Vacuum advance knob

[AUSMHLY]

Merry Christmas everyone.

What is the purpose of the vacuum advance knob on the Lucas Distributor, car is a 64BJ8.

My distributor was just rebuilt. Once back in the car the timing needs to set.
I've read twisting the distributor sets the timing to I believe 10-15 degrees.
Does turning the vacuum advance knob do the same thing?

Does the vacuum advance knob affect the points gap?

Did the advance knob get set to a certain place in the rebuild process?
Is there a middle position setting? In other words what will happen if the knob is turned too far to the left or right?

I am currently running points being that is what the rebuilder put in when I got it back. I was running pertronix ignition and will put it back in after running the points for a while for comparison.

 

[Keoke]

distributor was just rebuilt. Once back in the car the timing needs to set.
I've read twisting the distributor sets the timing to I believe 10-15 degrees.
Does turning the vacuum advance knob do the same thing?---
WELL kinda:
it is just a fine adjustment ,generally it is set to the center of its mechanical range to allow proper fine adjustment of your timing.

 

[HealeyRick]

it is just a fine adjustment ,generally it is set to the center of its mechanical range to allow proper fine adjustment of your timing.

Exactly. Who remembers when the television channel would change by setting the dial to the correct number, then an outer ring for tuning, then a separate knob for fine tuning? Same thing and eventually you'll get a sharp picture in glorious black and white.

 

[AUSMHLY]

distributor was just rebuilt. Once back in the car the timing needs to set.
I've read twisting the distributor sets the timing to I believe 10-15 degrees.
Does turning the vacuum advance knob do the same thing?---
WELL kinda:
it is just a fine adjustment ,generally it is set to the center of its mechanical range to allow proper fine adjustment of your timing.

Thanks Keoke and Rick. Merry Christmas.
How do I find out where center is?
If I turn it all the way right or left, will it stop? Find out how many rotations right then left then find center?
Does it matter if it's not centered?
It has nothing to do with the points gap, correct?

 

[glemon]

Thanks Keoke and Rick. Merry Christmas.
How do I find out where center is?
If I turn it all the way right or left, will it stop? Find out how many rotations right then left then find center?
Does it matter if it's not centered?
It has nothing to do with the points gap, correct?

Yes you can turn it to the extremes and count the turns to figure out the center, but exact center is not critical approximate center is, just so you can do some fine adjustment either way (advance or retard) if you center it as is being discussed you will need to set your timing again because you will have just changed it by moving the fine tuning knob. If you think the timing on the car is good now I wouldn't worry about centering the fine adjustment.

Point gap affects timing, but timing doesn't affect point gap, if you change the gap on your points it can affect timing, but if you turn the cap or fine adjustment to change timing it will not affect point gap. Always set the point gap before setting the timing when doing a tune up for this reason.

 

[AUSMHLY]

Thanks Keoke,Rick and Glemon
I've read timing is anywhere from 10-15 degrees.
Idle is recommended 500-1000 rpm.
What is the ideal combination, idle & timing I should shoot for?

 

[RAC68]

Hi Guys and Merry Christmas and Happy New Year,
That fine tuning venire feature of the Healey’s distributor always intrigued me and validated my belief the car is an enigma. I often wondered if someone took pictures of our expressions when we first discover we have a tool that can get our timing to within a Nate’s hair of perfect and then read the instructions on timing with a light bulb and TDC mark.

With all these Special in a car expected to last only 3 years, who would have thought I, and the car, would still be around driving it for close to 50 years (50 this coming April). I guess it’s the car’s continuing entertainment value.

All the best,
Ray (64BJ8P1)

 

[Patrick67BJ8]

Thanks Keoke,Rick and Glemon
I've read timing is anywhere from 10-15 degrees.
Idle is recommended 500-1000 rpm.
What is the ideal combination, idle & timing I should shoot for?

You'll find a total of 4 "hash" marks on the vacumm advance shaft where it goes into the distributor. There will be a large hash mark with 2 smaller ones on one side of it and 1 hash mark on the other side of it. The largest hash mark should just be visible where the advance shaft goes into the distributor housing. The distance between each hash mark is 5 degrees. Adjustments for altitude changes and grades of gassoline can be made with the adjustment knob instead of hooking up a timing light and manually rotating the distributor.

This info was explained to me back in the '70's and I have used the adjustment knob for altitude comensation and it works as it was explained to me. I guess you can also use it to tweak the timing if needed and maybe there's another purpose for it to. I can't find my pic of the hash marks but I can take another one tomorrow and post it??

