I am the worst driver....I get 9 mpg...help!

[GregW]

That might make a difference, but not enough of what you're looking for.

 

[100DashSix]

Are you sure the car isn't running excessively rich? Here is a chart that can help you check the condition of the plugs after you've recently turned the car off: https://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

 

[TomFromStLouis]

Well, this thread has now got me calculating my mileage for the first time. I just filled up and drive mostly city miles, so I am anxious to find out.

It is too bad you did not post this a week or so earlier Roger, since we could have had someone look into the gubberment program that might have given you up to $4500 for that gas guzzling clunker of yours! Just think, you could be cruisin' in a brand new Prius!

I do not have any other suggestions other than make sure you use an electronic calculator to figure mpg. Long division is trickier than you think.

 

[AUSMHLY]

This is just a theory. One of your carb floats might be sticking or perhaps even has a small leak and is partially submerged. When driving at higher speed (highway driving) the demaand for fuel is greater and the fuel is going into the carbs as needed. However, when you are driving slower or idleing and the demand would normally be less from the engine, the sticking or submerged float just dumps the excess gas out the overflow, causing the miles per gallon to decrease more than normal. OK, just a theory. I only suggest this as I have had experience from brand new floats that are not always reliable.

Hey Shorn,
Per you're idea, here's what I just did. I zip tied a bottle to the frame and ran both over flow tubes into it. The bottle will capture what, if any, gas over flows.

Thanks,
Roger

 

[AUSMHLY]

Well, this thread has now got me calculating my mileage for the first time. I just filled up and drive mostly city miles, so I am anxious to find out.

It is too bad you did not post this a week or so earlier Roger, since we could have had someone look into the gubberment program that might have given you up to $4500 for that gas guzzling clunker of yours! Just think, you could be cruisin' in a brand new Prius!

I do not have any other suggestions other than make sure you use an electronic calculator to figure mpg. Long division is trickier than you think.

Tom,
I certainly appreciate your sense of humor. I am so the gas clunker. I pick Prius' out of my Healey grill! Long division, what's that? Is that what my parents use to say to us kids, that's new math, ask your father/mother.

Cheers,
PS. lie to me and tell my you got 8 mpg.

 

[AUSMHLY]

Are you sure the car isn't running excessively rich? Here is a chart that can help you check the condition of the plugs after you've recently turned the car off: https://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

I showed the plugs to my local mechanic Steve today and he said they look good. Not sure what David Nock gaped them at, being he did the last tune up. Maybe .025?
Here's photos, starting with plugs 4,3,2,1

It would appear the my plugs 4 and 2 look like carbon fouled?

 

[AUSMHLY]

Plugs 6 and 5

 

[wheelwright]

Which year/model Healey do you have?I have an idea about your problem,need to know which motor.....And it is not your driving style,Roger, or the plugs......Wheelwright

 

[AUSMHLY]

Which year/model Healey do you have?I have an idea about your problem,need to know which motor.....And it is not your driving style,Roger, or the plugs......Wheelwright

64 BJ8.

 

[Bob_Spidell]

Your plugs look normal, even lean (except for #2 and #4). Looks like #1 has some damage to the side electrode--possibly from detonation--and should be replaced.

Did you try monitoring your pump cadence like I suggested? There's a possibility you have a leak, which is more severe at idle when the needle valves stay mostly closed and less severe at speed when you're using more fuel and there might be overall less pressure in the system.

Changing your plug gaps won't help, and might induce missing--even crossfiring--as the higher voltage spark seeks a path to ground with less resistance. Stock Healey ignitions aren't designed to handle ultra-high secondary voltage.

 

[AUSMHLY]

Your plugs look normal, even lean (except for #2 and #4). Looks like #1 has some damage to the side electrode--possibly from detonation--and should be replaced.

Did you try monitoring your pump cadence like I suggested? There's a possibility you have a leak, which is more severe at idle when the needle valves stay mostly closed and less severe at speed when you're using more fuel and there might be overall less pressure in the system.

Changing your plug gaps won't help, and might induce missing--even crossfiring--as the higher voltage spark seeks a path to ground with less resistance. Stock Healey ignitions aren't designed to handle ultra-high secondary voltage.

Hi Bob,
My mechanic said the same thing you did, normal/lean.
I have looked for leaks, none, and the cadence is consistant.
Mechanic says to gap the plugs at .035 because of the sports coil output. You don't agree?

 

[Bob_Spidell]

Not sure what you mean by "sports coil output." If your mechanic thinks your coil has a higher <span style="font-style: italic">constant</span> output and you need to gap the plugs wider to use it you need a different mechanic. A coil is essentially a 'step-up transformer;' i.e. it steps up the primary voltage by a factor determined by the number of secondary windings divided by the number of primary windings. The greater that ratio the greater the maximum <span style="font-style: italic">potential</span> output voltage of the coil. However, as soon as the secondary voltage has risen sufficiently for a spark to jump the plug gap--or find another path to ground--the coil will discharge its energy and the voltage will rise no higher. IOW, a stock coil and a 'sports' coil will fire at the same voltage with the same plug gap (hence, there is no advantage to a 'sports' coil in normal usage). If you increase the plug gap enough, however, at some point the stock coil will not produce sufficient voltage to jump the gap and you'll have a miss, whereas the 'sports' coil will still fire.

