Calculating valve shims

thebaldyman

Member
Hi
I am in the process of rebuilding a spare engine I have and will be needing to adjust the valve gaps. I have read previous posts where people had tables to help work out what size shims are needed to alter the gaps to spec. Does anyone have a table they could send to me at all please? No doubt I'll be asking about getting hold of shims later lol...

Cheers. Jamie
 
Hi Jamie,

Try downloading this spreadsheet I made for doing mine. Valve clearances.xlsx

Measure and fill in the valve clearances you have already on the engine. Then, once you ever removed the camshaft measure the thick and thin shims for each valve and fill it in. So the light green fields in the table.

The adjustment value will automatically change for each valve and because you now know what shims you have you can try and sort the correct ones easily. Good luck, and remember, it's worth it at the end as the engine feels so much better afterwards.
 
That's excellent!! Just what I was looking for. I'll give it a go over the weekend and see how I get on, I'll let you know.

Cheers Jamie
 
When measuring the shims, remove the 2 shims, and then measure them together, in the way you pulled them off, in the center, where they are touching the tappet, and valve. Then use this value to calculate the new shimming. Measure your new shims in the same way. I suspect that they wear slightly where they touch the valve, and to a lesser extent on the tappet. Since I changed to measuring like this, I can get the shimming right the first time. The first time I shimmed valves, the cam was on and off three times. I can tell you that gets a little tiresome!
 
If the shim has worn because of being on the top of the valve just turn it over. I've not known shims wear down off the tappet.

For the OP:

I have a decent selection of shims, but the popular sizes are becoming difficult to get.
 
When measuring the shims, remove the 2 shims, and then measure them together, in the way you pulled them off, in the center, where they are touching the tappet, and valve. Then use this value to calculate the new shimming. Measure your new shims in the same way. I suspect that they wear slightly where they touch the valve, and to a lesser extent on the tappet. Since I changed to measuring like this, I can get the shimming right the first time. The first time I shimmed valves, the cam was on and off three times. I can tell you that gets a little tiresome!
Hi James

I've set this sheet up to automatically add the values of the two shims when measured separately. That way you can mix and match shims to get the correct values on the sheet before switching them on the engine.
 
Many thanks for the replies. Due to it being the school holidays I've been pretty busy but will be looking at carrying this out in the next few days... Beaulieu on Sunday may get in the way though! :)
 
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