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TR2/3/3A tune up

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S

STeve 1958

Jedi Hopeful
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I was adjusting a few things on my car and, on someones advice, I advanced the timing to about 7 degrees before TDC. When I test drove the car I spun the wheels without trying. For the first time I had all the horse power I remembered from my youth. Lesson is that the advance under idle is unimportant compared to the advance under power.
Happy motoring !
 
Back in the dark ages, before everyone had a timing light, it was common to adjust the timing by advancing it a bit at a time, using that convenient little thumbwheel, until the car started knocking. Then back it off until the pinging stopped. Today we have different fuel and maybe different compression (since heads get shaved a lot during rebuilds) and the shop-manual timing spec isn't really gospel anymore. So, you can go back to the idea of experimenting a bit with it.
 
The other problem is that the TR3 distributor had an advance curve that can start below idle rpm. So using a timing light may not be accurate.

I always use the "road test" method, but with the engine fully warmed up and slightly lugging (eg full throttle at 30 mph in 4th gear). Advance until you can just make it knock, then retard a degree or two (I like to go two just to be on the safe side).
 
Yep, the book gives an "initial" advance as a starting point...then it is very explicit in explaining how to perform the final adjustment with a road test.
 
Sometimes the old ways are the best ways. I did the same on a TR6 years ago and picked up a lot of power with no knocking.
 
JohnnyMead said:
For those of you who use the driving test, is it easy to hear the engine knock?
Click to expand...
I've never had any trouble at 30 mph; though it's best to do it in a relatively quiet area. (And I do have a moderate amount of hearing loss.)
 
Randall:
All part of listening to too many loud mouth race cars for too many years - ask me how I know!

Lou Metelko
Auburn, Indiana
 
JohnnyMead said:
For those of you who use the driving test, is it easy to hear the engine knock?
Click to expand...

You have to "tune in" to it. When you've heard it once, it is like nails on a blackboard after that. Not the sound...but your reaction to it.
 
Wasn't it lugging the engine in 4th gear what used to cause the crankshaft to break at the 4th journal? I guess "slightly" is the key word here.
 
As a rule (normal operation) it's best to avoid "lugging" (shift to a lower gear instead). But a brief test isn't going to hurt anything.

Breaking the crankshaft is normally associated with sustained high rpm operation, where the stresses on the crankshaft are much higher. Not just more power being produced (1500 rpm will only get you about 1/3 max power on a stock engine), but the greatly increased stress from having to stop and start each piston & rod assembly at the end of every stroke.

The TR2-4 crankshaft also suffers (according to Kas Kastner and others) from resonance effects. If you hang a bare crankshaft up and tap it lightly with a metal object, it will actually ring like a bell (this is an old-timer's trick for checking for cracks, a cracked crank won't ring). At various certain speeds, the impact from each cylinder firing can excite the resonance and, in effect, make it ring louder (more deflection). Added to the other stresses, it can flex the steel too far and eventually break it.

IIRC, Kas said that the first such danger point happens around 5200 rpm.
 
5200 RPM is about 100 MPH in fourth gear. Not a good time to have a crank shaft break!
I keep mine under 3000 RPM at all times. Forty five years ago ( when I was invincible ) I had my 1960 TR3A up to 104 MPH. Never again.
 
Makes you think real hard before removing the stock extension and radiator fan. Those are the stock crank “dampers”.
 
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