[TR] TR4 road draft tube plug

[Brad Kahler]

I forgot the TR3/4 engine was also used in a few other Triumph models.
Maybe Andy Mace will chime in with his knowledge of the other Triumph
models.



On Tue, Sep 8, 2015 at 10:10 PM, Dave <dave1massey at cs.com> wrote:

> Well, of course the upper part isn't sealed from the lower.  The oil
> pumped to the rockers has to drain back down somehow.  As was mentioned
> previously, it goes through the push rod tubes.
>
> My guess is that the cover is used in other applications (Vanguard?) and
> whatever it was for was not implemented on the TR.  Not enough space under
> the hood.
>
> Dave Massey
>
> -----Original Message-----
> From: Brad Kahler <bkahler1 at gmail.com>
> Subject: Re: [TR] TR4 road draft tube plug
>
> Alan,
>
> So much for the official Triumph documentation!
>
> Does anyone know why the real early TR4s (and I think late TR3Bs) had the
> brass plug in the top of the valve cover?  I've never seen anything
> relating to that plug written anywhere.
>
> I don't think the bottom end can be completely sealed due to the openings
> for the push rods.  When the switch was made to the "sealed" system the
> draft tube went away for good.
>
> Thanks,
>
> Brad
>
>
> On Tue, Sep 8, 2015 at 4:48 PM, Alan Myers <amfoto1 at aol.com> wrote:
>
>>
>>
>> ... 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
>> cover
>> along with a "sealed" valve cover cap and no road draft tube.  TR4As had
>> a
>> gulp valve with a vented (1/8" metered opening in the cap) valve cover
>> cap
>> and no road draft tube.  This information was found in Service
>> Bulletin
>>
>>
>>
>> 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
>> http://www.triumphowners.com/to-car/tr4-14/
>>
>>
>>
>  <http://autox.team.net/mailman/options/triumphs/dave1massey@cs.com>
>
>
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