[cdtscout]

I'm looking for some advice on replacing my 968’s cylinder head in my garage. I have a refurbished, decked and checked cylinder head that I would like to install on my 968 in my garage/workshop while doing a complete front end reseal/water pump/belt(s) /roller service….I have all the tools/parts for the reseal/belt job including the Anworx kit. I have done a lot of work on my 968…most recently RMS/flywheel/clutch….but I have never swapped out a cylinder head.

To the point, I have read all the available reference material and very informational message boards on this topic and based on some of the more technical information about pressurizing the variocam and some other timing issues….is this a DIY….or should I leave this one to the pro’s? I need some practical advice/tips. Thanks in advance for taking a moment to respond.

Partial Post: Please Login or Register to read the full post.

[Dave]

I DID NOT do the work myself, but do recall that when I had the head done (headgasket time)... there was some secret-squirrel Porsche tool that my shop acquired to work with the vario-cam and timing testing/set-up.



Hopefully someone with first-hand knowledge will jump in to take the mystery out of it.

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='Dave' post='35446' date='May 12 2007, 07:02 PM']I DID NOT do the work myself, but do recall that when I had the head done (headgasket time)... there was some secret-squirrel Porsche tool that my shop acquired to work with the vario-cam and timing testing/set-up.



Hopefully someone with first-hand knowledge will jump in to take the mystery out of it.[/quote]



Thanks for the reply... I have not had the best of luck having others work on my 968 and I really do enjoy doing the wrenching myself. I do hope someone responds with some practical advice... maybe I went too far with the whole wisdom comment...

Craig

Partial Post: Please Login or Register to read the full post.

[Dave]

No, you just have to wait for someone smarter than me to catch up to this post. I'm sure there is a wizard on vario-cam timing here somewhere.

Partial Post: Please Login or Register to read the full post.

[mefforddk]

[quote name='cdtscout' post='35422' date='May 12 2007, 06:39 AM']I'm looking for some advice on replacing my 968’s cylinder head in my garage. I have a refurbished, decked and checked cylinder head that I would like to install on my 968 in my garage/workshop while doing a complete front end reseal/water pump/belt(s) /roller service….I have all the tools/parts for the reseal/belt job including the Anworx kit. I have done a lot of work on my 968…most recently RMS/flywheel/clutch….but I have never swapped out a cylinder head.

To the point, I have read all the available reference material and very informational message boards on this topic and based on some of the more technical information about pressurizing the variocam and some other timing issues….is this a DIY….or should I leave this one to the pro’s? I need some practical advice/tips. Thanks in advance for taking a moment to respond.[/quote]



I pulled my head due to a bad head gasket and had the head reworked including new valve springs. I then pulled the front end and replaced the rod bearings and piston rings as well. I used the shop aid that you can cut out of the manual to align my cams. Fired right up. Getting the cams in/out can be tricky with the variocam unit. But the key is to take your time and not move forward until your sure that the timing is right. Just my experience.

Partial Post: Please Login or Register to read the full post.

[968workaholic]

[quote name='cdtscout' post='35447' date='May 12 2007, 08:18 PM']Thanks for the reply... I have not had the best of luck having others work on my 968 and I really do enjoy doing the wrenching myself. I do hope someone responds with some practical advice... maybe I went too far with the whole wisdom comment...

Craig[/quote]





Craig, i wouldnt recommend doing the head yourself other that for the reason of timing the cams. Before you can put the cams in to time them they have to be in the right position on the variocam assembly. You are right about pressurizing the variocam assembly in order to time it. For that you would need a special tool. Even when it is all setup, getting the cam to the right specs is time consuming and takes patience. My advice is to do the rest of the front end yourself, but leave the cam timing to someone who has the experience and tools to do it.

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='968workaholic' post='35536' date='May 15 2007, 06:43 PM']Craig, i wouldnt recommend doing the head yourself other that for the reason of timing the cams. Before you can put the cams in to time them they have to be in the right position on the variocam assembly. You are right about pressurizing the variocam assembly in order to time it. For that you would need a special tool. Even when it is all setup, getting the cam to the right specs is time consuming and takes patience. My advice is to do the rest of the front end yourself, but leave the cam timing to someone who has the experience and tools to do it.[/quote]



Really appreciate your reply...as much as I would like to be involved in this process for learning purposes...your approach sounds like the right thing to do. Again, thank you.

