Valve Timing Challenge

bobber · Post by **bobber** » Sat Aug 11, 2007 8:04 pm

I'm not sure I understand the latest advice but I think I'm getting closer. I've checked the pinion dot and keyway and can confirm that they are both at the 12 O'clock position when the engine is at TDC. Starting at this position can you please walk me through the correct valve set up procedure. Incidently, the engine was working with these cams. I also tried using the number 2 dots which gave me at TDC: Exhaust valve closed Inlet apparently closed although I couldn't twist the push rod. Using the number 1 dots, at TDC the Inlet valve is closed and Exhaust valve is open a little.

Biscuit · Post by **Biscuit** » Sat Aug 11, 2007 8:45 pm

Right. From that position turn the engine back,(anticlock)until the pinion dot points to the inlet cam bush, insert the inlet cam with the no.1 dot in line with the pinion dot. Turn the engine forward (clockwise) until the pinion dot points to the exhaust cam bush, insert the exhaust cam, lining up the no.1 mark with the pinion dot.

If the tappets are adjusted for running, it can be difficult to insert the cams, it would be better to slacken off the adjustment.

As Don says, a further full revolution of the engine will bring you to TDC on the firing stroke.

bobber · Post by **bobber** » Sun Aug 12, 2007 12:07 am

I've followed the instructions but sadly I'm no better off; at TDC the Inlet valve is closed and the Exhaust valve is open albeit just off its seat. When the engine is turned backwards the half inch for ignition timing, the Inlet valve is still shut and the Exhaust valve open more. Is it possible that I have the wrong cams i.e. with the dots in the wrong postion for this engine (1950)?

Biscuit · Post by **Biscuit** » Sun Aug 12, 2007 12:38 am

After inserting the cams are you turning the engine one full revolution to the next TDC?. This you need to do for ignition timing, not the TDC either side which you inserted the cams.

bobber · Post by **bobber** » Sun Aug 12, 2007 11:41 pm

Problem sorted (I think); everything lines up and is in order when I set the Inlet cam using the number 2 dot and the exhaust cam using the number one dot. I've set the ignition timing and will try and fire up the engine tomorrow (time permitting). Many thanks for all the advice and guidance.

Circlip · Post by **Circlip** » Mon Aug 13, 2007 2:55 am

quote:
I've followed the instructions but sadly I'm no better off; at TDC the Inlet valve is closed and the Exhaust valve is open albeit just off its seat. When the engine is turned backwards the half inch for ignition timing, the Inlet valve is still shut and the Exhaust valve open more. Is it possible that I have the wrong cams i.e. with the dots in the wrong postion for this engine (1950)?

Your on TDC exhaust stroke there. If you had have turned forward you would have the exhaust closing and the inlet opening. Both valve can be semi open at the same time ,--this is called overlap.

The exhaust will close after TDC as will the inlet close after BDC.