Who needs cam cores?

Hello all. Just finally getting around to my 6.9 build ( yes this is #4 but who's counting? ). Just yanked the cam today to install my typ4 cam so I have this one as a core and also the one from the doomed 87 6.9. I certainly don't want to scrap them but I don't want them sitting around forever Perhaps someone wants a typ4 cam but doesn't want to wait to yank theirs or pay a up front core? Let me know.

OI82

Its always nice seeing members paying it back to others. My thanks to you for doing this.

Check clearances on that cam while installing it , also you MUST use comp 910 springs shimmed to correct height.

What is the proper way to go about doing that? Can I handle this or should I go back to the machine shop? Can this be done on the work bench heads alone, or do the heads have to be on the engine? I have two spring compressors, the little hand held crank 'em up guy and the monstrous clamp type. I also have a basic feeler gauge and a cheap micrometer. Can you tell me EXACT part numbers for the springs and the shims?

I knew about none of this. I'm sure you saved me from a very bad engine death. Tell me what to do and I'll do it. Only doing this once.

Thank you!

I'm looking for a core.

PM me we can work out the details

To the Moderators: I just discovered the Virtual Boneyard. I didn't know of it's existence. I will not post subjects of this matter in this forum anymore...

OldIron82 said:

What is the proper way to go about doing that? Can I handle this or should I go back to the machine shop? Can this be done on the work bench heads alone, or do the heads have to be on the engine? I have two spring compressors, the little hand held crank 'em up guy and the monstrous clamp type. I also have a basic feeler gauge and a cheap micrometer. Can you tell me EXACT part numbers for the springs and the shims?

I knew about none of this. I'm sure you saved me from a very bad engine death. Tell me what to do and I'll do it. Only doing this once.

Thank you!

Click to expand...

Ill dig up some shim numbers and get back to you, work is busy. The springs are comp cams 910. summit or jegs, and your c clamp compressor will be fine.

Ok I'll order the springs tonight!

I feel its important to note our engines are different from most others when it comes to valves and springs. Even though the intake valve is larger and heavier it uses the same spring as the exhaust valve. Many high performance engines have very differant springs on the intake and exhaust because the intakes are usually so very much larger and heavier.. Our valves MUST be sunk in the heads at specific amount or the risk contacting the pistons. Our pistons come up out of the cylinder bore as much as 31 thousands. Our heads are flat. The only reason our pistons and heads don't make contact is the thickness of the head gasket. In the end the volume of the full 4.110 bore and stroke is squished into an area about 42 thousands deep. that is the estimate of the separation from piston to head. This also is the reason for compression ignition. Compressing all that air into that small area as fast as it is done creates great amounts of heat. compressing air scientifically will create heat. diesel requires 940 degrees for ignition too. So we must make at least that much cranking heat to fire off our engines. Russ aka typ4 was looking into the valves. He was attempting to determine if the piston chases the valves or the valves are chasing the pistons. I don't know if this was ever determined or not. sure is interesting.

So, I just want to chime in that valve recession is /IMPORTANT/.
The correct specs are:
Intake: .042-.054"
Exhaust: .051-.063"

I would err on the high side if at all possible; a few thou of extra clearance is a /lot/ better than not enough.

Remember that if you end up a few thou shy, you won't know it immediately - the engine is loud enough, and the lifters will end up compensating.

10-20K down the road, however... you'll wonder why you are hearing a slight tick/chuff noise, and find your valve guide totally gone and a nice impression in the piston.

Yeah... Not fun. The good news is you probably won't bend/snap a valve off like in other engines, simply due to the valve being square to the piston.

Ok I'm confused. ( shocking ) Wouldn't valve recession be achieved by how deep you cut the seats? Deeper cut seats would equal the higher the valve goes into the head no? How do shims have anything to do with that?

A shim is used to adjust spring pressure.. nothing more. It will raise the spring to create more open or closed pressure on the valve. Only sinking the valves in the seats will raise a valve.

I have my rebuilt heads, but they do not have the 920 valve springs installed.

The valves were recessed appropriately in the head, so I guess I need to check the valve stem height and install the 920 springs. Never having done this before, I would love to see a tutorial on installing the valve springs, setting the shim height and spring pressure.....