Piston & Liner Set for TR3/4

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Mike Moore TR4
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Joined: Tue Dec 24, 2013 3:09 pm

Piston & Liner Set for TR3/4

Post by Mike Moore TR4 »

Ken Knight races a very fast TR4 out in Las Vegas area. He is very active in sourcing/producing high quality American made parts for our race cars at very reasonable prices. He is currently placing an order for piston & liners for the TR3/4 engine, also used in Morgans.

If anyone is interested I can send you more details. Here is the info he provided so far

Three Dog Racing (3DR): Pistons & Liners
One of the goals of this project is to source a supply of high quality wet liners, racing
pistons and rings for the Triumph TR 3/4 engine. This motor is used widely in vintage
racing in both Triumphs and Morgans. The other goal is to bring parts to the market
which reflect current racing technology as developed and proven for SB Chevy/Ford V8
racing motors. They paid for the R&D and we can use it to build more reliable and higher
HP race motors!
A word about piston and liner sizes. The rules of many clubs indicate that bore sizes for
this motor should not exceed 87mm (3.425). However, the fact is the most common bore
size found in cars today is 89mm (3.504). This larger size is the least costly to supply and
gives more options for sourcing pistons. For most vintage racers cost and access to high
quality parts is a larger consideration in going to the 89mm bore than the very small
advantage of extra displacement. At this time 89mm pistons can be supplied as a blank is
available to make that piston. A kit with 87mm pistons/liners can be ordered but it will
depend on demand and take more time to source.

Piston Specifications: Pistons in the kit will be forged aluminum flat top pistons in a
4032 alloy. This is a very stable alloy that expands little when hot. Running clearances
for 89mm/3.504" bores are from .002-.0028 and I run this piston (coated) at .0025 with
Joe Gibbs 30wt oil. Combined with torque plate honing of liners this will insure a very
round bore and excellent ring life in the motor (my experience is two season and
counting). In a SB Chevy these pistons are used in spec class race motors that dyno
around 480hp or about 60hp per cylinder. This should be a very long life piston in a
typical ±165hp TR vintage race motor.

Rings: Rings in the kit will be from Total Seal and will include the gapless top
compression ring. My experience is that these rings are very durable in motors
with/without air filters and I run in the desert! The rings are not difficult to install but
attention to ring gaps will pay dividends in performance. Replacements are readily
available and since the liners are going to be honed to a tight specification, a light hone to
break the glaze means a long service life for the liner.

Liners: This kit will incorporate the following changes over what has been available.
The US made liners will be purchased at the nominal bore size and they will need to be
honed to fit the pistons. Previous kits have liners that are finished honed to a size that is
larger than needed for current ring and piston design. Honing using a torque plate (see
below) will allow liners to be trued and brought to spec for better sealing. However
honing can be done by your machinist as it is a standard service available in any location.

Order Size: The final price on the parts that I have been able to source will depend on
the size of the order. For instance, the cost of liners is fixed until the quantity ordered
reaches 50 units (in reality that means 52 in order to make up 13 sets). At 50+ there is a
price reduction per liner. The same is true for the pistons, pins and ring sets, the more
that are ordered the better the price. A commitment for 10 kits will mean a much better
price for all concerned. If suitable demand exists I will start stocking this item.
The 3DR Kit including Pistons, Pins, Rings, Liners: For a set of (4) US made 89mm
forged 4032 alloy aluminum flat top pistons, TR spec pins, Total Seal rings and liners;
base price $1095.00 + shipping. If 10 sets are ordered; $995.00 + shipping.
This kit is suitable for high performance street TR’s and Morgans!

Ceramic Coating: All modern racing pistons are coated for thermal protection (dome),
increased longevity and less friction (skirts). As an option the pistons can be ceramic
coated for $195.00 + shipping. Rod, main and cam bearings can also be purchased and
coated for a very reasonable cost. I can supply these parts and will quote you a price on

Liner Honing Using a Torque Plate: Liners in the kit will need to be honed to fit the
pistons (typically .0025 to .003). This can be done by the shop of your choice or through
my machinist. Several years ago I had a “torque plate” made for the TR engine. This
allows the liners to be honed as if the head were bolted to the block. When liners are
honed in this fashion they are more truly round and rings seal better. I have made
arrangements with my machinist to provide a block and my torque plate, he would hone
to size (you set clearance specification) a set of liners/pistons for $220.00. Each
piston/liner would be marked for position in the motor for ease of assemble. You would
still need to gap the rings.

Parts Quality: The parts supplied are the ones that I use in my racing TR4. The pistons
are ceramic coated, liners honed with a torque plate and I use Total Seal rings. This
motor turns 7,000 rpm at redline and pulled 6,800-6,900 rpm at the end of the long
straights at Road America with a 3.7 rear gear in 4th.

Order Times: I would like to have all interested parties make decisions as to ordering
by the end of next week, Aug 28th. I can then tell you what the final price will be. It
will take at least 3 weeks to get pistons made. Piston coating, if ordered, will take about
two weeks. Please understand that there is a significant financial commitment on my part
to having these parts made so get in touch soon! If all goes well orders could start
shipping at the end of September or October depending on what you order (coating,
honing etc). I look forward to suppling these parts to you! Ken Knight - 3DR
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