• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

TR2/3/3A Mech. advance

STeve 1958

Jedi Hopeful
Offline
I replaced my vacuum advance and while I was at it I check the Mechanical advance a little closer. The weights and springs are all there but there is a lot of slop which allows the weight to move without spring tension. Is this normal or should the springs be tight to begin with?

I also cleaned the carb. with some Gum Out and then had to completely re-tune the carb. as everything changed. I guess it needed it.

I'm ready to go for a drive.

Steve
 

Geo Hahn

Yoda
Country flag
Offline
The big (thick wire) spring needs to have quite a bit of slop - it comes into play only as higher RPMs are reached.

The small (thin wire) spring will have little or no slop.

The real test is to figure out the advance curve. Can be done on a Sun Machine those most do not have access to one or with a timing light that has an advance dial (most do). There you just plot the advance at various RPMs and plot the curve.
 
OP
S

STeve 1958

Jedi Hopeful
Offline
"The small (thin wire) spring will have little or no slop."

OH, There's a small thin wire spring ??? Not on mine. Hope someone has a picture
 

TR3driver

Great Pumpkin - R.I.P
Offline
The difference is perhaps less pronounced than Geo's description might imply. But he's quite right, one of the springs should be slightly smaller diameter wire, and slightly shorter, so it has some small tension with the engine not running. The other spring is wound with heavier wire, and is slightly longer so it doesn't come into play until the engine is turning 1200 or 1400 rpm (depending on which distributor you have).

Only photo I found is from an old article by Marcel Chichak, originally published (I believe) on the Jaguar Club of North America web site

LD8OoR4.jpg


FWIW, here's a plot I threw together long ago, to compare the centrifugal advance curve (including spec for initial timing) of several different TR distributors. Note that both rpm and advance are given in degrees at the distributor, so are 1/2 the values measured the normal way, at the crankshaft. The "knee" around 600-700 rpm (for the 3 TR2-4 distributors shown) represents when the secondary spring starts to take effect.

4yGQ6Hz.jpg
 
OP
S

STeve 1958

Jedi Hopeful
Offline
Thanks. I have a DK4A distributor that looks a little different but the theory should be the same. I have two identical springs, both loose.
This car was raced so maybe the previous owner altered it. It was also rebuilt by idiots..."non-british mechanics" who might have messed it up.

I'll look into buying new springs.

Steve
 

glemon

Yoda
Country flag
Offline
Not that I know everything, but I am always happy to learn new things, had no idea the one spring on a Lucas distributor was supposed to be a little loose and kick in later. I think I mucked around with one several years ago and tightened up that spring, live and learn (slowly).
 

TR3driver

Great Pumpkin - R.I.P
Offline
It's not just Lucas; the curve with the knee is very common across all cars and the loose spring is how they used to do it (before the computers took over timing duties).

Eg (for a small block Chevy V8)
igvance1.jpg
 

dklawson

Yoda
Offline
If you are uncertain about the curve in your distributor, consider contacting Jeff Schlemmer at Advanced Distributors. He can recondition your distributor and suggest a curve based on your engine build.
 

Joe Schlosser

Jedi Warrior
Silver
Country flag
Offline
Remember Engine advance is 2X distributor advance.
And Jeff is a great guy.
 

Snowkilts

Jedi Hopeful
Country flag
Offline
there is a lot of slop which allows the weight to move without spring tension.

Check to make sure that the holes in the weights themselves are not worn. Mine were severely oversize. The weights are made of a soft metal (lead?) with a brass sleeve pressed in where they sit on the pin. Mine had worn through the brass long ago and the holes were about 3x bigger than they were supposed to be. Timing would return to a random point after advance. Jeff fixed me up though.
 

TFB

Jedi Knight
Country flag
Offline
Jeff rebuilt my distributor with rebuilt vacuum advance module and new bushing,pointd and condenser, ,recurved ,cleaned to look like new for about 40 bucks more than a moss replacement vacuum module.Tom
 
OP
S

STeve 1958

Jedi Hopeful
Offline
I got the set of 5 springs from Moss Motors. One of them is longer and stronger, to use as the strong spring with some slack. The other 4 are shorter and still pretty strong.
My thought is to install the weakest of the four as my weak spring and check the timing advance. I was expecting that the weak spring would be much weaker so I was surprised at how strong they all are.

Any thought?

P.S. I had read that the weak spring was 15#/in and the strong was 205#/in. That was a typo and the weak is 150 #/in. which makes a lot more sense.
See I'm not as dumb as I look.
 
