Shimming the rocker arms without the spring washer?

Hello,

I am just working on my cylinder head. An exhaust valve guide is damaged and I have to renew it......


Here is my question: is it wise to shim the rocker arms without the spring washer [NM18103]?

Does it affect anything when I put the rocker arms in place without the spring washer?

chris

A local (to me) race bike builder does them that way, supposedly less friction than with the springs if the shims are machined carefully.
Not that it would make any noticeable performance difference on the road i suppose.
I presume the shim clearance would increase slightly as the engine heated up but it is hard to imagine that would be enough to cause any problems.
iain

IMO, do what ever it takes to have the rocker smash the valve stem as central as can be allowed.. Meaning "spring washer", shims or nothing etc whatever it takes!!!!

Dont forget these heads were cast 40+ yrs ago.. QA/QC ?????????

Thanks for the replies......thats what i wanted to know. cause my rocker doesn`t hit
the valve central with the spring in place.

ad olChris: what means QA/QC? me no english native speaker....

Chris Zet said:

Thanks for the replies......thats what i wanted to know. cause my rocker doesn`t hit
the valve central with the spring in place.

ad olChris: what means QA/QC? me no english native speaker....

Click to expand...

Quality Assurance and Quality Control.. ISO 9000 ??? (i think) if i remember correctly.. "international standard" for quality of products manufactured>... been a while ..

olChris said:

IMO, do what ever it takes to have the rocker smash the valve stem as central as can be allowed.. Meaning "spring washer", shims or nothing etc whatever it takes!!!!

Dont forget these heads were cast 40+ yrs ago.. QA/QC ?????????

Click to expand...

I have had issues with washers and shims ,as in the amount used on certain rockers seems excessive , I am going to try these instead of the spring washer on my next job, don't know if anyone uses them or not.

auldblue said:

olChris said:

IMO, do what ever it takes to have the rocker smash the valve stem as central as can be allowed.. Meaning "spring washer", shims or nothing etc whatever it takes!!!!

Dont forget these heads were cast 40+ yrs ago.. QA/QC ?????????

Click to expand...

I have had issues with washers and shims ,as in the amount used on certain rockers seems excessive , I am going to try these instead of the spring washer on my next job, don't know if anyone uses them or not.

Click to expand...

No way :shock: :shock: :shock: dont use them brass/copper/bronze shims they will wear down real quick... IMO must use H Tensile steel shims.. Wether it be spring washers or flat washers or shims.. But must be High tensile for longevity..

What you got will work if correct thickness, but if rocker or valve are "domed" and creates a tendency to push rocker either way it will either wear bronze shim or alloy head... Must, Must be HT Steel shimmed each side of rocker to wear on THEN alloys if required

No way :shock: :shock: :shock: dont use them brass/copper/bronze shims they will wear down real quick... IMO must use H Tensile steel shims.. Wether it be spring washers or flat washers or shims.. But must be High tensile for longevity..

What you got will work if correct thickness, but if rocker or valve are "domed" and creates a tendency to push rocker either way it will either wear bronze shim or alloy head... Must, Must be HT Steel shimmed each side of rocker to wear on THEN alloys if required[/quote]

Cheers for that olChris, that's the second time you've pissed on my chips( French fries) might just use them as ear rings then.

Humbled from Huddersfield

I think I was just being lazy or maybe they are for racers , but the shims can be a right pain at times.

If like stated that a slightly domed valve will shift the rocker sideways and cause it to wear, wouldn't this be worse with the spring loaded thackray washers, they're either staying still whilst the rocker is turning and wearing/notching into the rocker, till such time that they then start turning with the rocker and would grind away at the head alloy in short order!
I used solid bronze thrust washers and shimmed them to zero cold as per Ludwigs advice on this forum somewhere, make sure the rockers move up and down without any tight spot, I lapped the washers on a diamond oil stone to get them spot on. I used bronze as L.A.B. has stated on the britbike forum, quote:-I would agree with what Dennis B has said, as it is sometimes necessary to shim the rocker over slightly, and I have done this myself, although I use the solid bronze rocker spindle thrust spacers in place of the spring washers. 9/26/06.
I'll test for wear next winter but I'm not convinced I've given myself a problem, I hope not anyway!!

I build stroker VW engines for a hobby and the stock rocker shafts had the same setup as the Norton rockers. They both use a spring washer.
Now we use solid shafts with shims to locate and give the rockers 0.005" side play but in order for them to work there has to be at least 2 shims per side to act as a bearing, 3 would be perfect and they have to be hardened and smooth.
The thickness of the spring you'll take out allows enough room to put in thick shims on each side.
Plus it will help quiet the rocker noise because there is no side to side movement like the spring type, just 0.005" side play.
Works best with clean Valve stems or lash caps.

John Hudson, factory troubleshooter and more once known as Mr Norton, said in his 1970s tuning notes that the rotational resistance of the Thackeray Washer was inconsequential compared to the compression resistance of the valve spring....he said stick with them instead of messing with shims...he convinced me...

I used the then and I am fitting them now. You guys mess as much as you want.

auldblue said:

I have had issues with washers and shims ,as in the amount used on certain rockers seems excessive , I am going to try these instead of the spring washer on my next job, don't know if anyone uses them or not.

Click to expand...

I haven't honestly noticed any high rate of wear of the bronze (not brass or copper :shock: ) thrust washers (fitted by a PO) as described by olChris, (although I don't regard myself as being a 'high-mileage' Commando rider) but a placing a hardened steel shim each side of the rocker probably is worthwhile.

Hi Chris!
I have made my own shims in alu bronze and used them without any problem.
Like you I wanted to centralize the rocker on the valve and get rid of friction from the spring washer.

Sten

Hi

Same. I havn't used thackery spring washers for 30 years. Not since one cut its own channel in the rocker box of my 8 valve! & yes it did have a shim between it & the alloy. Ive run bronze spacers in everything & not replaced a set do far.

Chris

Often the wrong types or grades of metal can be used by the man in his shed with his little lathe or even companies with larger set ups. This may account of the parts wearing quickly in many cases.

The advice I got from Mick Hemmings when getting my big valve head was that for the road the standard arrangement is fine but extra shims my be needed to get the rocker over the valve correctly. Spacers are only of benefit to race motors holding high revs for long periods of time and with high lift cams all of which place higher loads on the valve train thus solid location of rocker may help keep it in alignment over the valve.