Testing 087 Ignition Coil

[Harry S.]

Looking at the shop manual I have the primary and secondary numbers for an 091 coil. Anyone know the primary and secondary resistance numbers for an 087 coil. My primary looks like 1.6. Bad news is I can't get a secondary.

Thanks

[Dave S.]

Re: Testing 087 Ignition Coil

Looking at the shop manual I have the primary and secondary numbers for an 091 coil. Anyone know the primary and secondary resistance numbers for an 087 coil. My primary looks like 1.6. Bad news is I can't get a secondary.

Thanks

The only sure way to test a coil is to put it on the car and run it until it gets hot. Install the shielding and close the hood. If the car runs properly then the coil is good. Sounds to simple but it is the only real way to be sure.

[Duke W.]

Re: Testing 087 Ignition Coil

Since the 087 coil was used for all 250/300 HP engines in '64 the data may be in the '64 Corvette Shop Manual Supplement.

I don't think the AMA specs list coil resistances... just current draw.

Duke

[Harry S.]

Re: Testing 087 Ignition Coil

The only sure way to test a coil is to put it on the car and run it until it gets hot. Install the shielding and close the hood. If the car runs properly then the coil is good. Sounds to simple but it is the only real way to be sure.

Dave, thanks... I plan on installing tomorrow. Just wanted to avoid the labor if I know it's fried.

[John D.]

Re: Testing 087 Ignition Coil

Harry, One might think the 087 coil would be in the 63 shop manual but all I see is the 091 coil listed
Checking the Corvette Servicing manual (my favorite) there are a bunch of coils listed. 083, 086, 091, 107, But no 087.
Just for playing around: 086 Primary Resistance (ohm) 1.24-1.46
Secondary Resistance (ohm) 6500-9500
The 091 is: Primary 1.00-1.16
Secondary 7500-10,500

I have a '65 supplement but lost my '64 supplement in the shuffle here. NOS '087's are still affordable compared to the big buck 091's. John

[Duke W.]

Re: Testing 087 Ignition Coil

The 087 coil information is not in the '63 shop manual because its use on 250/300 HP engine (along with the 1.8 ohm ballast) was a running change that was not approved until well after the shop manual was published.

As long as the primary side has continuity and is not shorted to the case, it should work, and because these coils have very low resistance, getting an accurate reading can be tough unless you have a high end meter.

Duke

[Richard M.]

Re: Testing 087 Ignition Coil

Harry, Did you try from center lead to each + & - terminals of the primary? Anything around 10k ohms should be a good indication. If you shake it do you hear the oil sloshing around?

Also, make sure the screw down inside the center terminal is tight. There nasty carcinogenic oil in there so use glasses, gloves and caution.

But I agree, the best test is on the car hot under load.

[Frank D.]

Re: Testing 087 Ignition Coil

I think we all try to avoid becoming random 'parts swappers' as part of problem diagnosis. But in the case of replicating the heat and vibration of a running engine to detect intermittent problems there's nothing like a 'real world' test...

[John D.]

Re: Testing 087 Ignition Coil

Anyone ever seen an old time coil tester. My friend Ron Booher had one. I believe it had a crank on it with meters. Wish I had gotten it.