"Were the threads previously BSF? (Back in the day, we referred to all British threads as “whitworthâ€.)"
Whitworth is a coarse thread system, roughly equivalent to the NC. BSF is finer. The unit cases up through 68 used 1/4 X 26 CEI cover screws and BSF for the larger bolts and studs, with....excuse me here, made a mistake.....NC threads showing up in 69. NOT NF. I usually use the term "U.S." to cover both NC and NF, but realize it isn't technically correct.....and there aren't any fine threads in the cases themselves.
"So much to learn. (The Bacon restoration book is available from the local library system and is being sent to my local branch, so I will have study material soon.) I didn’t know the case threads changed to UNF in ’69, although I was generally aware that later Triumph used threads other than Whitworth. I have done a little research and have found a useful site to share:
http://www.britishfasteners.com/Merchant2/merchant.mvc
Down the list of links on the left side of the page click on “Learn About British Threadsâ€.
I am hopeful that the Bacon restoration book will answer some of my questions, but would you discuss the changes in threads over time?
For the unit bikes, it's as above. CEI and BSF for the early bikes, NC for the later bikes. The NF shows up on studs, on the exposed end, for the gearbox studs, case joint stud, cylinder studs, alternator and oil pump studs.
“ ...larger oil pumps, better points, shuttle valve forks, dls front brakes, timed breather and separate primary oil system, encapsulated alternator and timing window on primary cover, oring pushrod covers, no oil bleed to the pushrod buttons in the rocker arms. And the Canadian Bonnevilles still had stainless fenders through 70!!!
I'd sneak a four speed from a 71 or 72 into the box, however....if I couldn't have the fiver.“
From reading other threads I understand (I think) Mecchanica’s preference for separate oil for engine and primary. What is a timed breather and why is it preferable?
The timed breather is incorporated in the end of the left inlet cam and bush. There is a hole in the camshaft and a rotating disc valve that allows the engine to push blowby out of a tube near the final drive sprocket. With this, the factory installed an oil seal between the left main bearing and the primary drive sprocket, sealing the joint there. In 70, the factory eliminated the timed breather and the left oil seal, and allowed the engine to breathe into the primary, using the volume of the primary case to mitigate pulses in the breathing system. Not a bad idea, except for the necessity of using engine oil in the primary case. Now that non-energy conserving synthetics are available which have excellent film strength without undue viscosity, it works better than it used to, when thicker mineral based oils with metal salts (like molybdenum disulfide....the "energy conserving" oils) were used.
"I seem to recall that later 650s had a single point setup as opposed to the earlier dual points. "
Nope, all dual points. But there are three basic types of points....63-67 used 4CA type, with the condensers mounted on the points plate. 68-74 used 6CA type, using a single hold down screw and eccentric adjusters for both the gap and to move the secondary plates. 76-on used the 7CA type, with dual hold down screws and a wedge and slot adjuster for the gap and eccentrics for the secondary plate. There are variations of the 6CA which used different primary and secondary plates. The 4CA used a shorter auto advance unit, 6CA and 7CA used similar auto advances, with the later ones using thick, non adjustable spring attachment pillars. Earlier ones you could bend out a little to get more tension, changing the advance curve. (You can grind the weights to slow the advance curve if you want....sometimes this helps with pinging at low to mid speed under acceleration.)
"I also recall from reading earlier threads that there were several oil pump improvements. Could you elaborate on those?
The pumps were basically the 63-65 pumps, small feed and scavenge, then the 66-68 pumps with slightly larger scavenge, then the 69 through E. 73 pumps with larger feed and even larger scavenge plungers, then the oval port 750 pumps.
(I'll have to recheck this info. and the years, but that is as I recall it off the top of my head)
"When did o-ring pushrod covers become standard? Can they be retro-fitted?
Oring pushrod covers came out in 69 and in 70 they were improved with the addition of a 3.5mm rectangular section seal ring, as per the 66-68s, with a "wedding band" to retain the seal, so that it doesn't squish out. So it has the dual seal.
They can be retrofitted to earlier tappet blocks, but you have to trial fit them, note the "squish" ...the space between the head and head gasket, and adjust with steel or fiber washers to get about .060". The best way is to use the 69-on tappet blocks in the cylinders, too. But you have to remove the cylinders to fit them.
What is the story on “…no oil bleed to the pushrod buttons in the rocker arms.�
The earlier engines used an oil drillway from the bore of the rocker shaft, out through the arm to the pushrod button, which also had a hole drilled accross it and then down the center, to feed oil from the rocker shaft to the pushrod cup. The factory finally figured out that it's more important to get the oil to the spring and valve than the pushrod cup, which retains oil fine, thank you. So the 69 and later arms and buttons were solid (making it easier to grind and lighten the rocker arms) and the oil exits from a notch in the inboard end of the rocker arm, drizzling onto the valve.
