# 1985 BMW 1 Series - Shim debate **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** bmw\ **Created:** [July 16, 2020, 6:20pm UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424 "2020-07-16T18:20:42Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Dennis40](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@Dennis40](https://community.cartalk.com/u/Dennis40)\ **Post date:** [July 16, 2020, 6:20pm UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/1 "2020-07-16T18:20:42Z")
I recently had the head re-worked on my ’85 BMW K100 (4 Cyl. /8Valve). The valve clearance is set via shims, which I have to have order from the dealer. So when I was resetting the valve clearance I had to estimate the shims I would need. All said and done most of the valves came out slightly on the high side of specification. The most out of spec. were two exhaust valves at .4 m, (specification .2 - .3mm). I was planning on running the engine for a few thousand miles and see where things settle in. Do you see any problem this with? p.s. two wheels to go four wheels to tow. ---
**Author:** ![oldnotdeadyet](https://avatars.discourse-cdn.com/v4/letter/o/a6a055/32.png) [@oldnotdeadyet](https://community.cartalk.com/u/oldnotdeadyet)\ **Post date:** [July 17, 2020, 1:00am UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/2 "2020-07-17T01:00:40Z")
Am I correct that recall that to choose a shim, you are using a feeler gauge to set a specific clearance. (My valve adjustment days involved a screw adjustment to set a specific clearance.) I think you will find that the clearance itself is what is critical, not the specific shim. You want the clearance to account for lengthening of the valve as the engine gets hot. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [July 17, 2020, 1:24am UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/3 "2020-07-17T01:24:36Z")
With shims you measure the clearances, and for those needing adjustment you remove the shims and measure each one. Then you work out which ones you can move around to meet spec, and which ones you have to replace. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [July 17, 2020, 2:38am UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/4 "2020-07-17T02:38:12Z")
Yes running with more clearance can be an issue. Loss in power smoothness and more wear on the cam lobe and valve tip. It likely won’t wear in very soon, if ever. And not in a couple thousand miles. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [July 17, 2020, 3:15am UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/5 "2020-07-17T03:15:44Z")
If you have too much clearance now, any wearing in will just make it worse. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [July 17, 2020, 11:06am UTC](https://community.cartalk.com/t/1985-bmw-1-series-shim-debate/167424/6 "2020-07-17T11:06:58Z")
There’s only a .004 difference so I tend to think things will be fine. However, I would not wait a couple of thousand miles to recheck and readjust them. I’d say 800 to 1000 at most. Since they’re exhaust valves they will have a tendency to stretch a bit when warmed up and the valves will also seat in a bit so that .004 can fade away pretty quickly. Better .004 too loose than .004 too tight.