[Lakeozark]

I have a 1965 Pontiac Catalina 2+2 with the factory Tach. The tach is restored and all electricals checked out and repaired by D&M Restorations in S. Caralina. The problem is it doesn't work! I am using an MSD PN 8528 RTR Distributor which does not require a "Box". I have installed it several ways with no luck. Theres a black Gnd. wire, a grey wire for the lights and the brown fused line for the pulse/power

Here's what I have done with the brown wire with no luck:

Tried it on the Pos. side of the MSD Blaster coil as per the Pontiac instructions.
Tried it on the Negative side of the coil.
Hooked the Brown to the Grey "Tach" wire on the MSD Distributor.
Anyone know what I'm doing wrong?

[george kujanski]

The ground wire needs to go to a ground which is connected somewhere to the battery negative. if you are connecting to sheet metal make sure the metal is connected to battery negative somewhere. The gray wire is for the light Does the light work?

No way would Pontiac instructions say to connect the tach wire to coil positive.

Since you say it's a factory tach, the remaining wire should go to coil negative. An aftermarket tach would probably have a separate power connection, are you sure there is no separate power connection?

George

[Carl S]

Originally Posted by george kujanski

No way would Pontiac instructions say to connect the tach wire to coil positive.



George

Sadly, he is right. I noticed this a number of years back on the Pontiac drawing for installing the tachometer on the 65-66 B body. It says to hook the brown wire to the positive side of the coil.

[johnta1]

That diagram shows 2 brown wires?
One fused goes to + side other goes to ground?
Seems like the fused brown is the power to the circuit and other is the trigger?

[johnta1]

I couldn't find the one Carl posted, the Tempest had a diagram that would be correct. (the B-body was pretty unreadable)


From 66 manual (Tempest)

[Lakeozark]

Yes, the grey wire is piggybacked into a factory gray wire with a factory built in Piggyback and the light works with the rheostat as it should.
The black ground wire is on the frame of the dash.
I'm using a Ready to Run MSD Distributor which does NOT require ma MSD box. The Tach is fresh back from D&M Restoration and tested out fine before being shipped back to me.

[Lakeozark]

This is the instructions i used.

[Lakeozark]

Originally Posted by johnta1

That diagram shows 2 brown wires?
One fused goes to + side other goes to ground?
Seems like the fused brown is the power to the circuit and other is the trigger?

Only one brown wire a black ground wire and the gray light lead.

[6869GTO]

Any chance the inline fuse blew when you connected it to the pos terminal and not the neg?

[johnta1]

I would check that the brown wire from the negative side of coil is the same wire at the tach. (continuity)
Not sure about your distributor, but some other types of MSD need an adapter to make an original type tach work? Digital tachs will work but not analog.

[Peter Serio]

That distributor is very good. However a GM tach from 60 years ago will not read the RPM at the coil using that set-up.
Do NOT wire any tach anywhere near the coil, that distributor has a built-in pre-amp signal as a dwell made specifically for a tachometer.




At this point your tach will need rebuilt with a completely different circuit board, the board you need is basically a version of a Delco TI board with one MAJOR EXCEPTION.
65 and 66 Delco TI option Pontiacs (big car as well as GTO) read the rpm signal off of the "+" side of the coil. That is because the "-" side of a TI coil is grounded via a black wire to the firewall. So the switched side (of the delco TI set-up) is at the "+." All 1960s era points distributor Pontiacs turn the coil primary on and off via the "-" post on the top of the coil. A one wire GM car tachometer will only work with the stock coil, connected at the "-" post & triggered by an original points distributor!

Your circuit board will need replaced with a different board so it can read the RPM signal off of the thin grey wire that exits out of the base of that MSD #8528 distributor. That grey wire carries almost no voltage but it has the dwell signal that a boosted circuit board can read.


The improved circuit board
will need at a bare minimum a total of 4 electrical connections to the car. One=ground. 2) a grey wire for night time driving; dash lights.
3) a wire that has 12 volts battery + (KEY ON ONLY) thru a 1 or 1 & 1/2 amp fuse from the fuse block (a separate fuse in the wire) and last an RPM signal wire (again fused= 1 or 1 & 1/2 amps) that connects directly to the pre-amp signal at the thin grey wire out of the base of that distributor.