View Full Version : Cylinder head machine, valve job & CC

04-23-2008, 06:57 PM
I picked up the block today, plus a card with 100 pictures of the engine rebuilding in progress. It should be running next week.

Some of the head work below:

04-23-2008, 07:52 PM
Looks like your shop is doing an excellent job.

04-23-2008, 08:13 PM
Tell us about the valve stem seals. please

Did they machine the guides, or find seals that fit without machining. What seals are they?

04-23-2008, 08:25 PM

The guides were machined and these are NOT Teflon seals. Bob won't use them anymore. Remember TR6 Bill noting that his were bad? Bob said that he sees them fail constantly.

Bob uses these on the racing engines that he builds and they are made for all standard size valves, but custom sizes are readily available. I'll have to find out what material they are. It looks like a spring on there, around the blue seal.

04-23-2008, 08:32 PM
I've got my new BPNW camshaft, new lifters (with the oil drain hole) and shorter pushrods so I'm set to do my engine shortly.
I plan to machine the head to raise compression also; how much did you have taken off yours and what does that push the CR to?

04-23-2008, 08:42 PM

If you follow this chart, you can be right on the money, but the key is allowing for zero deck height, which I have because of all of the work to the block.

You can measure your piston top travel and you will probably be very close, in stock form. I had 0.007" removed from the block and that's got the pistons about 0.0005" above the deck.

My head is machined at the 3.421" mark, which puts me right in between the 9.41 and 9.67, probably at 9.55.

I give you this chart as a reference because you don't know what's ever been taken off of the head before you got it, so it will get you where you need to be.

Which cam did you get? I got the new TH5, which Greg highly recommended based on what I was doing and my driving habits.


04-23-2008, 09:33 PM
Thanks for the info Paul....
I got the TH5 also, though BPNW reccomended only 80 thou removal from the head.
Just have to find a good machine shop now.
The yellow pages lists about 35 in my city.

Just curious, but at what amount of machining does valve/piston contact occur; or is there lots of room?

04-23-2008, 11:00 PM
Paul: Will you measure your head top down to bottom?
I'm curious to know how it compares to mine.

04-24-2008, 06:47 AM
The amount of machining cut of the head is a good reference but the only way to really tell the compression ratio is to cc the combustion chamber. One of Paul's pictures shows the procedure. It is the last picture of his first post. The head is positioned with the head surface leveled and up and with a clear plastic plate sealing the No. 1 combustion chamber. Notice the spark plug and valves in place to seal the chamber. A liquid is poured through a hole in the plastic and measured as it fills the combustion chamber. The amount of liquid used to fill it, measured in cc's, is the the size of your combustion chamber. My combustion chambers measure 44 cc's which puts me at about 9.98 combustion ratio. There is an equation used to figure that but you must know the deck height, the head gasket thickness (compressed), and the bore and stroke of the motor. You plug those variables into the equation and out comes the combustion ratio. WALA.

The thing I like about the photos is how clean the shop is. There are no shavings on the machines, no clutter on the bench and the floor is clean. Boy, that tells it all.

04-24-2008, 07:16 AM
Cleanliness=professionalism. That is one of the FIRST things I look for when going into a shop. ANY shop.

04-24-2008, 05:25 PM
There is a vacuum system attached to each machine that evacuates chips/powder from the landing areas after cutting. As the Doc says, excess chips cause issues and being a true professional shop, these are not permitted to affect any of his work.

When you build the kind of racing engines that he does, there is no room for error.

I believe that my chambers are matched at 45.5cc's across the board.

I'm having a bit of a problem understanding the .080" removal recommendation from BPNW. Did you speak to Greg about that? I told him that my head would ultimately end up with about .120" removed and he said it would be no problem. How else could I get to 9.5 to 1 without doing that and that was what I gave him for my desired CR when we discussed the best cam for the car to get it as close to 150HP as possible, yet street drivable.