[tom s]

15 years?Dont even check it,replace it!JMHO

[67GTONUT]

Originally Posted by tom s

15 years?Dont even check it,replace it!JMHO

LOL..... I hear ya, but would like to confirm its giving up the ghost....

I cannot think of anything else....

[67GTONUT]

Well.... That proved nothing.

Checked battery this morning.... 12.6-12.8 volts sitting there overnight.... Only dropped to mid 10's while cranking and car started fine of course....

Will keep meter in car, and do same test when issue occurs hot and see if battery is nose diving then....

[67GTONUT]

Well....
Found the issue...

After now installing a nice 2ga positive cable.... and then the issue re-occurring ....... I finally got it to start....

Got it home, let it sit for 10 min again...... once again..... Click, no start.....

On a whim..... jiggled the red key on my Taylor Battery disconnect...... and she fired right up...... Must be losing a good ground through the switch ....

Do I eliminate the Cut Off switch......

or

Can you guys recommend a brand of Cut Off switch?

Was using this one

https://www.summitracing.com/parts/tay-1037/overview/

["QUICK-SILVER"]

Originally Posted by 67GTONUT

Do I eliminate the Cut Off switch......

Need to know why you've got it. If it's for NHRA rules for drag racing or SCCA type racing that requires the switch....then you don't have choice but replace it. Safety crew has to be able to kill battery power in case of an accident, crash or fire either one.

If it's under the hood just because.....I'ld call it something else that can go wrong and cause problems.

IMO
Clay

[67GTONUT]

I got it because it made me nervous to have 50 year old wiring in the car and the slim possibility of a short/fire ......

I measured the Ohms of resistance through the switch today..... anywhere from 5+ to 10+ ohms and would vary just by jiggling the red key....

[Bill Hanlon]

Originally Posted by 67GTONUT

I measured the Ohms of resistance through the switch today..... anywhere from 5+ to 10+ ohms

5 ohms would limit the total amount of current through the switch to 2.4 amps. 10 ohms is even worse.

[My64GTO]

I too felt the same way about 50 year old wiring, espeicially with a garage under the house. Get rid of that switch and get one of these.

https://www.summitracing.com/parts/hfm-batktw/overview/

Even though I replaced all wiring harnesses last year, I still use it.

[My442]

Replace the ignition switch that is mounted on the column.

Make sure that you adjust it right per the CSM.

[67GTONUT]

Originally Posted by Bill Hanlon

5 ohms would limit the total amount of current through the switch to 2.4 amps. 10 ohms is even worse.

Which is why it would not crank at times......

Problem solved....

Just checked a few more things this morning..... 15yr old Optima still at 12.8v sitting and Alternator is charging great.

As far as that battery disconnect that is posted above...... I actually had one of those arc once and it welded itself together...... that is why I went to the "fancy" cutoff switch.....

As of now...... just going to run without a cutoff. I have now owned the car for 16years and have never had a shorted wire, so I much more comfortable now then I was 16 years ago when I 1st got the car.

Ignition Switch is dash mounted..... and seems to work just fine

Thanks for all the input.....

["QUICK-SILVER"]

EDIT: Just saw your above post. So never mind on this one.
Clay

Originally Posted by 67GTONUT

I got it because it made me nervous to have 50 year old wiring in the car and the slim possibility of a short/fire ......

The new under hood harness should have fusible-link protection on all the power wires. A short bad enough to start fires (melt wires) will either blow fuses or the fusible-links. If wiring is a cobbled up mess with fuses and fusible-links bypassed.....you need more than a disconnect switch.
New starter cable routed safe and secure? If yes...I wouldn't give it a second thought.

Originally Posted by 67GTONUT

I measured the Ohms of resistance through the switch today..... anywhere from 5+ to 10+ ohms and would vary just by jiggling the red key....

It's a goner with any ressistance at all.

The switch mentioned in the above post is getting borderline weak for cranking amp draw with a mini starter. And forget hot starting, with a factory starter, where amps could go over 300. It would have a limited number of cranks before it failed.

I'ld be worried more about fire hazzard while driving if the wiring on this car is in as bad a shape as you're thinking it is.

IMO
Clay