Triumph “Tri-Cor” 500 Cylinder Head (CD274)

Triumph “Tri-Cor” 500 Cylinder Head (CD274)

Back in 1961-1962 Tri-Cor in Baltimore, Maryland was offering race parts for sale and modification to dealers and racers alike.

Tri-Cor offered modifications that would allow the average Joe or privateer to have access to a professional service on factory parts.

Triumph 500cc Racing Engine Tri-Cor Sheet

Triumph Tri-Cor “Triumph 500cc Racing Engine Sheet” - Date approx 1961/1962 (click image to enlarge)

During this time period Triumph was offering race parts so you could “build” your own factory style racer using the 500 platform (5TA, T100A, TR5AC, TR5AR, T100SC, etc)

The Tri-Cor 500cc race parts list is just a clear example of some of the race parts or "hop-up" parts that Tri-Cor was offering to enthusiasts like you and I.

Race sheet contained some of the following parts 

  • Racing carbs
  • Racing magnetos
  • Distributors
  • Oil Tanks
  • Camshafts
  • Lifters
  • etc

Triumph race parts where special and where not available or found in your typical Triumph parts book.

If you wanted to obtain factory race parts and not aftermarket parts, you would need to obtain a Tri-Cor parts sheet and place your parts request directly with Tri-Cor or with your nearest Triumph dealer.


CD274 A myth?

Triumph 500 Tri-Cor Cylinder Head CD274


CD274 is not a myth that was only shown on a Tri-Cor parts sheet, it does in fact exist..

This piece is a Triumph 500 (unit) cylinder head that was sent to Tri-Cor perhaps from a racer or dealer.

I would assume this was sent by a dealer as this specific cylinder head is NOS (new old stock).

The information on the yellow flyer offers exactly what this cylinder head features. In fact this cylinder head has some interesting features like the E3991 casting and squish band machining on the combustion chamber..


Modified with the following parts:

Triumph 500 Combustion ChamberCD274 enlarge inlet port seats (unfinished)
  • Enlarged nickle-chrome inlet valve seats (unfinished) to accept 1 9/16 valves
  • 1 1/16” inlet ports welded to head

CD274 Tri-Cor Head Sheet

CD274 "twin carb" racing cylinder head specs (click image to enlarge)

If you notice closely on the Tri-Cor parts list you will see that this head does not have valve guides installed, no exhaust spigots, and the inlet seats have not been finished.

According to the flyer, this 500 cylinder head was not finished with the “complete” job.

The “complete job” would have been finished with guides, cut seats, porting, etc for just an additional $20 on top of the $20.04 for the "standard" work.


Enjoy the photos of this rare bird..

Bottom Of Head
E3991 Triumph 500 Head Casting
Welded Inlet Port Spigots

Thanks for reading

Thanks for reading today’s blog post, we hope you have found this topic to be interesting

If you have any additional history or information on this cylinder or on Tri-Cor race parts, please feel free to drop us a comment in the selection below or by sending us an email

Ride safe! -CBS


  • robert crabtree

    hello, your very lucky to have those I have the exhaust cam still looking for the intake. I would be interested in buying those from you if you choose not to use them. tri-cor has the specs on those at 38-58-58-38

  • robert h huttunen

    HI,was reading this with intrest as i am currently reduilding a 61 500 motor.this should have a distributor and single carb.i got with a later timing cover with points driven off ex cam.i thought the head to be a home modifide has to weldid intake pipes on fin on both sides are broke.when spliting cases i found it had no dist drive gear on had a right angle tach drive insted of dist.but couldent work because cam had no gear. looking at cams ex is tri corecd332/scc/63 and intake is tri core cd438/scc daytona.both cams look to be good shape.head has larger intake valves.head is diorty and other than the broke fin on each side not to ran when i pulled it for rebuild.i bought a good used twin carb head for replacement.i think the head and cams were put on years ago and will use the cams but cant seam to find any info on the 438 iontake.any advice on using these cams and timing them would be helpfull.

Leave a comment

Please note, comments must be approved before they are published