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Re: TR6 - Camshaft Questions

To: Nickbk@aol.com
Subject: Re: TR6 - Camshaft Questions
From: johnny hinman <jhinman@accucomm.net>
Date: Fri, 03 May 1996 21:30:27 -0400
Cc: don.guthrie@tols.co.nz, triumphs@autox.team.net
At 12:52 AM 4/30/96 -0400, you wrote:
>Don-
>You ask about cam specs...
>
>Factory specs say Inlet    Exhaust      Lift
>                          35-65    65-35         .250"
>
>Since this is a factory reference I do not know at what lift  they take their
>measurements, so as a comparison please note a carburated model TR6 specs,
>again from the factory.
>
>                            Inlet        Exhaust         Lift
>                           18-58      58-18            .240"
>
>Please note that there is a major difference in specs. The injected cars
>could run what would be a fairly hot street cam for a carburetted car, but
>still idle quite well due to the injection.
>
>Be very careful if you specify specs for the grinder, as most all
>specs you will see are from emasculated US cars. You will probably be better
>off showing the grinder what you have and asking his opinion how to increase
>the HP. (IMHO, I would increase the lift somewhat and leave the
>opening/closing points where they are).
>
>To measure any lobe wear, simply use a caliper and check total height of each
>lobe, measuring from the heel of the cam to the lobe. (Basically, just put a
>caliper on each lobe across the highest and lowest points where the lifter
>rubs on it).They should all be the same measurement, if not, that is how much
>wear you have.
>
>If you modify your cam specs, please check the valve springs very closely in
>regards to coil bind. Also ask your grinder if he thinks you will need
>stronger springs, higher lift=faster lift rates=need for
>stronger springs.
>
>The cam kit offered by many parts houses (Vicky Brit, Moss TRF etc etc) is
>intended for a US engine, but is probably a milder cam than what you have in
>your car now. Try to contact Triumphtune in England as they will have more
>knowlege of the PI cam, and what a wilder setup for that engine would be.
>
>                                                The Car Curmudgeon
>                                                        Nick
>
> 
>
Pardon me,
       if I'm intruding, but I have a copy of a "Competition Preparation
Manual" published by the Triumph Competitions Department of BLM sometime in
the mid-70's that applies to the TR6.  The camshaft portion of this manual
mentions that at the time there were two camshafts available for the TR6:
the S-2 cam, Part No. V578 and the S-4 cam, Part No. V579.  
        The following specifications were also listed:

For the S-2 Camshaft:
        Inlet:        opens 31 BTDC         closes 71 ABDC
        Exhaust:  opens 71 BBDC        closes  31  ATDC
        Duration  282                           Lift  .405"
        Checking clearance at camshaft -- .013"
        Operating clearance at valve hot -- .016"

For the S-4 Camshaft:
        Inlet:        opens 42 BTDC         closes 71 ABDC
        Exhaust:  opens 71 BBDC        closes  42  ATDC
        Duration  293                           Lift  .410"
        Checking clearance at camshaft -- .013"
        Operating clearance at valve hot -- .020"
  
The S-2 cam was recommended for street use with the following modifications;
        10.0 to 1 C.R., velocity stacks, and a valve grind.


        I hope this information may be of use to you.

Cheers, JohnnyB
--
jhinman@accucomm.com
'69 TR6, 79' Scout


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