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

[AUSMHLY]

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.

Hey Rich,
Here's where the discussion has now turned to.
.025 for the Lucas regular coil?
.035 for a Lucas sports coil?

I need the Lucas sports coil for the Pertronix, that's a given.

By the way guys, I just filled the tank and I averaged 12 mpg (town and freeway driving) (points at .025).
Let's see what I get with a set of new plugs at .035

Cheers,
Roger

 

[Keoke]

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).

Your problem is probably related to cheap aftermarket replacement parts: Caps,Rotors and secondary wires.An original Lucas system is quite capable of living with the higher output voltage provided by a sport coil coupled with a Pertronix.

 

[GregW]

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).

Them crappy parts aren't unique to our Healeys. I bought a set of plug wires for my Ford Ranger and they were arcing to the engine block within 2 weeks. What a pain to change too. The Healey is a dream in comparison.

 

[GregW]

The mfg should not matter. They should be gaped at .025 plus or minus .001.

I'm gonna side with Roger's mechanic on the .035 gaping. From the Pertronix website in regards to the Ignitor.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]<span style="font-weight: bold">What should I gap the spark plugs to?</span>

The Ignitor has no set specification in which the spark plugs should be gaped at. Every engine responds differently to spark plug setting. In most cases increasing the factory recommended gap by .005 improves the engine performance.[/QUOTE]

And for their Flame Thrower coil ( I couldn't find anything for Lucas, but they are both 40K)
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]While it's the perfect coil to go with the PerTronix Ignitor breakerless ignition, our 40,000 volt Flame-Thrower canister coil can benefit virtually any distributor type inductive system. Its higher voltage allows larger spark plug gaps for added power, smoother response and better fuel economy.[/QUOTE]
All these upgrades are cumulative, so adding .005 for each HP component shouldn't be a problem.


IIRC the Holy Grail of flame propagation is a .070" gap, not particularly easy to get.

 

[Genos2]

Not to argue, drivers handbook says .014-.016 pt gap& .025 plug gap.I've used either Lucas Sport coil or Bosch blue coils for years. Always gaped my pts. at .015 & plugs( usually NGK BP6es) at .025. On normally aspirated engines I've never gone beyond factory spec. On forced induction(turbo or supercharged) We usually decreased gaps to prevent flame blowing out-.030-.032. On very high-compression engines sometimes gap is decreased. Healey's aren't either of the above.As long as dizzy bushing is good pts aren't much of a problem, don't forget dist. cam lube. cheers Genos2

 

[tahoe healey]

Roger, I don't think anyone has asked but what are idling at? The black plugs are not normal (2 and 4). I'd ask your mechanic why. Black is either oil if it is slick (bad rings)or too rich if black powder looking. Check that all gaps are the same.
I did not read that you have a non standard coil. I'd start going back to standard things to test what may have changed your MPG.

 

[GregW]

Not to argue, drivers handbook says .014-.016 pt gap& .025 plug gap.I've used either Lucas Sport coil or Bosch blue coils for years. Always gaped my pts. at .015 & plugs( usually NGK BP6es) at .025.

Hi Genos,
Sure, the gap for the points shouldn't change with a different coil. They are still working at 12 volts regardless of what coil is used. The stock spark gap will work, but a bigger gap (within reason) will work better when used with the parts mentioned in this thread.


Apples to oranges, my low performance truck is gapped @ .045" from the factory. :laugh:

 

[AUSMHLY]

Roger, I don't think anyone has asked but what are idling at? The black plugs are not normal (2 and 4). I'd ask your mechanic why. Black is either oil if it is slick (bad rings)or too rich if black powder looking. Check that all gaps are the same.
I did not read that you have a non standard coil. I'd start going back to standard things to test what may have changed your MPG.

Richard, it idles between 7-10 depending on who knows what...how far I've been driving, day, temp, what shirt I'm wearing.

Mechanic looked at all the plugs and says, nothing to be concerned with, normal range. The back is dusty not oily. I did not gap the plugs in the photos and maybe those two were off. I now have new plugs installed which I gaped at .035.

I've always had this mileage issue. Even when I had point and the standard silver Lucas coil. I've always averaged 9-13 mpg, highway/town. Yesterdays fill up was 12mpg.

Thank you for your input Rich.

Cheers,
Roger

 

[AUSMHLY]

I've been talking to some other Brit Mechanics and one said that I may have the wrong needle, correct needle but worn, not set right etc. So I talked to my mechanic about the carb rebuild he did. He replaced the needles he tells me.

I replaced the gas filter yesterday. It is placed right after the fuel pump. It was not leaking by way. I change it every year. I checked for leaks after installing the new one. No leaks anywhere down the line right up to the carbs. I now have a bottle strapped to my frame that the two run off tubes from the float bowls now go into. The bottle will capture any gas and let me know if that could be the problem area.

I just can't seem to get a handle on this 9-12 mpg thing.

