TR6 TR6 Bottom End Work

[Guest]

OK guys, I could use some advice here. My oil pressure in my TR6 has been getting progressively lower over the last year or so, to the point now that I am uncomfortable putting any more significant miles on the engine. Cold idle pressure is somewhere around 75psi, with fully hot pressure running around 12-15psi, hot pressure @ 60mph being around 25psi. My car has 75K on the clock, what I believe to be accurate original mileage, and the bottom end of the motor does not appear to have ever been opened up. It looks like it's bearing and thrust washer time, and I'm planning on replacing the oil pump just for good measure. My question is, what type of bearings are good and bad, and where to source them from? The prices I've seen from Moss aren't bad, and since I will be at fallfest this coming weekend if I buy them there I get an additional 15% off. However, what brand does Moss stock, and is it any good? I've heard and read that Vandervell bearings are considered excellent but are very hard to find since they are no longer being produced for Triumphs. I've used Clevite bearings in just about every Mustang, Ford, and Chevy I've ever built and have been very satisfied with them. Do they make bearings for Triumph's and if so where to get them? Also, what kind of quality can I expect to get from the pump if I get it at Moss? Is there somewhere else to source this stuff from with better quality and comparable prices?

The actual job itself doesn't look hard at all, so I think I'm fine on the technical end of things. Only part that worried me is that front sealing block, seems everyone ends up with stripped holes in that thing and not enough torque to seal against the gaskets. I'll see if I can get away with using my stock piece but I get the feeling I may end up buying one of those solid steel blocks that there was a link for a few weeks back that somebody is making. Getting the other parts is what I'm concerned with. I've read a few things online about people using some crappy quality bearings and having them look like heck a few thousand miles later. I'd like to avoid that if possible since I don't plan on opening this motor up again until I'm ready to do a complete rebuild with some performance work, say 5 years from now, or possibly longer. I haven't done that much digging on my own yet, so I may find some options between now and whenever there are some responses here, but I'd rather hear from some with more experience with these parts and vendors than I have. This seems like a pretty common job for these motors, so I'm sure there are a bunch of people on here with good experience and expertise.

As always, thanks in advance.

 

[Mark_Gibson]

The Roadster Factory is a good source for engine components, I purchased most of my rebuild stuff from them and am happy with the results. They don't sell aftermarket bearings and such. Don't forget to look at your rocker assembly as well. A worn rocker shaft can cost you quite a bit in oil pressure readings..take it from someone who has experienced that! Good luck with your rebuild,

 

[SkinnedKnuckles]

Another thing to consider is the oil pressure relief valve & spring. Since you'd want to renew those with any rebuild, why not start there? Pull the spring & plug, inspect the plug for wear (replace if worn - you'll see it), try measuring the spring, then stretching it 1/8" and see if that boosts the oil pressure. Just to be sure it's the bearings. 75k miles is not really horrible - bought mine with that and ran another 25k before rebuild.

Brent

 

[Guest]

Scott, call Dave at TRF @ 1-814-446-4491 from 12:30 pm till late. Free tech help. Dave has forgotten more about Triumphs than some of us will ever know.

Bill

 

[Guest]

Some good ideas heres, thanks. Brent, I'm going to take your advice and play with the pressure relief valve first, maybe a cheaper and easier solution, if I could only get that lucky. I don't think my valve train is the culprit here. When I bought the car I did a top end rebuild and had the rocker shaft apart. The shaft itself was in good order (or so it appeared), but several of the arms had scoring to the inside of the bores, like a piece of grit got trapped in there and wore a nice groove. I replaced the arms that had scoring. I am running the external rocker oil feed line to the head, does using on of those tend to create a pressure drop? I did manage to find a retailer selling Clevite 77 trimetal bearings for this motor, but the cost for the mains alone was $85 for a set, double what the big three want for their brands. I saw a few others selling Beck-Arnley but I don't know anything about them. Still don't know what brand Moss sells, but it seems the cheapest out there are King, maybe thats what they supply.

