Does anyone have an idea how much current draw for the solenoid?

Would it be beneficial to use a relay on the solenoid circuit?

This car is NOT stock ("hitachi-style" Mini Starter and an aftermarket B&M shifter with Neutral safety switch, piggy-backed of original harness connector).


I am assuming the solenoid will pull more amps than a standard relay can support, are their higher amperage relays that would work?

How about the "Ford" relay/"solenoid"; I have a new setup, and wondering if that might be a good choice for just the solenoid wire...


I was planning on replacing the wire in the engine compartment (using #10 or #8 gage wire), but then I was thinking there's still all the old under dash wiring, the "supply" wire from the horn relay, the multiple connections (2 at fuse box, two at connector, 2 at switch, horn relay and solenoid)...


Or maybe its not necessary with the mini-starter?

Thanks

It seems that the real culprit is heat. If you have an exhaust system that is really close the solenoid, you may have problems. All of the resistance in the wiring system is a factor, but for a starter that is not baked, the original wiring works ok.

It seems that the real culprit is heat. If you have an exhaust system that is really close the solenoid, you may have problems. All of the resistance in the wiring system is a factor, but for a starter that is not baked, the original wiring works ok.

well,

Thats why I was thinking MORE amperage to the solenoid would help it to engage when its hot (using a relay and larger wire versus the factory wiring/bulkhead and new shifter switch) ... It doesn't matter how large the main cable and ground cable are, or how good the cable connections are, IF the solenoid can't get enough current to engage... Right???

My starter WAS working okay until a few months ago. I even did some hot laps at the drags (4 runs in 25 minutes) and shut it off each time for ~5 minutes in between races...

Then it had trouble starting in the heat (had to let it cool 45+ minutes). Could be bad connections and old wiring, but it started "out-of-the-blue" one day...

So I bought a mini-starter (headers on the car), and was planning on building some new large cables ( both positive and ground cables), but I am worried about the current that needs to go through all the old wiring to activate the solenoid...

Okay, so the factory wiring "should" be okay, but I was looking for suggestions on upgrades while I am in there...

Thanks

The original wiring should be adequate to activate the starter solenoid if all the connections are corrosion free and clean. There are several connections that need to be checked/cleaned.

The original wiring should be adequate to activate the starter solenoid if all the connections are corrosion free and clean. There are several connections that need to be checked/cleaned.

But I am looking for the current draw or alternatives, because its NOT all original...

1)I have an aftermarket shifter, which required a custom harness (using wire of the same guage as original). I extended that harness about 2-3 feet to the new shifter...

2) The aftermarket shifter has a small switch, probably okay but really not sure the amperage it can handle...

3) The factory wiring has been spiced by a previous owner (crimped). So I need to address that issue as well.

4) the car has headers, which may or may not cause more heat in the solenoid, necessitating more amperage to engage the solenoid at those times.

5) I was also thinking a relay-system could be used as a "anti-theft" device for novice car thieves... Not a primary objective, but a side benefit...


I GUESS it works fine right now, but I want to be sure it continues to operate in high temp situations.


Yes, I understand the factory system usually works well if in good shape. But that doesn't mean its the best system. Its a 45++ year-old design... I was looking for ways that I can modernize while also doing maintenance (cleaning and tightening contacts, soldering connections/splices, etc)...

If you are that concerned then install a relay.

You can use a relay like those used for electric fans and use it to activate the starter solenoid. Mount it on the radiator support, away from header heat.

Or you could use the Ford style remote starter relay to activate both the solenoid and starter, again mounting it close to the radiator support.

Both methods will mask wiring problems.

I think I would use a Ford solenoid myself.
Overkill but might as well use a relay that is extra heavy duty if you're going to do it.

If you are that concerned then install a relay.

It wasn't so much "concern" as much as I'd like to possibly upgrade the system...

I think I stated in my first post that I DID want to install a relay, which is why the topic of this post was inquiring about how much amperage goes to the solenoid...

You can use a relay like those used for electric fans and use it to activate the starter solenoid. Mount it on the radiator support, away from header heat.

