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I am trying to find a compression tester for my 1928 Packard. It appears the spark plugs are a 7/8"x18. All I can find are smaller adapters. Any suggestions are appreciated.

Thanks,
Gar

They make ones that simply are to be held over the hole. It has rubber on the outside so it seals as you press it onto the hole. Universal… but takes two people unless you have a remote starter button. Kinda like this in the link but the correct dial.

autotoolworld.com/Lincoln-Industrial-MV5 ... Sb221gFfG5fzb3EoNBYzWhoCZm0QAvD_BwE

FWIW adding an underhood remote starter to any Packard should not be of significant difficulty, unless you have your car judged at shows, in which case you will need to use something that connects with alligator clips and is attached as needed.

Also, I don't know the compression ratio on these cars, but if we assume it's 5 to 1, then that's almost 60 lbs pushing your tester off the car if it's a 7/8" hole, so keep that in mind as well if you plan to buy one.

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Maybe not so easy on this car if it has the foot operated manual starting switch.


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You might check with some of the Model A vendors. Many of them sell adaptor sets to convert the old 7/8-18 plugs to a modern 14 mm size and almost all compression gauge kits should have an adapter that would work with that size. This vendor has the adapters but down toward the bottom of the detail note he also says if you need an adapter to use with a compression gauge you can order a single adapter under a different number.

If that doesn't work out Summit has cheap 7/8-18 plugs and you could do the gut and braze of the plug base to make your own adapter.

Thanks for the clarification, Howard. One could buy a replacement 6V solenoid aftermarket and hook it up in parallel with (or bypass) the foot electrical switch if needed.

amazon.com/Tisco-8N11450-Starter-Solenoi ... ef_=fplfs&psc=1&smid=A1SPBZ57COJYFU

I think Cli55er was referring to the standard mechanic's tool.
Like this one: Remote Starter Switch

Thanks, gotcha. I meant that if you use that in conjunction with a solenoid, then you can remotely switch full battery current.

If you cant find an adapter you can use a old spark plug. Smash out porcelain and either tap the 7/8" plug housing for standard adapter or braze/weld an adapter on. BTDT. PB