Spark advance
 

Ok all you experienced A Modelers I need some understanding of the effects of advancing the throttle and power causing overheating...


Finally got the car started after a steering box leak fix, installing a 6 V Alt, fixing the brake rod contact area for the brake light switch, soundproofing/heat shielding the car and reinstalling the 12v power supply and CB radio....


As the car was idling and after the initial increase in RPM to "start" the Alt charging I was trying different settings for both the fuel and spark advance. The fuel is simple more fuel RPM increases less fuel RPM decreases.


Spark though is a totally different thing. With the spark retarded (up) the idle lopes or sounds like a Model A with it advanced (down) 3-4 notches it hums like a sewing machine. (smooth idle) my question is the smooth idle where you want to be or why is the loping "Model A" idle the norm?


Will the car warm up faster with the throttle advanced or should it just lope until warmed up.


THANKS for teaching me new things about these awesome cars!!

Re: Spark advance
 

Have your advance down where it hums as you say. The retarded idle is just a Model A thing where we all think it sounds cool, real slow and a little lumpy. For warm up just a little more RPM than at idle, in the hum position, lever down a few clicks.

Re: Spark advance
 

Personally I want my engines to hum, purr not lope! I think it is hard on the power train, each time the pistons come up, running too slow they stop before the flywheel carries them over and spark comes after TDC, I want that to be as smooth as I can make it. I think it is a dumb carry over from people that want to show just how slow the motor will run and in my OP has no place in the real world.

Re: Spark advance
 

The only time the spark lever should be full up is when starting, and immediately then pushed down about 1/4s down its travel for warm up and very low speeds. Use the Model A Ford Instruction manual for spark/GAV settings.

Re: Spark advance
 

I'm not sure what you mean when you say fuel. I think you are talking about the right lever which is the throttle lever. Left lever is spark lever.

Left up, right down a bit for starting
Once started left down about half
right lever up once warm enough, left down 1/2 to 3/4 for most running.
most overheating happens because of retarded timing.

Re: Spark advance
 

I agree that retarded timing is the main cause of over heating . Ford said full advance at speed . I fully retard the spark lever when starting the engine . I run full advance at speed . I feel that anywhere from 35 MPH on up would have been considered speed back in the day . At low speed I retard the spark as necessary to prevent timing knocks and bucking . It should be easy to tell when running too slow for the gear that is being used . Luging the engine at low speed is very bad for the babbit . Slightly retarding the spark at low speeds has worked well for me for the past 60 years .

Re: Spark advance
 

Thanks if you always hear them "loping" then that is the "normal" condition.



Yes the "fuel" I'm referring to is the lever on the right or as I call it 1930 cruz control. And thanks the overheating is the part I was more interested in.


Thanks



Idid read the owners manual and start full retarded and some throttle but needed to know the loping is not the best way as well as get a better understanding of the retard/advance for the spark control. When I'm driving I do have hte spark advanced and going up hills it really seems to gives a booost.

Re: Spark advance
 

DNLs1930'
"I did read the owners manual and start full retarded and some throttle but needed to know the loping is not the best way as well as get a better understanding of the retard/advance for the spark control. When I'm driving I do have hte spark advanced and going up hills it really seems to gives a booost." [/QUOTE]

Your last comment about having the spark advanced and going up hills it really seems to give it a boost.
I am not sure I understand what you mean by that part of the ststement so I would like to add the following comment:
When you climb hills and the engine is pulling hard, the spark should be retarded (left lever up some) to eliminate knocking and lessen the high pressures in the main and rod bearings. Two notches is typically enough. When you have reached the top of the hill and the car is mostly back to speed, return the left lever down two notches and continue on your way.
Good Day!

Re: Spark advance
 

Cruz control :D:D:D Yep, thats one way to look at it !

Where ever you have the spark lever set, if you start to hear the engine knock/ ping/ detonate, then quickly push the left lever up a few clicks to stop that knock. An engine can handle some detonation with no damage but it sure doesn't do it any good.

Re: Spark advance
 

My use of the spark advance lever:

Re: Spark advance
 

I would guess the "boost statement" is based on the fact I have been running the advance as taught which was about 1/2-3/4s advanced which when at speed and going up a hill I would advance it a little more and the car would smooth out seem to have a bit more power. The biggest hill we have locally is not that big but I do end up retarding the advance as I get closer to the top which I would guess coincides with the loading of the engine. I have net experienced knocking or detonation so I must be doing something right without really knowing it... Thanks for the lessons.

Re: Spark advance
 

Got it and I do retard the spark as the engine loads up I just did not realize that it is the right way to drive the car. I just listen to the engine and move stuff around to make it smoother (not really but kinda) Now if I could just learn to down shift...

Re: Spark advance
 

smoother, yep. The car will tell you, feel what its doing.

Downshifting. It'll come. Raise the engine speed more than you think you need. Better it be too high than too low.[ especially from 2nd to first.]

Re: Spark advance
 

Nice drawing easy to remember.

Re: Spark advance
 

Enjoyed the discussion. I know from our club meetings everyone has a theory.
This discussion cleared up some misconceptions I had.
Gerry Birch Bay WA

Re: Spark advance
 

Great illustration. Makes me think I may be keeping the spark too far retarded even with the 5.5 head.

Re: Spark advance
 

My philosophy is to give the Model "A" and the Model "B" all of the timing advance they will take without knocking. Doing so, the engine makes more torque and power. I find cleaner spark plugs and cleaner combustion chambers result.

Re: Spark advance
 

Same here !!!

