Fast road camshaft for triumph tr6 CP chassis - triple dell'ortos

[Fredell1977]

Dear all. I am sure this subject was discussed extensively but I need some help. I have my CP engine out for a rebuilt and would like to change the camshaft for a fast road. My mechanic suggested Kent cams but I am not too sure as there are various on the market ( moss, racetorations, revington). The car is running on triple dell ortos. Any suggestions?

[Guest ntc]

Just build the engine right ,a CP 150 cam will push to 180 enough?

[whatmore179]

If you want a new cam try Newman Cams

 

http://www.newman-cams.com/

 

Steve

[Fredell1977]

But does it make sense to change the original one?

[Red 6]

There will be a lot of opinion on this but I have had a 6 with triple dellorto's so happy to share my experience with you but first what are you looking for as an outcome?

 

Do you intend to modify other parts of the engine as well.

 

What kind of performance are you after

 

What will you be using the car for (racing/track days /trips to the seaside in summer.

 

If you are keeping the engine standard with std head and exhaust then just re fit a standard camshaft.

 

If you want a bit more grunt then 275deg should be as much as you want

 

Dellorto's do not give much manifold depression so a wild cam is of no use to you but a 285 will be as much as you can go to

 

Kent cams are as good as any and I have used them many times they even copied my broken 306deg cam which lasted 16k road and race miles often at 8k revs.

 

The greater the duration the higher the engine needs to rev to get any power, ideal if you do not mind pulling away at 1500 rpm to avoid stalling ie the power comes in higher and goes out higher so the head and exhaust need to be modified (improved breathing).

 

275 or 285 kent fast road cam will do the job TH5 is the one.

 

Good luck and with dellortos it is lucky petrol is only £1.04 a litre

[Fredell1977]

Thanks red 6. I am porting the head, rebore, balance etc. It will mainly be for road use with the odd track day or hill climb. I am seeing the moss site which suggests a 288. What do you think?

[Tom Fremont]

The CP cam has 280 degrees of duration. There are higher lift cams with less duration but these require different springs and impose higher stresses on the cam lobes. Some cams give enough lift to cause piston/valve collision if the sprocket comes off ( had this happen myself when a cam seized in the block ). If you use one of these better fit cam bearings as insurance against seizure.

 

The less duration the more vacuum it will pull at lower revs and the better the fuel economy will be.

 

I've got a CP cam in my driver on Webers with nearly 80K miles and undiminished performance. I also have a 292 degree / 0.502" lift cam in another engine which has considerably more power but I don't trust it to last long.

 

My next engine will have a CP cam, Peter Burgess head, Carillo super light unbreakable rods and forged pistons. I expect it to outlast me.

 

Cheers,

Tom

[peejay4A]

A Newman PH2 would be a good choice.

[Red 6]

288 you say? I thought moss still offered kent cams and the TH5 should be ideal.

 

The issue is manifold depression with webbers and dellorto's, when idling or low revs there is less depression to suck the air through to get it going unlike an injected engine hence the need of a calmer cam for that initial push.

 

There is a good explanation in graham bells book tuning 4 stroke engines and kent have some useful articles on their web site.

 

The head is worthwhile but you should add a nice flowed exhaust manifold whilst you are at it.

 

One of the biggest and most noticeable improvements is a lightweight flywheel. I have lightened standard ones and fitted purpose made ones and either will be beneficial.

 

If you are going to do sprints and hillclimbs you will be limited to tyre choice but as far as I can remember an lsd is permissible and essential, so fit a torsen diff as they are nice in a road car and will help no end when having fun.

[Stanpartmanpartwolf]

Most of Kent's regular offerings are Ford crossflow profiles, designed for a dished piston & vestigial chamber configuration.

BMC & Cosworth profiles are more appropriate for a non-crossflow chambered cylinder head in general.

You will find that Moss', Kent's, Revvy's, & several others' performance cams are all the same X-flow stuff that's been around for decades & doesn't necessarily suit our engines.

David Newman supplied my first upgraded cam in 1980, & very good it was too. Their range hasn't altered significantly since.

For best all-round performance, use a TT1740 manifold & a CR5 cam. Around 200bhp with total tractability.

Financial interest declared (;0}

[Fredell1977]

CR 5 cam from Newman ?

[Schnippel]

Hello ,

in this case, I would take a 260s cam of Newman.

Why ? This camshaft supports what the machine can well already,

Torque! And only you can feel in the back.

not performance at speed X

When the head has a good flow, the compression really at 9.5: 1

Then you get about 240 N / m on the clutch!

These are not dreams that is real.

I have a test bench and already many comparisons measured.

Very interesting comparisons

 

Much greetings

Ralf

[TriumphV8]

No recommendation for DHLE & Newman PH1.

We did one of the very rare back to back test with a

well prepared EFI engine and PH1 against the

Bastuck 290degree cam and little more displacement

and also with EFI.

 

Both cars pulled from idle nearly the same where the Bastuck

pulls away from 3500 rpm and when the PH1 runs short of breath

(beyond 5000) the Bastuck engine still makes real fun to drive.

 

The reason is that matching compression ratio for the 290degree cam

and the 5% more displacement fully compensated the loss in low end torque

theoretically expected from the wilder cam. Also with stock displacement I

would expect advantage due to the much wider power band.

