I use .003 - .004 for bronze guides & haven't seized one yet.
jim g
-----Original Message-----
From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
Behalf Of Edward Dunn
Sent: Tuesday, April 10, 2012 5:17 PM
To: Tim Murphy; fot@autox.team.net
Cc: rpm724@att.net; ryan.murphy@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@autox.team.net [mailto:fot-bounces@autox.team.net] On
Behalf
Of Tim Murphy
Sent: Monday, April 02, 2012 2:59 PM
To: fot@autox.team.net
Cc: rpm724@att.net; ryan.murphy@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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