 

[drambuie]

Thanks Keoke,Rick and Glemon
I've read timing is anywhere from 10-15 degrees.
Idle is recommended 500-1000 rpm.
What is the ideal combination, idle & timing I should shoot for?

. You should be shooting for 15 degrees at 600 to 800 rpm. I strongly suggest you buy a digital timing light with a built in advance and rpm read outs, such as the one they sell at sears for $99 dollars. It will pay for itself over and over again. Personally, I set my points to the largest recommend gap setting at .016 because the gap tends to get smaller after you put on the miles. I usually check the point gap every 3000 miles. Too small a point gap and you can overheat the coil which can result in a bursting coil... It happened to me a few years ago...Driving at 65 mph I heard a loud "pop" and then the car went dead with a big truck on my rear end! Drifted to the shoulder of the road, raised the bonnet and saw the guts of my coil dangling out of the casing hanging by just the coil wires! The oil from the coil sprayed all over my nicely detailed motor bay!

 

[RAC68]

Patrick,

Adjustments for altitude changes and grades of gassoline can be made with the adjustment knob instead of hooking up a timing light and manually rotating the distributor.

I never heard or read that before and it makes a lot of sense. Much more logical then using it to time the car using a light bulb and TDC timing mark.

Drambuie,

I have never been able to get a decent idle under 1000 RPMs. I do have increased compression rom an indiscretion in the late 60s when I replaced the head gasket and told the machinist to shave the head 0.060 when I really wanted 0.006. Over the years I have discussed this topic with other BJ8 owners and there seems to be many who share the same condition. As a result, I set the timing15 degrees at 1000 RPMs.

Ray (64BJ8P1)

 

[John Turney]

I have my idle at about 700 to 800 rpm (with a DW8 cam) and it idles fine.

I recall reading that the way to get the timing spot-on is to find a hill with no traffic, especially black & white cars, and make runs up the hill. Adjust the timing with the adjustment knob until your time up the hill is quickest.

 

[drambuie]

Patrick,



I never heard or read that before and it makes a lot of sense. Much more logical then using it to time the car using a light bulb and TDC timing mark.

Drambuie,

I have never been able to get a decent idle under 1000 RPMs. I do have increased compression rom an indiscretion in the late 60s when I replaced the head gasket and told the machinist to shave the head 0.060 when I really wanted 0.006. Over the years I have discussed this topic with other BJ8 owners and there seems to be many who share the same condition. As a result, I set the timing15 degrees at 1000 RPMs.

Ray (64BJ8P1)

. I am able to set my timing at 675 to 800 rpm with a 15 degree advance with no problem and have a even idle. However, not all our Healeys are subject to the same altitude, air pressure, and various weather temps and conditions, not to mention all the mechanical variations that each of our Healeys are in. So I think we all have to find a particular tune setting that works best for our individual cars. I have spent a good many hours trying to achieve a good general all around tune for my driving conditions... Setting the carbs mixture and idle, doing a lot of spark plug readings and dialing in point gaps and timing, and keeping records of gas mileage. If you unintentionally had your head shaved .060 you did yourself a favor I think! You may have bumped your compression to about 10:1 or 10.5:1 the better quality of fuel we have these days can easily handle the compression boost, so you did a good thing! Getting back to the idle settings...even though I found a good general tune setting I still have to adjust the idle of the S U carbs according to the hot or cold weather conditions here....it's just the nature of the primitive beast!

I still am toying with the idea of installing a electric ignition system because I want to achieve a more efficient fuel burn! There is simply too much raw gas not being burned with a stock system and I am looking for more fire in the hole for better gas mileage and power, not to mention cutting back on the gas fumes emitting from the tail pipe!

 

[57_BN4]

There is simply too much raw gas not being burned with a stock system and I am looking for more fire in the hole for better gas mileage and power, not to mention cutting back on the gas fumes emitting from the tail pipe!

A friend of mine did some post grad research on emissions at uni and found that up to 25% of fuel evaporates before it gets to the engine when old cars are used infrequently. Every time the fuel pump runs at key-on it is replacing fuel that has boiled off from the float bowls and while we are driving along the fuel is constantly escaping as the air temp in there is around 140F which is above the boiling point of fuel. Unfortunately fitting electronic ignition won't really improve fuel mileage a noticeable amount, however it does improve cold running.

Stealth EFI fixes the evaporation problem, among others...


Andy.

 

[Keoke]

Exactly. Who remembers when the television channel would change by setting the dial to the correct number, then an outer ring for tuning, then a separate knob for fine tuning? Same thing and eventually you'll get a sharp picture in glorious black and white.

WHEN wAS zAT!!!!----:highly_amused:

 

[TimK]

I remember back in 1968 when fine tuning was needed on UHF channels.

