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TR5/TR250 TR250/6 cam grind

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glemon

glemon

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I am about to send the cam to the my cam grinder.

I want moderate performance increase without sacrificing idle or much at the low end.

So anyway I think I want something in the nature of the GP2, S2 grind, but I would like to work with Delta Cams, who I have been happy with in the past, they offer a "Mild Street" cam

The specs they sent me lobe lift .284 (intake and exhaust)
Duration (.016) 262 degrees


Not sure what the .016 after the duration means.

Anyway eny experience with any of these cams appreciated as well as your thoughts on whether they help me accomplish what I want.

Motor will have approximately 9.5 to 1 compression, stock intake and exhaust manifolds, probably a free flow exhaust of some type.
 
Can't help you with cam experience, I have a 4 cyl. TR. But, the .016 means "262 degrees duration at .016" valve clearance."
 
I don't know about TR6 cams either, but the original duration on a TR3-4 engine is 250 deg. I don't know if that takes into account the 0.010" valve clearance. My re-grind on the TR3 is 282 deg with 0.016" valve clearance (again, I don't know if that's included in the duration specs) and that is a mild grind according to Ken at British Frame & Engine...at least for the four cylinder TRactor motors. Also, my regrind lift .287"*(1.5 rocker ratio)= .431". I don't know what the original lift spec is.

What the heck is the original duration of the TR6 cam?? 262 deg isn't much more then a stock TR3-4 grind.
 
Elgin Cams lists the TR250 cam at 233 "seat duration" this cam also came on the early TR6, was replaced with one that had 246 duration for the later TR6
 
The stock US TR6 cams were 240 and 256 degrees duration for the early and late cams (that is "advertised" duration - probably measured at 0.010" open but not specified very clearly). So if this cam is 262 at 0.016" open it is somewhat more duration than the later cams. The lift is certainly more than stock also since the lift was 0.220" and 0.240" for the early and late cams, respectively.

That sounds like a nice mild cam to me. I just ordered a similar cam from APT and I'm also going to 9.5:1 with stock intake and exhaust. I haven't put the engine together yet but I expect to get good torque in the 2000 to 4000 rpm range which is where I do most of my driving. I'm guessing peak HP at about 5300 rpm. The GP2, I think, is just a little more cam than this - but pretty similar. The S2 is quite a bit more duration and I expect it will give less torque than a stock cam in the 2000 to 3500 rpm range but more HP at higher rpm. I think it gives peak HP in the 6000 rpm range.

If you like to run higher rpm and want more peak HP, the mild cam is not what you want. If you want more low rpm torque and tend to drive around at lower rpm, the cam you're looking at sounds like a reasonable choice to me (but what do I know? just my 0.02).

Bryan
 
Thanks, I am thinking I want torque, I will be driving around town and occasional autocross. Good luck with your car, I am about a month away from the motor being back together, but much longer for the rest of the car!
 
Go to BPNW and check out the TH5 grind. That is what I got and it is great for the street and has plenty of low end torque as well as power when you kick it in the pants.
 
I understand the affect of greater duration, but what is the effect of greater lift--obviously potentially better flow, but what is the downside, faster wear, more mechanical resistance?

Thanks, Greg
 
If you use a stock carb camshaft, latter yrs. , it is the same as the CR PI cars in the UK. They got 125 HP at the crank, and idle smooth. There is no better cam for this amount of HP, it's that simple. However, you will play H--- getting the HP without the PI, and of course the othere mods, but the PI will be key to getting the 125. The original factory parts are the best. If you put the Lucas PI on the car, if you ever sell it, it will do well in the Uk, as they like these, and convert them to RHD, and they have a TR5. If you do this, use the CP 150 HP cam, however, the idle is marginal, at best.
 
It has a smooth idle at 1,000 RPM and has plenty of power right up to 5,000RPM, which is as high as I've taken it. It is a bit loppy below that, but it will idle at 850-900 if you like the shakes and an occasional stall.

I do have an aluminum flywheel, triple ZS, headers, recurved ignition with Pertronix & Coil, .030" over pistons, shaved and cc'd head and 9.5 compression all on a completely balanced and blueprinted engine.