You'd think that increasing the secondary voltage would be a good thing, and for high-compression and lean-running engines that's true, BUT the secondary ignition system has to be designed to handle the increased energy, else the spark will take the easiest path to ground, which may be down the side of the rotor or cap, or even across the plug wires (aka 'crossfiring'). The Healey ignition, being of 1950s design, may not be capable of handling increased secondary voltage, as would be created with a larger plug gap. You'll likely get missing and/or crossfiring, if not right away then eventually as the greater spark energy cuts its own path to ground. At any rate, your poor mileage isn't due to ignition unless your engine is missing (a lot--you'd know it).

 

[bob hughes]

Guys

I am not quite sure what all the fuss is about, I have not exactly worked out the performance on the current car a BJ7 but when I had a 100/6, 34 Years ago, the engine was rebuilt by John Chatham and I was recording 13 around town and 23 on a run. Now I realize that you are down a bit on this but you are not a million miles away from it.
I think some one has done a survey on the subject on this forum some time ago.

I can say that with the BJ7 I was unwittingly recording much better figures than this but the top speed was 70 MPH, finally found the cause of the problem - running on one Carb. Once the problem was sorted, speed went up and MPG dropped drastically to match.

Bob

 

[AUSMHLY]

Hi Bob Spidell,
Thank you for taking the time to explain.
I rely on my mechanic to keep my car running it's best and to keep me from sitting on the side of the road waiting for the tow truck.

The reason I have the gold toned Lucas sports coil is because the Pertronics runs better with that then the stock silver Lucas coil. I was told because I am running the pertronics and the Lucas sports coil, then I should try setting the gap to .035 See how the car runs then we'll take a look at the plugs and see how they look.

I don't think this will impact my mpg.
Just following recommendations that some parts work better with other parts when set up a certain way. (Pertronics required the Lucas sports coil)

Cheers,
Roger

 

[AUSMHLY]

Guys

I am not quite sure what all the fuss is about, I have not exactly worked out the performance on the current car a BJ7 but when I had a 100/6, 34 Years ago, the engine was rebuilt by John Chatham and I was recording 13 around town and 23 on a run. Now I realize that you are down a bit on this but you are not a million miles away from it.
I think some one has done a survey on the subject on this forum some time ago.

I can say that with the BJ7 I was unwittingly recording much better figures than this but the top speed was 70 MPH, finally found the cause of the problem - running on one Carb. Once the problem was sorted, speed went up and MPG dropped drastically to match.

Bob

Hi Bob,
The fuss is about why such a low figure. Does it mean something needs adjusting or is there a leak or some problem I should be aware of? Or is it simply my driving style. (Which by the way is very conservative, no jack rabbit starts)
Cheers,
Roger

 

[Keoke]

Well take the plugs on out to 0.040" not an Inch more and see if the low end mileage improves a bit.

Certainly you need not have any qualms about doing this because:

A good original Lucas secondary electrical system is quite capable of handling the 40KV output from the sport coil and that puts a whole lot more fire in the hole, which is what it's all about I have been told.--Keoke :laugh:

 

[AUSMHLY]

Well take the plugs on out to 0.040" not an Inch more and see if the low end mileage improves a bit.

Certainly you need not have any qualms about doing this because:

A good original Lucas secondary electrical system is quite capable of handling the 40KV output from the sport coil and that puts a whole lot more fire in the hole, which is what it's all about I have been told.--Keoke :laugh:

Thanks Keoke,
Always good to see you've taken interest in my posts.

 

[GregW]

However, as soon as the secondary voltage has risen sufficiently for a spark to jump the plug gap--or find another path to ground--the coil will discharge its energy and the voltage will rise no higher.

Hi Bob,
That is not how I understand the process. The coil doesn't discharge when it reaches any particular voltage. It discharges when the points open, causing a drop in voltage in the primary wiring of the coil. This change causes the secondary field to collapse-causing the high voltage discharge.

The Healey ignition, being of 1950s design, may not be capable of handling increased secondary voltage, as would be created with a larger plug gap.

The plug gap doesn't create a higher voltage, it creates a higher resistance. Using a higher voltage coil can overcome that resistance and jump a larger gap. This can create a larger flame kernel for a better and more complete burn of the fuel mixture.

 

[Bob_Spidell]

Greg,

You are correct, of course. I was thinking the plug would fire at a lower voltage with a smaller gap--which it will--but the spark voltage is determined by the strength of the collapsing field. Found this: https://www.custom-car.us/ignition/spark-plug/gap.aspx

Still not convinced a stock Healey ignition can handle uber voltage. I've had trouble with arcing down rotors and over distributor caps with a stock coil. Of course, some of the parts were aftermarket and that could be the problem (I won't use anything but Lucas caps any more).

 

[tahoe healey]

The mfg should not matter. They should be gaped at .025 plus or minus .001. Checking the color of the plugs will tell you if you are running one carb richer that the other. Also listen to the exhaust for even soft tones.These are easy things to do before spending money with your mechanics.