no tappet adjustment ?

andy johnson

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hi folks , just had my cylinder head reconditioned , new valves ,guides springs etc , trying to fit the head back on and when fitted (balls and sockets of push rods all in place , long to inside , short to out ) the rockers are touching the top of the valves without the head even being tightened down ? could the tappet blocks be stuck ? I'm going to take off the head and strip it to check the valve length , anything else you could suggest ??
regards
andy
 

storm42

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Are they all touching ?

Hows it going Andy, have you done any trials this year?

Ralph.
 

p400

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you need to remove the cam to solve this issue.
plenty of clearance will be found.
 

andy johnson

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Are they all touching ?

Hows it going Andy, have you done any trials this year?

Ralph.
yo ralph !!!!!! only thinking about you a few days ago !! trials has just started up , one tomorrow at macclesfield , last week at bradfield . how are you ??
yes the rockers are touching the tops of the valves , don't understand it ? was working fine before i stripped it (head gasket gone) , u on same number ?
 
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Did you make sure the pushrods were in the sockets of the lifters? One cylinder will always be under tension from cam overlap. Try and get the pushrods as close to even by turning your engine, then offer up the head onto the barrel. Use rubber bands between the rocker intake and exhaust for each cylinder to keep them under tesion. Place a head nut between the head and cylinder to keep the head slightly away from dropping down completely. Then go and make sure the tappet balls are truly home for each pushrod. Once confirmed with a flashlight, remove the nut and bring the head down to contact the head gasket/barrel. The rubber bands should keep the rockers in contact with the tappet sockets. Tighten the center head bolt first. Once contact is made between the mating surfaces, recheck the rockers and pushrod sockets have not slipped off with the flashlight again. If all looks good, remove the rubber bands.
Turn the crank of the engine by hand to TDC and one cylinder will be on the firing stroke and the rockers int/exh for that cylinder should be loose enough to rattle. The other will be under tension from cam overlap. Roll crank over 180 degrees and the other cylinder should be on the firing stroke and rockers should rattle. If all is good then tighten all head bolts and nuts to torque speck and sequence pattern, adjust your tappet clearances to the cam spec. Bobs your uncle.
Cheers, edit, it should be a 360 degree rotation not 180.
Tom
 
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This is not my greatest area of expertise,... but it sounds like your pushrod didn't properly hit the cup in the lifter, so it's on the edge of falling into place and subsequently too high. The answer is to unload the pressure from the rocker to manipulate the pushrod to drop into place.

With the known million ways to skin a cat, I can think of 1 for this. Untighten the head bolts until the head pops up a little, then wiggle the offending pushrods to see if they visibly fall into place. The visible drop in the pushrod height pretty much confirms that the bottom of the pushrod was missing the pushrod cup molded into the lifter. If you can't get that to happen, you are looking deeper and should pull the head off to inspect the pushrods to make sure they are correctly located and sound... good luck!
 

storm42

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There is a chance this might be sorted but he won't be looking at it until tomorrow.
 

andy johnson

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thanks for the replies so far (and a great conversation with storm 42 on the phone ) i won't have time to look further into it until monday morning as i ride trials on sunday with my kids , but if we finish early enough i may get time in the afternoon ....
 

p400

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hi folks , just had my cylinder head reconditioned , new valves ,guides springs etc , trying to fit the head back on and when fitted (balls and sockets of push rods all in place , long to inside , short to out ) the rockers are touching the top of the valves without the head even being tightened down ? could the tappet blocks be stuck ? I'm going to take off the head and strip it to check the valve length , anything else you could suggest ??
regards
andy

I think you will find this condition is what you find with normal head install,.
Valves will be opened as you tighten the head down.
 
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There it is right there ^^^^^^^ You don't get rocker/valve clearance on both sides at the same time. You tighten the head down and roll the engine over and you'll be able to set the clearance on the valves, One side at a time.... (the obvious went right by me on that one...)
 
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Commando has long valves with short pushrods.
Atlas/P11 have short valves and long pushrods.
You cannot fit long valves with long pushrods.
Change valves or pushrods.
Hope this helps.
Ciao
Piero
 
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Very good point. shorter valves.
P11 / G15 /Atlas:
INLET VALVE (NM24330) L100.2mm, D38.1mm
VALVE - INLET & EXHAUST (D12/142)(D12/143)(NMT2010)(NMT2204) L99.5mm, D33.3mm

Commando 750:
INLET VALVE (NM25501, 06.3283) L102.3mm, D37.8mm
EXHAUST VALVE (NM25500) (06.3282) L101.9mm, D33.0mm
 

andy johnson

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so gentlemen !! seems ive just had senior moment , there's nothing wrong with anything ! i just got a bit 'flustered' with the way the rockers without adjusters hit the valves , its perfectly normal . just how its designed !!
the heads on , all seems ok , will fire her up tomorrow !
andy
 
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