Cylinder Head Rebuilding

[gnavs]

Alright so I'm nearing the re-assembly stage in my build and the more I think about the head the more nervous I become.  At the moment it's completely stripped, the pre-cups and valve guides are still there though.  I'm really thinking about bringing it to a shop to have spec'd and assembled mainly because this is my first rebuild and I'm not 100% confident in my abilities.  I don't want to spend the money to have someone else do it because this is the best way for me to learn, but at the same time I don't want to drop a valve.  I guess what I'm asking is, as a first timer is this something I can handle or would you spend the extra coin and trust it to a pro? 

[Turbinepowered]

If you took it apart, you should put it back together. Read your reassembly steps, read them again. Make sure you're familiar with the general flow of the procedure, then just take it slow.

[Vincent Waldon]

Yes, you can do it... at least, most of it!

There's two things I outsource to a machine shop:

- dressing the gasket surface... they have the right equipment to remove 1 or 2 thousand of an inch of material (assuming it's not warped in the first place) to make the head sealing surface perfectly flat.  I've tried glass-and-sandpaper lapping and have never been happy with the results.

- replacing the valve guides (if needed)... a particular set of tools and a good press are needed... for me easier to let someone else do it.


Lapping the seats, installing new seals, etc. are all within the range of the average dude... you'll need a valve spring compressor tool to get things apart (should be some details on building your own in the FAQ)

[Smokey Eddy]

this is my method of doing the keepers
All you need is a bench, any C clamp tall enough and a piece of alluminum pipe at least 4 inches long.
I used a seat post.
the pictures with the lever arms and wood and all that nonsense is irrelevant. Just place the tube with the cut out on the keeper retainer and clamp it down.

but it sounds like you already have a method for removing the valve keepers?
You need not be worried about dropping a valve if your valves aren't cracked or weakened anywhere or have any reason for concern (like they came into contact with the pistons).
Im not too sure how to pull the old valve stem seals off though. mine are being a pain to get off... when you do the new ones protect the rubber lip from the sharp grooves in the valve stem.

[gnavs]

I just got to the point where I started realizing the severity of what I'm doing and got a bit nervous, but I've got some confidence now after reading this.  I've got everything labelled and have good memory of how things go back together, so I should be alright (in theory). 
Vince, I feel the same way about the guides so I'll probably have new ones pressed in by a machine shop, I found a good one here in Calgary that are machining my crank for undersized bearings as we speak.  I'll probably look into dressing the gasket surface as well.  My valve guides are still installed and was wondering about reusing them as well, is there a wear limit for them?
Eddy, I didn't see any piston/valve contact marks at all so I'll assume the valves are intact and ready to be reused.  I ended up just cutting the old stem seals off before really thinking about what I was doing.  Do the seals come with new guides or is it a separate part?

Thanks for the encouragement, once things are back together I'll post some pics.

[Vincent Waldon]

Yup, the Bentley has a listed wear limit for "wobble"... you extend the valve a certain amount and then measure side-to-side with your dial indicator.

[gnavs]

Good stuff, I'll have a look through it tonight.  Is it in the cylinder head reconditioning section?

[Vincent Waldon]

I think so... there's a picture of the head on its side with a dial-gauge attached... kinda like this:

http://www.oneilcastro.com/A2Bentley/GE01/ch4.9.6.html

[fatmobile]

I used my drill press to press the springs down and pull the head apart,
 used a pipe much like Smokey Eddy.

But the slot in the side of mine wasn't big enough to put the keepers back on and I haven't made the seal removal tool yet so I took it to a shop to check out and put back together.

[rodpaslow]

Most places call it a spark plug removal tool - works good for removing the seals off the valve guides.  http://www.cylinderheadsupply.com/valve-seat-tools.html?gclid=CLqD78n9oqICFaJL5wodpn-rxg - cylinder head supply is where I got it from as well as a reamer for doing my own guides as I have a press.

[gnavs]

I ended up getting the big spring compressor from Princess Auto (I'm loviong that place more and more) and it works fine, definitely glad it's only an 8V though, wouldn't want to be doing this on a 1.8T 

[Vincent Waldon]

Princess Auto (I'm loviong that place more and more)

Yuppers... they have the valve lapping tool and compound as well, should you be so inclined.  ;-)

[gnavs]

Is there a special tool necessary for lapping valves?  A quick googling mentioned lapping it against the head using a small suction cup or a piece of hose attached to the valve stem.

[rs899]

I have this kind of dowel with two suction cups sticking out at either end.  I have always wondered if , with enough persistence and care, one can do a reasonable job manually lapping valves, or is this something one needs to let a machine shop scr... handle?

[Smokey Eddy]

Eddy, I didn't see any piston/valve contact marks at all so I'll assume the valves are intact and ready to be reused.  I ended up just cutting the old stem seals off before really thinking about what I was doing.  Do the seals come with new guides or is it a separate part?

Thanks for the encouragement, once things are back together I'll post some pics.

You dont need new guides unless yours are damaged in some way. but if the valves are fine chances are the guides dont need to be removed. You can buy stem seals seperately almost everywhere.

I have this kind of dowel with two suction cups sticking out at either end.  I have always wondered if , with enough persistence and care, one can do a reasonable job manually lapping valves, or is this something one needs to let a machine shop scr... handle?

I bought one specifically for lapping valves which was a dowel with suction cupsbut a hose on a drill bit with the valve jammed in the other end of the hose works so much better.