Triumphrat

JohnG · 01-14-2008

I've been reading the posts in this forum for quite sometime but I've never registered until today. I'm John, I live in Vermont and my ride is a '79 T140E which is due for a rebuild from the cases up. Since we get more than our fair share of snow up here, winter serves as the ideal time to undertake such a project.

I don't want to screw this up so I've decided to get some help. The engine is ready to take out of the frame and my AMAL IIs are residing in my music room waiting for attention. I've read some posts awhile back that mentioned the cams on the T140s being mismatched. The posts describe the intake as a fairly hot cam and the exhaust as detuned, in order to save the main bearings. A simple fix is, upon rebuild, to install a t120 cam or after market for the exhaust. I think I'll give it a try.

I have several questions that need to be answered soon, since this project is going to happen quickly. The first question is, what about the main bearings? Are the new replacement bearings going to be able to take the power increase? What bearings do you recommend? Any suggestions would be much appreciated.

Second question is will the new cam install without any case modifications? I hope so, I don't want to get out of hand with this project, I'm interested in realizing the T140 that could have been . . . .nothing more.

Third question is tappet clearence, what is it with new exhaust cam, does it stay the same at .006?

And last but not least, the AMALs. The were sitting in the living room until my wife got sick of the gas smell so now they're in my music room and as a result my guitars smell like Joe's garage. I've got to get these rebuilt and out of here. I plan on keeping the stock exhaust but nevertheless, a different cam may require different jetting? Any suggestions . . .

I think most of my posts here will be asking for help as opposed to offerring advice, however if I can ever answer an HVAC question I'll be glad to help.

JohnG

GrandPaulZ · 01-14-2008

Modern replacement bearings, and stock T120 cams are drop-in replacements with settings by-the-book, including valve lash.

My wyfe HATES when I work on carbs, especially when I've been dipping the metallic parts in Berryman's Chem-Dip.

Welcome, and have fun with it!

Mecchanica · 01-14-2008

Aloha, and welcome. Yep, new bearings will do you right, MRJA 1 1/8 roller on the left and a 6306 on the right. I believe the tolerance on the roller is C2. different from the C3 used by the 650s. Or is it the other way around? I'll find my notes. Remind me later.
You should be able to find a 6306 ball bearing with eleven balls, compared to the standard bearing with eight. But the standard bearing is fine. RHP, SKF, or FAG make good ones. Tolerance code is C3.
The only arcane operation you will encounter is replacing and fitting the cam bushes, should you need to or want to change them. Check the clearances with the new cam and the cases bolted up in a mock up, before fitting the crank or any sealer is applied.
Remove the sludge trap and thoroughly clean it and the crankshaft. Remove any nicks in the alloy of the con rods and polish. I would also have them shot peened and have the big end checked for ovality.
You want a 69-72 nitrided exhaust cam. Or a Norman Hyde replacement which has the same Thruxton grind as the inlet.
Fit new tappets or have yours reground. I believe the Hyde cam uses STD tappets, as does the stock inlet cam in your bike. You have R radius tappets in the exhaust. The 650 exhaust cam used the R tappets, too, so that stays the same, unless you want to run the STD tappets there....that softens the tune just a little but gives better midrange torque which is the forte of the short rod 750 engine. Better durability, too.
I like a lightened valve train, even with stock engines, as it makes everything last longer and you do fewer adjustments. Grind and polish the rocker arms, allen adjusters and alloy locknuts, tubular pushrods with steel tips, lighter tappets (I run lightened T100 unit tappets and special pushrods to get even less mass). Alloy or titanium top retainers. Fit new springs and check the pack length. Use Ampco 45 nickel-bronze alloy guides and Kibblewhite Black Diamond valves, no others will do.
Lighten and balance the clutch chainwheel. I usually fit the duplex chain 650 primary set up in place of the triplex 750 if I am looking for more snap. You will get a little more wear, but since the load centerline moves closer to the bearings, I see fewer broken transmission mainshafts and less high gear bearing wear with that set up. You could also just fit a duplex chain on the inner two rows of teeth on your triplex sprockets. Belt drives are also pretty neat for getting rid of mass, but are pricey. Drilling and balancing the chainwheel does a good job and it allows oil to be slung out faster, so less slip. I have some alloy plain plates which need to be garnet blasted and hard anodized to work properly, but they save at least a half pound of rotating mass. I use the MAP alloy pressure plate. Doesn't save much mass, but is stiffer and has an extension on the adjusting screw which keeps it centered on the mainshaft. It uses a coarse thread, so you have to reduce the amount you back off on the adjustment to get ten thou. clutch rod end clearance.
The gears are fine as is, you should have the low-inertia camplate fitted already, so just install new bearings and thrust washers and you should be good.
Beautiful forged 9.5 to one pistons are available and, with this cam, will significantly up your midrange pull. Your stock pistons are 7.9 to one.
Have the crank, rods, rod bearing, and piston assemblies dynamically balanced.
Use a free flowing exhaust and rejet the carbs as needed.
Adjust valve clearance to .008 inlet and .006 exhaust, unless you use the tubular pushrods. You can drop the clearance by a couple of thou with them, as they grow less with heat.

DAGAD · 01-15-2008

Hi John, good sound advice from Mecchanica, as usual. However, the stock T140E exhaust cam has the fast road E3325 T110 profile as std with 3/4" radius followers. If you fit the E9889 with casting #E3134 you will get the effect that Mech says, better lower torque. Hydes cams are; 3/4 race ones are the 71-7016 'SPITFIRE' profile and his 1/2 race are the E3134 profile. The Spitfire profile is std inlet cam on your bike. Using a Spitfire inlet and exhaust with single carb makes a quick responsive street motor.

