3c valve clearance

[laverda74]

hi all, re 3c valve clearance, engine stone cold ? or hot? when checking , thanks brian

 

[mauricejota7604]

Cold

 

[AndyW]

I?ve heard it said (on here) that clearances are actually wider on our DOHC motors when hot than cold: is that true??

 

[helicopterjim]

Anything is true ..... if you believe in it hard enough.

 

[2622]

Cold

I'll second that

Think about it..hot would make no sense at all 

 

[Tippie]

"that clearances are actually wider on our DOHC motors". Pushrod motors can do because of metal expansion when hot and the engine castings expand more than the pushrods. IIRC Americans had valve clearsnces set at zero due to this. It can be a long way from the cam to the valve. Always do them cold, but on my diesel ute we did them with it idling.

 

[AndyW]

I knew I?d read it somewhere.. https://www.motorcycleproject.com/text/lies_mother.html
so a push rod motor?s clearances generally tighten when hot: In a DOHC motor the expansion of the valve head generally outweighs the lengthening of the valve when hot.

 

[Dellortoman]

Always do them cold, but on my diesel ute we did them with it idling.

Why on earth would you want to do the clearances with the engine running?

 

[AJ]

Why on earth would you want to do the clearances with the engine running?

Standard practice with hydraulic tappets- loosen them off until they rattle and the tighten a turn from there. Probably not many bikes with hydraulic tappets though.

 

[Tippie]

Almost impossible to turn the motor over by hand. A diesel mechanic showed me, standard practice he said, was dead easy.

 

[sfcpiet]

Why on earth would you want to do the clearances with the engine running?

Normal practise with old Opel OHV car engines.  The CIH (cam in head, NOT OHC!) motors would also be adjusted at idle, the factory supplied special covers so the timing chain didn't spray the entire workshop with hot motor oil  Adjusting on running engines made feeler guages to become consumables, they didn't stand the hammering for long.

Lots of bike motors with hydraulic lifters of some sort, H-Davidson and several Honda SOHC types.

piet

 

[CLEMTOG]

"Standard practice with hydraulic tappets- loosen them off until they rattle and the tighten a turn from there. Probably not many bikes with hydraulic tappets though."

adjustable hydraulic tappets?????
new one on me
CLEM

 

[sfcpiet]

"Standard practice with hydraulic tappets- loosen them off until they rattle and the tighten a turn from there. Probably not many bikes with hydraulic tappets though."

adjustable hydraulic tappets?????
new one on me
CLEM

Never worked on a pan- or shovelhead Harley, Clem?

Later engines had different-length pushrods to keep the hydros within working range.

piet

 

[murphus]

Standard practice on U.S. pushrod engines back in the day, 6s and 8s.

 

[helicopterjim]

Probably not many bikes with hydraulic tappets though."

My 2003 Guzzi California has them as well.

 

[wdietz186]

I used to do Volvo pushrod  engines running, retard the timing to get them to idle slowly [about 500 rpm on the ones in good shape] and with the feeler in place tighten until the eng. note changes then back off a smidge.