List,
I got this from my fellow racing friend, Henry Frye. His experience with a
machine shop is similar to mine, only I had the great fortune of getting the
right machine shop the first time. My machine shop specializes in stock car
engines, but also does wet sleeve work as we are in the heart of wet sleeve
liner country....Waterloo, Iowa/John Deere. (They also kept me out of trouble
on bronze guides, also...which is another story)
So, it appears that the key is a shop that can inspect and set up for bore
properly. Read on for Henry's experience.
<< Here's the post...
Greetings,
Several years on the big Triumphs list gave me the impression that the
consensus was boring liners is an iffy proposition. There are two camps
represented, those that say it does not work, and those that say it CAN
work. The bottom line is if you find a shop that knows what they are doing,
you have a great chance at success. The trick is the liners must be under
the torque of a device that is acting like the cylinder head while the
boring is taking place.
I took up Vintage Racing this past year, I built up two race engines. On
the first I used a set of liners that came with my race car. The PO told me
the liners were freshly bored. I did not have the machine shop check the
liners, and on my first race weekend I found out one of the liners was not
perfectly round. By day two I had copious amounts of blowby. My machine
shop gave me the bad news, I had trashed on of my racing pistons. There was
several thousands off the skirt. On each power stroke the piston was
cocking sideways in the bore. On the next engine I started from scratch.
All parts went to the shop for checking, no more assuming the parts I had
were OK.
Luckily, my local machine shop is no stranger to the wet liner TR engine.
They do all the machine work for Morgan Spares, so they do several of these
engines a year. When I explained my concerns about boring the liners to the
machinist, he quickly put me at ease. This is what they do.
After boiling out the block and magnifluxing everything, the liners are set
back into their bores in the block on top of a new figure 8 gasket. They
install the head studs, and bolt on a torque plate. This puts the liners
under the same torque they will see under the head. Then, the block is set
up in the cylinder boring machine and they carefully bore each hole to
specification. Then, there is one guy at the shop who sets the liner
protrusion.
Liner protrusion is a critical element to success with these engines,
especially if you are using a radically shaved head. The stock spec is .003
to .005 proud of the deck. This will work fine with a stock copper/asbestos
head gasket. Many racers use either the steel shim headgasket or a reusable
solid copper headgasket. Remember the steel or copper headgaskets are not
compressable, so the need for uniform liner protrusion is more critical.
Also, you want to be at the low end of the liner protrusion range for the
non-compressable head gaskets.
Last item about used liners. It is imperative that two areas seal
perfectly, the flange on the bottom where the figure 8 gasket seals, and
the top where the head seals. Any pitting in these areas is unacceptable.
Also, check the recess in the block carefully where the figure 8 gasket
sits. That shelf must be perfect as well.
I believe most racers are buying forged racing pistons and getting liners
bored to match. New liners are available in a variaty of sizes as well.
Henry Frye, Connecticut, USA - thefryes@iconn.net
Stag, TR3B, TR250's and a TR4 Vintage Racer
Return-Path: <thefryes@iconn.net>
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for <N197TR4@cs.com>; Fri, 8 Dec 2000 06:10:57 -0800
Date: Fri, 08 Dec 2000 09:10:58 -0500
To: N197TR4@cs.com
From: Henry Frye <thefryes@iconn.net>
Subject: Liner boring post
Joe,
Not knowing where to post this, I put it on Jeff McNeal's Totally Triumph
Garage, under TR mechanicals... You might want to tell the big list.
Here's the post...
Greetings,
Several years on the big Triumphs list gave me the impression that the
consensus was boring liners is an iffy proposition. There are two camps
represented, those that say it does not work, and those that say it CAN
work. The bottom line is if you find a shop that knows what they are doing,
you have a great chance at success. The trick is the liners must be under
the torque of a device that is acting like the cylinder head while the
boring is taking place.
I took up Vintage Racing this past year, I built up two race engines. On
the first I used a set of liners that came with my race car. The PO told me
the liners were freshly bored. I did not have the machine shop check the
liners, and on my first race weekend I found out one of the liners was not
perfectly round. By day two I had copious amounts of blowby. My machine
shop gave me the bad news, I had trashed on of my racing pistons. There was
several thousands off the skirt. On each power stroke the piston was
cocking sideways in the bore. On the next engine I started from scratch.
All parts went to the shop for checking, no more assuming the parts I had
were OK.
Luckily, my local machine shop is no stranger to the wet liner TR engine.
They do all the machine work for Morgan Spares, so they do several of these
engines a year. When I explained my concerns about boring the liners to the
machinist, he quickly put me at ease. This is what they do.
After boiling out the block and magnifluxing everything, the liners are set
back into their bores in the block on top of a new figure 8 gasket. They
install the head studs, and bolt on a torque plate. This puts the liners
under the same torque they will see under the head. Then, the block is set
up in the cylinder boring machine and they carefully bore each hole to
specification. Then, there is one guy at the shop who sets the liner
protrusion.
Liner protrusion is a critical element to success with these engines,
especially if you are using a radically shaved head. The stock spec is .003
to .005 proud of the deck. This will work fine with a stock copper/asbestos
head gasket. Many racers use either the steel shim headgasket or a reusable
solid copper headgasket. Remember the steel or copper headgaskets are not
compressable, so the need for uniform liner protrusion is more critical.
Also, you want to be at the low end of the liner protrusion range for the
non-compressable head gaskets.
Last item about used liners. It is imperative that two areas seal
perfectly, the flange on the bottom where the figure 8 gasket seals, and
the top where the head seals. Any pitting in these areas is unacceptable.
Also, check the recess in the block carefully where the figure 8 gasket
sits. That shelf must be perfect as well.
I believe most racers are buying forged racing pistons and getting liners
bored to match. New liners are available in a variaty of sizes as well.
Henry Frye, Connecticut, USA - thefryes@iconn.net
Stag, TR3B, TR250's and a TR4 Vintage Racer
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