YOU MUST EITHER FIT NEW FOLLOWERS OR HAVE YOURS RE-FACED PRIOR TO FITTING TO A NEW CAM.

I would advocate a dry belt primary, but you will need to do some engine breather mods as well. If your std primary is not too bad, just rebuild that. Please make sure you strip the shock absorber and replace the rubbers and back plate AT LEAST. This item is often over looked and can be the source of bad clutch operation. I like the idea of fitting the duplex chain wheel but I like a belt better!

A better main bearing, as fitted to the T140W (TSS) and subsequently ALL post 1981 bikes is the NUP306ECP roller bearing for the TIMING SIDE. DO NOT use a 6306, replace it with the NUP, far, far better and no more expensive. It is a 3 piece roller bearing comprising inner race, outer race and clamp plate. Fit the inner race to the crank with the shoulder up to the crank cheek. The clamp plate and outer race are fitted into the crank case with the clamp plate nearest to timing gear, but INSIDE the bearing housing. Vey strong and durable.

The MRJA 1 1/8 on the drive side, IT MUST BE C2 CLEARANCE, VERY, VERY IMPORTANT.

Finally, attention to detail and cleanliness, remove all sharpe edges, pay particular attention to con rods and as Kim says see if you can, get them shot peened. This removes the surface strees and helps to reduce any surface imperfections which could lead to a fatigue crack and result in a rod failure.............. YOU DON'T WANT A ROD FAILURE, BELIEVE ME. Boy does it make a mess! Fit new con rod bolts and nuts as a matter of course.

Big D Cycle did a fact sheet and on it was their suggestion to convert / modify the MKII Amals for easier starting and better running. It may still be available from them but if not, PM me with your email address and I will send it to you. I have used their settings on various T140s with MKII's fitted and it does make a difference.
Roy.

JohnG · 01-15-2008

Thanks for all the advice. I'm going to print it off and decide what to do once the cases are split and we look to see the condition of various parts.

I found the bike while I was on a service call out in the boonies of VT. I always dreamed of finding a treasure in a basement and it came true. While I was working on the customer's equipment, I noticed what appeared to be an old bike under a tarp over in the corner. Covered in dust and spider webs, I lifted the edge of the tarp for a peek and was greeted by a big Lucas headlight, HELLO. I had to call the customer and tell him that there was a problem with his equipment and at the end of the conversation I said "Oh by the way, love the old Bonnie." When he replied that he was thinking of selling it . . . . . well to make a long story short I bought it. It ran well for its first outing in years but the seals are hurting as are the AMALS.

The engine ran fine for a bike that was run sparingly for at least the last 6 or 7 years, in fact the bike hadn't been inspected since '02. The more that I drove it the worse the oil leaks became until the exhaust pushrod tube sprang a serious gusher; that's when push came to shove. Granted, the compression was down to 120 psi but it was even across both cylinders.

All seals will be replaced, sludge trap replaced, new rings, rebore if necessary, new main bearings, and a new yet to be determined cam setup. I'd like to do more but I'm on a budget due to eldest daughter deciding on getting married this summer . . . . weddings aren't cheap.

I think the AMALS were in bad shape since heavy carbon on the plugs was a problem and yet if I was accelerating hard at say 3.5 to 4+k RPMs it would spark tick hard as if it were running lean. I think that they sat way too long.

DAGAD, I could sure use some advice rebuilding the AMAL IIs, I'll be in touch. Say . . . DAGAD . . . is that something like DADGAD . . . that's a type of tuning I play some songs on guitar with. . .just curious.

If anyone can think of anything that I should know please don't hesitate to give me a heads up.

Thanks for the help
JohnG

Mecchanica · 01-15-2008

Thick crusty carbon is likely from the oil you are burning, as well as leaking. Late Triumphs are lower compression, so 120 isn't excessively low for a 79. I would suspect the valve guides. Wet sumping is something to keep in mind, too.
Tell the darling daughter to elope and then do the bike right. It'll be around your home longer than she will.

DAGAD · 01-16-2008

John, DAGAD is what my Grandson calls me.
Mecchanica, not sure about your last sentance, one thing is for sure they both EAT MONEY.
Roy.

Mecchanica · 01-16-2008

Yeah, that would be the worst of both.....she gets married and both of them stay at the house. Whatever. Do the bike and you won't regret it.

JohnG · 01-16-2008

The wedding decision is out of my hands, so are funds unfortunately.

I think that I will go with the T120 exhaust cam. If I wanted a screamer then I wouldn't be rebuilding a '79 bonnie. You mentioned a better breathing exhaust to go along with the cam. Presently the bike is running stock canisters and I like how they look, plus I want to keep it looking original . . . any suggestions?

I agree that the valve guides will need attention as will valves and springs.

The rods and several internals will be shot peaned, another good idea and my friend agreed.

The carbon on the plugs . . . . I really think that it was running way rich some how.......I took off the exhaust this past weekend and you can collect the soot in the exhaust outlet by the spoon, it's a mess. It's not thick or oily . . . .you can blow on it and it comes back at you , , ,lots of soot

JohnG

Mecchanica · 01-16-2008

Ok, good call, it sounds like soot. Check the choke setting. Some people run around with them in the ON position without knowing it.....ON is the default position for the spring loaded choke. You want to rotate the lever all the way clockwise and tighten the center screw in the lever assy so it doesn't move.