• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR6 Blue Smoke and Bulletproof TR-6 Engine

Share this page

Mark_Gibson

Mark_Gibson

Jedi Trainee
Offline
Now that I've found the culprit to the insect fogger engine problems on my car, I'm going the extra few steps and renewing those parts I should have done in the first place when rebuilding my engine. The valve guides are shot, so the head is getting a total rebuild. The rocker shaft was worn badly, so new rocker shaft and rocker arms. I measured the cylinder walls to determine just how much wear was on each and the numbers are pretty amazing. Standard bore is 2.940 inches. My numbers ranged from 2.943 to 2.945. This is an engine with at least 150K on it before overhaul! I'm replacing the pistons with new (std) along with the rings since the ring seats were worn as well. This time the engine should run correctly, no smoke, and better oil pressure. Lesson learned..always time to do it right the 1st time, or plan on doing it at least twice.....ha!!

Mark
1970 TR-6
 
Hi Mark.....
If I read your post correctly your engine has not been rebored or anything in over 100K miles. Also, you've got wear of about 3 to 5 thou, probably different amount on each cylinder and likely varying top to bottom of bore and varying around each cylinder, more on the thrust face.
I would say this is really a candidate for a rebore. If you just stick new pistons and rings into it you are only doing half a job and might be disappointed with the results.
If you do decide to leave the bores as is, you need to break the "glaze" on the cylinder walls with a hone you can rent it and chuck it into your power drill, go slow in a herringbone pattern and cover the crankshaft journals with cloths to keep the filings out, this will let the new rings bed in quicker. There is always a ridge that forms at the top of the cylinder wall where the old piston rings didn't sweep, you MUST remove that with the hone or the sharp corener on the new top ring will hit it and the ring will be broken on the very 1st stroke./ubbthreads/images/graemlins/hammer.gif
Good luck with the project, let us know how you make out.
By the way, the mosquitos are coming on strong up here, maybe I can borrow your car! /ubbthreads/images/graemlins/jester.gif
 
Hey Graham,

The cylinders were honed and ridge reamed before we put the new rings in before, and the car only has about 45 minutes of total run time, so they should be fine. As for being a candidate for a rebore, most of the LBC mechanics up here told me that with wear at .005 or less, reboring the motor isn't necessary or warranted. I had excellent compression with the rings, just no oil ring action. Good luck with your mosquito problem!!

Mark
 
Back
Top