We have found that Manganese-Bronze guides have greater "lubricity" (are
more slippery) and last longer while causing less wear of the valve stem
than cast or "chilled" iron guides. The issue is clearance between the valve
guide and the stem. The bronze guide material has a much greater coefficient
of expansion than does iron. When an bronze guide is used in an iron head,
as the head gets hot, the material of the guide wants to expand. It cannot
expand outward because it is "captured" by the iron head all around it.
Consequently it grows inward, reducing the clearance between the id. of the
guide and the valve stem. We have had valves get stuck in bronze guides in
iron TR head and others as well. The fix is the correct amount of clearance.
In a TR-4 iron head, in a racing application, ie hard use, high
temperatures, 5/16" stem inlet valves need .0015" to .002" stem to guide
clearance, exhaust valves with 5/16" diameter stems need .002" to .0025"
clearance. We DO NOT USE VALVE STEM SEALS. It is not necessary with even
increased oil delivery to the valve gear. We get much longer life out of
the Manganese-Bronze guides than with any iron guides we have used and with
these clearances you will not have any seizure problems.
Greg Solow
----- Original Message -----
From: <n197tr4@cs.com>
To: <fot@autox.team.net>
Sent: Thursday, November 03, 2011 7:12 AM
Subject: [Fot] Zinc Additive. now use of BRONZE GUIDES
> Sent: Thu, Nov 3, 2011 8:25 am
> Subject: Re: [Fot] Zinc Additive. now use of BRONZE GUIDES
>
>
> FROM TED SCHUMACHER:
>
> Why dont you use bronze guides? How did you come to this decision?
>
>
> Ted,
>
> I discussed with highly regarded performance engine shop.
> Whenever they encounter bronze guides they clearance them.
> If it doesnt get done, there is a danger of seizing.....which can get very
> hard on lifters and cams.
>
> Some engineering folks tell me that cast iron guides provide superior
> performance.
> And say that bronze cause more heat/friction/wear......................
>
> This and observing various failures over the years caused me change.
> Certainly it is the right decision for me.
>
> Others may have a different conclusion and I would invite them to discuss
> on
> this list.
>
> I have long suspected that there have been a lot of failures attributed to
> 'soft lifters', and faulty cams, when it may have been caused by seizing
> of
> valves or severe drag in bronze guides.
>
> Thanks for asking Ted. It seems like it is an important subject for this
> list.
>
> Joe Alexander
>
>
>
>
>
>
>
> -----Original Message-----
> From: tedsimx <tedsimx@bright.net>
> To: n197tr4 <n197tr4@cs.com>
> Sent: Wed, Nov 2, 2011 8:54 pm
> Subject: Re: [Fot] Zinc Additive.
>
>
> Why don't you use bronze guides? How did you come to this decision? Ted
>
>
> Connected by DROID on Verizon Wireless
>
>
> -----Original message-----
>
> From: n197tr4@cs.com
> To: lang@isis.mit.edu, JAR7U@hscmail.mcc.virginia.edu
> Cc: fot@autox.team.net
> Sent: Wed, Nov 2, 2011 21:16:11 GMT+00:00
> Subject: [Fot] Zinc Additive.
>
>
> Use of bronze guides is or can be an issue here.
>
> ESPECIALLY those not properly clearanced.
>
> It ALSO seems that cast iron guides are 'slippery' while bronze can create
> added friction and wear.
>
> We dont use bronze guides anymore.
> _______________________________________________
> fot@autox.team.net
>
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>
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