Hot Rods Myth and facts of ignition timing explained

Hi, new to forum. reading this because facing issues with my 6v Y256 block '54 mercury that is spitting thru carb while light accerleration and wot. in my case i don't have mechanical advance but only vacuum advance which is ported vac. what i'm finding is at the factory spec of 8*static timing, it's falling flat on it's face. but if i give more timing, say around 25* it seems to drive better. issue then is i can't restart after hot soak......6V system. i'm still running points and condenser but with present day type of ignition wires......the carbon centre!!!! any advice would be appreciated

 

Welcome to the forum.

There is a pretty big difference between 8 degrees advance and 25 degrees advance static timing. I might suggest you start someplace between those two timing settings, and run a trial and error until you reach the performance level you can live with and can still start the motor after it heat soaks. There is very likely there is a sweet spot in the timimg that will work for you.

The other option (and probably the best option) is step up to a distributor with a mechanical advance and a vacuum advance.

 

Why no mechanical advance? You have to have it.

 

here's a reply, and just something to read....as I know nothing about automotive...but... could you be having a carb problem??? shooting ducks is lean...maybe no accelerator pump??? and also, did you verify that the vac advance is working????easy to do with the timing light...does the timing advance when you gas it???

 

nice!!! anymore pics???

 

also, with the air cleaner of, and engine off.... look down the carb and see if there's pump squirt... also check that there is good spark... running up to 25 degrees advance IMO is a bandaid for some other problems

 

I would make sure the distributor vacuum advance diaphragm is working properly, along with targeted 27 degree point dwell before you make any timing changes.

 

Ford used vacuum-only advance loadomatic distributors from '49-'56 on V8s and later years on some 6s. The system works fine on a stock engine with correct matching carb that provides the correct vacuum signal.

 

for me , the two must do's for Y blocks is marvel in the oil, and lucus in the gas... Y blocks like to get sticky valves.... you'll notice driving that when you come to a stop sign the motor shaking like it's running out of gas and stalling. then no start... marvel and lucus keeps eveyything clean and running smooth, with easy starts...

 

Is the vacuum line to the vacuum advance disconnected and plugged when you set your initial timing?
Dan

 

YAY!!!! Finally, someone who knows what they are talking about, and how to explain it. Thanks.

 

Really...??????

 

@2FORCEFULL

Is there an update on your progress?

 

I gues in 1954 they didn"t think of it.....

 

Not a fuel issue because it responds great to more timing. And Vac advance it definetly working as timing light indicates close too 47* when i set static to around 20* acceleration no load.

 

Just installed rebuilt vac advance diaphragm and timing light indicates 47* acceleration no load with the 20* static i am running

 

And thats what i have is a stock 7.5 compression engine with the Teapot carb and ported vaccum off carb. If i set static at factory spec of 6* and rev her up with no load, the timing light indicates around 22* when vac kicks in. But at those settings she spits, bucks and hisses through carb. And idle shows healthy 18inHg manifold vaccum by the way. So i then set static to 25* and drive her with with decent throttle response but of course that's when she won't restart after short hot soak.

 

no but didn't think necessary since it's ported vac

 

For a stock factory engine I always unhook and plug the vacuum advance line then set the timing to the factory spec at the recommended rpm. You can find out how much if any the vacuum advances the timing at idle by simply checking the timing with and without the vacuum hooked up. I don’t know if your engine has a harmonic damper but if it does the outer ring may have slipped which will cause an erroneous timing reading.
Dan

 

Also welcome to the HAMB
Dan

 

The Briggs & Stratton on your lawnmower most likely runs just fine without any kind of advance changes. It works okay there for two reasons. One, the engine works under relatively steady conditions - the same rpm all the time, similar load most of the time, and two, the demands aren't that high - a better ignition system could provide both a bit more power on some rpm and a bit better fuel economy, but as it's a simple engine and it doesn't use a bunch of fuel as is we're happy enough with it anyway.

On a street car some extra low/mid range power and fuel economy is a far bigger deal, so there we really want a more advanced ignition system adjusting advance to be closer to ideal under all working conditions. We don't HAVE to have it, as many early cars and other types of engines have proven, but we WANT to. One of those things that eventually will pay for itself just in the fuel saved.

 

What is the point dwell?

 

As usual, another thread has gone off the rails.

 

Bschwoeble how has this thread gone off the rail? A new guy is asking questions in regards to his car, he found this thread and thought it would be a good place to post his problem. I for one learned that mid century Fords didn’t have mechanical advance and used ported vacuum advance which I also thought was only used in the bad old 70s Another myth busted for me anyways.
Dan

 

The Ford flathead loadomatic carb vacuum signal is not simply ported, but an internal combination of manifold and venturi vacuum, resulting in max values of about 6" Hg for around 18-20 degrees distributor advance, depending on year, car, etc.
I'm not sure about '54-'56 Y-block loadomatic timing but I'll get back when I have some info.

 

Thank you
Dan

 

Could a previous owner have possibly changed either the carburetor or the distributor? These must both be properly matched for the Loadamatic system to work as intended.

If you're not real familiar with working around points style ignition systems, the link below should help clear up some of the mystery.

https://www.jalopyjournal.com/forum/threads/hot-rod-technical-library-basic-ignition-systems.983424/

 

Mechanical (centrifugal) ignition advance did indeed exist prior to 1954. And it's a safe bet that most other manufacturers were making use of it. Ford probably went with the Loadamatic system because it was a bit simpler, seemed to work OK for the most part when everything was in good working order, and mainly because it likely saved them something like 28¢ on the cost of every vehicle built.

 

Actually, '32-'48 Ford V8s had dual points WITH mechanical advance, made by Mallory. Spark retardation under low vacuum load was accomplished by a vacuum "brake" that slowed/stopped the advance plate. The later Loadomatic was a simpler lower cost ignition that worked fine in stock applications but was
not designed for higher performance engines that became common in the mid '50s.

 

A couple corrections to my above (earlier) post.
The '49-'53 flathead max distributor advance was around 10 degrees from about 4" Hg input, resulting in 20 or so crank shaft degrees. (Most flatheads are happy with 22-24 degrees total advance).
The '54 Y-block max distributor advance was around 15 degrees from about 4" Hg input, resulting in 30 or so crank shaft degrees. Later '55-'56 Y-block specs are similar.
Sorry for any confusion.