Or you could use the Ford style remote starter relay to activate both the solenoid and starter, again mounting it close to the radiator support.

Both methods will mask wiring problems.

Both will mask wiring problems, IF THERE ARE ANY PROBLEMS!

I was asking for the current draw, so I could "design" a better ssytem (not just adequate for most situations). I am planning of checking/cleaning/tighening all connections, soldering any fittings, but since I need to replace wiring anyway (due to splices), I wanted to see what guage wiring I should be running, and IF a standard relay would be sufficient or easily overloaded...

Okay, so I am NOT an electrical expert, but wouldn't it be better to design a modern system, rather than running the current though all the existing wiring connections and switches? Even if everything is in Top Shape, there are still numerous connections (junction block, horn relay, firewall, fuse box, column connector, neutral Safety switch- two connections, firewall again, and solenoid... And mine also currently has the additional connections for the extension.

Then theres the "contacts" that can where/pit over time, causing increased resistance... Ignition switch and NS switch and solenoid itself...

I was previouisly told that one starting issue could be from pitting on the solenoid contacts... IF the solenoid contacts can get pited and cause higher resistance, then can't the ignition switch contacts and NS contacts also become pitted? I KNOW my starter and solenoid are MUCH newer than "original", yet they might already be showing signs of pitting? I realize that the solenoid will always received high current, just trying to minimize the issues of high-current within the interior of the car...


On Modern vehicles, its seems that most (if not all) high current-draw systems utilze relays. Maybe the designer just got a financial kickback from the relay suppliers so they threw some into the design, but somehow I thought it was a better design to use relays...

And why is it that even with a car with fresh, clean wiring, the "headlight relay" modification results in brighter headlights???

So sure, MAYBE the existing system will be adequate, but that wasn't the point... I didn't post in the "restoration forum ("where Originality come first")

Plus, this car is NOT original, and it has had some of the typical "hot rod" wiring butchering. So I could buy a repro harness, based on 45-year-old "design", or I could ad some modern safety and functionality to the system (trying to eliminate/reduce the high-current from the dash harness)...


And the "Ford" relay solenoid is NOT always a crutch used to "mask wiring problems"... Sure, Many people MIGHT use one to make up for poor connections and corroded cables, but not everyone... I never liked the idea of the "live" battery cable, and had considered the Ford-type relay even in situations where the starte system worked fine... I have also know numerous racers that liked the idea for "bumping" the starter when checking valve lash, or making sure they had enough amperage to turn over a High Compression race motor when needed...


So please, enlighten me... Tell me why a relay system is bad... Don't just say "it will mask wiring problems"...

Lets assume all wiring is fresh, connections tight and clean, better quality wiring than stock, so there are NO wiring problems... Now, how can I improve the system? Not looking for merely "adequate" for a stock application, looking for methods/ideas to IMPROVE the system...
Thanks...

Rant on...

How do people manage to convince themselves that the slow cranking issue has anything to do with the solenoid?

The solenoid helps kick the bendix out to engaage the flywheel. If the engine turns, its working and so is its wiring.

The solenoid also has a pair of contacts and a disk that switch the starter motor on. If the engine turns, its working and so is its wiring.

If the starter motor turns the engine over slowly, its the starter motor, the big cables, or connections--NOT the solenoid.

Installing a Ford solenoid involves redoing the high current wiring, which I would suspect is what actually resolves the problem...

Rant off...

Installing a Ford solenoid involves redoing the high current wiring, ............................
Rant off...

Not necessarily.
The ford solenoid can be used as a H.D. relay to operate the GM solenoid ONLY.

Tony,

Take a deep breath and calm down.

Since no one has responded with an answer to your question "how much amperage goes to the solenoid" may suggest no one has measured it. The presence of a heavy wire (10 ga I think) to activate the solenoid suggests draw could be significant.

No one has suggested it is bad to install a relay. I have installed Ford starter solenoid/relay on cars with headers to minimize heat soak problems.

