[TR] TR4 road draft tube plug

Dave Connitt dconnitt at fuse.net
Fri Sep 11 16:30:06 MDT 2015

Hi Alan,
I enjoyed reading about your TR4 on your website. I have a TR4A that is finally back on the road after 15 years. The reason I am writing you is that I have been working through crankcase breathing issues since getting the car drivable about 1-1/2 years ago.
I have a aluminum valve cover on my engine which as you know has a spigot for the gulp valve but is missing a baffle to keep the oil mist from being sucked directly into the intake manifold. I discovered this by accident though.. When I originally had the head rebuilt back in 2007, the machinist installed bronze valve guides which was OK I suppose but the bad news was that there wasn't enough clearance between the valve guide and the valve stem. The result was that if I got about 2,400 RPM the valves would start making clicking noises like a collapsed hydraulic lifter makes. It seems the valves were sticking in the guides at speed.. Ruined my new BP270 camshaft and lifters.. BUT the reason I am telling you this is when I had taken the engine apart to fix this after only 500 miles of operation, there was a ton of carbon buildup on the piston tops, combustion chambers and exhaust ports. The gulp valve was completely soaked with oil also. 
The engine crankcase ventilation system was completely stock at the time (minus the fancy aluminum valve cover).  I decided to go "old school TR" and install a TR4 road draft tube and figure out something for the valve cover breathing. Removing the plug in the side of the block was a giant PIA as there is no room down there at all but I finally got it out by drilling a hole in the middle of it and screwing a drywall screw in and pulling it out that way. After carefully cleaning out all the drill filings (not much there at all) I installed the road draft tube. Regarding the gulp valve, I removed it and plugged the hole on the intake manifold and installed a K&N breather in the spigot on the valve cover. The volume of leaking oil diminished greatly but it still leaks some. The engine uses about a quart or less of oil every 2,000 miles and pretty much all of that is leaks. 
It's amazing where these engines leak from.. I had moved the ignition coil off the block and onto the fender well right across from the distributor to keep it cooler. Never understood why they bolted the coil to the block?? Anyway, I hadn't replaced the two small bolts in the block that hold the coil. I noticed drops of oil spattered on the driver side inner fender but couldn't figure out where it was coming from until I had a friend rev  the engine while I bent down and watched the engine. That was when a drop of oil flew past my head after coming out of one of the coil bolt holes!
Back to the venting issue, I have considered replacing the K&N breather with a catch tank arrangement. I found there are some two stage designs out there that have space to actually distill  the oil mist into a liquid but where can you plumb the oil back into the engine? I think if you had blanked off the mechanical fuel pump, it would be fairly easy to plumb a drain back into the block from the catch tank that way which I think is what the GoodParts system does but I am still a fan of the mechanical fuel pump so I am stuck..
I am enjoying this thread as this is something I am currently working.
Thanks to all for the good information!
Dave Connitt
  ----- Original Message ----- 
  From: Alan Myers 
  To: triumphs at autox.team.net 
  Sent: Tuesday, September 08, 2015 4:48 PM
  Subject: Re: [TR] TR4 road draft tube plug

... Then at
engine number CT14234E through end of TR4 production the
cars had air
filters with vent openings coming from a flame trap from the valve
along with a "sealed" valve cover cap and no road draft tube.  TR4As had
gulp valve with a vented (1/8" metered opening in the cap) valve cover
and no road draft tube.  This information was found in Service
  I can tell you for certain that's incorrect. The change from open breathing to flame-trap, etc. came later than that.

  CT17791E (fitted to CT17602L, built in late October, 1962) originally had the vented cap and the road draft tube. 

  The cap is the push on type, has big vents on the underside and filled with coarse  "steel wool" to reduce oil spray, I'm sure. 

  The road draft (or draught, I suppose) tube is large diameter, press fit into the side of the block and locked in place with two screws (maybe 1/4 or 5/16"). 

  The original valve cover has no vent, but it does have a large brass plug where one could be fitted. 

  Never had a problem with oil out of the push on cap or an unusual amount of leaks.... but the road draft tube kept most of the underside of the car rust free! 

  The car now has an aftermarket cast alu valve cover with a breather pipe and a low profile, twist-in filler cap (with a single, tiny breather hole). 

  I've replaced the road draft tube, but didn't plug it. It now has a nipple for a 1/2" or larger hose fitting. I don't think it's a good idea to completely seal up the bottom end of the engine. It needs to be able to breathe, same as the top end. 

  Car is not yet back on the road, but when it is the plan is  to have a catch tank or can fitted with a breather cap, with hoses running from both the valve cover and the fitting at the draft tube.

  I intend to use a catch can similar to this: http://www.summitracing.com/parts/jrc-555-6402

  Alan Myers 
  San Jose Calif. 
  '62 TR4 CT17602L
  amfoto1 at aol.com


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