TR2/3/3A TR3 Timminge

[RonR]

Folks,

The information on the 25D Lucas distributor I have in my TR3A says the maximum timing advance should be 16 degrees at 3000 rpm.
A friend said that at the crankshaft pulley, it would be double that amount, 32 degrees.

Is this correct?

Thanks.
Ron

 

[sp53]

I do not think so about having to double the degrees. There is a 2 to1 ratio with the cam and the crank, but 16 sounds about right not 32. I would not think a 4cylinder would run well at 32 unless something is special. How does the car run when you punch it?

steve

 

[RonR]

Tight now, the timing is set static, per the shop manual. That is around 4 or 6 degrees, as I recall.

I am switching to electronic ignition and will be resetting the timing.

 

[TFB]

Your friend and is correct.I run 34 degrees ,at the crank.
Tom

 

[RonR]

Thanks, Tom

 

[CJD]

+1. 16 deg is distributor degrees, which equates to 32 at the crank. You would then add initial timing to that...usually 3 plus as far as you can get without "pinking" in road tests.

 

[mctriumph]

All the numbers are without meaning if the motor does NOT run well on the fuel
in your area. After the rough tune, test drive it and listen carefully for the sound
of detonation under load(find a hill). advance the spark until there is a slight "knock"
under load , then go back 1or 2 degrees. This is the real world setting that works for your
motor, in your local ,with your fuel. Remember that premium fuels will lose octane in the tank
if the car sets a lot. If you get a high speed detonation due to stale gas it is NOT good. This will
also contribute to heating up on the highway,watch the temp gage!
Mad dog

 

[TFB]

Things maybe different now ,but early 1980's I worked in an oil refinery.
Gas formulas changed everyday depending on component stocks available to blend for most production.
Octane was tested in large building that was filled with car engines on test stands that would test the blend with a running engine while a tech observed knocking.
This building was adjacent to the rail cars of tetraethyllead from DuPont in delaware.
Tom

 

[mctriumph]

Tom, this is probably now an EPA super site.The horror's of Pb poisoning!
Mad dog

 

[Sarastro]

Here's what I have:

I don't remember where this came from, but it agrees with other info I have seen.

This shows that 16 degrees is a bit high for the TR2-4, but remember that there is at least +-1 degree of tolerance on these curves.

 

[TFB]

I wonder why the max advance for the tr4a is so different from the others at only 20 degrees.
Are the cams that much different?
Tom

 

[RonR]

Steve, my TR3 uses a 25D 40919 distributor rather than the factory DM2 units used in both the TR3 and TR4 cars. The 25D unit is 16 degrees at 3000 rpm per attached.
The 25D unit was in the car when I bought it. Jeff, at Advance Distributors, recommended keeping it as he considered it a "better" unit than the DM2.