Different way to do static tappet adjustment on flathead six.

[MarcDeSoto]

Over on the AACA Technical forum, there is an interesting post by Phantom.  He says you can do a static tappet adjustment with the crankshaft in just two positions, rotor at 7:00 and at 1:30.  So at 7:00, TDC for no. 1 cylinder you can adjust these tappets:

1 cyl.  Ex and In

3 cyl. Ex

4 cyl. In

5 cyl. Ex and In

 

With the TCD at firing position for cyl. no. 6, and the rotor at 1:30 you can adjust these tappets:

2 cyl. Ex and In

3 cyl. In

4. cyl. Ex

6 cyl. Ex and In

 

Interesting to know if that is correct.  

 

 

[vintage6t]

Here's a recent thread on the same technique: 

 

[vintage6t]

BTW - This works because you adjust any given valve when its fully closed. If you reference the cycles of a four cycle engine: intake, compression, power, exhaust. Then you'll see that the adjustable valves when at 1 TDC are in the non-overlap portion of the other cycles and the same for the adjustable valves when 6 TDC.

 

Firing order: 1, 5, 3, 6, 2, 4

1 TDC - Start of power:both closed

5 - Compression:both closed

3 - Intake:exhaust closed

4 - Exhaust:intake closed

 

Then

6 TDC - Start of power:both closed

2 - Compression:both closed

4 - Intake:exhaust closed

3 - Exhaust:intake closed

 

 

 

Edited March 3, 2023 by vintage6t

[Semmerling]

True, but the important part is to not confuse between the FIRING TDC and the EXHAUST TDC.

The graphic reveals the relationship between a PROPERLY set-up distributor and the cylinder entering FIRING TDC by  a quick observation of the distributor to know which is which. It is 100% correct. 

[vintage6t]

2 hours ago, Semmerling said:

True, but the important part is to not confuse between the FIRING TDC and the EXHAUST TDC.

The graphic reveals the relationship between a PROPERLY set-up distributor and the cylinder entering FIRING TDC by  a quick observation of the distributor to know which is which. It is 100% correct. 

 

By definition start of the power stroke is equivalent to "firing tdc" and more common terminology. The position of the crank and valves dictates the distributor position, not visa versa. True if installed properly the rotor position can be used as an indicator to determine Power or Exhaust cycle.

 

I'll add that the best way to find #1 TDC is plugs out, compression comming through the plug hole and both valves closed. When the piston hits the top of it's travel your at TDC, start of the power stroke.

 

 

Edited March 4, 2023 by vintage6t

[Sniper]

On 3/3/2023 at 6:22 AM, vintage6t said:

BTW - This works because you adjust any given valve when its fully closed. If you reference the cycles of a four cycle engine: intake, compression, power, exhaust. Then you'll see that the adjustable valves when at 1 TDC are in the non-overlap portion of the other cycles and the same for the adjustable valves when 6 TDC.

 

Firing order: 1, 5, 3, 6, 2, 4

1 TDC - Start of power:both closed

5 - Compression:both closed

3 - Intake:exhaust closed

4 - Exhaust:intake closed

 

Then

6 TDC - Start of power:both closed

2 - Compression:both closed

4 - Intake:exhaust closed

3 - Exhaust:intake closed

 

 

 

 

Pretty much how I do it. 

[keithb7]

I think it would be interesting to see a graphic exactly where the cam lobes are in these 2-only crank positions.  How far away is each cam ramp from the each tappet when only using the 2 crank positions. Gotta be real close in some positions. Just curious.

 

I do find when I am down in the fender window, my head in the valves, its easy to mix up what valve you are on. Sticking your head in and out of the cavern many times to review the check sheet, and mark down your numbers. As we know the inconsistent pattern of intake and exhaust valve placement can add to the confusion. I find myself re-counting valve pairs from #1 cylinder back, reviewing my place to be sure I am on the correct valve. I was thinking. A paint-pen marker would be ideal. Once a you have set a valve, place a single paint-pen dot on the block near the valve you just set. This would ensure accuracy and the entire valve set job would be quicker I think. No mix up, and you'll be confident when all valves have the colored dot. 

 

A little brake clean or kerosene on a rag. Wipe the oil off. Then you have a clean surface for the paint pen to mark. When you are done, use the cleaner again to take off the paint dots. Easy-peasy.

 

Like this image below. I think I am going to do this for sure, next time I do a valve set.

 

Edited March 4, 2023 by keithb7

[MarcDeSoto]

I did something similar.  I put a yellow dot on all the exhaust valves permenantly, just so I'm not confused when I'm setting the tappets.