Adjustment of the Ignition System of my BN6

[BN6_2197]

Gents,

I want to adjust the ignition system of my BN6 as part of the regular maintenance and in the hope that it will reduce the fuel consumption of my car (currently 20-22 liter per 100 km / 63 miles). Are there any hints, things to take care apart from the procedure documented in Section B of the Workshop Manual?

Regards,

Volker

 

[Bob_Spidell]

Doing a rough conversion in my head: 22L is about 5 gallons, 5 gallons in 63 miles is about 12-13MPG; that is quite a bit low. Look for anything; stuck enrichment system (aka 'chokes') is a possibility, as is a fuel leak and/or a way rich mixture setting. Unless the engine is way out of tune a tuneup might bring just a couple MPG.

We've had lots of discussions about mileage on this forum, and I've not heard of anybody getting much more than 24MPG, and that's flat highway miles at 60MPH give-or-take (I get about 15MPG in stop-and-go traffic and 18-19 in the mountains or 'hotdogging' it, or both ). That's the best I've gotten in 130K miles or so on my BJ8; I'm waiting to see if an expensive engine rebuild--with slightly increased compression--improves on that. Still, I don't expect more than 1MPH improvement if that.

 

[vette]

Of course the driving conditions greatly affect the mpg. I get about 15 to 16 mpg running around two lane country here in Pa. That usually includes constant up and down hills. I also have HD8 carburettors which are the 2 inch model so they probably contribute to alittle less mileage during normal driving with a fairly standard engine. If your ignition system hasn't been tuned up in a while then I would recommend that . New Plugs and points will make a difference. If you have an electronic ignition system then there are no points to renew and the electronic ignition should not have to be touched. But just new spark plugs can make a significant difference. You can use carburettor spray cleaner to spray around your carbs to wash any deposites away. This can help to free up moving parts of the carburettors without taking anything apart. You could take the big round dashpots (suction chamber) off the carbs and spray the cleaner inside and clean the body of the carb there as well as the spring, piston and inside of the chamber. This is to make sure that the piston and needle drop and slide smoothly. There is no re-adjustment in doing this as long as you are careful to not bend the needle or disturb it's setting. I would not take the carbs apart any further than this at this point for a standard tune up. Also make sure you have the correct type and amount of oil in the small plunger on top of the dashpots. Cheers.

 

[BN6_2197]

What is the recommended intervall to change the spark plugs? Mine are at least 8 years old with a little bit of more than 5000 miles running in that period.

By the way: can anybody tell me the meaning of "T.D.C." mentioned in the Workshop Manual in Section B about the Ignition System?

 

[dcarlg]

Top Dead Center #1cylinder.

 

[Bob_Spidell]

What is the recommended intervall to change the spark plugs? Mine are at least 8 years old with a little bit of more than 5000 miles running in that period.

If they're running 'clean'--no oil or excessive soot--you can pull the plugs, clean them up and re-gap them and they can go for quite a while. You only have to chuck them when the center electrode gets worn excessively (edges get rounded-off). Clean with soft brush and maybe a little solvent like brake cleaner; avoid abrasives lest you scratch the insulator and possibly create a ground fault. I've run them 20K miles or more this way.

 

[johnea]

Also check the vacuum advance unit on your distributor. A leaking unit contributes to a higher fuel consumption.

 

[BN6_2197]

Is it really neccessary to adjust the timing of the ignition? It seems to be a complicated procedure. Note that I bought the car in good condition with a reasonable fuel consumption.

 

[blueskies]

Is it really neccessary to adjust the timing of the ignition? It seems to be a complicated procedure. Note that I bought the car in good condition with a reasonable fuel consumption.

If it ain't broke, don't fix it.

 

[BN6_2197]

If it ain't broke, don't fix it.

Do you mean that I should remove the timing chain cover only if the timing chain is broken?

I want to adjust the ignition since I do not know if it where ever be done and as measure to tackle my high fule consumption. According to the workshop manual one should adjust the sparkling plugs, the contact breaker points and the ignition timing. I realy do not want to remove the rocker cover and all the things to see the timing chain. It there a way to adjust the timing just by means of the distributor?

Two other questions:
* where can I obtain the starting handle and where should it be attached to the car for rotating the crankshaft?
* What is the expected position of the rotor of the dostributor when the recess in the crankshaft pulley is in lign with the pointer on the timing chain cover?

Pleas apologize all the rookie questions.

Volker

 

[dcarlg]

Hi Volker.
I'm a rookie here, but I'll try to help.
Ignition timing is adjusted by loosening the distributor clamp and rotating the distributor while the engine is running. A strobe timing light will help you here. Some owners can set the timing by listening to the motor as they make adjustments.
I think the first step of any tune up is to check the valve clearance, so the valve cover will need to come off.
The timing cover protects the timing chain which is not adjustable, if stock. Leave it alone.
Ask for help if you are unfamiliar with this maintenence. I highly suggest that you thoroughly review a workshop manual. It has detailed procedures and explainations.
Good luck. You will gain experience and confidence.
Douglas

 

[vette]

Do not remove the timig cover to set timing. Timng is adjusted by rotating the distributor. If you change or move the ignition contact points in the distributor the timing setting can change. I believe you have two options with this. If your points look clean and the point gap is correct just let the points alone and do not touch your timing. If you want to learn how to do this, then you might as well go for it. In which case you should install new points and condenser, then set the timing. The Healey crankshaft pulley does not have incremental degree marks, it only has the one mark which denotes TDC (top dead center of the #1 cylinder). Depending on your engine as ascertained in the book, the timing might be anywhere from 6* to 12* BTDC, (Before Top Dead Center). You should scribe a mark which is described in inches or cm from the TDC mark on the pulley which correlates to the distance the book calls for.

