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TR6 Best cam for a TR6

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J

johnnycaker

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I'm in the process of rebuilding a 74 Tr6. I'm going 30 over, Ted S. is redoing the head, bumping to 9:5 to 1. I am running the stock exhaust going to two ansa mufflers. I will be installing a GP triple intake with 175's. I like Ted's 425 lift 275 duration which produces a flat curve from 3 to 6500..I also looked at GP's GP3 which pulls from 2500 to 6000. Any preferences between the two? Others you would recommend? Any help is appreciated..
 
There is a world of cams out there. The only advice I can give is watch out how high you go on lift without cam bearings, because you'll have uprated springs, too, I guess. Ask Ted & Richard about that.
 
This is an area that can help or hurt an engine by going too far in either direction.

I have a complete rebuild, including cam bearings shown in great detail on my website starting here: Brosky Block Machining Part 1 of 6 Pages

I also have a TH5 cam from BPNW and the results of the 9.5 to 1 compression, headers, triple ZS carbs, aluminum flywheel, reworked distributor curve are all shown on a dyno report here ( Brosky Dyno Run Old vs New ) with a before and after. That is the real truth shown and at the rear wheels, not what I think it should be.

That being said, my car will run with anyone and the power and torque are exactly where I feel they are needed for "spirited" street driving, not road racing, which would be something altogether different. You will notice my power curve starts to drop off at 5200rpms. That is what the cam will allow and is very practical for low end power and drive-ability. As I said, I have not lost any challenges yet.

My car idles with a slight lope at 950-1000rpms and has gobs of low and mid range torque. I can pull from a very low speed in 4th gear and the car is great in traffic. Being comfortable in the rpm range that we are most in will win out over high revving potential with a lot less strain on the drive train and will usually be a more fun car to drive around daily. If you want to do serious racing, then you move to another level.

This is JMHO and is subject to you accepting whatever you feel is of value.
 
Thanks..I've read everything in your website, extremely well done and imformative. Appreciate folks like yourself that do sites, great way to learn. I have a hard time posting a picture..Anyway, was it necessary to install cam bearings with your cam profile?
 
you can also check out wishbone classics and call and talk to Kai about cams, very informative about whats out there and what to look out for and whats not right

Hondo
 
The higher lift cams can feel deceptive. My TR6 had a GP3 camshaft. Below 2500rpm it had the same level of torque as a stock engine so you could still putter around below 2500rpm if need be. Easy roll away from a stop with power steadily increasing from 1500rpm to 2500rpm. The difference between stock and the GP3 from 2500-6000rpm was amazing. So much more torque that it actually made the power below 2500rpm seem underpowered. To maintain a smooth idle though it had to be set at 1200rpm. Below that and it had a lope, if you tried to set the idle below 1000rpm it would lope so bad that it would nearly stall and the triple carbs would load up something fierce.

I would get invited to Hot Rod shows, they all loved the sound of the engine when I would pull in and were completely suprised to see an inline 6 when I opened the bonnet. It would still turn their heads when I would fire it up to leave too.

If Ted is working on your cylinder head though, he might be the one to talk to so he could match head work to one of his cams.
 
As usual, Shawn's advice is right on the money. Talk to Ted and get your parts all matched for your driving preference. You can see what I meant from his comparison of the idle and torque characteristics between those two cams and there are many variations that differ slightly, but make a big difference in how the car drives at lower speeds.

The TH5 has been renamed to match the other cams numbering sequence. This is what is now the cam that I bought just over two years ago: BPNW BP 290 Cam
 
Some more reading here if you are interested in the technical side of camshaft design.
 
You may also look and see what APT offers, one thing abuot them is either they offer new cam blank or regrinds, but everything is ion nitrited for proper hardness, and now APT has the Triumph .800" 60 Rockwell C rated lifters, the .800" lifter work in almost all the Triumph engine, except the early 1147s.

Maybe one of you can answer this for me. When I build a 1500 engines, which like the TR6 rides the cam directly on the block, I use a Spitfire 1300 camshaft and then install 1300 cam bearing in the 1500 block, which requires no block mods, because all the factory did with the 1500 engine is increase the cam journal size on the cam to work in the block without cam bearing, obviously a cost saving deal for the factory. Knowing the cam journal size of the TR6 cam is the same as the 1500, I've often wondered if it is possible to turn down the cam journal diameter on a TR6 (this could be easily done on crankshaft grinder) to that of a 1300 Spit cam and then use those cam bearings in a TR6, anyone ever heard of this? I'm rebuilding a TR6 engine, or more like fixing what another bulder missed, and I think I have some 1300 cam bearing lying around, so I might look into this, not for this engine but for future reference. Since so many things is simular for the 1500 to the TR^, this could be a easy way to put cam bearings in a TR6.
 
Hap,

When buuilders put cam bearings into the TR6 blocks they use Spitfire camshaft bearings but they have to line bore the block to get them to fit. The journals on the TR6 camshaft are the same as the 1296cc engines, not the 1500's.
 
I used a grind from Delta Cams called low torque, I didn't drive the car before I rebuilt everything, but it seems to live up to its name, also went with a 9.5 head and I have a pair of Ansa mufflers I want to put on (the ones I have now are "turbos" from the muffler shop, it sounds like a a derelict 80s GM full size with a bad muffler, very deep loud and rumbly, but not sports car like, hope the Ansas will give it a milder but livelier sports car growl)

The specs are not real agressive, not much more than the petrol injection cam. I have yet to really wring it out because of the break in period, but generally agree with Brosky's philosophy, accentuate the torquey characteristics of the motor, Depends on what you want but I know a number of people that have gone very agressive with cams and compression to the point where they don't enjoy driving their cars on the street, mine has a smooth idle and really good grunt off the line, if time an money were no object I might experiment with slightly more agressive grinds, but I am happy with what I have.
 
I also have a TH5 cam from BPNW and the results of the 9.5 to 1 compression, headers, triple ZS carbs, aluminum flywheel, reworked distributor curve are all shown on a dyno report here ( Brosky Dyno Run Old vs New ) with a before and after. That is the real truth shown and at the rear wheels, not what I think it should be.

Brosky,

I think you have commented on this before, but is your engine build still compatible with a supercharger, such as the Moss unit?
 
From what I read on the original Moss setup of the super charger, yes, it would be. They stated that they used a 9.5 to 1 compression engine, if I remember correctly because it made me think that if I had not already had the triples, that would have been my next move.
 
Brosky
I saw some red colored "stuff" around the insert bearing in your picture. Is there some lub or other "stuff" that is used to fit the insert? How is the insert installed, press of some type or by hand??
 
swift6 said:
Hap,

When builders put cam bearings into the TR6 blocks they use Spitfire camshaft bearings but they have to line bore the block to get them to fit. The journals on the TR6 camshaft are the same as the 1296cc engines, not the 1500's.
Click to expand...

Ok, gotta ya, I just assummed they were the same as the 1500, my bad. Yeah I had this done to the MG 948 engine before, as for line boring for cam bearings.
 
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