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Tips
Tips

TR2/3/3A TR3 engine building tips needed

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59Rob

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Hi guys, just cobbling together parts to rebuild the TR3 motor and was looking for any tips and suggestions for the build. I've never done anything major with a Brit motor. I have the 87mm piston/liner kit, new cam and cam bearings. Not sure what all else I'll need until we tear it right down other than a gasket set.

Cheers
 
Sounds like a good start. I would plan on replacing the timing chain & tensioner as a matter of course; if the old chain is badly worn then replace the sprockets as well. There is a new 'Viton' rear main seal conversion available that seems very worthwhile to me; but even if you don't do the conversion be sure to get (or machine) a proper mandrel for setting the seal in place. The dimensions given in the factory workshop manual appear to be a misprint, the largest diameter should be 2.818 instead of 2.822.

When you install the rear cam bearing, make sure it is turned the right way so the passage to the cylinder head is open. Also be careful to position all 3 inserts so the locating hole is centered and the tip of the special bolt can't grab the edge of the insert.

I hear that some gasket sets don't include enough felt for the rear main cap, so you may need to source additional felt. Soak the felt in your favorite sealant (I use Permatex #3) and tamp it into the hole until you can see the sealant fill the seam.

Valve springs are almost certainly tired. Probably the guides as well. And might as well install the hardened exhaust seats while you have it apart.

Be sure to carefully check the piston ring end gap in the cylinders. They should be fine since it is a set; but mistakes happen and some ring sets are supplied slightly oversize. Also check the liner protrusion on both sides. I've found two TR3 motors in a row now where the liner bores are not perfectly perpendicular to the block surface, resulting in the protrusion being different from side to side. And if it is less than the book value on either side, you're going to have a head gasket leak eventually.

Last gasket set I bought didn't have the fiber washer for the timing cover support, so I cut one from an unused air filter gasket.

Best to reuse the old oil pump, if it isn't too badly worn or broken. If you do replace it, check the new one for the cross pin holding the lobes to the shaft. Some of the aftermarket pumps don't have the pin, and the lobes tend to work loose with disastrous results. Also best to rebuild the original fuel pump, IMO. If you replace it, check that the pivot pin is positively located in the housing (eg clips on each side) rather than just staked in place. The staked version sometimes works loose and can break the camshaft when the lever jams.

Get the lifters refaced. If you do use new ones, be sure they are 100% tested for hardness. Be sure to use plenty of good assembly lube. On initial startup, run the engine at fast idle (1500-2000 rpm) for 15 or 20 minutes. According to Kas Kastner, this helps work harden the faces of the lifters & cam, to let them live longer. Use an oil that has plenty of ZDDP (like Valvoline VR1).

That's all that occurs to me offhand, tho I'm sure there is more.
 
Have the cam bearings placed by a machine shop. Invest in having the machine shop balance the engine. Makes it last much longer. Be sure to confirm all assembly tolerances, like plastigaging the main and rod bearings, filing the compression rings for end gap. If your pistons are not brand new, be careful that the ring lands are absolutely free of carbon or the rings will never fit. All this is detailed in the manuals. Have the machinist install hard valve seats and modern valves, as promoted in the Moss catalog. Use STP when assembling the rod and main bearings, engine oil on the rings/cylinders. Turn the engine thru a full revolution after each bearing is torqued. This will alert you to tightness problems immediately. I used a new original aluminum rear main seal; couldn't bring myself to drill the two extas holes in the rear main cap that the Viton kit called for.
More, of course, but I can't think of it now.
Bob
 
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Not much to add, but I can confirm what Randall says about the mandrel dimensions being wrong in the workshop manual. I made my own mandrel to the dimension suggested above (2.818") and so far, (knock on wood) no leaks from the rear main. I firmly believe that if set up correctly, the TRactor rear main "seal"...it's really not a seal per se, will keep the oil where it's supposed to be. One of the guys in the club with a TR4 used a mandrel he got from Moss, which was even larger then the workshop manual shows. I warned him about it BEFORE he stuffed the engine in the car, but I guess it fell on deaf ears. He's now suffering the consequences.
 
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