help rocker ajustment

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j par

j par

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I just got the locking adjusters for the 273 rocker arms and filed the tops flat for the locking nut as per rusty rat rod, thank you.I need help understanding either what my machine shop wrote down as the procedure and/or why I wouldn't just adjust them under base circle like at the time of the power stroke? I'll shoot a picture of the piece of paper that my machine shop with the procedure on and see if it makes sense. I put the picture on a different thread that had already kind of died out and I need help with this today as I'm going to start addressing these so I can put the motor in. Mind you when I posted it last time it came up sideways so you may have to look at your computer a little sideways or have the ability to turn it caddywhompus upright. Thank you for any help, jason .View attachment 20150227_205943.jpg

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Just do it like this:
312P4452989.jpg
 
if you can see the cam decent then just adjust them when you are on the base circle, I use what your machine shop wrote, I will explain it like I tell others, "when the exhaust valve just starts to open adjust the intake valve on that same cylinder, when the intake valve just start's to close do the exhaust valve on the same cylinder" so I just rotate the motor until the exhaust valve just starts moving and then do the intake, then I rotate until the intake is all the way open and then watch until it just starts to come back up (closing) then I adjust the exhaust, your machine shop wrote to do it when it is almost closed, I don't do it that way. I have used the chart posted above and that work's also, until you get into some of the more radical cams, also if you don't have 90 degree lines on your dampner you might not get it exactly right.
 
torkflight said:
if you can see the cam decent then just adjust them when you are on the base circle, I use what your machine shop wrote, I will explain it like I tell others, "when the exhaust valve just starts to open adjust the intake valve on that same cylinder, when the intake valve just start's to close do the exhaust valve on the same cylinder" so I just rotate the motor until the exhaust valve just starts moving and then do the intake, then I rotate until the intake is all the way open and then watch until it just starts to come back up (closing) then I adjust the exhaust, your machine shop wrote to do it when it is almost closed, I don't do it that way. I have used the chart posted above and that work's also, until you get into some of the more radical cams, also if you don't have 90 degree lines on your dampner you might not get it exactly right.
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for some reason the first one seems easier to me and I do have the motor on a stand with the intake manifold off so I can see everything and this will be the first start a brand new build. There is all that break in goop all over the cam and I would rather not turn the motor over lord knows how many times to adjust the valves as opposed to two or three revolutions and done, but I do want to do things the right way regardless.
 
you now have three methods. only two can be used after the engine is finished. either the chart or the note you got is good. here watch this thing

[ame="https://www.youtube.com/watch?v=3gMYWLMAzao"]COMP Cams How to Set a Valve Lash - YouTube[/ame]
 
j par said:
for some reason the first one seems easier to me and I do have the motor on a stand with the intake manifold off so I can see everything and this will be the first start a brand new build. There is all that break in goop all over the cam and I would rather not turn the motor over lord knows how many times to adjust the valves as opposed to two or three revolutions and done, but I do want to do things the right way regardless.
Click to expand...

That's a good idea on a fresh engine. If you're setting them cold add a couple thousandths to the spec. They will tighten up when the engine warms up. You will want to break things in and go back and check them hot. Kind of sounds like a pain but with good locks and adjusters once the engine is broke in you probably will adjust them once a year or maybe every other year depending how hard and how many miles you drive. I ran the valves on mine 2 years ago. I will go through it this spring. I only put a few thousand miles on a year. tmm
 
Did the valve ajust as per (69 340 GTS) valve lash ajusting chart. Then for a double check - checked a couple of valves as per my machine shop and the comp cam video provided by (DDodger). Every one was .002. - .003 loose ??? That kind of defies all logic? So, we kept going through the second processed and called it good.
 
Nice job on the rockers!
 
When we were adjusting the valves on Dads 273, I called Comp Cams to get the valve lash, they actually told me to set them a little TIGHT cold. Apparently they "loosen" up when hot....
Cant remember what I set them at last spring, I believe .020 for exhaust and intake.
Nice job on the rockers by the way.
 
j par said:
Did the valve ajust as per (69 340 GTS) valve lash ajusting chart. Then for a double check - checked a couple of valves as per my machine shop and the comp cam video provided by (DDodger). Every one was .002. - .003 loose ??? That kind of defies all logic? So, we kept going through the second processed and called it good.
Click to expand...

Cam lobes are not perfect. The lash closes when hot on Iron heads. When you adjust your lash using the methods above, the lobe may or may not be at the lowest point of the base circle. If you adjust them as above and rotate the crank every 10 to 15 degrees rechecking the lash on all the rockers you can, you will find that you will be adjusting the lash on quite a few rockers. This is why we do the final adjustment to the lash hot and running. Readjust after 5,000 miles after break in. Then you should be good for years.
 
