TR2/3/3A Camshaft Recommendation

[TR-3rg]

Hi,

I am looking a camshaft recommendation for my TR-3a. I want a good street cam with a power band from 2000-6000 RPM. What have you used that works well? My engine is a 87MM TR-4A, with the long intake. The carbs are the SU H6 with a 4 tube header, Mallory distributor and MSD. The head has been cut .030". I also have an aluminum flywheel.

The Isky TR-23 or the TSI TR-Torque grinds are on my short list. Thought?

Thanks, Roy

 

[trrdster2000]

Roy, I'm sorry to say I don't remember all the specks on my Isky except the one, a .428 lift, which is real lumpy for a street cam. I was running 2 inch HS8's, not a lot of fun seating at street lights or in traffic. I really think the .39? something would be a better choice. Just call Ted and see what he thinks, explaining what your needs are.
Wayne

 

[Tybalt]

I would suggest that you get a copy of Desktop Dyno and build yourself some engine models. While I don't necessarily believe in the exact numbers that come out, we found when we were racing a GT4 car in SCCA Club Racing that the models were very good at indicating trends and relative power and torque levels.

I used it to build a number of engine models for my TR6 with a couple of different camshafts from Isky, various "factory" camshafts including the S-2 that Kastner mentions, as well as different grinds from APT, Kent and Reed. You need to get the full camshaft specifications to build your models as well as input bore, stroke, compression ratio, intake CFM, rocker ratios and such. In general what I found was that many of the cams did not offer as much power/torque in the rpm ranges that you would typically use in street driving even though they eventually produced higher HP at higher revs compared to the milder cams. The big surprise was just how lame the Kent cams were. Not only were they slow to build power and torque until higher in the rev range, they didn't make as much power and torque as some of the more practical for street use cams.

I wound up using the Reed XS266 grind as it represented a good compromise of building power and torque at lower revs, and then kept building power before falling off at revs that I deemed had higher piston speeds than I wanted run. Reed requires a usable core on Triumph applications for a regrind to the specs or a cam blank that they can grind to the specs. It was one of the "more powerful" cams at 2000 rpm, only the mild cams modeled more power in these lower ranges. It was also one of the "more powerful" cams at 5500 rpm with only the hotter cams showing higher numbers in the model. Power starts dropping off slightly between 5500 and 6000 rpm in the model. My selection seems to have have worked as predicted. A friend put a hotter Reed cam in his TR250 (since sold) and it is not nearly as street friendly as my TR6. It would pull after mine begins to fall off, but it is so high in the rev range at that point that you become a ticket magnet.

Since I did my build, BPNW has introduced a cam that looks promising when I ran some numbers on it, looked to be similar to the XS266. I did not have the full set of specs so there could be some variance once those missing values are tossed into the mix, but it is worth investigating.

 

[Simon TR4a]

kent cams in England has a wide variety of cams for this engine and the descriptions they give on their website of the characteristics are accurate in my experience.
The technical data provided is also quite detailed.
I have no doubt there are other manufacturers about whom the same could be said, and I have heard positive remarks from guys with Web cams, but I can only comment on products I have used personally.
My cam is a tarmac stage rally cam, with asymetrical design, and has a broad power band, but is more cam than you want as it gives a lumpy idle at about 1100rpm and comes on strong at 3,000rpm. I have not tried to find the upper limit as cranks are expensive.

 

[Got_All_4]

Roy

Keep one thing in mind when choosing a street cam and that is lift over duration. You want good street performance and drivability . To much duration and you will have to run a high idle and or keep your foot into it so it doesn't stall. In choosing a cam it's good to know your compression ratio too. If unsure about which profile to choose always go with the lessor one. You can go more latter on or get a higher ratio rocker arms.

I was really happy with my cam in my TR250 that was rebuilt and reground by Delta cam shaft out of Tacoma Washington. I will look for my info and post later if I can find it . If not call them and they will email you their profiles. I'm redoing my TR3 and have the engine out and like you I have 87 mm pistons in it too. Didn't take that much off the heads but don't remember how much because that was like 1977 or 8 when I did that work. I can tell you with no other mods there was a lot of power just going to the oversize pistons. Did very well in auto cross too. Like you this time I was toying with a different cam for more power but I think I am going with just higher ratio rocker arms and probably roller rockers. I have them in the 250 and love the quiet valve train. Less strain on the tappets too. good luck.

