Triumph Universal Valve Shim Calculator Tool

[Triumph] Valve Shim Calculator Tool

Version 2013

(shhhh..... it's really a "Universal Valve Shim Calculator" tool)

To jump to the Current Version (see disclaimer and link at bottom of page)

Best viewed on a full size (desktop or laptop) screen, at least 1366 x 768.

Not recommended for mobiles or tablets.


Youtube demo

(Having found this page)  you likely already know what valve clearances are. You may already have been warned of the dubious joys of calculating what size shim to install, in order to correct out-of-spec clearances.

The math is REALLY simple. Pluses and minuses. Loose clearance requires a thicker shim to fix (and vice versa)

Q: What's worse than doing it up to SIXTEEN TIMES?

 A: Doing it another sixteen times, when trying a different target clearance.

This web-based tool (most browsers and devices support Javascript) will auto-calculate a shim to fit based on:-

  • current clearances
  • installed shims
  • target clearance

This is the only tool of its type that I'm aware of to comprehensively deal with the process, right through to saving the service record and re-use for next time. As a bonus it's also entirely web based. There are a plethora of excel-based tools, with only basic functionality.

You may set a shim "strategy" for inlets and exhaust shims (eg. "tight", "midrange" or "loose"). The tool will provide a shim to match that profile.

You can also specify the shim increments range. Your supplier may only provide shims in 0.05mm increments. Or choose an alternate supplier with 0.025mm.

Each valve shim can also be manually specified instead.

Immediate notification as to whether a shim will be over-, under- or in-spec.

Just follow the numbered steps and print off your new shim sizes (plus old sizes and clearances) for a complete record.

Also generated is a shim table so you know what quantities of each size shim to order (that you don't already have installed or in the tool box).

Or save the URL (email it to yourself) for next time. You won't need to re-type all the measurements in again.

Latest News -

29 March - New features...

  • SAVE current shim/clearances/data values as a single URL (or as a condensed "tinyurl").
  • TRANSFER the calculated/fitted shims from the saved URL into the MEASUREMENTS page.
  • Load Sample shims and clearances (default now is blank values).

19 March  - Now supports FOURS as well as TWINS and TRIPLES.

15 March -

Major formula breakthrough, enabling full web-version functionality.

Order Sheet now works for web version. Now functions same as Excel version.

  • Lists what qty and size of shims to order
  • lists spare/leftover shims (to swap out)  
  • accounts for spare shims already in your toolbox
13 March 2013 / 13-3-13
An appropriate date for the Triple version to go live!


My original Triumph (3 cylinder) Valve Shim Calculator (Excel version only) was launched in January 2003 and still resides on the Triumph Torque website (formerly 

Screenshot - 2003 Excel version

This latest (evolutionary) version is now totally web-based. No need to install Excel, download files etc.

Superseded graphic/version

The layout is significantly improved. Needless to say, a web version also greatly improves accessibility.

It works on a range of browsers and devices; Firefox/IE8+/Chrome/Safari, iPad, android tablets, PC's, mobiles.

Features include:

  • automatic shim selection to fit a desired shim "strategy"
  • manual override of all valves (with auto-recalculation of estimated clearance).
  • Tabbed menu, easy to switch between the current measurements to the calculations page
  • Selection of shim size increments ranges (eg. 0.025mm (OEM), 0.02mm and 0.05mm coarse)
  • Print out each page
  • SAVE a web link of YOUR SETTINGS AND MEASUREMENTS for next time. With one click, transfer the shims installed at the last service straight into the MEASUREMENTS page, ready to take new measurements.
  • (pending) email your records to yourself

Is it overkill for something you may use only once every couple of years?

Well, hopefully it frees up some thought space for the task at hand.

It's also useful to try on some what-if scenarios with switching shims, or seeing whether you can get by on shims already in the toolbox. 

Scroll down to bottom and select the Calculator button after reading the Disclaimer.

Other Projects

If you have a need for developing a similar (commercial or otherwise) project, requiring the functionality of a spreadsheet provided via a web interface, please contact me to discuss. I have developed various solutions including registration forms (e-commerce payment gateway integration), online estimator/calculators and checklist/reporting solutions.

The only requisite for the client-side is a javascript-enabled browser.



Ant (Triumph Rats) for initial layout and test bed (Bonneville T100). Yeah, that '04 spreadsheet  layout has bugged me for ages too!

The Grovel Bit

This is where I grovel for spare dosh so I can get a sulking Triumph back on the road and pay some bills.

If you think this tool took some of the headache out of keeping track of all the shims, clearances and what size to put in, consider the hours I should have spent down in the potting shed with the Triple, instead of finessing Excel formulae :-)
Thanks and trust you find this useful! Scroll to bottom for a link to the web version.


Copyright AGBUZZ (2003-2013)


This Valve Clearance Shim Calculator (the "tool") should be used as a guide only.

No guarantees or warranties are provided as to the suitability of this tool to your situation.

You are strongly advised to refer to service documentation, detailing the correct procedures and specifications, for undertaking any aspect of engine service covered by this tool.

In particular, satisfy yourself that the estimated shim sizes required are as recommended by your service manual.

Nothing presented in this tool should be considered as professional advice, including the target clearances, recommended shims or the use of non-OEM shims.

OK- take me to the Calculator

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