66fs said:
Cam lobes are not perfect. The lash closes when hot on Iron heads. When you adjust your lash using the methods above, the lobe may or may not be at the lowest point of the base circle. If you adjust them as above and rotate the crank every 10 to 15 degrees rechecking the lash on all the rockers you can, you will find that you will be adjusting the lash on quite a few rockers. This is why we do the final adjustment to the lash hot and running. Readjust after 5,000 miles after break in. Then you should be good for years.
Click to expand...
you set your lash with the motor running?
 
So how much trouble am I going to have if don't get locking nut
69 340, 284/484 purple shaft and Rhodes hydraulic lifters.
 
trapster said:
I usually do
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doesn't that get messy? and how are you turning the adjuster and lock nut accurately when it is moving up and down like that? I remember my old shop teacher in high school telling us to do it running, that just seamed weird to me, more trouble than its worth, I have never done it running and never had issues
 
The base circle on a mech (and probably hydro) is only about 45% of the sweep of the lobe, opposite the nose. The procedure is so that you are on the real base circle when you adjust. If you were to to be able to see the cam, youll see the Mopar sticker puts your rocker being adjusted at the true base circle.
cam-lobe.jpg
 
torkflight said:
doesn't that get messy? and how are you turning the adjuster and lock nut accurately when it is moving up and down like that? I remember my old shop teacher in high school telling us to do it running, that just seamed weird to me, more trouble than its worth, I have never done it running and never had issues
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When I adjust rockers while running I set a piece of cardboard about 6 inches wide and as long as the head down between the valve cover rail and valve springs to keep the splattering oil from goin everywhere.
I'ts a little hard on feeler guages doing it running, and you have to use a loose grip on the locknut and adjuster wrenches so they can move up and down while turning them.
Kind of just have to let them float around in your hand.
 
trapster said:
So how much trouble am I going to have if don't get locking nut
69 340, 284/484 purple shaft and Rhodes hydraulic lifters.
Click to expand...

They might come loose, they might not. The adjuster modification just assures they will not.
 
torkflight said:
you set your lash with the motor running?
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A little, They don't spray all over like a Chevy. For factory rocker arms, without lock nuts, you use a ratchet with an extension and a universal socket. I was skeptical the first time I did it but, really a piece of cake. I also like the go no go style. To start the engine you should set them cold. Even the base circle is not uniform. A lot of the old lobe patterns were machined and "adjusted". I've tried the cam adjustment chart, with very poor results. It probably will not take much checking to verify how far off your lash can be from setting by the chart. I'm talking about cast iron heads, I have no experience with Aluminum heads. It does make sense they would "grow" and loosen your lash when hot.
 
trapster said:
So how much trouble am I going to have if don't get locking nut
69 340, 284/484 purple shaft and Rhodes hydraulic lifters.
Click to expand...

273 were interference adjuster, meaning there is a mean drag on the adjuster so it doesnt back off under its own load (supposedly, the thread pitch wears over time). The more you mess with it, the looser the adjusters get, so the locknuts are a good measure. IIRC, the stock adjusters were hollow hex heads and the after market were slots. Allen head would be the best, put a ball end in there on a spring loaded telescoping T-handle and you could adjust them while they are running without the T-handle jumping around. Hey, thats my million doller idea!
 

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4spdragtop said:
When we were adjusting the valves on Dads 273, I called Comp Cams to get the valve lash, they actually told me to set them a little TIGHT cold. Apparently they "loosen" up when hot....
Cant remember what I set them at last spring, I believe .020 for exhaust and intake.
Nice job on the rockers by the way.
Click to expand...

Whoever told you that, either thought you had aluminum heads, or they didn't know what the FLIP they were talkin about. When an iron headed motor heats up, everything expands. That means you need to adjust cold a little loose because when the valve tip and rocker expand, the will close the gap a little. You will likely not notice a difference, but It would be nice if the guys at Comp knew what to tell you.
 
RustyRatRod said:
Whoever told you that, either thought you had aluminum heads, or they didn't know what the FLIP they were talkin about. When an iron headed motor heats up, everything expands. That means you need to adjust cold a little loose because when the valve tip and rocker expand, the will close the gap a little. You will likely not notice a difference, but It would be nice if the guys at Comp knew what to tell you.
Click to expand...

Yeah, what he said!
"...For an engine with cast-iron heads and steel valves, you can expect the lash to tighten up a couple of thousandths of an inch as it heats up-so for the cold lash you would set the valve lash a couple thousandths larger than the cam manufacturer's recommended hot lash setting..."
 
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