VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 28 plugs and points. Standard Gap or Increase?

You don't say what coil you are using. Are you running a stock coil or a more modern one. If you are not running a modern I suggest you install a 1954 6-volt coil along with the 1954 condenser.

Why 1954? What is special about that year? will any modern 6V coil work? Inquiring minds need to know.

Try to make things simple to the parts kid. If you specify a 1954 you will get the latest 6-volt coil and it is designed for a 6-volt system as you have. Same for the condenser. Ask for anything else and it is a crap shoot as to what will be laid up on the counter. Don't confuse them with too much information.

perfect sense, been there done that.

Right, if the 54 is available do it! makes for a much simpler transaction. If they aren't available at the chain auto parts store find a Mom & Pop Auto Parts and farm store down in the old part of town.

Gentlemen,

ARE THERE ANY CHEV WHISPERERS OUT THERE ?????

The saga continues, and I would like to thank everyone for their suggestions and comments so far, in particular an aussie chev man, CJP'S 29, who is holding my hand through this very frustrating "event".

Today's developments are:

1. Replaced the coil with a modern 6V unit, making sure it was suitable for a non ballast resistor ignition system.

2. With the W14's fitted went for a run, engine ran fine,no miss, but lacked the power increase and response of the 3077.

3. Fitted the 3077's, engine developed miss again in the same location, approx, but in all other parts of the run, was fine, more power, ran smoother, pulled very well on hills.

4. Replaced the condensor, did one circuit, no miss, thought I had solved the problem, then another lap, miss returned.

I should point out again to all the miss is in a spot during the run when the engine is not under the greatest load, and the series of events are, engine looses power, audible miss and vibration, pull over, engine runs rough for 1 maybe 2 seconds the full power again regardless of train or speed.

If it was not for the fact that their is no problem with the W14's I would be looking at fuel.

At all other times the engine is without doubt running better on the 3077's, otherwise I would say it's too hard and stick with the W14's or 3076's

I have no idea why my engine appears to not like 3077's.

I have changed back to the W14's and will do as many runs as I can after work tomorrow.

Any Suggestions??????

Regards

Ray

For a "suggestion"
Try the standard gap on the 3077 plugs but install a second washer to pull it back a bit from the combustion chamber.

I get a feeling that the 3077s may be a bit hot for your engine. After pulling a grade (heats the cylinders) you are getting pre-ignition from the hot plug electrodes. Once the plugs cool a bit they work as they should. An extra gasket might help. AC 78S plugs (out of production) could be a better fit for your engine. Another possibility is to use adapters and modern plugs. There are a bunch of modern longer reach plugs with various heat ranges.

I had the same thought about the temp of the plugs as Chipper just said. One thing you didn't mention is the outside temperatures while during the runs.

Of course I didn't think to ask about the fuel being used. Is is straight gasoline or have ethanol or other stuff added? I said stuff to be nice and since this is a family oriented site.

I do have one other “suggestion” and that is to try the actual spark plug that Champion catalog for your car the W16Y (2001 catalog).
The W14 Champion (3076 Autolite) works but may be too cold.
The 3077 Autolite (W89D Champion) appears to be too hot
The W18 has a longer reach and should not be considered
Moving to the W16Y will give you a slightly hotter plug than the W14 but with the projected core nose of the 3077 Autolite
The W16Y are easily available as they are sold as a modern day replacement for the 3X Champion on the Model A and sold by F**d vendors as Snyders ( $7 US)

Hi Guys,

I do appreciate the replies, and thank all for taking the time to make a posting.

GOOD NEWS AT LAST, as I may have finally broken through, and come up with a possible cause of the miss with 3077's.

I don’t know what I have worn out more in the last 3 days, either the threads on the head from 1 Million plug changes, or the 7 kilometer test track I have been using.

I have done 100 miles in the last week and a bit, but have not been more than 5 kilometers from home.

The latest and most fruitfull developments are as follows:

I did 2 runs with the W14’s. No miss, no problem, but definitely not the same smoothness and response of the 3077’s

Then I did 1 run with the W18’s. No miss. No noticeable power increase, but engine a bit rough on fully advanced.

Then did 1 run with W20’s. No miss. Power seemed a bit better than the W14’s. But again engine a bit rough on fully advanced

Then the penny dropped. TIMING.

My Chev has never seen a timing light. I have allways tuned by ear, and with W14’s fitted.

So I did 2 runs with the 3077’s fully retarded, driving it very hard, pulling up hills at 20 mph etc, no miss

Did 1 run, fully advanced, exact same miss, exact same spot, pulled up, rough idle for 1 to 2 seconds then fine again all the way home.

Just to confirm, did another run fully retarded, no miss.

I SHOULD MENTION THAT THE ENGINE SEEMS TO RUN BETTER, SMOOTHER, AND MORE RESPONSIVE WITH THE 3077, THAN WITH ANY OTHER PLUG TRIED SO FAR. OUSIDE TEMP DURING ALL RUNS WAS BETWEEN 10 to 20 DEGREES CELCIUS.

Interesting observation was that there was not the noticeable power difference (with the 3077's) at road speed when changing to fully advanced as with the W14’s, or the roughness when changing to fully advanced with the W18’s or 20’s.

