[Fot] TR4 valve guide clearance

[Jim Gray]

I use .003 - .004 for bronze guides & haven't seized one yet.
jim g

-----Original Message-----
From: fot-bounces at autox.team.net [mailto:fot-bounces at autox.team.net] On
Behalf Of Edward Dunn
Sent: Tuesday, April 10, 2012 5:17 PM
To: Tim Murphy; fot at autox.team.net
Cc: rpm724 at att.net; ryan.murphy at fdlco.wi.gov
Subject: Re: [Fot] TR4 valve guide clearance

Valve guide clearance...



At the VARA Willow Springs race recently, my GT6 crapped out. (again...)
Pulled the rocker cover, and discovered a broken rocker and a stuck valve.
Once at home, I pulled the head. Piston, etc look ok.  Head is now at
machine
shop undergoing restorative surgery.  Initial look by machinist indicates
seized valve due to tight valve guide clearance.  This is a freshly rebuilt
motor.  Engine builder says he honed guides to 0.0025" tolerance.  Machinist
is pulling all valves to check...  Shall he go .004" clearance?



Ed











-----Original Message-----
From: fot-bounces at autox.team.net [mailto:fot-bounces at autox.team.net] On
Behalf
Of Tim Murphy
Sent: Monday, April 02, 2012 2:59 PM
To: fot at autox.team.net
Cc: rpm724 at att.net; ryan.murphy at fdlco.wi.gov
Subject: [Fot] TR4 valve guide clearance



I took our head up to a machine shop in Appleton, WI to have it checked for

cracks and primarily to get the valves ground.  Here is what the machinist

has reported to me:







Intake valve guides a little loose                Intake valve stems okay







Exhaust valve guides okay                           Exhaust valves about

0.001 wear on the stem







The intake valves are a nice fit into the exhaust guides.  This is not the

usual type of wear he sees on the more common (Chevy and Ford V-8's) that he

works on.







Question:  What is the "normal" clearance valve stem to valve guide for the

TR4 engine when used for racing?  To put it another way, can we run the

engine with the intake guides loose and the 0.001 wear on the exhaust valve

stems?  And, is this the usual wear pattern on the TR4 engine?







We are running a stock crank with stock rods, all balanced, and forged

WISECO pistons with 87 mm liners from Ken Gilanders.  We try to keep to a

5500 RPM redline with occasional use of 6000 for overtaking.  For what it's

worth we have a 4.3 rear end and overdrive.







I recall a discussion on the list some time ago regarding different

materials being used for guides and a problem with getting the proper

clearance.  As I recall, a number of folks were using these guides and

unfortunately had valves get stuck with somewhat disastrous results.  I

think the guides were bronze or some alloy with bronze in it.  I don't

recall any discussion on clearance for stock valves and stock guides.  My

gut feel is that I'd rather have the guides/valves a little loose than have

a valve stick and destroy the head and maybe the rest of the engine.







Thanks for your help,







Tim & Ryan Murphy



1961 TR4  #317

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