On old cars I disassemble the ignition switch and clean/polish contact and reassemble with new grease. I usually find corrosion is the cause of trouble, not serious pitting in the switch. Contacts in the ignition switch are sliding. Pitting in the switch occurs at the leading edge and the contact slides across so current flow is mostly in non-pitted surface. (same applies to light switches) A starter solenoid contact is straight contact, not sliding, hence you get pitting that will cause trouble.

Late model cars and trucks have starter relays and fuses but the socket is integral with a fuse block. If you wanted to use one of those look for a fuse block out of a small car (=small fuse block?) I have used fuse blocks out of mid-late 90s GM pickups for power control in old cars when adding significant power loads.

I said the stock wiring is adequate. It must be adequate because many thousands of these old cars have been running for 40+ years with everything from 6 cyl to 502s. Can you improve on the design? Sure, everything can be improved if you want to put the effort into it.

So go ahead and install a relay if you want, no one will criticize you for it.

In the mean time, please don't shout at people who are trying to help.

I could be wrong but I'm thinking that he is getting frustrated because he is asking about the solenoid operation ONLY and getting answers related to heat soak and starter MOTOR operation rather than just SOLENOID operation. :confused:

I could be wrong but I'm thinking that he is getting frustrated because he is asking about the solenoid operation ONLY and getting answers related to heat soak and starter MOTOR operation rather than just SOLENOID operation. :confused:

Exactly Dean... I truly apologize, as I was getting frustrated because it ddi seem as though no one wanted to answer my question about solenoid current draw... I do appreciate some of the other info.

I also apologize because I tend to use BOLD and "all caps" to stress what I was saying ( not always "yelling"), kind of a way to highlight the important aspects of my response...

Such as:
My starter does NOT turn over slowly...

BUT, this summer I have had a problem where when the engine was hot, the starter wouldn't spinat all... Not even a "click" that usually occurs when a solenoid/bendix tries to engage but the armature/widings are "seized"... The starter just sounded dead... Nothing... For 15-25+ minutes, I tried, and still NOTHING... After 45 minutes of sitting, the starter would crank over like it was new, with no signs of problems... No dragging...

There was a slight dimming of the dome light when turning the key, but not as dim as when a strater cranks slowly from heat soak... All of which was leading me to believe either the solenoid and/or solenoid wiring as likely culprets...


I have a small block with headers, with not-too-high compression, so It shouldn't be a really bad case of heat soak etc...


I have had people telling me to change the solenoid, change the whole starter, switch to a mini-starter, go to a "ford" relay, do NOT go to a Ford relay, etc... It gets confusing...

I know from experience that there is a big volt drop (and amps?) in the factory headlight system, and thats where I was thinking about a relay solely for the solenoid wire... Thats why I wanted to know the typical amperage carried to the solenoid, so I could determine IF I could get a relay (typical headlight/fan relays seem to only be 30-50 amp)


In the mean time, please don't shout at people who are trying to help.

I apologize Verle... If you are that concerned then install a relay...
Both methods will mask wiring problems Sorry, I took that response more like " no need for a relay, you're stupid because you aren't fixing the problem only masking it, but do it if you want"...

You latest response was probably more what I was hoping to get... I am swapping steering columns, so I will try to clean up the ignition switch contacts while I have it out on the bench.


My aftermarket shifter uses a small NS switch, and I am not sure on the amp rating of that switch... So thinking of all those contacts, all that extra wiring and that switch, thats where I was thinking this might be a good place for a relay... And since some of the wiring is already modified, it wouldn't be like I was cutting up a pristine, well-working system...

Thanks...

My aftermarket shifter uses a small NS switch, and I am not sure on the amp rating of that switch... So thinking of all those contacts, all that extra wiring and that switch, thats where I was thinking this might be a good place for a relay... And since some of the wiring is already modified, it wouldn't be like I was cutting up a pristine, well-working system...

Thanks...