Last edited:
OP
S

STeve 1958

Jedi Hopeful
Offline
I replaced the weak spring and kept the existing strong spring since it seemed to fit the best. The car runs and advances with RPM. The vacuum advance also works now that it doesn't have to fight against two strong springs.
I'll get it out and drive it this weekend to see how good I did. Also getting a digital timing light to check the curve.
Thanks for all the help, I wouldn't have had the guts to do it without some guidance.
 

Geo Hahn

Yoda
Country flag
Offline
...The vacuum advance also works now that it doesn't have to fight against two strong springs...

Glad it is working better, but FWIW I do not think the vacuum advance works against the springs. It merely rotates the plate so if the plate is binding there can be some resistance. There are (nylon?) nubs that help it slide -- I usually use a small amount of lube (e.g. Lubriplate) between the plate halves.
 
OP
S

STeve 1958

Jedi Hopeful
Offline
but FWIW I do not think the vacuum advance works against the springs.

Your right, I miss spoke. I also replaced the vacuum advance. Separate issue.
 
Similar threads
Thread starter Title Forum Replies Date
Zitch General Tech Nice mech fuel pump video Triumph 0
T TR6 TR250/TR6 - Improving hand brake mech advantage Triumph 11
R mech. water temp gauge repair? have you tried this Spridgets 4
M_Pied_Lourd TR2/3/3A TR3 Mech/Elec Fuel Pump Question Triumph 9
G Mech Spec Vendor MG 2
R TR6 Limit Mechanical Advance on TR6 distributor? Triumph 8
S TR2/3/3A Distributor vacuum advance hook up to the inner plate Triumph 9
S TR2/3/3A Vacuum Advance Union Size Triumph 1
vette Distributor Advance Austin Healey 14
WHT Vacuum Advance Pipe Austin Healey 7
J TR6 1975 TR6 Alternator Advance/Retard spring(s) Triumph 1
JPSmit Today's question - vacuum advance Spridgets 2
B Anyone have spark advance data for Piper camshafts? Spridgets 1
B Vacuum Advance Pipe Austin Healey 2
steveg TR6 Moss advance kit maximum advance question Triumph 13
S Ignition advance weights - how to lube? Austin Healey 5
D BT7 Timing Advance Austin Healey 17
Joe Schlosser Distributor advance Spridgets 0
6TTR3A TR2/3/3A Vacuum advance questions Triumph 2
Rob Glasgow Advance Timing Light Austin Healey 11
Lin Advance Performance Technology [APT] - Great customer service Austin Healey 1
D TR2/3/3A Vacuum advance tube Triumph 6
C Distributer with no vacuum advance Spridgets 15
D Need to get a vaccuum advance rebuilt Jaguar 2
K TR2/3/3A Are these brake adjusters Locheed for 10" drums? Thanks in advance. Triumph 3
Griz Testing Vacuum Advance Austin Healey 5
BJ8Healeys '72 Midget Vacuum Advance Line Spridgets 2
J BJ8 Vacuum Advance - disconnected -RIGHT - when setting total advance?? Austin Healey 6
T MGB Vacuum advance and Electronic ignition conversion MG 5
S ignition advance curve 25d6 Austin Healey 10
jfarris TR2/3/3A Vacuum Advance Thread Size Triumph 9
Merlin63Tr4 TR4/4A Gasoline in vacuum advance unit. Triumph 10
jfarris TR2/3/3A SU H6 Vacuum Advance Fitting Thread Size Triumph 2
RAC68 BJ8: 650 RPM steady Idle at 45 Degree advance??? Austin Healey 26
W BE vacuum advance line and fittings Spridgets 2
W Vacuum advance nipple Spridgets 0
B TR4/4A Advance Auto Wire for TR4A Triumph 4
bigjones Vacuum advance on a 1500 Spridgets 13
jfarris TR2/3/3A Early 56 TR3 H6 Carbs, distributor vacuum advance/retard Triumph 3
B TR6 Moss TR6 Vacuum Advance Conversion question Triumph 8
T TR2/3/3A Is it possible to drill vacuum advance port in SU H6 carb? Triumph 14
AUSMHLY Vacuum advance knob Austin Healey 21
DanLewis Vacuum advance question Spridgets 5
apbos H1 SU vacuum advance frustration. Spridgets 9
DMShuman TR5/TR250 TR-250 Vacuum advance module.... Triumph 5
C TR4/4A TR4A with TR3 distributor and Vacuum Advance Triumph 4
Tinkerman TR2/3/3A 1960 TR 3A vacuum advance line installation Triumph 7
smaceng TR6 TR6 distributor advance and retard hook up Triumph 6
DanLewis Overheating problem solved, or ... did you disconnect your vacuum advance? Spridgets 4
S TR2/3/3A vacuum advance tr3 Triumph 2

Similar threads

Top