Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: valve springs and shim question...
furryeggs

posted on 12/6/19 at 06:00 PM Reply With Quote
valve springs and shim question...

When changing the valve springs on a blacktop can you use the existing shims or do you have to change them for new... Iíll try my hand at most things but i think iíd find my engine building limits rather quickly trying to measure shims and gaps etc
View User's Profile View All Posts By User U2U Member
big_wasa

posted on 12/6/19 at 06:25 PM Reply With Quote
You can use them if there in good serviceable condition and more importantly in tolerance.

You build the head up and measure all the gaps with a feeler gauge. You keep moving them and re measuring them until you get the best tolerances. If there out you have to buy them at what ever size you need.

You will save your self hours if you donít mix them up when stripping it down.

Just fitting the st springs wonít change the shim tolerances. Lapping in the valves will.

Unless your going mad you only need them on the inlet to stop valve float.

The st has differant length springs on the inlet / exhaust. So donít mix them up.
Also turn the cams before you fit the head as the the longer springs can coil bind on some cams.

[Edited on 12/6/19 by big_wasa]

View User's Profile View All Posts By User U2U Member
furryeggs

posted on 12/6/19 at 06:42 PM Reply With Quote
Itís just going to be st springs, so if i keep the shims in/on the same port i should be ok?
View User's Profile View All Posts By User U2U Member
big_wasa

posted on 12/6/19 at 06:46 PM Reply With Quote
Depends on ware and tare but yes the distance between the valve seat and cam lobe will remain the same.
View User's Profile View All Posts By User U2U Member
rusty nuts

posted on 12/6/19 at 06:48 PM Reply With Quote
Make a note of the shim thickness before you build the head up , possibly like a spread sheet , then measure the clearances then do the maths to arrive at the correct size shim . Lapping the valves in will reduce the clearances but only very slightly unless the seats and valves are refaced.
View User's Profile View All Posts By User U2U Member
nick205

posted on 13/6/19 at 10:16 AM Reply With Quote
As mentioned you can measure the gaps using feeler blades (a set of feeler blades aren't expensive and are handy to have).

You can measure the shim thickness using digital vernier calipers. You can buy a set of calipers that measure millimeters to 2 decimal places for less than £20 from Halfords. Again a handy tool to have for measuring many things and they measure internal and external distances as well.

https://www.halfords.com /workshop-tools/tools/hand-tools/laser-digital-vernier-caliper-150mm?_br_psugg_q=vernier+caliper

https://www.screwfix.com/p/magnusson-digital-vernier-caliper/7093v

[url=https://www.screwfix.com/p/hilka-pro-craft-32-blade-feeler-gauge/4406r]https://www.screwfix.com/p/hilka-pro-craft-32-blade-feeler-gauge/4406r[/ur l]

[Edited on 13/6/19 by nick205]

View User's Profile Visit User's Homepage View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.