mostly the later. So nice to pick up shiny, "new" heads in plastic bags.

Rock on, Dan.

928mac

$1000 is a lot of money depending on how much you have to spend, but
doing a proper valve job is time consuming and is a key to how good it will run, compression etc.
Like Sean, I think I would spend the money if I trusted the shop.
I would take them out, inspect and lap them if I could get away with just that.
My $.02

Podguy

Glenn,

Remember I am not suggesting doing the heads yourself if you have no experience. Remember my shop rebuilt hundreds of VW engines with virtually no failures. I designed the production and engineered the procedures. At the time the competition was putting on new barrels and pistons. I decided to hone the barrels, bead blast the pistons, select fit the pistons to the barrels and put on new rings. Never had a burned piston. It is not a matter of guessing. It is having enough knowledge and experience to make judgement calls on what is good and what is bad. After all this is a science and not a religion.

With a valve job there is a wide range of things that can be done. If you have several sets of heads there is a good chance the valve guides will be good. In grinding the valves taking off the least amount of material is the key. A fine well lubricated stone can end up be more a polishing of the valve facess than grinding them. The grinder will insure you are not working with slightly bent valves.

Doing the seats again with the least amount of removal of material and it goes pretty fast. Then lapping is not a big deal either. it is not that you sit there for hours lapping one valve. There is not much to take off once the seats and valves are ground.

Valve guides add a bit of time to the job. First they need to be pressed out and new ones pressed in and then they need to be reemed until the valve stem fits correctly. Reeming is a bit of a pain and requires some patience but I am betting of the heads I have probably do not need guides. If there is a job to be left to a machine shop the first I would pick is installing new guides.

Mako 928

Dan,
Here is what I used along with the WSM. http://members.rennlist.com/bigdave/

I will call you later when my screwed up Comcast phone system is working.

danglerb

Dan, have you considered casting a wider net and finding a better shop, more 928 experience etc with a better price?

$500 each for a 32v head doesn't seem all that bad to me depending on the quality and reliability of the work, but shop around some more, maybe a better deal could be made that everybody could take advantage of (shipping heads isn't "that" painful).

Or maybe find all the tools, practice on some heads and hang out your internet shingle?

GlenL

Perhaps this didn't come across but I'm supporting you in what I see as an ambitious effort.

dr bob

My take is that the guides are the most likely failure item. When they wear, valves and seats also suffer. Big thing is that its impossible to cut the seats accurately or lap the valves successfully with worn guides. The spring tool is cheap. You have a dial indicator to measure guide and stem clearance. Replacing guides in Al heads usually involves heat and a press, too often gets a hammer and a drift instead. Dry-ice the new guides into a hot head and they almost fall in. The reamer is darn simple. It all just takes time, patience and care. And money for tools and parts. :-)

Podguy

Dr Bob,

Thanks for the advice. Of course the first order of business is to measure the valve guides.

You must be better with a reemer. I always found it to be a bit time consuming.

brianrheffron

This tool might help with the valve lapping process.
Fixed into an electric drill it rotates the valve slowly
while at the same time making multiple short clockwise
and counterclockwise movements.
I used one of these many years ago and was very
pleased with the ease of use and the results.

http://www.gunson.co.uk/item.aspx?item=1825