Valve Lashing

[SeamusNZ]

Hi all fron New Zealand,

I have a very strange situation that I need some expert guidance with. I am in the process of rebuilding my Corvair engine and am at the stage of lashing the valves. My problem is that when (supposedly) on No2 TDC, the pushrods are fully extended on the valves that the book tells me that I should be lashing. Ie How can I lash a rocker on a valve that should be open. All marks line up on the crank and cam for No1 TDC.

Is it possible that the mark on the cam has been stamped on the opposite side of the cam to what it should.

All lashings are fine when at No1 TDC. It is No2 TDC that is the problem??

Kind regards from New Zealand

SeamusNZ

[skipvair]

Are you sure you're not 180 out? Find compression on number 1 then go thru the sequence. Don't assume that lining up the gear marks gets you to TDC. I don't know if it does or not on a vair, but i know it does not on some engines.

Alternately, you just have to make sure whatever cylinder you are on is off the lobe to adjust them. It really doesnt matter the sequence. Just more crank turning that way.


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[66vairguy]

I assume you haven't gotten the end cover and pulley (with timing mark) installed.

Not difficult to get out of sequence or not at the cam low spot. If the engine top cover is off it's easy to see when the piston is top dead center and BOTH cam lobes low spots are at the lifters in question. Since the rockers can pivot to the side with excess lash it's always good to pull up and down on the push rod GENTLY while tightening the rocker nut until all the play is out, or at zero lash. Today the general consensus is to turn another 1/2 turn after zero lash. Some like to go with 1/4 turn or less to prevent lifter pump up - not recommended as the lifter won't pump as much oil up the pushrod. Lifter pump up is mis-understood, it's not the lifter - it's when high rev's prevent the valve springs from closing the valves fast enough and the lifters "pump up" trying to close the gap. Only cure is higher tension valve springs - always recommended with more aggressive cam shafts.

[64powerglide]

Again a big thank you to Dave for this video.