TR6 Some cam questions

Hello all,

after some time, deliberation, and money, I have sourced a fresh cylinder head that hasn't been shaved to a height a little less than 3.37"... and won't have any detonation problems here on out as I'll have reduced the compression ratio due to the previous head working with .060 pistons. While the head is off, I have been poking around checking various elements of the motor, and was able to discover that my camshaft is indeed an early configuration stock piece, which was a fact unknown to me prior. I've observed its behavior through the tappet holes, and when the #1 cylinder is TDC of its exhaust stroke, numbers 11 and 12 are in their 'fully closed' state, as the lobes aren't visible at all.

Have I got the right idea, or should I pull the timing cover and get a degree wheel to make sure everything is absolutely correct?

One more related question; the picture attached is the #1 intake lobe as seen through the tappet hole. Am I looking too carefully or is the edge of the lobe 'chipped' a bit? The cam and motor have less than 500 miles on it, however I could believe the crook that put it together for me could have used a worn bump stick. He did lie and say it was a 'fast road' cam, anyway.

Yes, it does look chipped. I wouldn't take any chances and I would degree the cam properly. I'd probably want to remove the cam and have a look at it before doing anything...you might want to look for some markings on it to know exactly what you have.

Wouldn't want anything catastrophic to happen....at +060, you would have to get a new block or look at re-sleeving.

My 2 cents.

Cheers
Tush

Wellllll, that's sort of what I expected to hear, and what I was thinking myself. I was able to see the markings along the shaft and the numbers do match the stanpart early carb camshaft. I had thrown around the option of pulling out the cam to see hat it was before I figured out I could see down the holes. I've been round and round with all sorts of little careless issues due to a less than professional mechanic...the last time I ever let someone else work on my car...but I was stuck in a place without a garage. Oh well. I suppose I'll start looking through Goodparts cam selection.

Erich72TR6 said:

I've observed its behavior through the tappet holes, and when the #1 cylinder is TDC of its exhaust stroke, numbers 11 and 12 are in their 'fully closed' state, as the lobes aren't visible at all.

Click to expand...

I'm not following you here. Yes, both valves on #6 should be fully closed, no matter how wild the cam is. When #1 is at TDC between exhaust and intake, #6 is at TDC between compression and power.

Also, with a stock cam, even the base circle is normally larger than the shaft diameter (to give allowance for regrinding). If by "aren't visible at all", you mean the lobe is the same diameter as the shaft, then it has been reground by quite a bit.

IMO a degree wheel & dial indicator is the only way to know for sure what you've got. If you don't want to buy a degree wheel, you can make an adequate substitute by printing the pattern on your printer and gluing it to a piece of cardboard. Eg, https://www.tavia.com/free_degree_wheel.html

I might be using the wrong descriptors. What I mean is that the lobes aren't visible; they're facing either to the sides or down. If there was a tappet in, it wouldn't be on the ramp at all, meaning the timing can't be wildly off more than a few degrees, if any.

attached is a picture best I could get of the #6 intake lobe. It looks wrecked. Is this another item on the bill of ****e goods I was sold, meaning it was a bad cam, or could something have caused this in such an short time?

Erich,
Im going to be a bit on the optimistic side and hope that the cam may have been welded and reground. I've had some other LBC cams that were rough on the side of the lobe, but not as rough as your appear to be. Before doing anything drastic you can make a small investment in a magnetic dial gauge and measure your cam and you can also buy one of those cheap bore scopes they sell on eBay for a better inspection. If you decide to buy either, Summit is a good source for the dial gauge. Good luck and let us know what you find.
Rut

I do indeed have a dual gauge AND a degree wheel. I've got to learn how to use the wheel, and this looks like the opportunity. I had a few hours this evening to mess around with the car as the wife was away, so I decided to remove the cam. I was already more than halfway there, what with the head off.

attached are some pictures of the lobes so far. Confirmed it is a stanpart stock shaft. You all would help me greatly in evaluating the rough edges and what wear is visible on the lobes. I have the original service manuals, which deal with removing and refitting, but no information on measuring lobe heights, etc. I have a caliper I can do that with, if I had the figures.

What should i do I do from here? If the consensus is the cam is fine for another 80k miles, I'll put it back in and learn how to set the timing. If not, I'll get this one out all the way and look for another. There's another month before our daughter is due, and I've got a pass to spend some more on the Trylump before then. I have a lot of Goodparts components on the car already, and they've all been excellent in every way. I'm thinking about his GP2 cam.

I would take it to a local engine shop and have them look at it before I'd reassemble and degree it. Reassemble it like that and that engine may not be long for this world! Your engine builder may have not use the proper cam lube for break in or none at all to get that kind of early surface damage. Delta cam in Tacoma Washington is a great place to send it to for inspection and repairs. Sent mine there and they rebuilt it and reground it to a nice mild street cam. Lots of power nice idle at 8 to 900 RPMs. They can even regrind the tappets too. Best of all it was under $150. This was back in 2004.

How did you confirm that it hasn't been reground? Sure looks the part to me, judging by how close the base circles are to the main shaft. Like I said before, the original cam had a substantial allowance for regrinding, but yours appears to have been reground as far as it will go. Reducing the base circle is exactly how you make a performance camshaft from a stock one.

Here is a chart of cam specs, including the original cams.
https://www.hottr6.com/triumph/tr6cams.html

I haven't confirmed whether it's been re-ground or not. As 'mr.cancelli' as I knew him previously did business under the shop name 'performance research industries- PRI' of PRIrace.com, I guess the cam may correspond to the one on the hottr6 chart under that name. After he had my car for almost two years, gave me a motor back with a knock that threw a rod mere miles from his shop, and then almost 8 months later gave me the 'quality' build I've been undoing piece by piece since, I don't have much confidence in his ability or investment in his work.

I am under the assumption that there isn't any redeeming quality to this cam, especially if what we're seeing is damage this early on? Could it be salvageable in light of what appears to be previous modification?