 

[Got_All_4]

TRF has some on sale. https://trf.zeni.net/TR6-TR250GB/index.php?menu=A&page=115

 

[TR3driver]

There are some good comments, worth reading IMO, at https://www.tildentechnologies.com/Cams/TriumphCams.html
Unfortunately, Larry seems to have lost interest in making his cams available for sale. I have one of his street grinds (TilTech 270), which I expect will work very well if I can only manage to actually put it in a motor

 

[sagebrushbob]

Here's the one going into my engine: "Kent Road Performance Grind" (278 degree, 0.290" cam lift, Inlet 31-67, Exhaust 67-31) Setvalve clearances to 0.013". Using aluminum head, 10:1 CR, 87mm bore.
Can't give you any feedback yet, as it's still in assembly.

 

[Tybalt]

Roy

Keep one thing in mind when choosing a street cam and that is lift over duration. You want good street performance and drivability ....

That was demonstrated when building the engine models in Desktop Dyno mentioned above in my earlier post. The general rule was the longer the duration, the higher the rpm before you started to build power. A point to keep in mind though is that it's not necessarily about total duration. From the link posted by TR3driver (very nice link, thanks for posting it), you should also pay attention to the duration at partial lift points and the ramp rate of the lift.

 

[PeterK]

Here's the one going into my engine: "Kent Road Performance Grind" (278 degree, 0.290" cam lift, Inlet 31-67, Exhaust 67-31) Setvalve clearances to 0.013". Using aluminum head, 10:1 CR, 87mm bore.
Can't give you any feedback yet, as it's still in assembly.

That's the same one (Kent Road) Moss sells 851-051 Improved Street "more grunt" same specs. The Isky TR23 is higher lift but less duration. I have both but not installed yet.

 

[TR-3rg]

All,

Thanks for the responses. Prior to this thread, I contacted Tildon in regards to the TilTech 270 cam. They confirmed they are no longer grinding cams. I really like the suggestion of Desk Top Dyno and I will give it a try. I don't want to do a cam swap twice because I got it wrong the first time! I plan this as my winter work so as the above mentioned cams get installed, please update with the results.

Thanks Roy

 

[glemon]

I did a lot of research on TR6 cams before I got mine for my TR250, I don't know as much about 4 cylinder TR grinds, but I agree with the people who have said if you are torn between two, go with the less radical grind. I have known a lot of guys in the club who want to build the ultimate big HP motor, and they end up with something they don't want to drive, too much compression and cam and it doesn't want to behave on the street, and even if it does its not that much fun to drive. I got a grind from Delta Cams called "low torque" it is not much different from a TR5 grind, anyway, it makes good power throughout the range, no lopey idle, no special springs required. I clocked consistent 16.7 quarter miles with it a couple years ago, Road and Track had a stock TR250 at 17.9, neither is a rocket ship by modern standards, but an appreciable gain.

The four cylinder TRs (**** the 6s for that matter) are long stroke engines that don't like to rev, and in fact will break if you rev them to high to often without some expensive modifications. So take advantage of the low torque, raise the compression ratio with a big bore kit, lighten the flywheel, you will have a strong running TR, I remember my 4A with nothing other than the 87mm high compression kit moved pretty well without any other mods.

Have fun and good luck.

 

[TriumphantMan]

Roy, I have a '63 TR4 that I am doing a frame off restoration. I just bought a cam from Piper Cams in the UK. Workmanship and quality look great. I bought the Fast Road Cam which has a Power Band of 1300 - 5500 RPM, 8 BHP increase, with 272 Duration. This works for me.
They also have an Ultimate Road Cam with a Power Band of 2000 - 6000 RPM, 12 BHP increase, with 286 Duration.

Which ever way you choose to go, be sure to check with the manufacturer about the lifters. Piper Cams requires you to buy their lifters to keep the warranty in place. I recommend replacing the lifters any time you replace a cam anyway.

Hope this helps.

 

[doc50]

'Sagebrushbob', where is la Quinta?
I would like to visit nearby TR3 owners. (We're in Wildomar, CA...SoCal).

Thom
1959 TR3
#TS34909L(O)