Re: Spark advance
 

I agree with Bob Bidonde and Purdy, you need to get as much advance as possible to get maximum performance. Too much advance robs performance. Proper advance is kinda specific to your engine's setup. High compression head? What is your point gap? Are you really timed correctly? Lots of other variables. I have two engines for which I am responsible for the care and feeding of. Basically all stock except for the cylinder heads: On the one I have a 5:5 head, with stock Zenith carb, stock distributor with points set to 0.020" I can advance about two-thirds for high-speed driving. My other engine has a 6:1 head, also with stock Zenith carb, stock distributor with points set to 0.020". The 6:1 won't take quite as much advance-I call it "5/8 advance" or just a little over halfway. At this setting it runs at 50mph nice and pretty all day long. Once I find the sweet spot I rarely move the advance lever but will if going uphill or at low low speed or a combination of both. Most of the time, I can take a gentle hill just by giving it more gas and can pick up speed going uphill. I say all this to point out that a lot depends on whether you run a stock head or a high(er) compression cylinder head.

Re: Spark advance
 

Personally with my A timed correctly have been unable to hear knocking/pinging, including full advance on hills, but still retard the lever on hills as a safe guard. Rebuilt motor with standard head, 87 octane ethanol free.


Have wondered if on the standard head it is not as much as a problem since the A was designed in the 20s when octane was lucky to be rated at 50. Now it is 87 or above.


What do you think?

Re: Spark advance
 

Observation: I have rebuilt 190 engines using insert bearings. About 15 are full pressure, another 15 have unfiltered oil direct to the center main and the rest are gravity fed. Of these engines I have had 6 engines come back to date with damage from running the engine with too much advance. In all 6 cases, the crankshaft was not damaged. The main bearings were the first to fail with the center main being the worst, the front journal following closely. The rear main had the least damage.

When the bearings failed, the bearing material was at the worst, pulverized, at the least shattered into course chunks.
The rod bearings in these failures all showed high pressure marking on the bearing surfaces. A couple of them had some early bearing material fractures.
The repairs to the main bearings were easy and not expensive to make. Change the inserts and thoroughly clean the engine. As a precaution, the rod bearings, also all inserted, were replaced even if they showed no distress.

All of the engines that returned for repair were fitted with High Compression heads. Most of the guys thought they were running their engines with the proper advance but when I checked their timing they were all over 30 degrees advance with one hard-of-hearing gent over 40 degrees. One gent ruined his bearings during a 6 hour run and less than 2 tanks of gas. Yes, It can happen that fast!

My point and advice: Too much advance will shorten bearing life. Back the timing advance down when using a head with higher compression than Ford's stock head. In most cases with heads of 6:1 compression, the advance should not be over 26 degrees before top dead center at full advance.

More concern: A new 7:1 head I dyno tested early this year, produced phenomenal power but started to noticeably knock at 22 degrees advance. No significant power was gained over 19-20 degrees advance. The owner brought the car back to me saying the engine "will just not run without knocking" and would I check it over. I immediately checked the timing and found he had the timing set at 28 degrees. I set his timing at full advance to 19 degrees and sent the car back with him. He reports: "It goes like stink but sure requires fiddlin with the timing to keep her from knockin". So don't assume by the book normal timing will work with anything but a standard head.
Good Day!
www.durableperformance.net

Re: Spark advance
 

People love rules to follow. The trouble is "half way" or "5 clicks" or any other measure is simply a general guidance. Every car is different. Listen to your engine. Learn what ping sounds like. If you can't hear good enough then train a set of young ears what to listen for. Advance should be set for max until it pings when pulling, then back off timing just until it quits. Simple and straightforward, no guesstimate or magic involved.

Re: Spark advance
 

Again, I agree that retarded timing is the main cause of over heating . If momentum is kept up there will be much less problems when running at full advance . I feel that if the engine is in good condition , running at 50 MPH will greatly reduce the possibility of timing knocks and lugging . My model As easily cruise at 50 MPH and I have ran most of them that way for years .

Re: Spark advance
 

It sounds like you’re running a little retarded under your “normal” speed. As advancing upon giving it more gas seems to produce more power. The best way to tell where your timing is, would be to ( at any speed),move your timing lever advance and then slowly retard and you’ll feel where the engine starts to loose power. That is the “sweet” spot for that speed.

Re: Spark advance
 

SOOOOO many learning points here!! Guess I shouldn't even ask about the automatic spark advance... ;-)

Re: Spark advance
 

Nooooope ! :D Moving that lever is just one part of the wonderfulness of owning one of these monsters.

Re: Spark advance
 

Guys, I am finally getting to under stand the spark advance from this thread. I met Chuck one day by chance in Blaine Wa; and discovered we have engines rebuilt by the same fellow.
Long story short, being a newer Model A type at the time and still am, Chuck and I had a quick conversation about spark advance which helped my understanding. However this thread has really brought together my understanding and cleared up some miss-conceptions.
My question is; with being hard of hearing, I have being advancing the spark to the point of engine hesitation then back off a notch or two until no more hesitation.
Is that point of hesitation where the the engine begins to ping, I can't hear it but I feel it. In other words, I am advancing the spark until I get a nice surge of power from the engine and it runs smoother. I notice now that my car is running cooler, thanks to Chucks explanation. I know this because I shoot the Rad and brake drums temperatures after most outings. By virtue of the area I live in (not a big city) the car is my daily driver so am getting used to the vibrations and what little I can hear.
Once again thanks to all who have contributed to the thread a big thank you. The pictures were worth a thousand words.
Gerry Birch Bay WA