Tachometer to Rectifier?

[jaybirddog11]

I have 100hp 1979 chrysler model #1007H9A
It looks like I have to replace the CD unit. The replacement from CDI,
part#115-3301 looks to be the correct one. However CDI states, "This unit does not contain an active tachometer circuit. If the original tachometer is still on the boat and connected to the old CD module, you will need to use a tachometer that can be connected to one of the stator wires on
the rectifier."
Will my old tach work if I wire it to the rectifier? It worked fine before.
Thanks

 

[moparman]

Re: Tachometer to Rectifier?

I would contact cdi to see if it's compatible with your tach'that way you are talking to the manufacture and there's no error.Keep us posted on your results. MOPARMAN ROLLTIDE

 

[Frank Acampora]

Re: Tachometer to Rectifier?

NO! Your old tach will not work. If you take the signal off the rectifier, it is an A/C signal from the alternator as opposed to pulsing D/C from the CD box. You MUST have a tachometer that will accept a 12 pole alternator signal. Your distributor ignition Chrysler is 12 pole alternator while later non-distributor models were Prestolite 20 pole alternator.

I have only see one tach as I have described in the past. It used one position for 12 pole and one for 20 pole. You will need to ask around for the correct tach to use with a 12 pole A/C signal.

Before you buy a new CDI unit, why not ask Franz at franzmarine @aol.com if he has the correct NOS CD box or a used one? Then you won't need a new tach.

'Smatter of fact: Why not get online tonight at 9 PM Eastern time at the Chrysler Crew chat room and ask him if your current tach will work or if he has a replacement CD box?

I never tried it but you could try attaching the tach signal wire to the white terminal on the distributor--Don't know if it would confuse the CD box but it is a pulsing DC source and might work with the original tach.

I just thought about this: Before you replace the CD box, check to be certain that there is a ground wire from the movable distributor body to the dist. mount on the block. This short wire is critical as the distributor itself is insulated by grease. If this wire is missing or broken, no spark will be generated. Also be certain that the ground wire from the coil is not broken. Both these wires attach with the same screw.