General Tech Cam bearing line bore

[tinman58]

O.K. I have 3000 miles on the 250. Oil pressure at idle is 0, oil consumption is high. Pulled out the pistons and found #6 connecting bearing wasted. Pulled the motor out of the car and started the tear down. Pulled out the cam and the bearing at the rear is also wasted. Something went thru the motor. I have ordered cam bearings. Bit the problem is I can't find a machine shop that can line bore a six cylinder triumph motor. Does anybody have a idea where I can go? I am in Brentwood CA. (Bay Area) Thank for the help.

 

[Jerry]

Dan,
Was the oil consumption always high? We rebuilt 3 engines last year after a big sale at MOSS and the oil ring did not work. High oil consumption in the two engines that had oil scraper rings with the squigly piece of metal in the middle. The tabs broke off the ends and so the oil was being burned.
I do have someone here in North Sacramento that does old engines but I don't know anyone close to you.

Jerry

 

[tinman58]

Hi Jerry
Yes the oil rings that expand in the middle broke at the ends. I lapped them over. Their is a red and green color on the ring. You are supposed to see both colors when installed on the piston. I installed mine with the green color only showing. (WRONG). Their was something left in the oil passage way that did not blow out with compressed air. That piece of metal wasted the #6 connecting bearing and also the rear cam journal. I will drive to Sacto. if the Guy can do a line bore on the TR6 motor. Send me his name and I can call them.
Thank you Jerry!!

 

[Keoke]

Hey Dan:

Since you are willing to drive why not go to British Specialists -David Knock In Stocton CA????

 

[titanic]

I have noticed that GoodParts bores the blocks for $300 (plus parts), which is about half of what many people have reported paying. Of course, the shipping to PA would probably wipe out most of the savings. OTOH, they are familar with the job.
Berry

 

[tinman58]

Thank You BCF! After calling about 20 machine shops around the bay area, Keoke (post above) said the obvious! Just called them and they will call back with $ and time!

 

[PatGalvin]

Dan, are you line boring the crank mains or the cam holes? Just wondering. Tryin' to learn something new here. Really sorry to hear about this engine work. Your car is a beauty!

 

[tinman58]

Hi Pat
It is the cam bearings that need to be installed. The TR6motors did not come with bearings. The cam rides right on the block. When the bore is tore up, then you install bearings (from a spitfire). The connecting rod bearing is also toast. Along with the crankshaft.


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[Jerry]

Sent you a private note: Also, we replaced the bad oil rings with rings from Hastings and the oil consumption went away. Those tabs broke off in two engines, multiple cylinders. I think something is wrong with them.

Jerry

 

[tinman58]

Thank you Jerry
i will call him in the morning!

 

[PatGalvin]

Thanks for the explanation Dan. I have much to learn about the TR6 engines. Haven't dug into the 250 project yet. Maybe this winter will be a good time to start?

Best of luck with this engine work.

Pat

 

[tomshobby]

When my engine was machined for cam bearings it was done at a diesel shop. None of the engine shops could do the work because the bore was too small and deep for the tooling they had for their boring bars. The diesel shop did it using a hone.

 

[tinman58]

I called British Specality in Stockton. They can send it out to be done. $700+ (ouch) I think it might be looking for another block in good shape. Clean, clean, clean and do it yourself! Expensive lesson.

 

[tomshobby]

Dan, that is about the going rate. Glad I did it though. I did other things often overlooked when guys rebuild their engine but I wanted to use my TR6 for touring and since have traveled through 28 states coast to coast and in western Canada. It has over 50,000 miles on the rebuild and does not use or leak oil. Most folks have no intention to use their car that way so for them cutting corners can work fine.

 

[CJD]

Clean, clean, clean and do it yourself! Expensive lesson.

Sorry to hear...

The best way to clean passages is with a rifle cleaning kit, using different caliber brushes as needed. Use plenty of carb/brake cleaner, and brush the passages till you can't stand it anymore. I finish with soap, hose well with water, then brush some more. Of course, oil immediately after to prevent rust.

If you have tanked the block or had any machine work at all done, then all the oil gallery plugs must come out before cleaning. I never start the build till I can say I have no question about any passageway being scrubbed raw.

 

[Jerry]

If it makes you guys feel any better about stuff left in the engine, my first TR3 froze up about 50 miles from rebuild. Apparently a chuck of metal was left in the crank after turning. It wedged between the bearings and locked up the engine. Now I really wash out the cranks and oil passages of the blocks prior to re-assembly.

Dumb lesson number XXX

Jerry

 

[CJD]

Every amateur rebuilder makes this mistake...once!

 

[titanic]

As I mentioned in a previous post (#5) Good Parts will bore the block for the cam bearings for $300+$60 for the bearings+$30 for installation. I don't know what it would cost for the shipping, but might not hurt to check. Probably the total cost of rebuilding a locally obtained block would be in the same ball park.
Berry

 

[smaceng]

BTW Jerry, what brand were the faulty rings?
Scott in CA

 

[CJD]

Was it bad rings or the overlapped spacer that caused the failure?