40 Ford condenser question

M

mcgarrett

Well-known member
What should the correct (acceptable) capacitance range be for a good condenser for a stock 85 HP flathead? I have several condensers I would like to test.
Thanks for the input.
 
Actually, anything between .20 and .45 microfarads. Points ignition systems are very forgiving about this. Here is a list of capacitors available from Ford I stole from an old publication. The numbers look like Ford numbers and the ratings are all over the place. Also, points 3.) and 4.) are important.
 

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tubman said:
Actually, anything between .20 and .45 microfarads. Points ignition systems are very forgiving about this. Here is a list of capacitors available from Ford I stole from an old publication. The numbers look like Ford numbers and the ratings are all over the place. Also, points 3.) and 4.) are important.
Click to expand...

569454
 
mcgarrett said:
What should the correct (acceptable) capacitance range be for a good condenser for a stock 85 HP flathead? I have several condensers I would like to test.
Thanks for the input.
Click to expand...

I have found 30mfd to provide the best performance with my 36 - 40 Fords.
 
mcgarrett said:
What should the correct (acceptable) capacitance range be for a good condenser for a stock 85 HP flathead? I have several condensers I would like to test.
Thanks for the input.
Click to expand...

on my '37 i run a remote coil and condenser standard motor parts FD72.28-.32 mfd.the ecklin condensers failed.i believe i got the FD72 from Good Guys auto parts and amazon has also. Tom.
 
Some members here have reported that purchased condensors sometimes fail testing and also say that age (sitting around) can effect them.
 
Drbrown said:
Some members here have reported that purchased condensors sometimes fail testing and also say that age (sitting around) can effect them.
Click to expand...

A few years back I'd tested the dozens of NOS Ford (OEM) condensers I have. I no longer recall the number of good ones there were but believe it to be about one or two out of ten.
 
And bench testing is not easy to do. Even with specialized equipment that can measure capacitance, things change with heat. Condensers (and coils) often work fine on start-up then start breaking down as they get warm. I think simplest test is to put it on the car and see how it does. (bring your old condenser with you on the test drive)
 
Generally, they can be anywhere within reason. The actual lead to the capacitor has slight capacitance in itself, and an extremely long wire lead would slightly increase the capacitance. Two or three feet would not make enough of a difference to worry about. This is why high-end capacitor testers have a set of very short leads to minimize this effect in cases where extreme accuracy is required.
 
Wires have resistance which is negligible on short leads but the longer the lead, the higher the resistance. A coil that is in the inductance phase of high energy output, launches a pretty good back flow to the condenser while it's kicking out the stored energy that builds during dwell time. While a condenser can work in a short distance from the coil or distributor, it may not be as effective at protecting the breaker points so I'd try to keep it as close as possible to the points.
 
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