Craig

Partial Post: Please Login or Register to read the full post.

[flash]

putting a head together is a tedious job, requiring patience and precision - valve matching is critical to optimum performance, as is cam timing



the latter is no simple task, requiring special tools and close precision



i would contact pete at rs barn

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='flash' post='35539' date='May 15 2007, 07:22 PM']putting a head together is a tedious job, requiring patience and precision - valve matching is critical to optimum performance, as is cam timing



the latter is no simple task, requiring special tools and close precision



i would contact pete at rs barn[/quote]

Thanks for the reply, the cylinder head will be all assembled by the performance machine shop ....just not installed...but, still looks like a job for someone with the right tools for the task. I will look for someone in the Boston area... Thanks for the response.

Craig

Partial Post: Please Login or Register to read the full post.

[FRporscheman]

It's not that hard if you take your time, and take lots of photos. I did the chain and pads on my car's variocam and that was my first time taking the dohc stuff apart, and the car started on the first try.



Now I'm doing my mom's 968's head gasket and I already have the head off.



Taking out the cams, you need not compress the tensioner. I think the same goes for putting it in. You only need to compress it when reinserting it into the chain. To compress it, I used a large simple vise. To time the cams, I just made marks at TDC before taking them out and then lined up the marks again. Easy peasy. But if you're still doubtful, just take it to someone. Better safe than sorry.

Partial Post: Please Login or Register to read the full post.

[rustech]

I've also done it. I locked the cam pully and backing place together w/ 3 10mm bolts and marked inside the pulley cutouts with black marker (just in case) to preserve the timing, then took it off. The timing changes based on belt stretch etc, so if anything, the timing should be more precise once the job is completed with new belts. The job is long (esp if you do everything including water pump, front seals, etc) but is not extremely difficult if you have a creative mechanical nature. Good luck with whatever you decide to do.

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='rustech' post='35889' date='May 23 2007, 05:43 PM']I've also done it. I locked the cam pully and backing place together w/ 3 10mm bolts and marked inside the pulley cutouts with black marker (just in case) to preserve the timing, then took it off. The timing changes based on belt stretch etc, so if anything, the timing should be more precise once the job is completed with new belts. The job is long (esp if you do everything including water pump, front seals, etc) but is not extremely difficult if you have a creative mechanical nature. Good luck with whatever you decide to do.[/quote]



Rustech,

1st thanks for the reply....appreciate it!

My situation is slightly different since I am replacing the old head...with a newly reworked head....so, I will not be able to establish any baseline timing marks to work from. At least, that is what I belive to be my core dilema... doing this work myself.

Craig

Partial Post: Please Login or Register to read the full post.

[flash]

if you are reworking the head, cam timing is going to be very critical if you want all of the power



i would put it together, and then trailer it to a shop that knows how to do that, and has the tools

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='cdtscout' post='35891' date='May 23 2007, 07:53 PM']Rustech,

1st thanks for the reply....appreciate it!

My situation is slightly different since I am replacing the old head...with a newly reworked head....so, I will not be able to establish any baseline timing marks to work from. At least, that is what I belive to be my core dilema... doing this work myself.

Craig[/quote]



Flash,

Thanks.... that is indeed what I plan on doing.

Craig



Anyone have a recommendation in the Boston area for this work...and/or any idea of the cost.

Partial Post: Please Login or Register to read the full post.

[Mark]

No idea how far Mansfield is from Boston



http://www.jmengines.com/index.htm

Partial Post: Please Login or Register to read the full post.

[rustech]

Craig,



Timing of the motor is as follows (skiping non-timing steps):



Each of the cams has one marked tooth which have to be positioned IIRC 7 chain links apart (the links are marked as well) and then the variocam assembly slides in between. The entire assembly is then placed into the head. The timing of the intake cam is automatically determined by the variocam chain and tensioner. "Which head" new or old, first or second, has no effect on timing.



