How do you remove the SV tach?

[bohemianway]

I need to do Tom's repair and don't want to muck things up try to figure out how they come out of the dash. Please let me know.

Thank you,
Charles

 

[gordonra]

First, stand on your head so that you can get your hands under the dash. Two thumbnuts on the back of the tach hold a U braket which clamps the tach against the dash. Remove the nuts and the ground wire, slide the u bracket off and gently push the tach out the front of he dash.

Now you can get out from under the dash.

The tach is still captured by a 12v supply wire and the ignition loop. Unplug the 12v wire and carefully remove the nut holding the loop. Do not drop or loose the loop components!

The tach should now free of the dash.

Rich

 

[Ken Ellis]

Behind the dash are the serrated nuts (hand-tightened) holding the instrument to the back of the dash. Contorting yourself to reach that is the easy part.

The challenges are: A) removing the plastic clip that holds the sensing coil of wire to the back of the tach, without losing or breaking it. If you do remove it, count and record the number of turns, and the orientation of the turns. (Or, cut the wire and install connectors.)

...and B) removing the instrument so it doesn't mess up the dash covering. Over time, the instrument rim will stick to the dash vinyl, and can easily tear it away, or separate it from the dash. Easing a thin plastic "blade" into the gap and breaking the "seal" all the way around will help if it's sticky. I wouldn't use an actual knife, because you want to separate, not cut.

But, it's all worth it once the TomMods (tm) are done, and you actually know the RPM of your engine.

 

[bohemianway]

Thanks,

If I don't post a reply in the next week call 911 to have me lifted out from under the dash.

Charles

 

[mikephillips]

There's also the lighting bulb that plugs into the back, it should just pop loose. Also there's a rubber O-ring, or what's left of it, between the dash and bezel. If you need to replace it you can get MGB ones if our normal suppliers don't have them.

 

[agmason54]

tach removal...

I was not going to respond but I put my left hand on a tachometer thumbwheel while driving down the road today. I'm sure you could do it while sitting and not doing 50mph. If you had a picture of one you could finger it out with yer right hand...Agm

 

[agmason54]

tach removal

PS I don't drive while standing on my head-at least not lately
agm

 

[Tom H]

I usually include a thin O-ring as part of my rebuild kit. It is a true "O-ring" and not square cross section like the original bezel-to-dash ring, but does an effective job.

Tom

 

[bohemianway]

Tach is out

Thanks for the assistance. I am safely out from under the dash. I found three wires attached to the ground post though instead of just one. Now comes the rebuild....

 

[bohemianway]

Tom's fix's installed

Reworked and recalibrated the tach. Works great except now I know what RPMs it is really at. 3700 @ 60 MPH (4.22 and 13" tires) since I have been running at 75 MPH the poor engine has been stressed. Now I am going to keep it under 60.

Thanks for the advice,
Charles

 

[65beam]

tach

i remember what one old guy told me many years ago. if the alpine engine is turning high RPM's then you're moving the oil and the pressure may be a little higher.

 

[bohemianway]

As to oil pressure. My SV stays up at 65psi until warmed up and then the Idle is at 20 psi at ~1000RPM. I just keep my fingers crossed that it stays that way. It still has points and stock strombergs to boot and it starts and runs great. Knock on wood and the engine does not knock. Although fuel economy is 25 mpg and hot restarts can be kinda rough.

 

[George Coleman]

If you are having problems with hot restarts, your timing may be off, if it drags when restarting the timing is to far advanced!