hi fellas
can anyone tell me if you have to heat the barrell up to insert the guides, and which one goes were as one is longer than the other, also i ordered them for a wm20 forgetting i was fitting them to a m21 sleeveless barrel.

mark

email (option): markbrob1@hotmail.com

Hi Mark, they should go in from the bottom, there is no need to heat the barrel up. The valve guides are tapered so the further they go in. The tighter they should grip, however some pattern ones don't have the taper and can seem loose. The longer one is for the exhaust side

email (option): davmax@ntlworld.com

Note also the counterbored end of the exhaust guide is at the top after fitting. Correct positioning of the guides in the barrel is determined by measurement from the top face of the barrel. The relevant dimensions are in the worksheets. Stem clearance in both guides should be checked after fitting and sized as required. (.0035"-.005" inlet and exhaust)....Ian

what work sheets are you refering to and were do i find them
mark

email (option): markbrob1@hotmail.com

Have a look at my post of Feb 28, 2012...

PS: PM sent

email (option): viaconsu [at] planet [dot] nl

thanks hans,

I was informed by dave that you press in from the botton not top, and buy the sound of it they only go in one way

email (option): markbrob1@hotmail.com

Hi Mark..The top of the exhaust guide can be identified for correct fitment by the counterbore at that end as previously mentioned. You will need to measure the inlet guide with a micrometer to determine which is the smaller end of the taper..and that will be the upper end.
However, a perusal of the tolerances in the M20 standards book indicates that if the smaller end of the guide is on the upper limit of the tolerance and the larger end on the lower limit there is, in fact, no taper...Very odd..and in that case obviously it wouldn't matter which way it was fited....Ian

Hi Dave,
The "Maintenance Manual" says on p. 11 that "...the new guides can be driven in from the top..." and so did I before this discussion started. They went in smoothly, taking care of the taper (they were NOS). Depth control seems to be easier to me, especially using the two plugs as I did.
Any particular reason to do the bottom-up thing

email (option): viaconsu [at] planet [dot] nl