 

It is no good idea to put the engine with tripple carbs into the sporty direction

and cut the fun off with a cam better suitable for twin carbs. You will loose

from the carbs at lowest end full throttle because they hesitate a bit at that

working point and when the carbs are willing to improve at high revs the cam cuts off.

[Fredell1977]

Thanks but u lost me . What cam are you suggesting then?

Edited April 2, 2016 by Fredell1977

[Fredell1977]

Also. I looked at the bastuck site. Since it is German it Makes sense for me to buy from them ( pay in euro). Has anyone bought anything from them?

[TriumphV8]

Thanks but u lost me . What cam are you suggesting then?

 

Something around 280 degrees where there is the Kent, WBC or Goodparts

or Bastuck. If in doubt take the 280 Bastuck. Its in the middle of the suggestions.

 

As you say, they are Germans and in our TR Register Germany many have the 280,

some the 290 and few the 300 in use.

 

I would estimate to know about 20 here around to have such a cam.

Quality, like at many suppliers, depends an what item you buy

the cams are okay, I think they may be from Kent although the say its not.

[Stanpartmanpartwolf]

CR 5 cam from Newman ?

No- one of mine. Ground by Kent cams on a new blank. The high lift/short duration suits both PI & Webers, giving excellent tractability.

I'd bet that Bastuck's are copied from the Kent x-flows. They're not exactly noted for originating components!

[TriumphV8]

Its a good idea to decrease degrees and increase lift while the lobes become steeper.

Its not that the engineers did not know about those benefits in the early days and up

to the geometric problems that the steeper lobe from a point need bigger ground circles

and bigger tappets (dont want to go into the details) that could be somewhat increased

 

...... but steeper lobes cause increased wear and that was the reason not to do too much.

Modern sporty cams already increase that a bit but hopefully stay on the safe side.

 

The best way to stay on the safe side with that problem is to swap to roller cam and roller rockers.

The Rover V8 has similar valve train concerning wear and lubrication and the wedge shop offers

the described solution:

 

http://www.thewedgeshopstore.com/products/Roller-Cam-setup.html

 

For the TR6 this has not been done yet but seems to be possible. All the problems with

camshaft wear in these days also enforced by the miss of ZDDP in the oil and a lot of

idling what is bad for a sporty cam, could be overcome in one bigger step!!

[Tom Fremont]

...or keep it simple, tried and true with a proper CP cam whose record buries the rest. If you need 200+ HP you can always go modern. Even my Cadillac is getting 136 BHP/litre.

 

 

Cheers,

Tom

[GT6M]

 

For the TR6 this has not been done yet but seems to be possible. All the problems with

camshaft wear in these days also enforced by the miss of ZDDP in the oil and a lot of

idling what is bad for a sporty cam, could be overcome in one bigger step!!

 

Says Adreas

 

seen this stuff Ole bean,

fully snyc too, which is an odd ball,

but no if its got Olde engines in mind

https://www.penriteoil.com.au/products-categ.php?id_categ=1&id_brand=3

 

Ive had decent reults with the piper cams, they got the same,ish timings as a CP, but a wee bit moer lift

and ex is no advanced so nee bigg drop around 25-35 ish in touques and BHP charts like the Kent offerings

 

M

[Damson6]

Rebuilt the engine at about 85,000 miles, I fitted a Kent cam which lasted about 15,000 miles so have refitted the original cam which has now done more than 100,000 miles in total.

[Fredell1977]

Thank you all. To be honest I am more confused than ever before at this stage. If I understood correctly a new cam should have a higher lift and a shorter duration.

[Andy Moltu]

One of the issues with non-standard cams are that they are ground onto old cams rather than new blanks and then not broken in properly so can have a short life as a consequence.

 

The important thing is to go for a cam that has been ground on a new blank and decent quality followers used.

[TriumphV8]

I drove reground cams in my Lotus engine for years in motorsport and daily traffic.

They had been nitrided after reground and are swimming in oil in the 4 valve head.

Although its pretty right what is said above its not a single reason for the cam to fail.

 

We put more stress on the valve train, especially when lift is increased and duration not that

required amount expanded. So the material comes to its limits and as always in life

the more its stressed to the limit the more it requieres perfect conditions to work reliable.

So besides bad quality of parts also bad fitting and beding in conditions can be the culprit.

 

TR6 needs good oil with ZDDP

proper hardening or nitriding of cam and tappets

proper valve springs, not harder than requiered

best running in procedure with preparation with cam lube.

Matching geometric of tappet (plain) and cam lobe (rectangular)

 

Did I forget something?

[Tom Fremont]

In 2001 a noted ( notorious? ) UK TR specialist recommended the CP cam for service of 100K+ miles ( which I stipulated as a goal ) - without hesitation. I reckon more has remained the same than changed since then, and some of the changes are for the worse ( like ZDDP in oils ).

 

Not many cams have seen 6-figure miles in the current crop of running engines, but unless changing cams is a pleasure the record warrants a look before leaping. On the other hand, if it's no bother to swap cams / tappets / oil pumps it can be done without removing the head ( see archives or PM me ).

 

Cheers,

Tom