SAAC Forum

The Cars => 1967 Shelby GT350/500 => Topic started by: oldcanuck on February 17, 2020, 09:15:44 AM

Title: Distributor Question
Post by: oldcanuck on February 17, 2020, 09:15:44 AM
My buddy and I were installing a Pertronix Ignitor HEI kit in my GT-350 yesterday.

While in the process, noticed a little play on the shaft. Would this just be bushing wear after all these years I'm thinking.

Can the bushing or bushings be replaced ?

Thanks,

BG
Title: Re: Distributor Question
Post by: shelbydoug on February 17, 2020, 09:21:58 AM
There is always a degree in play to the shaft.

Look at the inside of the cap. There will be an indication of how the rotor is tracking. Are there groove cut into the metal inserts in the plastic? If yes, then there is too much play. If not, leave it alone. You could just make it worse if you try to rebuild it.

Also there should be no metal growing on the tip of the rotor. It should show no indication of metal to metal interfernce.

They actually should have only minor indications of touching. The arch actually jumps the gap.

The only thing that should be in constant contact is the spring on the rotor that contacts the distributor wire lead.
Title: Re: Distributor Question
Post by: rmarble57 on February 17, 2020, 09:28:57 AM
Also, ensure from the instructions of the Pertronix unit if it wants 12v power or the 9v to the unit.  The Pertronix ignitor generally takes its' power off the "+" lug of the coil.   The stock setup for power to the "+" side of the coil on the car has the wire running from the key switch running through resistance wire to knock down the voltage to the coil.  If the Pertronix requires 12v to the coil, and you bypass the resistance wire then you will find your factory tach will no longer function properly.

Been there, done that.

Title: Re: Distributor Question
Post by: rhjanes on February 17, 2020, 09:36:39 AM
My 1969 302 went around 100,000 miles, then started running rough at different engine speeds.  With a dwell meter and timing light, I could slowly rev it up and see the dwell start "bouncing" and the timing moving even with the RPM constant at that point.   Worn distributor bushings causing the point plate to move, at certain RPMs. 
As noted, a slight shaft play is normal.  If you don't have the issue I had and no tracking issues, as noted above, then you are probably fine.
Title: Re: Distributor Question
Post by: Bob Gaines on February 17, 2020, 01:00:17 PM
Quote from: rmarble57 on February 17, 2020, 09:28:57 AM
Also, ensure from the instructions of the Pertronix unit if it wants 12v power or the 9v to the unit.  The Pertronix ignitor generally takes its' power off the "+" lug of the coil.   The stock setup for power to the "+" side of the coil on the car has the wire running from the key switch running through resistance wire to knock down the voltage to the coil.  If the Pertronix requires 12v to the coil, and you bypass the resistance wire then you will find your factory tach will no longer function properly.

Been there, done that.
You maybe able to bypass the resistor wire another way. Run a seperate wire from the on position of the ignition switch for a 12 volt source out to the pertronix unit leaving the resistance wire intact to to the coil ,distributor and tach circuit. 
Title: Re: Distributor Question
Post by: rmarble57 on February 18, 2020, 11:02:48 AM
Bob,
That is exactly what I did.  It is easy enough to tap into the switched power wire on the key-switch.  Helps if you have midget arms as well.

Now.....for reconnecting the speedometer cable back up to the speedometer when you have removed the dash cluster............that takes a magician!
Title: Re: Distributor Question
Post by: shelbydoug on February 18, 2020, 11:22:00 AM
Quote from: rmarble57 on February 18, 2020, 11:02:48 AM
Bob,
That is exactly what I did.  It is easy enough to tap into the switched power wire on the key-switch.  Helps if you have midget arms as well.

Now.....for reconnecting the speedometer cable back up to the speedometer when you have removed the dash cluster............that takes a magician!

Small hands. So simple a 12 year old can do it, so borrow a 12 year old from someone.


Actually I've had mine out at least a dozen times. Connecting the speedometer cable is by far the most difficult although not really hard, just needs a nack to do it. Sometimes you need to take the clamp off of the cable on the firewall so that you can pull a couple more inches of slack.

You put your hand in the dash from behind where the tach is and you need to angle the dash out to the extreme of the harness and the nut will JUST CATCH. I hate doing it. The sheet metal is just sharp enough to scratch you all up.

I have to get myself super calm and relaxed. State of mind is actually important here.
Title: Re: Distributor Question
Post by: oldcanuck on February 20, 2020, 08:07:06 AM
Guys,

Thank you very much...... as always great insight and info.

Always appreciated.

BG
Title: Re: Distributor Question
Post by: oldcanuck on March 09, 2020, 10:08:37 AM
Guys,

Conversion done and running very well..... just one question since I am getting conflicting plug gap information.

Being the stock plug gap spec is .028 to .032 for points, I have always been under the impression to add about .005 when converting to HEI...... so I gapped my new plugs at .035 during the install. A local dirt track engine builder told me that I should run them up to .040 for more spark and the Hi Po will be much happier. 

What say the Fourm experience here ?

As always.... thanks for your advise.

BG
Title: Re: Distributor Question
Post by: roddster on March 09, 2020, 10:24:43 AM
  Shaft play would cause different dwell readings on points type distributors.  It makes less of a difference on electronic conversions.  If wayyyy worn, it would.
Title: Re: Distributor Question
Post by: oldcanuck on March 09, 2020, 11:08:12 AM
I guess I should have mentioned the shaft play is normal due to the rotor and cap indicators.

My only concern is the gapping of the new plugs for the HEI, per my last.

Thanks