Coil and Resistance wire question

[RexJohnson]

I've always heard that the coil is suppose to run cooler when mounted on the frame but I've never seen any data to support this claim. The cylinder head is a huge heat sink with air blown past it. Then there is the tin shrouding between the head and the outside world. The coil bracket is also a pedestal which gives a large air gap between the tin shield and the coil inself. I've seen smaller air gaps with parts mounted next to hot exhaust parts. So how much cooler does the coil run?

[joelsplace]

I hadn't thought about it much but I would think being bolted to something that runs 250 degrees or more would cause it to run hotter than being bolted to something that stays at ambient temperature. I'm not sure it matters. I've never had an oil filled GM coil fail. I have had a lot of the newer epoxy coils fail.
Lots of V8 and other water pumpers had the oil filled coil bolted to the engine and also exposed to the high under hood temps that Corvairs don't have. (Except for hot soak)

[Gasman63]

My coil is a Flame Thrower 3.0 ohm.
I tried to look it up to see if it was oil or epoxy filled and wasnt able to definitely say one way or the other.

[Richard]

The old chevy stovebolts had the coil mounted vertically, but not the way some of you would think is correct.
In the late 50's they flipped them over with the terminals on top.
If I were to guess, they flipped them about the same time Dwell meters and Tachs became readily available. You needed to be able to see the + / - markings. Previously everyone simply set the Point Gap and then rpm's by ear.

The GMC 702ci V12 (Twin Six) had the twin coils mounted horizontally.

I think in most cases, including other manufacturers, mounting orientation was simply a matter of convenience.

The oil in the coil is used as a dielectric. An electrical insulator.
If the purpose of the oil was to cool the wire, wouldn't you think GM would have found a way to cool the oil?

You can always go to JC Whitney or K-Mark and get one of those coil cooler sleeves. I'm sure they know more about Ignition coils than GM.

[joelsplace]

"The GM engineers know everything" is a bad argument. They didn't.
If they did they would have used hot rivets in the flywheel and Viton push rod tube o-rings. Viton was available.
A lot of things were done because it was cheap or because they could get away with it when warranties were 1 year or less.

[Lane66Monza]

Coils were mounted on the engine because that is where they were used. Nothing about being the best place for the life of the coil. Engines were built and tested in another state from the car assembly plant. Makes sense to have a complete running engine delivered to the assembly plant, whether an air cooled engine or a water cooled engine.

All components survive longer if away from heat, just like the human body. Just a fact of life and manufacturing. The older yiou get, the less you can tolerate the heat. Same with components as they age and breakdown.

ps: I have my coil mounted vertically on the back rail. New A/C unique coil wire has a 90 dergree terminal and wire. (thanks, Seth)

20200527_054239_resized.jpg (105.02 KiB) Viewed 151 times

[Richard]

>>"The GM engineers know everything" is a bad argument.<<

Ok, I can't argue that, but between GM and JCWhitney, GM never sold toilet paper oil filters.

[66vairguy]

"The GM engineers know everything" is a bad argument. They didn't.
If they did they would have used hot rivets in the flywheel and Viton push rod tube o-rings. Viton was available.
A lot of things were done because it was cheap or because they could get away with it when warranties were 1 year or less.

Corvair engineer Benzinger stated GM had little experience with riveting flywheels and hired a well known rivet manufacturing firm to design the rivets and the machinery to install the rivets. Well with failures showing up around 50 to 100 thousand miles it wasn't like they were incompetent, just not enough knowledge. After all the Corvair is the ONLY vehicle I'm aware of that uses a "flex" flywheel. BTW - none of this would have happened if GM had listened to the engineers about designing a manual transmission setup from the beginning. As Chevrolet engineer has stated, the engineers were told that due to demand the Corvair would ONLY be sold with an automatic. Then Ford and Chysler announced their compacts would come with a three speed manual and the automatic be an EXTRA cost option. Suddenly the base price of the Ford Falcon and Plymouth Valiant were considerably lower! GM marketing ordered the Corvair engineers to install a three speed manual and make the PG an extra cost option. This was AFTER all the Corvair tooling was done. Considering everything the engineers did a commendable job.

As far as the Viton seals go. Again cost overrode the engineers. In the Corvair books it is stated that Chevrolet said there was never a pushrod "O" ring issue. Technically this was true because "O" rings did not fail until AFTER the 12 month/12,000 mile warranty expired!! This "attitude" of just good enough to get through warranty is what led to the Vega fiasco and the adoption of Japanese cars in the 70's.

While engineers make mistakes, they often are on the money, but are overruled when it comes to doing it better costing more.

[joelsplace]

"GM had little experience with riveting flywheels"
Isn't that the very definition of incompetent?
"not having or showing the necessary skills to do something successfully."

I never heard the engineers specified Viton.
I have read the engineers were ignored on the Vega aluminum specs for the block.

[Lane66Monza]

"Viton® was introduced in 1958 and ever since, scientists and engineers have relied on Chemours Viton® for its superior performance and unique properties."

https://www.globaloring.com/viton/#:~:t ... properties.

Since the Vair engine was already in testing, I doubt GM engineers or bean counters wanted to go with something untested by them. By 1965, no changes except for safety or FED mandated were being made, so the Viton seal was never introduced, as it was expensive to change drawings for such a small possibly reliability improvement item.

[66vairguy]

"GM had little experience with riveting flywheels"
Isn't that the very definition of incompetent?
"not having or showing the necessary skills to do something successfully."

WOW Joel you are on a roll today -
Benzinger said that BECAUSE GM HAD LITTLE EXPERIENCE WITH RIVETS, they used a rivet manufacture to design the rivet and machinery to install it. Hardly incompetent to know when to go to others for expertise. Since the Corvair was a new and different product (too different for GM some say) Chevrolet did a lot of testing. No flywheel rivet issues showed up. Of course back then cars tended to need a lot of work by 50,000 miles. Some might argue the riveted flywheel did just fine lasting over 50,000 miles for a 60's car.

[RexJohnson]

The 60's used I believe a 1/4" rivet and the rest used I believe 5/16". GM must have noticed something fairly soon to change the size after 1 year.

[66vairguy]

The 60's used I believe a 1/4" rivet and the rest used I believe 5/16". GM must have noticed something fairly soon to change the size after 1 year.

Interesting.
In 1960 the engine produced an advertised 80HP, although a 95HP engine became available.
In 1961 there was an optional 98HP engine. I wonder if the extra HP resulted in the rivet size change?

[RexJohnson]

Or they figured out that they weren't big enough?