TR6 69 TR6 static vs moving timing - what is better?

[ichthos]

More questions. What is more accurate when timing an engine - static or when the engine is moving (not sure what it is called when you use a timing light and dwell meter)? If they are both accurate, why would someone perform anything but static timing since static uses less equipment?

Thanks,
Kevin

 

[TR3driver]

Depends on circumstances, and the specific distributor. If the distributor has no centrifugal advance at idle (which the vast majority don't), then dynamic timing (engine running) is both easier and more accurate. Plus a timing light is a pretty basic tool, so even the occasional shade-tree mechanic should have one, IMO. It also gives you a quick and easy test for spark scatter (shaft wobble) and advance operation.

However, on some engines, like the TR2-3 (not sure offhand about the TR4/A), the centrifugal advance curve starts so close to idle that it may already have changed the advance. In that case, static timing may be more accurate(although personally I don't it's any better even then, especially if the dizzy is a bit worn).

The real question is what difference does it make ? The stock timing curves really don't apply any more, even if the distributor is perfect (very unlikely), since the gasoline we have today bears little resemblance to what they burned 35 years ago. The TR2/3 handbook calls for 95 octane ... where are you going to buy that ?

 

[RonMacPherson]

A quick note on the octane thing. That rating has also changed over the passage of time. Now the octane rating is assessed by adding the two octane ratings(US and European) ad dividing them. So what used to 95 is now around 90, If I remember fight.

The 6 engine, unless compression and bmep overlap(radically altered camshaft) are altered, then maximum advance should be 32 @ 3500. That isn't static.

So use a timing light with an advance feature to dial your timing in. That will set up your idle timing. Slightly different curve if you have an earl PI engine, but basically curves are close.

 

[piman]

Hello Kevin,

there's no doubt that a timing light is a far more comprehensive way of checking the timing. However the real test is how the car drives. Once you have got an optimum setting, check the timing and make a note of it and at what idle speed. As stated earlier, depending what idle speed you have the mechanical advance may already be active (Don't forget to disconnect the vacuum advance)
You can now reset the timing easily with your strobe to your optimum setting whenever you need to.

Alec

 

[YankeeTR]

Ron, Thats research Octane Number(RON) and Motor Octane number(MON)...

 

[Dave Russell]

Re: 69 TR6 static vs moving timing - what is bette

A quick note on the octane thing. That rating has also changed over the passage of time. Now the octane rating is assessed by adding the two octane ratings(US and European) ad dividing them. So what used to 95 is now around 90, If I remember fight.

The 6 engine, unless compression and bmep overlap(radically altered camshaft) are altered, then maximum advance should be 32 @ 3500. That isn't static.

So use a timing light with an advance feature to dial your timing in. That will set up your idle timing. Slightly different curve if you have an earl PI engine, but basically curves are close.

Hi Ron,
There are several octane rating systems. The research octane number (RON) the motor octane number (MON) & an aviation octane number.

The RON is determined under ideal conditions & is higher, maybe 96. This is the published number that is used in Europe.

The published USA octane number is the average of the research octane number (RON) possibly 96 & the motor octane number (MON) possibly 88. ((Ron + MON)/2). Thus the USA published pump octane number of 92 would be the equivalent to the 96 European number.

Earlier USA octane numbers were also published as (RON) & thus higher.

I certainly agree that the timing should be set at a maximum, static plus centrifugal, no vacuum, of around 32 degrees at 3,500 to 4,000 rpm. If an engine with 24 degrees of centrifugal advance (12 degrees distributor) were set at 15 degrees initial advance, the resulting total advance of 39 degrees would be dangerously high.

If a person really wants to run at 15 degrees initial, the centrifugal should be adjusted to limit it's advance to 17 degrees engine or around 8 or 9 degrees distributor.

Detonation at higher rpm due to over advance may not be heard, but it can do tremendous damage. The slight possible power advantage is not worth the risk.
D

 

[TR3driver]

Re: 69 TR6 static vs moving timing - what is bette

Detonation at higher rpm due to over advance may not be heard, but it can do tremendous damage.

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gifAnd I've got the broken piston to prove it !
Actually was caused in my case by a dislodged valve stem seal (and horribly worn stems); but the effect is similar.