Why is the ’71-’72 four speed preferable?
The engaging dogs are larger and less numerous, making engagment easier and quieter, and the camplate was hardened and ground, and the false neutrals were eliminated.
"For the “ultimate†Triumph I gather you would go with a five speed and alter the final drive ration to make 5th gear a poor man’s overdrive."
Exactly. I would have to adjust this depending on what the primary drive ratio is on the belt drive. But with the stock primary chain set up, I would do (and have done) just as I wrote....five speed with 20T and a 43T rear. If running two up a lot, I would go down to 19T and use a heavy flywheel.
“A small weight difference if you are comparing stock systems, but you can save a lot of weight (unsprung weight, at that) if you dump the iron lump of a caliper and fit a Grimeca or better yet, a four pot from Performance Machine, or it's ilk, and drill the disc, or better yet, get the 12" conversion.â€
Is there a practical way to reduce unsprung weight on the DLS? Drilling it full of holes may be ok for competition, but for a street rider?
Alloy rims are a good start. You can bore some holes in the side of the hub, and put some screen on it. I don't use the "nave plate", or left side cover plate....just extra weight to me. I also bored the ends of the axle and turned the center down a little. I removed the grease seals and installed sealed bearings. I drilled the brake shoe webs and the retainer ring. I plan to drill the hub flange between the spoke holes and I would like to turn the hub to thin it a little. I made alloy axle caps and other light parts for the forks, too. Delrin or teflon bushes are on the list.
"What is involved in installing a lighter caliper? Do you need to fabricate a different mount?"
The Grimeca, Lockheed alloy, and Performance Machine calipers are all direct mount, as per the stocker, if you use the stock disc. The larger disc will need an adaptor mount, supplied with the kit.
" I never tried to drill a disc. Can I do it myself, or is it best left to machinists? What about hole sizes and patterns?"
I've used holes from 3/16 to 3/8" and it doesn't seem to matter much as far as function or noise. I used a swirl pattern done on an indexing head in a mill, and I would use that system to keep the pattern regular and the disc balanced.
“You can fit a larger filter in the air stream and get some additional oil volume and surface area to cool. HD aftermarket companies used to carry an aluminum finned cup that pushed onto the filter housing and supposedly pulled heat out of the oil. Looked trick.â€
"I remember seeing some of those finned covers for oil filters; they did look trick, and no doubt helped to cool the oil too. I viewed the oil filter as both a filtration and cooling benefit. Even if I removed the filter eventually (to save weight) it seems like a mod easily installed/removed and particularly useful during break-in."
Right. I removed my oil filter after changing to synthetics and doing an autopsy on a couple of filters after changes.....no metal in the filter, they looked nearly new inside...just some carbon bits barely visible....nothing which would attract to a strong magnet. I'm using this engine as a test of synth. oils and have been extending the change period every time. I am up to over a year or 8K miles. now. I will be pulling the engine down after nearly 90K miles and doing a report on what I find.
"The nikasil cylinder thing is interesting, but I am afraid there is no room for bling in the budget right now (and for that kind of bling, no room in the foreseeable future!). But even alloy cylinders with steel liners should be good for weight savings. Is there any other option besides the MAP alloy cylinders? (I realize I am getting off the Triumph parts only exercise here, but curiosity is getting the better of me.)"
There were long rod alloy kits made by Wellworthy and by Chantland, but both are hard to find and had stud retention problems. The Harris short rod kits were ok, once the threaded inserts were installed, but are not common anymore. If you aren't going all the way for light weight with the nikasil, I would stick with iron barrels...they are very sturdy and act as an anchor in the center of the alloy engine, tying everything together firmly. It also makes it much easier to get the squish area right and stable, as the alloy cylinders grow much more than do the iron cylinders.
â€OOPS, missed this...the shuttle valve forks were installed on the 650s and Tridents from 68-70 and on the 500s from 68-74. Only the very last few 500s got the disc fork in 74.
The early 68 forks had CEI threads on the caps and bottom nuts (in the stanchion) but the rest had NF threads.â€
"Were the disc brake forks any better or worse than the DLS shuttle valve forks?"
They are comparable, but you will change stanchions more often with the disc brake forks, as they do not have replaceable bushes, and the chrome eventually wears off at the loaded points, one on the bottom, one at the top of the slider. Both are dual damping, unlike the pre-68 forks, which only damp on the rebound stroke. It's easier to adjust the spring tension with the internal spring forks, but I have seen early forks converted to internal springs. I still think adapting the thin wall chromemoly Ceriani stanchions and guts to the disc forks would be the bomb.
"Ultimate horns?"
Ballast. Toss 'em.
" Thanks for all the input guys. As in so many other things, the more I learn the more I realize how much more there is to know."
And you will know it, just takes time.
