Measuring degrees of advance

Steve51

Steve51

Member
I inherited a 51 Custom sedan from my father. Has the 8ba v8. The small white dimple on the crank pulley is at 4 degrees btdc to my understanding. So when one sees recommended degrees of advance at certain rpm are these measured from the mark at btdc or is it measured from tdc? As an example if you want 24 degrees of total advance is it actually 20 from the dimple plus the 4 to tdc making it 24 or 24 from the dimple?
 

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i've seen the dot is 2 deg/ Whatever, total advance would be determined from TDC or zero. In your case 24 total would be 20 plus the 4.
 
Flatjack9
Yeah I have seen 2 and 4 also. I thought it may be 4 for the later 8ba engines....2 for earlier engines. I am going with 4....that close it may not matter.
 
Every stock 8BA distributor I have worked on with a good vacuum advance can had a good curve. Don't over think this.
 
Steve51 said:
Flatjack9
Yeah I have seen 2 and 4 also. I thought it may be 4 for the later 8ba engines....2 for earlier engines. I am going with 4....that close it may not matter.
Click to expand...


The crank pulley dot/bump IS 2 degrees BTDC on ALL late F/M flatheads. I suggest procuring a '49-'51 Ford shop manual that will be very helpful if you are keeping your father's '51.
 
a vacuum gauge and your timing light will help you adjust your timing. The vacuum gauge gives an accurate reading of the air moving through your engine. And is helpful
with adjusting the mixture on the carburetor.

I cut each page out of this book, put them in plastic sleeves in a binder, and add separate sheets with notes from my own work, part numbers of replacement parts and from the advice from the crew on Fordbarn.

Have some fun with the car, don't overthink things.

https://www.amazon.com/1949-1951-Ford-Repair-Manual-Reprint/dp/B00435MUFG?tag=atomicindus08-20
 
Thanks all for the replies. I do plan on keeping the car. I have my own 63 Galaxie so I am more familiar with 1960's vintage stuff. So far I have rebuilt the fuel pump, the carburetor(leaking power valve and missing accelpump checkweight), installed a new voltage regulator, and rewired the shorted out front lights. Otherwise the car is a solid rust free car that has been inactive for the last 4 years. The engine was rebuilt about 8 years ago and it is all stock....no mods.
I set the initial timing, vaccum disconnected, right on the dimple. Vaccum hooked up at idle seems to be 12
degrees advance. Pulls a steady 20 on the vaccum
gauge hooked to manifold vaccum port. I did notice that
the advance did not seem to increase much past 12-15 at
higher rpm but ran out of time to investigate. The car is
not at my house but at my mother's place 70 miles away. I did notice a kink in the steel vaccum line near the
distributor possibly causing a restriction. Or my other
thought is I will not get a proper advance reading at higher rpm unless the engine is under load with the lodeomatix distributor. I may cut out the kink in the line and patch with rubber vaccum hose as a temp fix. Going out today
to work on the car. Will report back my progress.
I am pretty handy with a wrench and prefer to do my own work. I just haven't worked on cars this old before.
 
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It sounds to me like you have everything under control. The total advance seems to be a bit low, but I think you have a handle on that.

A Load-A-Matic works well with a completely stock engine, buy be aware that any modifications will probably require a change in distributors.
 
An update....Finally got out to do some work on the 51. The idle was way too high when I set the timing originally so everything was off. Once I reset the idle and retimed it and adjusted the idle mixture screws it is running very smooth. The vaccum advance is working properly. Very quiet and smooth at idle and starts instantly. Took it out for a 20 mile run last weekend.....first time on the road in several years.
 
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