Cap for tachometer fitting at oil pump

[Thomas Sottile]

I need a cap to close off the tachometer cable fitting, I am converting to Electric tachometer from cable driven I need some options Thanks.. Stay well Tom

[David Baugh]

Hi, Thomas.

You'll need to use something other than a simple cap. If the washer isn't held tightly against the tiny seal, it can blow out causing an oil leak. I've cut the end off an old tach cable sheath. Then install it as normal, and slip a rubber vacuum cap over the end to keep dirt out. You might want to change the seal at the same time.

Dave

[Michael Foster]

Simple fix, use the hole plug for the later 912 type vented heads. It is often provided in upper gasket kits or you can probably get one from a provider or even a friend!

Michael Foster

[Dave Wildrick]

I need a cap to close off the tachometer cable fitting, I am converting to Electric tachometer from cable driven I need some options Thanks.. Stay well Tom

I still need to address this same capping issue on my 64C. My friend Frank Petersen said he found a pipe end cap in the plumbing section of a hardware store, which screwed right on in place of the tach cable end. Unfortunately, he lives 80 miles from Houston and does not remember where he got it.

So I took the female threaded end of an old tach cable to Home Depot and found a pipe fitting end cap with the same thread; however, it would not work to cap off the tach drive because it was not deep enough to allow you to screw it down on the threads. Got a different brand from Lowes, but same problem. I lost interest after 2 strikes, but maybe a different supplier would have a deeper cap.

[Ron LaDow]

Dave,
How about the right-sized coupling and a plug in the other end?

[Albert Tiedemann]

Simple fix, use the hole plug for the later 912 type vented heads. It is often provided in upper gasket kits or you can probably get one from a provider or even a friend!

Michael Foster

This is a fix that will work, but you will have to reduce the flange diameter of the hole plug to 16 mm to clear the minor diameter of the threads in the nut that you need to salvage off a useless tachometer cable housing. The body diameter of the hole plug will clear the hole in the tachometer housing nut without modification to either. The depth of the cavity in the hole plug is sufficient to clear the protrusion of the gear shaft that normally drives the tachometer cable. Be sure to use a new seal in the oil pump cover and do not forget the tachometer washer that fits over the protrusion and bears against the seal face. Install the modified hole plug into the tachometer cable housing. It should bottom out in the tachometer cable housing nut. Thread the two piece assembly onto the oil pump cover threads and tighten. Old tachometer cable housing nuts have a couple of knurls for a better grip with your fingers. Newer nuts are not so nicely made.

This is an elegant looking fix that can be made up from unused/new and discarded parts. The flange diameter of the hole plug can be reduced a number of ways. I would use a lathe, but not everyone has a lathe in their basement; so, I leave it to the DIYers to devise their own means.

[Thomas Sottile]

Thanks everyone for you input. Stay well Tom

[Ron LaDow]

Tom,
Here's another couple of solutions:

[Albert Tiedemann]

Simple fix, use the hole plug for the later 912 type vented heads. It is often provided in upper gasket kits or you can probably get one from a provider or even a friend!

Michael Foster

This is a fix that will work, but you will have to reduce the flange diameter of the hole plug to 16 mm to clear the minor diameter of the threads in the nut that you need to salvage off a useless tachometer cable housing. The body diameter of the hole plug will clear the hole in the tachometer housing nut without modification to either. The depth of the cavity in the hole plug is sufficient to clear the protrusion of the gear shaft that normally drives the tachometer cable. Be sure to use a new seal in the oil pump cover and do not forget the tachometer washer that fits over the protrusion and bears against the seal face. Install the modified hole plug into the tachometer cable housing. It should bottom out in the tachometer cable housing nut. Thread the two piece assembly onto the oil pump cover threads and tighten. Old tachometer cable housing nuts have a couple of knurls for a better grip with your fingers. Newer nuts are not so nicely made.

This is an elegant looking fix that can be made up from unused/new and discarded parts. The flange diameter of the hole plug can be reduced a number of ways. I would use a lathe, but not everyone has a lathe in their basement; so, I leave it to the DIYers to devise their own means.

Here are a few pictures I took after finding the solution I used in 2001[same as that mentioned by others and myself above] when my Carerra 7500 tachometer was sent off for repair while using a 12 volt electric one. These photos answere the question originally asked.

[Dave Wildrick]

[quote="Albert Tiedemann
Here are a few pictures I took after finding the solution I used in 2001[same as that mentioned by others and myself above] when my Carerra 7500 tachometer was sent off for repair while using a 12 volt electric one. These photos answere the question originally asked.[/quote]

Rats Ab!
I thought maybe you were going to sell some of these to us "as needs 'em."

Now I not only have to find the 912 head plug but also get a lathe.

[Vic Skirmants]

Gee; That's exactly what I posted a couple of years ago. I was immediately slapped down by someone who said it wasn't a very elegant fix, and I should just get a proper cap off an industrial engine; yeah; we all have a couple of those in the garage.
HA!

[Brad Ripley]

As Vic suggests, of course the industrial engine parts are long gone --
cap was 539-07-132
holding nut was 999-104-003-30

912 cyl head hole plug is 616-104-393-00, about $1.65.

[richard pike]

Right you are, Albert! I did this simple fix decades ago.
cheers,
Dick

[Dave Wildrick]

Found an off-the-shelf solution to capping the mechanical tach drive area (see photo).

It does not require a lathe to make it work, although Ab Tiedemann’s solution was much more elegant--using a 912 head plug, machined to fit.

You can buy this at Lowes hardware in the plumbing section for a couple of dollars. It’s a brass flare cap, Watts brand, their part number A-263 (see photos); also available on line (http://www.airdelights.com/W-17000263.html).

FlareCapWatts-A263.jpg (45.23 KiB) Viewed 1618 times

You have to remove the tach drive (see photo),

but this just pushes out with your finger or a screwdriver after you remove the large nut (and safety wire on the nut) that keeps it in its tube/passageway.

Add the brass cap, using Teflon pipe dope (tape) to prevent leaks, put the large nut back on the other end of the tube/passageway, and that’s it.

[Albert Tiedemann]

I have a one piece solution that does not require you to remove the tachometer drive. The monolithic solution from aluminum bar stock alloy 6061-T6 simply threads onto the male thread [M18 x 1.5] of the oil pump cover. Use with the oil pump shaft seal and the shim. I had it at the Hershey Swap, 2014. I will post a picture to compare with the previously proposed solution. It will eventually get to the classifieds when there is better light level for picture taking.