I'm gonna buy all the stuff for the bearing job tomorrow at the Moss show anyway, the 15% off is something I don't like to miss, plus I'll pick up a new relief valve spring and plunger. If the pressure relief valve or something equally simple is kaput then I can always return the unneeded parts, they're only about a 45 minute drive from me. I have to adjust my valves anyway, so I will take a closer look at the current condition of the rocker shaft and gear just to make sure there's not something funky going on in there. Hopefully thats OK, those parts are expensive.

Once this is done I can start tearing apart my rear suspension, one of my hubs is humming like crazy. It never ends.

 

[vettedog72]

With 75K miles, I would put new pistons (about $275 w rings and pins and circlips) in and have a machine shop ck the rods and true as required; also have the machine shop put the pins through the small end of the rod and ck for proper clearence, unless you have experience with that fitment. I would faint if the pressure relief spring and ball was binding in a way to prevent required oil pressure, but I would put in a new one anyway. Oil pumps for TR6's all seem to be near OEM with no HP or high volume options available but, I would put in a new pump anyway.

While you are there, you will be remist if you dont get the "new" valve cut (3 angle, 5 angle what ever is in vogue) and work the head a little (mate the intake ports to the head ports and ck the valve guides; if it is '74 and newer, and the head has never been shaved, take 90 thousands of more off to get 9 to one ratio. The amount to shave is measure by the hight of the combustion chamber to the head surface. If you are interested in doing a shave, get the specs from some very knowledgeable forum members here. Also, you will have the water pump off, at 75k put a new one on with new hoses all around.

Can't waite to hear what break in oil and procedure you will be using!

Got the head off yet? /ubbthreads/images/graemlins/grin.gif

 

[Guest]

Vettedog, what you're describing is a little more involved than what I wanted to do at this point. A full rebuild is in my plans but not for a few years. Basically I just want to get the motor in good enough shape to last the next few years. I don't put but 2 or 3 thousand on the car /year anyway so if I can throw in a new set of bearings and whatnot and that gets me through then so be it. However, what you've mentioned is the way i will be going when the time for a full rebuild comes. New pistons, some balance work, some head work, etc.. I had a 3 angle valve job done on the head back when I did the top end (about 4 years ago) and at some point someone before me had already had the hardened seats put in, although I don't know if I agree with the need for those given the mileage I put on this car, but whatever, it was already there. I also had a few thousandths taken off the head just to true it up, but nothing significant enough to bump the compression. I've already got a new water pump and all new hoses, did those when the head came off. Overall the car runs excellent aside from the low oil pressure. I had some problems with fuel delivery a few years back, the mechanical pump crapped out twice, the second time only a few weeks after a rebuild. Thats when I went to the Facet electric pump, since then no worries.

I'm going to buy a new spring for the oil pressure relief valve, but here's a question. Moss sells a stiffer spring that they claim can boost pressure a bit more, is it worth getting this for a tired motor? Also, should I get the plunger as well or is the spring typically the only part of the mechanism that sees wear? I'm really hoping replacing this will bump my pressure enough to buy me some more time before having to tear into this motor. I've got a ton of other things going on around the house and with the kids right now and I was hoping to be able to drive the car a bit more before the really cool weather sets in.

 

[jimbar]

Hi Scott, I'll chime in here as well. IMO in most cases new bearing shells will do the trick. I'd also add the new pressure releaf valve and spring (mostly because they're cheap) just because your already there. Speaking of which you might as well add new thrust bearings. BTW oil presure is measured in pounds per rpm not mph, most rebuilders suggest min. of 40lbs at 2k rpm (at normal runing temp.)and don't even worry about idle pressures. Another note I'll add since we're on the subject, is new oil pumps. I've purchased 3 new pumps earlier this year and not one of them were in spec. . I ended up mixing up the parts from 2 of them and and bought a rebuild kit from BPNW to make one that barly made it under .004 (the outer limits of the lobes).

 

[vettedog72]

Sounds like you have a plan that will work well. I don't think the spring "wear out" on the oil pressure regulator. The only way to tell is to measure the strength (I have never seen a spec on the tension) When the bearings need replacement the best and least costly thing is to replace them. If you are like most enthusiasts, you have changed the oil far more than needed and the pump and regulator need no attention. I think the TR6 is a little hard on rod bearings and the thrust bearing failure or premature wear (IMHO) is a function of the pressure plate spring strength.