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What's this hole in my valve cover

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doughairfield

doughairfield

Jedi Trainee
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I'm thinking this hole in my valve cover is for where a rebreather would go and then port to the air cleaner. All the pics I have seen just have a bolt in that hole as I don't think a rebreather was standard on my 64 TR4 car. I'm guessing that I'll have to pull the valve cover off and try to back that broken piece out from the underside. Or maybe I'm totally off on the whole thing.

Any thoughts?
 

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I think it is about the worst thing that could happen to a TR4 and that you should sell yours to me! :yesnod: :laugh:

If I remember from the '64 I had (45-43 years ago) there is a kind of "Y" tube that goes to the air cleaners for a crankcase vent.
 
That valve cover usually has a big brass bolt head in that spot (no idea why).

Yes, somewhere about 1964 a tube was added to the manifold side of the cover to accomodate the first generation PCV -- it wasn't very 'P' (i.e. not enough ventilation to offset the elimination of a breather tube.

Your TR4 may be registered as a 64 but have been built prior to the changes to the cover, etc. Do you have a crankcase breather tube on the block just below the fuel pump? If so, then I think that is the correct valve cover for your car.
 
Here is a photo of my 64 TR4.
 

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Yes, I think I do have that breather tube. It sticks straight down and has a ~45 degree edge at the bottom.

Any suggestions as to how to fix that hole in mine?
 
Looks like you have an earlier TR4 (62-63?) that was titled later, or an earlier engine was swapped in at some point. I agree with Geo, it normally was a brass threaded plug at some point in the hole - you might just check and see it is a common thread size and put in a shortened bolt to fit.

Randy
 
It's very possible it was titled later. I know it had a frame off restoration about 25 years ago, so some shenanigans could come from that. It was also hidden in my friends basement from the ex wife for a few years after that. Interesting past.

I'll work on backing that broken bolt out and putting a brass one in at some point. Thanks for the help.
 
Geo Hahn said:
That valve cover usually has a big brass bolt head in that spot (no idea why).
Click to expand...

Funny thing about that brass plug and the many different valve covers that were used on these engines. My original valve cover from TS23677L doesn't have that plug. The chrome on the original cover was pretty bad, so I bought two other VCs off e-bay...one for use with a road draft tube, and one that has the tube coming out for the PCV set-up in case some day I decide to hook-up a proper PCV on the TR3. It also has the low, positive sealing oil filler cap. As it turns out, the non-PCV cover from e-bay has that brass plug in it. Also, my original VC has the oil filler hole in the front, whereas the one with the brass plug has it in the back. Then, of course, there were the real early VCs that were painted and not chromed.

It's enough to make a concours judge just shake his head! :laugh:
 
Yes, that was the sequence: Unpainted, Chrome w/breather cap forward, Chrome w/breather cap at rear and brass plug, Chrome with sealed cap and tube for connecting ventilation to carbs.

Here is a photo of a cover with the plug you're missing:

Early%20TR4%20Valve%20Cover.jpg
 
Weren't there also some other variants? Eg, filler forward and brass plug? ISTR I've also seen one with the side port and a push-on cap, but I could be mistaken on either point.
 
TR3driver said:
...ISTR I've also seen one with the side port and a push-on cap...
Click to expand...

I could almost go for one of those. There was a post awhile back where someone converted a sealed cap to a push-on cap using a piece of chrome pipe from a sink drain.
 
I've looked all through the Bently manual, but I can't find the torque spec for putting the valve cover back on, anyone know what it is? It wasn't on there very tight to begin with.
 
TR3driver said:
Weren't there also some other variants? Eg, filler forward and brass plug? ISTR I've also seen one with the side port and a push-on cap, but I could be mistaken on either point.
Click to expand...
I don't recall seeing either of those variations, but....

Basically, I'd have posted the same list Geo did. And I believe the push-on rear-cap, brass-plug-in-the-middle cover was introduced with the TR4 and TR3B engine.
 
Andrew Mace said:
Gee, it's only 1 1/2 ft/lbs for a Herald/Spitfire valve cover. Makes me wonder about Triumph's use of "nyloc" nuts there. At least the initial installation must've taken more torque than the specification!?
Click to expand...

You're supposed to measure the amount of torque it takes to turn the nyloc nut by turning it with a dial or beam torque wrench. Then add this torque to the specified torque for the nut to determine the final torque wrench reading. On airplanes, anyways.
 
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