620 valve adjustment?

[dflippin08]

Does anyone have a setting that they use cold. I don"t like hot adjustments. I know things change ( get tighter when hot) but there has to be someone that knows how much. Anybody have any suggestions?

 

[gtx1967jewison]

Nobody knows how much because it depends directly upon the temperature- what exact temperature is "hot". That's why you do it hot, to get as close as you can to maximum operating temperature. Do it hot, & the hotter the better. If not, then set it up loose. Too tight is bad, too loose won't matter unless it's excessive- you can double it & have no ill effects except accelerated wear, which won't happen because you won't run it long enough, & in theory a slight power loss but not enough to find on a dyno.

 

[dflippin08]

We'll this is what I've found when giving the old girl a checkup. The compression on both cylinders was 85psi cold and 90psi hot. I pulled the rocker cover and this is what I found. Both #1 valves were at .010 and #2 exh was at .010 and the intake was at 0.00 . I adjusted them all to .025 cold and I will readjust them when she gets on the dyno next weekend. After I adjusted the valves the compression on both cylinders is 115psi. I was looking for a good cold starting point. But I guess .025 is ok.

 

[rustred]

add .003 to the hot spec. and its good for cold setting.

 

[BushogPapa]

The Manual will give you both HOT and COLD settings, as well as a reference to what potion of a TURN Equals .022" (Cold) or .020" HOT.

Ron.

 

[Anonymous-0]

actually to loose is worse on a cam than tight is . Cold lash according to a cam grinder mike jones should be tighter . In order for heat to tighten lash up the pushrod would have to grow at a faster rate than the rest of the materials valves ,rocker stands, block , cylinder head etc.

 

[Anonymous-0]

ps the reason you gained cylinder pressure by opening lash up is two reasons.
1 reason it killed lift.
2cnd reason it killed valve duration by causing lifter to have to ride further up flank before taking up lash and moving valve.

 

[molineman]

LOL, what foolishness. You best
retire from posting until you have
actually had your hands in an
engine young man, or at least until
you comprehend what you read. As
everyone knows who as actually had
their hands on an engine the lash
will close up on a cast iron push
rod engine when hot. Engines of
usual tractor size. 001 /.003 on
the intakes and from. 002 /.004 on
the exhausts from stone cold to
operating temperature. If cast iron
block and aluminum head the lash
stays close to the same due to the
extra expansion of the head. Only
with aluminum head and block does
lash open up when hot. This is not
only common knowledge but easily
learned out in the shop with a set
of feeler gages and an engine that
actually runs,,, something that
apparantly you lack?

 

[Anonymous-0]

Just because you gained cyl pressure when running the valves does not mean you gained power. I can think of a few people who ran their valves for max psi and it ran like crap until they changed it back to stock setting. be interesting to see what yours does. Maybe it will work on a jd.. These were on MMs.

 

[Anonymous-0]

(quoted from post at 05:37:58 02/17/14) LOL, what foolishness. You best
retire from posting until you have
actually had your hands in an
engine young man, or at least until
you comprehend what you read. As
everyone knows who as actually had
their hands on an engine the lash
will close up on a cast iron push
rod engine when hot. Engines of
usual tractor size. 001 /.003 on
the intakes and from. 002 /.004 on
the exhausts from stone cold to
operating temperature. If cast iron
block and aluminum head the lash
stays close to the same due to the
extra expansion of the head. Only
with aluminum head and block does
lash open up when hot. This is not
only common knowledge but easily
learned out in the shop with a set
of feeler gages and an engine that
actually runs,,, something that
apparantly you lack?

have you ever checked cold lash against hot lash or just assumed. One way to know only way to know is check it. It is better to be a couple thou tight than loose . Loose kills cams.

 

[Anonymous-0]

(quoted from post at 05:37:58 02/17/14) LOL, what foolishness. You best
retire from posting until you have
actually had your hands in an
engine young man, or at least until
you comprehend what you read. As
everyone knows who as actually had
their hands on an engine the lash
will close up on a cast iron push
rod engine when hot. Engines of
usual tractor size. 001 /.003 on
the intakes and from. 002 /.004 on
the exhausts from stone cold to
operating temperature. If cast iron
block and aluminum head the lash
stays close to the same due to the
extra expansion of the head. Only
with aluminum head and block does
lash open up when hot. This is not
only common knowledge but easily
learned out in the shop with a set
of feeler gages and an engine that
actually runs,,, something that
apparantly you lack?

have you ever checked cold lash against hot lash or just assumed. One way to know only way to know is check it. It is better to be a couple thou tight than loose . Loose kills cams. I have never killed a cam breaking one in but seen several come ito shop that were. Your choking gnats 1 to4 thousandths really like thats going to hurt anything. Dude said he went from .010 to .025 .015 looser may hurt the cam where 4 thousandghs tight wouldnt

 

[dflippin08]

I don't want to set them to max cyl pressure. I want to set them to the cold spec. CORRECT is what I was looking for.

 

[dflippin08]

Thank you. The only truly helpful post. I don't have a manual

 

[Anonymous-0]

only way to know that in confidence is lash it cold get her hot and see how much it movse if any . If you were looking for cylinder pressure you would be better off to advance cam than to play with lash. Cams lash ramp was designed by grinder for a certain lash with a certain rocker ratio if you open lash up past grinders recomendations damage can occur to the cam. Cams are more forgiving to tight lash than loose lash

 

[wi50]

You guys have done it now!! You got pank to say things tighten up after the engine warms up, a complete contrary to what he was preaching a year ago...at least he's learning from all his time on the forums.

 

[guido]

Hello,

Engine valves cold setting is usually.002 more for most engines. Setting valves a bit tighter will have a slight increase on engine timing, and no other ill effect. Valves that that are way out of adjustments ( tight or loose) will cause at times a cam to fail, together with poor first time engine start up lubrication. All adjustments are made with engine NOT running,

Guido.

 

[molineman]

Did you see anywhere in my post
where it says "I read" or "I
heard"??. 35 years of fingers in
engines my friend, I dont need to
read or do a Google search to
answer a post about valve lash
changes or in what direction. We
are in agreement about loose valves
killing parts, cams, rockers and
valve stems all take a beating but.
004 for a few minutes to warm up
the engine is going to hurt not one
thing. However too tight when the
piston is chasing the exhaust valve
closed by a few thousand of an inch
can cause bad damage in one
revolution.

 

[The Dukester]

I was always told to set the lash clearances to spec. Or even
a tad loose When the engine had been overhauled, never to
the tight side because those valves are "seating in" and could
tighten the clearances up and possibly not seat properly after
running a while.....After the engine has been run and warmed
up real well another check of the lash setting is required.
When an engine is well broken in I do a final setting, but I go
by turns in the adjusting screw and then double check with the
feeler gauge....and on my John Deere two-poppers I confess I
set 'em .002 or.003 thousands tighter than spec. and they are
quieter and idle smoother.....But I make sure the engine is well
warmed up when I do this and am real careful doing this.

 

[buickanddeere]

Something to consider. It's difficult to set the lash when the rocker arms and valve tips are worn curved instead of flat and square.

 

[Anonymous-0]

I agree on piston to valve no google or read here either been in engines .Nothing like playdough to know exactly how close the piston to valve get with 0 lash then you know you have margin/ insurance with lash .got as many years wrench tourning. Running every machine in shop by 16 with exception of crank grinder . Surfacer . Valve grinder boring bar power hone etc.