 

[Deleted member 8987]

Exactly. Who remembers when the television channel would change by setting the dial to the correct number, then an outer ring for tuning, then a separate knob for fine tuning? Same thing and eventually you'll get a sharp picture in glorious black and white.

WHEN wAS zAT!!!!----:highly_amused:

Well...couple of years ago relatives brought their kids over and left them here for a while. They wanted to watch TV...sure. Where's the remote?
No remote. Go up and turn it on.
How do you change channels?
Go over and turn the big knob. Then we had to "tune" it a bit.
Worked better when I put an adaptor on it for the cable when it came down the street.
Then, asked if they wanted to listen to the radio.
Directed them to the big, old wood cased upright RCA in the corner.
Turned it on, they cranked the knob all the way, turned and said "It's broken" about the time the tubes warmed up and that 12" electro-dynamic speaker about blew the front door outta the house.
Then, asked them if they wanted to call their folks. Handed them a Western Electric type 300 dial phone.
Boy, was that fun!

I recall driving into town with other relatives in my 1950 Ford for diner. Valet parking. Valet at my window. I looked at him....said "pushbutton start, manual choke, three speed on the column" and he pointed to a guy down the block, said drive down there, he'll tell you where top park.

Then, drove out to a casino for my Mom's birthday dinner. Drove the Jag.
All the valets start hustling out until they see the steering wheel on the right, and they all, as in every one, turned and walked away.

Ain't technology grand?
Dave

 

[Patrick67BJ8]

Patrick,



I never heard or read that before and it makes a lot of sense. Much more logical then using it to time the car using a light bulb and TDC timing mark.

Drambuie,

I have never been able to get a decent idle under 1000 RPMs. I do have increased compression rom an indiscretion in the late 60s when I replaced the head gasket and told the machinist to shave the head 0.060 when I really wanted 0.006. Over the years I have discussed this topic with other BJ8 owners and there seems to be many who share the same condition. As a result, I set the timing15 degrees at 1000 RPMs.

Ray (64BJ8P1)

Ray,
I had an "old school" mechanic tell me about the knob adjsutments. Everyone should remember that in the '70's we still had a lot of mechanics doing British cars even though most of them were located in shops that specialized in foreign cars. Those of us who had big Healey's back then had to know/learn everything we could to maintain them or pay a small fortune in repairs for the privlege of owning one. One very good mechanic in North Kingston, RI told me to never baby the Healey engine and to "drive it".(I was stationed at Quonset Point Naval Air Station in the early '70's and was lucky to find hte guy).

 

[RAC68]

Hi Patrick,

After picking up my Healey from the dealer, I treated it like a new girlfriend and it reciprocated by treating me like an old boyfriend. That year a friend and I embarked on what turned out to be a 13K mile odyssey in the Rt 66 style. Over that period, I must have met your mechanic’s cousin who gave me the same advice. Ever since I have treated my Healey with care but commonly shift at around 5K RPMs and the engine has performed reasonably well (knock on wood). Since the engine is still very close to original mechanically (new water pump, valve train bushings, and lifters), I must conclude this was good advice. Over the close to 50 years owned, it has transitioned form my daily family car to an occasional ride and I have grown to see its idiosyncrasies as its charm and any issues encountered as entertainment. And, I still enjoy pushing it to around 5K RPMs before shifting.

By the way, Keoke, I do remember the fine tune ring on the channel changer. Even more, in the '50s I remember moving a wing-backed share close to the TV, laying across the arms and using my toes to change channels and adjust the fine tune. It really ticked off my father but I guess it could be considered my first remote control.

All the best to all in the NEW Year,
Ray (64BJ8P1)

 

[Patrick67BJ8]

Exactly. Who remembers when the television channel would change by setting the dial to the correct number, then an outer ring for tuning, then a separate knob for fine tuning? Same thing and eventually you'll get a sharp picture in glorious black and white.

WHEN wAS zAT!!!!----:highly_amused:

Remember those electrically controlled rotating antennas? That was the hot setup in its day! Almost everyone had a "TV Lamp" for on top of the TV.

 

[AUSMHLY]

Remember those electrically controlled rotating antennas? That was the hot setup in its day! Almost everyone had a "TV Lamp" for on top of the TV.

We had one of those too. I think it was a Channel Master?
Anyway, funny how my question about the vacuum advance knob side tracked to a TV's tuning knob. All good stuff here.
I remember as a child, up at 6-7am East Coast time, parents fast asleep, turning on the black and white tv, turning the knob looking for cartoons and it seemed every channel was showing another NASA rocket taking off. Where's my cartoons! It's saturday morning, cartoon time. lol