Author Topic: rocker spacing - distance from rocker to valve top  (Read 1704 times)

tyssniffen

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rocker spacing - distance from rocker to valve top
« on: October 19, 2019, 07:42:02 PM »
I know there's specific numbers for the gap between the rocker arm and the valve top, and they're different for the inlet vs exhaust... but I can't  find those numbers anywhere. 

Can someone clue me in?
6/1 with 2 tank for WVO.  pushing power into off-grid house battery bank, in winter.

sirpedrosa

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Re: rocker spacing - distance from rocker to valve top
« Reply #1 on: October 19, 2019, 08:05:53 PM »
Hi tyssniffen

Yes I can! as long as you tell me what the brand and model of engine is.

Cheers
VP
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx
Lister 12/2 - 12651227, the pearl!

tyssniffen

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Re: rocker spacing - distance from rocker to valve top
« Reply #2 on: October 19, 2019, 08:09:32 PM »
sorry, thought I had a signature on there.  a listeroid 6/1
6/1 with 2 tank for WVO.  pushing power into off-grid house battery bank, in winter.

glort

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Re: rocker spacing - distance from rocker to valve top
« Reply #3 on: October 20, 2019, 06:39:05 AM »

In my experience, you won't go far wrong with any engine with 8 thou on the inlet and 10 on the exhaust.

tyssniffen

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Re: rocker spacing - distance from rocker to valve top
« Reply #4 on: October 20, 2019, 05:48:25 PM »

0.008 of an inch? I thought it was bigger than that. 
6/1 with 2 tank for WVO.  pushing power into off-grid house battery bank, in winter.

sirpedrosa

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Re: rocker spacing - distance from rocker to valve top
« Reply #5 on: October 20, 2019, 11:34:09 PM »
Hi tyssniffen

Take a look here: http://www.utterpower.com/lister_s.htm

Cheers
VP

Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx
Lister 12/2 - 12651227, the pearl!

listeroil

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Re: rocker spacing - distance from rocker to valve top
« Reply #6 on: October 21, 2019, 12:22:02 PM »
This is from a genuine 1971 Lister manual and shows

17 thou inlet and 32 thou exhaust for the 6/1 engine

8 thou inlet and 8 thou exhaust for the 8/1 engine



« Last Edit: October 21, 2019, 12:55:47 PM by listeroil »

mikenash

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Re: rocker spacing - distance from rocker to valve top
« Reply #7 on: October 22, 2019, 06:10:53 AM »
Hi there

Please see PDF attached which is a summary of some work by one of the "Masters" on here a while back

Briefly:  Valve clearances are about (a) operating clearance and (b) valve open-and-closing timing

(b) being the thing that matters as long as there's working clearance

So see PDF?  Try using the valve clearance adjustment to open the intake and close the exhaust at the degrees of rotation (timing) as per the PDF and never mind the actual clearance . . .

Others may wish to chime in?