Again I welcome any comments as to wether you think its timing or pre ignition.

Regards

Ray

What this all illustrates is how critical is the ignition of the flame in the cylinders. What most people don't understand is that the gas/air mixture is ignited at the spark plug and then travels at some speed across the cylinder. If the flame proceeds too fast the maximum pressure is created too soon and power is reduced (if fast enough then "spark knock" occurs). If too slow then the maximum is too late and power also lost.

It should be deduced from the above that the timing, intensity and strength of the ignition spark is critical. But also the ratio of vaporized gas to air [1:14 is stociometric (ideal)], total amount and temperature of the mixture are factors.

I think that Ray's experiments illustrate that small differences in ignition intensity and timing can have a noticeable effect on the performance. Normally these factors are not noticed without using a dynomometer in a laboratory and strictly controlled conditions.

What may not be understood is that changes in carburetion, flow pattern in the intake system and fuel used can also effect performance. It would be interesting to know what the effect of adding 10-15% diesel to the gas would do. Also the difference in regular gas with ethanol, without and premium gas. All those gasoline mixtures will have a slightly different burn rate. May or may not make a noticeable difference. The scientist inside me wants to know. Ray, I fully understand that there is a limit to the time, desire and dedication needed to run the experiments. Just would be interesting to know the effects.

Going by memory here, so the numbers might be off. If you run full retard, then at idle, it is 0deg. and at full speed, about 22 deg due to the auto/mechanical advance in the 28 distributor. At full advance, this moves to 22 or so at idle and about 45 at full speed. This gets tricky, since you can't go below zero as the starting point. As I see it the only way to limit the top end is to fabricate some sort of a stop on the manual advance. this all done once timing is determined to be correct. Another observation is that since you did not overheat with no initial advance, perhaps this is what's off and a simple adjustment is all that is required.

Shawn and Chipper,

Thanks for your comments. The easy way out, but I suspect not the right way would be either just drive it retarded, or adjust the advance retard bracket so that the current dist position at retarded now becomes fully advanced. But as Chipper says, the scientist in us wants to know what's going on. I know how to time a modern engine with a timing light, so if there is a way to use the same on a 28, can you please advise things like where is the timing mark on the pulley, and what is the static reference point to measure buy.

I am now starting to feel better as the muddy water is starting to clear.

Regards

Ray

I would prefer you drive sensibly and not retarded.

very clever, never thought of that.

Beginning with the late '27 engine, there are two timing marks on the flywheel and a window with indicator in the clutch housing. They can be timed with a modern timing light as long as the last person put the flywheel on the crank in the correct position (it is possible to put in in six different positions)[ask me how I know][It will be corrected soon]. With full retard the UIC mark should be on the indicator. UIC is for upper center with the actual line between the two letters. Modern term is TDC or top dead center. Full advance should be at the 25 mark on the flywheel. That is 25 degrees before TDC or UIC. According to the "book" the mechanical advance begins to function at 22 mph and full advance is 40 deg.

Of course that suggests another possibility. If the springs and weights do not operate properly then the mechanical advance could occur at too low rpm. Sticking advance mechanism would render too much advance at low speed and loss of power/poor idle etc.

Have fun and let us know occasionally what you find.

Thanks Chipper,

I will check tonight but suspect I also removed the flywheel several times over the years and cant recall being too dillegent about mounting back in the same spot.

Cheers

Ray

I just went out to the garage to take a look at the timing mark. I found the pin in flywheel housing, but in order to see it, my face has to be an inch from the exhaust manifold. Or I use a mirror.

Just connecting the dots with this post.

A followup from Ray: Spark Plug Update

Cheers, Dean

Hi Dean,

Pleased to say that 7 years on and the 3077's are still running fine.

I am also still adding a litre of diesel per tank of gas to a/ lower the temp in the combustion chamber due to the long reach plug and B/Its a very economical upper cylinder lubricant.

I reflect on the days when I had to clean the W14's every few hundred miles, versus the 3077's being never.

Cheers

Ray

Hey Ray,

Glad to hear your update about the 3077 plugs.

Also, cool tip about using diesel fuel as a cooling and lubricating additive.

Cheers, Dean

Hope you guys don’t mind me adding this and also asking a question but it’s directly related to plugs. When I received a customers 31’ Chevy car for restoration, he also asked me to evaluate how it ran saying that it had been tuned up but I don’t think he was happy with the way it was running. While it did run decent, I found that whoever did the tuneup, gapped the plugs at .028 which I believe is original spec or close to it. The timing had been advanced some but not to the 18btc. The car ran ok but idled roughly and power was only fair. Gapped the plugs to .040 and it was like a new car. I realize many here know this already but JUST the gap change made all the difference. Now my question is this. Seeing since we’ve learned to advance the timing and increase the gap with our somewhat better gasoline, will I need to do the same with my 32’ Olds flat head 6? I will be running the original AC G-9 plugs and started to think doing the same improvement on the plug gap as we do on our chevys, would be worth a try. A fellow 32’ Olds owner who’s finishing up his coupe and hasn’t run it as of yet, was unaware of the Chevy “fix” and wasn’t sure if it would be needed. There are other guys running their Olds to spec but none I’ve spoken with have even tried experimenting. Thoughts?

You will never know until you try it.