2manycrashes
12-16-2004, 08:09 PM
Ok guys,
I will try to explain this one the best that I can. I am new to motor work and have a friend that is showing me how to re-build the engine.
I am installing a new piston. I had the head ported and polished. I believe they also did a 3 angle valve grind. Anyways, here is the scenario.
The problem or question deals with the exhaust shims. The prior exhaust shims were 2.18 (218) shims. After installing the cam and torqueing it to spec, the following issue arose. The required shim is now 3mm, per the honda service manual, that is the highest allowed shim without refacing the valve seat.
Keep in mind that the Intake Valves are perfect with the old shims.
Honda has looked at the head, dis-assembled the exhaust side, said everything looks perfect, but is unable to tell us why there was such a drastic change in the size of the required shim for the exhaust side.
The 3mm shim will put the clearance at exactly .28 mm per the service manual on page 4-11. This was measured by 3 different people at honda and so far no one can give an explanation as to why this is happening.
I've been told it will work okay this way, but honestly I am not 100% comfortable with what appears to be a drastic change in machine tolerances.
Let me know if I can provide more info, once again I really appreciate the help !!!!!!!!!!!!!!!!!!!!!!!!!!
I will try to explain this one the best that I can. I am new to motor work and have a friend that is showing me how to re-build the engine.
I am installing a new piston. I had the head ported and polished. I believe they also did a 3 angle valve grind. Anyways, here is the scenario.
The problem or question deals with the exhaust shims. The prior exhaust shims were 2.18 (218) shims. After installing the cam and torqueing it to spec, the following issue arose. The required shim is now 3mm, per the honda service manual, that is the highest allowed shim without refacing the valve seat.
Keep in mind that the Intake Valves are perfect with the old shims.
Honda has looked at the head, dis-assembled the exhaust side, said everything looks perfect, but is unable to tell us why there was such a drastic change in the size of the required shim for the exhaust side.
The 3mm shim will put the clearance at exactly .28 mm per the service manual on page 4-11. This was measured by 3 different people at honda and so far no one can give an explanation as to why this is happening.
I've been told it will work okay this way, but honestly I am not 100% comfortable with what appears to be a drastic change in machine tolerances.
Let me know if I can provide more info, once again I really appreciate the help !!!!!!!!!!!!!!!!!!!!!!!!!!