By all means, use a relay. This will significantly reduce the current going through the ignition switch, neutral safety switch and the various wiring normally used to activate the solenoid. A Ford relay is quite inexpensive and will provide all the current your solenoid needs. As previously mentioned you don't need to modify the high current wiring, just relocate the wire that activates the starter solenoid.

http://home.comcast.net/~onovakind67/starterrelay.GIF

By all means, use a relay. This will significantly reduce the current going through the ignition switch, neutral safety switch and the various wiring normally used to activate the solenoid. A Ford relay is quite inexpensive and will provide all the current your solenoid needs. As previously mentioned you don't need to modify the high current wiring, just relocate the wire that activates the starter solenoid.


Thanks onovakind...

That was my current thinking ( no pun intended).

The "Ford" solenoid is kind of big and ugly, and so I was wondering what the current draw was, and therefore could I possibly use a smaller relay... But I really don't think they'll last (cooling fan/headlight relay)... But I already have the Ford relay (Summit kit)...

Several people have suggested not to use the Ford relay with the mini-starter ( for the high-current cable connections AND solenoid activation)... Still not sure why thats a "bad" idea, as the solenoid trigger is coming from the cable ratehr than the 10 gage wire...

I was thinking along the lines of the diagram you provided...

I do agree with all those that mentioned the connections need to be clean and tight...

One big potential advantage to the Ford solenoid is the button on many allowing a remote engine turnover feature from under the hood :thumbsup:

If you want to know how much current the solenoid or many electrical devices use... just pull out the ohm meter and measure their resistance. E = I * R or 14v / resistance in Ohms == Amperes of current. This generally works for devices except electric motors and will get you pretty close if not exact.

I hate crimpon splices. Horrible things to have in a wire run :clonk:

I stick a 2" piece of quality heat shrink tubing over one wire. Strip about 1/2" of each wire and lay them side by side overlapping. Take about a 6-12" length of wire and remove all insulation so I have a bunch of thin wire strands. Carefully wrap the overlapping splice wires with a strand. Hit the splice with a soldering iron. Slide the heat shrink over the splice and shrink'er down. About as good as a virgin wire :thumbsup:

That diagram is not bad... but wiring it that way really does make for one big azz relay. If you just want to do a relay pur in a relay. Generic Bosch mini relays are typically good for 20-30A which is a lot more than your original wiring was going to put out :yes:

I might wire the main battery cable through the Ford solenoid to the starter. Then just jumper the main power and the solenoid power on the GM starter. Nice thing about that is you could hide the Ford part up closer to the battery. It could provide a convienient extra power tap point. Wiring that way would also reduce the amount of big azz battery cable with full time battery voltage... less risk of shortage and smoke that way ;)

This is an old thread, but here is what I did.

Battery in trunk, Ford starter solenoid in trunk, big positive battery cable is only hot when starting. (8 ga wire wire w. fusible link connects bat to main harness)

The Ford solenoid can be triggered by the purple wire that used to go to the starter, but I wanted to accomplish two other objectives:
-eliminate the aftermarket neutral safety switch from high current
-Have the electric radiator fan turn off while starting.

Using a common Bosch 30 amp relay as the neutral safety contactor for the purple wire does both.

Basic terminal layout for relay:
30-power in
85-positive trigger
86-ground for trigger
87-normally open relay out
87a-normally closed relay out

30-ign keyed wire
85-purple/white wire from key
86-wire that goes through neutral safety switch then to ground
87-output to Ford Solenoid
87a-signal wire for electric fan relay to turn on

"If you want to know how much current the solenoid or many electrical devices use... just pull out the ohm meter and measure their resistance. E = I * R or 14v / resistance in Ohms == Amperes of current. This generally works for devices except electric motors and will get you pretty close if not exact."

Except in this case where the solenoid isn't a completely resistive load a magnetic field is generated around the conductors and will likely reduce the current.

I installed a relay on mine over a year ago for the same low-voltage issue. Sometimes the cranking voltage at the solenoid would be as low as 9 volts! I installed a relay on the firewall that feeds directly off the battery. Never had a problem since. It's nice to get 12 volts at the solenoid EVERY time.