Next, the backing plate and sprocket are installed. The tick mark on the camshaft sprocket should be aligned to the tick mark on the back of the belt housing if that's the way you removed them. (other positions might offer less valve pressure on the cams)



The crank should still be locked at TDC (top dead center of piston #1). Then the belt is installed and hydraulic tensioner released. Now, all of the fine adjustment to gain maximum performance out of the vehicle is done between the cam sprocket and backing plate (exhaust cam position vs sprocket position). The head has nothing to do with timing.



Even Bob's (Flash) cams were off 5 deg (almost sounds like one tooth of the belt) and on his second set of belts. It isn't quite as critical as some will have you believe. You could always do 95% of the job, and then drive it down to someone with the proper tools to do the last 5% of timing. I believe only the ignition cap and rotor has to be removed plus a few other steps to get it perfectly timed.



I'm not trying to convince you one way or the other. Honestly, it sounds as though you don't really have an interest in attempting it, I'm just trying to give you the proper picture. Hope it helps.

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='rustech' post='35911' date='May 24 2007, 12:59 AM']Craig,



Timing of the motor is as follows (skiping non-timing steps):



Each of the cams has one marked tooth which have to be positioned IIRC 7 chain links apart (the links are marked as well) and then the variocam assembly slides in between. The entire assembly is then placed into the head. The timing of the intake cam is automatically determined by the variocam chain and tensioner. "Which head" new or old, first or second, has no effect on timing.



Next, the backing plate and sprocket are installed. The tick mark on the camshaft sprocket should be aligned to the tick mark on the back of the belt housing if that's the way you removed them. (other positions might offer less valve pressure on the cams)



The crank should still be locked at TDC (top dead center of piston #1). Then the belt is installed and hydraulic tensioner released. Now, all of the fine adjustment to gain maximum performance out of the vehicle is done between the cam sprocket and backing plate (exhaust cam position vs sprocket position). The head has nothing to do with timing.



Even Bob's (Flash) cams were off 5 deg (almost sounds like one tooth of the belt) and on his second set of belts. It isn't quite as critical as some will have you believe. You could always do 95% of the job, and then drive it down to someone with the proper tools to do the last 5% of timing. I believe only the ignition cap and rotor has to be removed plus a few other steps to get it perfectly timed.



I'm not trying to convince you one way or the other. Honestly, it sounds as though you don't really have an interest in attempting it, I'm just trying to give you the proper picture. Hope it helps.[/quote]



Rustech,

Thank you for taking the time to explain this process in practical terms and reducing the ever present free-floating anxiety around this process. My cylinder head should be back from the machine shop next week... in the meantime I plan on learning as much as I can.

Craig

Partial Post: Please Login or Register to read the full post.

[flash]

actually, to time the cams, the valve cover has to come back off too - this is why i recommend NOT firing it up, and instead trailering it or towing over - the hour plus of labor to R&R the valve cover, reset to zero, clean up the oil that has now gone everywhere in the engine, etc, will outweigh the tow cost, and complicate the mechanic's job



how far is boston from pete's? - he is happy to run you back and forth to the train station - he does that all the time for people who tow their cars to him

Partial Post: Please Login or Register to read the full post.

[cdtscout]

[quote name='flash' post='35920' date='May 24 2007, 09:04 AM']actually, to time the cams, the valve cover has to come back off too - this is why i recommend NOT firing it up, and instead trailering it or towing over - the hour plus of labor to R&R the valve cover, reset to zero, clean up the oil that has now gone everywhere in the engine, etc, will outweigh the tow cost, and complicate the mechanic's job



how far is boston from pete's? - he is happy to run you back and forth to the train station - he does that all the time for people who tow their cars to him[/quote]



Flash,

Thank you again for taking the time to respond....Pete is quite a distance from the Boston area...325 miles...now that would be a significant towing fee!

Craig

Partial Post: Please Login or Register to read the full post.

[flash]

hmmm - yeah - that's a bummer for sure - give him a call though - he might be able to recommend somebody close to you



i've watched this process, and been to a LOT of shops - so far, he is the first to actually even do the job, let alone have what is needed to do it - most just put it together, roll the cam, and lock it down - getting the exact setting, with the valve open just the right amount, at exactly the place it is supposed to be, does not happen on the first try



it's very much like hitting a baseball - you can hit it, and get on base, or you can nail it square and put it out of the park

Partial Post: Please Login or Register to read the full post.