 

[Bob_Spidell]

Gotta admit, this problem has piqued my interest--and others' too, obviously--so I'm gonna keep throwing things out there (as soon as I wipe the egg off my face for the 'gap gaffe').

Have you checked compression? If you had very high compression--say, over 175psi/cyl--you may have to run very rich to prevent detonation ('knocking'). There may be valve and/or ignition timing issues that could affect mileage, but I'll defer to others on those.

Also, I wonder why your idle is so inconsistent--my idle moves between 600 and 800rpm, but it's consistent depending on a few variables (air temp/density, engine temp, clutch in/out, etc.).

On a side note, last time I checked my plugs they looked a lot like yours. A couple, actually, are almost too clean; i.e. white, with no deposits. A couple had the brownish deposits like your #2 and #4, and the other two had the greyish deposits you'd expect from a good mixture of unleaded gas. I don't expect a carburetted car to have perfect mixture distribution, but the too-clean plugs have me baffled. I wonder if different fuel additives can cause different-colored deposits? Ideas, anyone?

 

[GregW]

...it idles between 7-10 depending on who knows what...

...I've always averaged 9-13 mpg, highway/town. Yesterdays fill up was 12mpg...

Here is a wild idea. Are you sure you have the stock cam? Both of those symptoms could be a hotter grind. Does the car go like stink in the higher revs?

 

[Keoke]

I was not aware that a local mechanic had rebuilt your cargbs. I have little faith in there ability to do a decent carb rebuild and most lack the ability to balance and flow bench them on completion. I suggest you pull them off and send them to JOE Cutro for a professional overhaul.--Keoke

 

[TomFromStLouis]

It's so obvious I can't believe these experts have missed it. It must be the extra weight of all those non-standard parts: GPS, chromed engine parts, cupholder etc.

Roger, Have you driven other Healeys? Is your performance normal at high and low revs?

 

[AUSMHLY]

It's so obvious I can't believe these experts have missed it. It must be the extra weight of all those non-standard parts: GPS, chromed engine parts, cupholder etc.

Roger, Have you driven other Healeys? Is your performance normal at high and low revs?

Hey Tom, nice to hear from you.
Dude, I think you're on to something! You forgot the vanity mirror. Don't think for a minute that dash mirror is used for traffic, lol.

Yes, I've driven other Healeys. Mine seems the same as others.
I'm at Witt's end. I've talked my mechanic into keeping my car and using it as his daily driver till he goes through a full tank of gas. I told him, if he gets 12 mpg...he's now on the hook to find the problem. If he tells me he averaged 16 or above....then I need to go to driving school. He'll get my car in a couple weeks.

 

[Sarastro]

A simple point: if you are getting 9 MPG and expecting 13, your fuel consumption is 13/9 what you expect, or almost 50% higher. This is not a small difference, even though 4 MPG may not sound like much.

Big problems are caused by big flaws, not little ones. Spark plug gap is a little one--might affect mileage a few percent, not 50%. And, if the gap were too wide, you'd know because it would miss. Plugs also look OK, maybe a little lean. (You should see mine!) Small errors in mixture also won't cause a 50% increase in fuel use.

So, ignition is probably OK, carbs are probably OK. Are you sure you don't simply have a leak somewhere? Also, (dare I suggest...) have you checked compression?

By the way, I wrote up a section for the Wiki on ignition systems, where I addressed the coil-voltage issue. It's under General Technical Articles|Ignition Systems. About the last three paragraphs under the "Conventional Points-Capacitor Ignition" section.

 

[AUSMHLY]

A simple point: if you are getting 9 MPG and expecting 13, your fuel consumption is 13/9 what you expect, or almost 50% higher. This is not a small difference, even though 4 MPG may not sound like much.

Hi Steve,
I think you misread my expectations. I'm getting between 9-13 average. I believe BJ8's average between 17-19. If I drive exclusively freeway I may get 21. Just town I get 9-10.

Cheers,
Roger

 

[AUSMHLY]

I was not aware that a local mechanic had rebuilt your cargbs. I have little faith in there ability to do a decent carb rebuild and most lack the ability to balance and flow bench them on completion. I suggest you pull them off and send them to JOE Cutro for a professional overhaul.--Keoke

Anyone besides Keoke, heard of Joe Cutro?
Anyone provide Joe Cutro's contact information?
Cheers,
Roger

 

[GregW]

Here it is. Joe Curto

 

[Lin]

Roger,
Joe Curto did a complete rebuild of the HD8s on my Big Healey. They have worked fine since.

Lin

 

[AUSMHLY]

Roger,
Joe Curto did a complete rebuild of the HD8s on my Big Healey. They have worked fine since.

Lin

Lin, were you having problems with them?
Did you notice any improvements after?
If so, what?
Did it affect your mpg?
If so, what was the mpg before, then after.

BTW, I think our cup holder article may be in the October Healey Marque.

Cheers,
Roger