autocolor

I am re-routing the part of my wiring loom that passes through the engine bay across the bulkhead and taking the opportunity to replace old hard cables .
I run a 61 but with a later mid 70s 350 motor with Alternator and single points distributor .
Questions :- Do I still need to run the resistor before the coil and if so is taking the starter solenoid lead from the resistor going to cause any issues with engaging or running the starter ?
It has been running in its current configuration for a few years with no problems but following an engine rebuild the starter ( new ) is struggling a bit to pick up from stationary and I was wondering if the solenoid wire via the resistor may be contributing ?
I also run a 350 auto box so which wire should go to the neutral / safe switch , I am currently using the wire from the starter switch to solenoid is this correct ? and again could this effect the starter working efficiently

On the mechanical side I am getting high oil pressure with the new motor , typically hard on the stop (60 psi ) until hot it then idles at around 45 but back up to 60 by 2000 rpm , the pump is new but standard , is this cause for concern ?
Your thoughts please
Mike .

76rich

I can answer your question about the solenoid wire. It does go through your neutral safety switch. I don't think you have changed anything about the resistor by changing out gen for alternator, so I would think you still need to use resistor before coil.
Richard

waynec

"Do I still need to run the resistor before the coil and if so is taking the starter solenoid lead from the resistor going to cause any issues with engaging or running the starter ?"

Yes, the starter solenoid lead comes off the plus side of the coil (the side connected to the resistor).

autocolor

I do currently run the solenoid wire from the + / coil side of the resistor but I was just wondering whether the starter motor loading may be different on the later type starter motor ( 350ci ) and if running through the resistor may restrict it ?

JohnZ

I'm baffled. The wire that energizes the starter solenoid (purple from the "start" terminal on the ignition switch) has nothing to do with any resistor; the only resistor is the one in the ignition feed circuit from the "on" terminal on the ignition switch to the coil (+).

autocolor

Hi John
so what does the other solenoid wire do ? the wire I refer to is "the other" wire to the solenoid which runs from the bottom of the ignition resistor (+ coil ) terminal to the solenoid terminal . The wire you refer to indeed comes from the start side of the ign switch , this is the one I have running via the neutral safety switch on the auto box ,so am I doing something wrong ?
cheers
Mike

Plasticman

Mike,

The wire from the solenoid to the resistor is a bypass for when starting.

Normally, the ignition coil sees a reduced voltage through the resistor (from the ignition switch).

However, when starting, the starter draws down the available voltage, and the ignition coil needs all the voltage possible for firing. So that wire bypasses the resistor, so that the ignition coil gets full available voltage, but only when the solenoid is engaged and the stater is engaged. As soon as the starter is disengaged, the coil is receiving a "reduced" voltage through the resistor (to keep it running).

And no, the wire from the solenoid to the resistor is not the correct wire to go through the neutral safety switch. The correct wire would be the solenoid wire that would normally come from the ignition (start) terminal. This is normally a 14 ga. purple wire. That wire would prevent the starter solenoid from engaging unless the trans was in neutral or park on an automatic equipped vehicle.

And also, yes you still need the resistor to reduce the voltage to the coil, unless you wish to replace the coil often!

What wgt. oil are you running? Typically, I see the same type pressures while running 15W-40 diesel motor oil when cold, but it reduces to around 45 when hot while cruising. Your pressures are higher than "normal", but it is a new engine, with hopefully tight clearances. You may also have a hi-po oil pump (with a high pressure relief spring). This spring is replaceable (with a lighter spring), but the oil pan and pump need to be removed to do it. Since you really don't know how high it is really going (with a gauge max limit of 60 psi), it might behoove you to attach a different gauge to find out how high is "high". If it is not going past 70-75 psi at full rpm (with warm oil), I would not be concerned, other than possible damage to the gauge.

Plasticman

autocolor

Thanks Plasticman
that answers why there are essentially two "live" wires going to the solenoid , perhaps I didnt explain myself too well , I am running the neutral switch from ign switch start wire to the solenoid , not from the resistor .
Just one other stupid question , the solenoid terminals are marked "C" & "S" which I thought were Coil & Switch but if I connect the resistor coil wire to "C" and start wire to "S" it dosent work but seems fine the other way around is this correct ? do the letters stand for something else ?
Regarding oil grade I am using a synthetic 15/40 which is what I normally use so perhaps it is an upgraded pump in some way , I always had good pressure with the old engine typically up to 60psi when cold but this used to drop to 45 when running hot and about 30 on idle .
Your thoughts appreciated
Mike .

Plasticman

Mike,

You can see that another way (C = Coil of the solenoid, and S = internal Switch of the solenoid). If it works with those 2 connections, then I cannot argue. Bottom line is that there has to be a solenoid coil energized by the ignition switch. I really don't remember seeing those letters (never paid any attention).

There should be a purple wire connected to the solenoid and it connects at the inner terminal (towards the engine block). That is the starter solenoid coil, and comes from the ignition switch "start" position through the neutral safety switch.

The green wire going to the solenoid goes to the outer terminal, and goes to the resistor.

I would look at a different gauge, so I knew exactly how high your oil pressure really is going (before pushing the panic button).

Plasticman