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Discussion Starter · #1 ·
I have a failed vacuum advance, that has the following stamped on the flat part: "118 15" (which I seems to be short for 1116118 w/15 degrees advance)
I assume this should provide 15 degrees advance at full vacuum.
I see some on ebay that are stamped "118 18". Would that provide 18 degrees advance?
Which is the correct part for a stock '57 283 4GC Power Pack w/original PowerGlide?
Or does it matter?
All casting numbers and date codes match the presumed production date for the car, except for the starter (1956), generator and water pump.
The distributor also seems to be original: 1110890 7 D 20 - April 20, 1957

0258_15_233908_57ChevyDistributorCodes.jpg
 

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Discussion Starter · #3 ·
Yes, I saw that listing earlier today. It shows "118 15" stamped in the flat part, which matches my old one.
I've seen other Delco-Remy vacuum advance units with the same part number 1116118, but stamped with "118 18".
So my question is: which is correct for this car? 15 or 18 degrees advance?
 

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Is that your condenser wire grounded under the vacuum advance mounting screw? If so it shouldn't be. It should be with the primary wire under the breaker point connector .
 

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Discussion Starter · #5 ·
Is that your condenser wire grounded under the vacuum advance mounting screw?
No, that wire is grounding the plate that hold the points and condenser (since it has to rotate with vacuum and centrifugal advance).
There are three wires in the picture.
The blurry wire in the foreground connects the condenser to the points.
the other wire connected to the points leaves the distributor through a grommet below, and it connects to the coil.
The ground wire you are referring to is spot welded to the points plate, but that connection is mostly obscured by the condenser wire.
 

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Towards the bottom of the post, you'll see that advance is 8 degrees at the distributor or 16 degrees at the crankshaft (where we usually read these things).

Personally, I wouldn't worry about whether it's 15 or 18 degrees. The octane of the gas will be more important than that difference.
 

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Discussion Starter · #7 ·
Personally, I wouldn't worry about whether it's 15 or 18 degrees.
OK. I bought one off ebay labeled "118 15", which comes to ~$50 with shipping and our governor's 10% sales tax.
I just hope the diaphragm in the NOS one I bought holds up for a while. I'll test it with a vacuum pump as soon as I get it.
Thanks for the link to the other post. Interesting reading.
 

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OK. I bought one off ebay labeled "118 15", which comes to ~$50 with shipping and our governor's 10% sales tax.
I just hope the diaphragm in the NOS one I bought holds up for a while. I'll test it with a vacuum pump as soon as I get it.
Thanks for the link to the other post. Interesting reading.
Yeah, just some geeky stuff I wrote some years back I thought might be helpful.

Keep in mind that the actual timing = initial setting (typically 4 degrees BTDC for a stock 283) + vacuum advance + mechanical (centrifugal) advance.

It's not unusual to see someone push the initial setting to 6 degrees on a stock engine. That's why I wouldn't worry too much about 15 vs. 16 vs. 18 degrees, if you stick with the specified 4 degrees setting.
 
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