You do not have to remove the rocker cover unless you want to check or adjust the valve rocker clearances.

With the spark plugs out the engine turns very easily. I usually do it by pinching down on the fan belt and pulling the engine around by pulling on a fan blade. Having said this, maybe that is not a good idea because some fan blades are not very strong. You should be able to get a socket and ratchet on the crank pulley nut.

If the #1 cylinder is at TDC on its compression stroke, then the rotor of the distributor would point to the position of the #1 spark plug wire on the distributor cap. If my memory is correct I believe that is about the 1 o"clock position. But you should not have to worry about this even if you change the points. Just put in the new points, set the gap and the engine will start. With the engine running set the pointer at the crank pulley at the mark you scribed for your particular engine. Then your timing is set. Cheers.

 

[blueskies]

The reason I wrote, "If it ain't broke, don't fix it," was because you wrote "Is it really necessary to adjust the timing of the ignition? It seems to be a complicated procedure. Note that I bought the car in good condition with a reasonable fuel consumption."

Does the car start and drive well? Is there unusual noise from the valve train? If everything is working well, be thankful and enjoy driving it.

If the car does not start well and if it runs roughly and does not have good power, you need to investigate. If your fuel consumption is much worse now than it was at one time, yes, look for the reason. Fuel consumption also is related to the condition and adjustment of the carburetors.

When was the valve clearance last adjusted? If that has not been done for many miles, it may be time to do that. That is not difficult to do, but you want to be sure to do it right, as having valves set too tight can cause serious damage.

The advice given above for checking your points and timing is good, and those things are among the easiest things to master.

 

[BN6_2197]

Gents, does anybody know the exact timing point for cylinder 1 ignition for the engine of a BN6? It was mentioned by vette that it is between 6 to 12 degree before TDC.

Another question: at which rpm of the engne should the ignition timing point be adjusted? Heared from car owners of another brand that they adjust the timing at 900 rpm.

 

[vette]

Hi Volker, Here are some pages from the Healey workshop manual. If you don't have a workshop manual I hope you can find one as it is immeasurable help. For some reason the book does not give the idle speed in the BN6 section, but as an example I attached a page for the BJ7 and later engines which shows timing at specific idle speed. Don't get too excited about exact idle speed and or timing setting because most road going engines will operate very well at a broad range of settings. I believe the book states that 600 rpms is the idle speed setting for the BJ7, but I will guess that very few people will have their idle set at 600. I like my engine set at about 800. Although one of the best ways to do it is to set idle to 600 then set the timing, then move your idle up to something more suitable for everyday driving.
Quite a while ago I copied some crankshaft pulley measurements from this forum and this is what I got,
5 degrees = 17/64"
10 degrees = 17/32"
12 degrees = 21/32" (approx. 5/8")

 

[johnea]

For the BN6 the static ignition timing is set at 6 degrees BTDC. First set the contact breaker gap to 0.015"

 

[BN6_2197]

5 degrees = 17/64"
10 degrees = 17/32"
12 degrees = 21/32" (approx. 5/8")

What is the connection between the degree figures and the static ignition timing for adjusting the ignition?

 

[Jim 58 BN6]

What is the connection between the degree figures and the static ignition timing for adjusting the ignition?

It is the timing spot - the number of degrees before top dead center - where the spark plug fires (almost always referenced using the #1 cylinder). The timing can be set with the engine off, and the engine manually rotated to the spot where the correct timing mark - using one of the distances above - is then lined up to the engine's reference pointer.

Note: If an engine has a vernier adjustment on the distributor, then the engine can be static timed to TDC, and the vernier is then adjusted to the final timing BTDC - IF the vernier has enough adjustment. Sometimes you have to set the vernier to its center of adjustment, static time to the nominal advance, and then use the vernier to fine-tune the timing.

With the engine not running (but ignition is on), a light bulb or DC volt meter can then be used to set the static timing. You slowly rotate the distributor until the light just comes on, or the volt meter reads battery voltage, and that's the static timing. Search on-line for the way to do static timing. If I can find a link, I'll post it.

Edit: I found this link: https://www.howacarworks.com/ignition-system/adjusting-the-static-timing

Also, the engine can be timed while running at idle, using a strobe timing light, and the same timing marks, or to check and fine-tune by using the distributor's vernier adjustment. The strobe flashes when the #1 cylinder fires. If no vernier is present, the distributor is then rotated so the strobe-lit mark lines up with the reference pointer (the strobe's synced flash 'stops' the motion so you can see the mark). It is then then locked in that place. If present, the vernier can then be adjusted for the fine-tuning. That's it.


Changing the breaker (points) gap also changes the timing slightly, so the timing needs to be checked after adjusting the breaker gap. I hope I haven't further confused you.

 

[BN6_2197]

Jim, thank you for the detailed clarification. But I still did not get the reason for the three numbers (i.e. 5, 10, and 12 degrees before TDC) to adjust the ignition.

Til now my understanding is that there is exaclty one value for the degree before TDC for static timing (e.g. 6 mentioned by john and in the waorkshop manual) and probably another for strobe timing. I am looking for these two values for a BN6 engine.

 

[dcarlg]

Per my manual:
Static advance setting for BN6 is 6° BTDC.
Maximum advance is 36° BTDC. No rpm are listed.