I only got to drive it about 1,200 miles before the accident, so I can't tell you about the fun from 5,000 RPM and up, but I will by the time that winter begins. Another few weeks in the body shop and I'll get a few hundred more miles on it.
 
glemon said:
I understand the affect of greater duration, but what is the effect of greater lift--obviously potentially better flow, but what is the downside, faster wear, more mechanical resistance?
Click to expand...
Greater lift puts considerably more strain on all the valve train components and depending on the amount of lift you would possibly need to look at roller rockers, changes in the valve springs and potentially more wear on the tappets/cam.

I put the same TH5 cam in my car as Paul did, I also took 100 thou of the stock head and used tuftrided lifters and shorter pushrods, all from BPNW; with this cam I was able to leave my valves and springs alone. I'm very happy with the power, though like Paul, I struggle to keep the car idling if I set it lower than 1000rpm. It's a good fairly cheap way to a bit more power. I still have the stock carbs.
 
You need to understand that the TH5 they are talking about in this thread is not a Kent TH5, it is a copy. The best cam for this power output would be an original CP cam, IF you can find a good reground original. Also, I like the APT cam. However, the only springs to use in my opinion are the stock CP springs and collars, and make sure that they don't bind. That is the only spring I would use based on what I know at this time. The down side is you can get a few more, very few more, horses with the TH5 on carbs. You need to understand, I called Kent on the phone, you can too, they grind TH5's, however, they told me the best cam for the car was still the 150 HP CP camshaft. In fact, if I was you and my cam was in good shape, I would put it back. You don't have any idea about how many problems people are having with TR6 cams and lifters, no idea at all. Also, bear in mind, the stock CP springs may not work properly with other camshafts.
 
Graham,

Very good points that I forgot to mention. That's why I have a website with pictures!! Then I can't forget too much.

I did have to go to shortened push rods and lifters and springs from BPNW. I had new guides installed and used Viton valve seals, NOT Teflon, as my machinist refused to install them.

And I did install Cam Bearings in the block.

I had special spacers machined for under the springs and used the Vernier Cam Gear set, which is nice, but overkill, unless you're racing.

Anyhow, for more go here. This will keep you busy for a while:

Machining Block

Machining Head

Silicone Valve Cover Gasket

Damper Rebuild

Cam Bearing Installation

Thrust Washers

Engine Assembly

Engine Installation
 
LMHO, over 50 bucks with shipping for a valve cover gasket? Get some 1/4" O ring material, measure length around groove in valve cover, cut O ring, super glue ends together. Long lasting valve cover gasket for less than 5 bucks. Cam bearings? Most likely over a $1000.00 installed, not worth the price. Thrush washers? Nothing wrong with original, unless you have clutch pressure plate problems. Also, that TH5 cam blank mentioned in this thread is made in India. When you install it in the block, look at the dist. gear, is it centered in the opening? NO. Look at the lobe position on the rear 5 lobes. These lobes were moved because the company who has this blank made, and grinds them, did not have the machine necessary to grind the gear with the lobes in the "factory original" position. So, he had the lobes moved. Who knows how this will hold up? But, they can always blame it on the motor oil now can't they? Don't drink the koolade dude.
 
You are entitled to your opinions and to spend your money your way. That doesn't mean that everyone will agree with you either.

And just for your information, that TH5 cam was ground in England, not India. Every lobe of the cam and the gear lined up perfectly or the machine shop would not have installed them.

Where do you come up with some of this stuff???? I think that you better avoid anymore of your KoolAid, Dude......

And one more thing, please explain to every reader of your rant how my distributor drive gear is NOT centered in this picture. That statement is about as accurate as the rest of the crap that you've posted above. I never knew you were such an expert on an engine build that you never personally saw.

PLEASE NOTE LOCATION AND POSITION OF GEAR IN BLOCK BELOW. THAT LOOKS PRETTY WELL CENTERED TO ME. ANY OTHER INCORRECT COMMENTS TO RANT ABOUT????
 

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