Cold lash after 500 miles, yikes!
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Re: Cold lash after 500 miles, yikes!
Those are some big differences. I hope some error on your behalf....I've done it to. I would check retainers for a crack, rocker trunions in the correct position. Did the keepers fit tight on the valves? I would relook all this stuff. Very important to be on the base circle of the cam when setting lash.
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Re: Cold lash after 500 miles, yikes!
F-bird88, you had me concerned on your IOEC statement for a while.
Re: Cold lash after 500 miles, yikes!
I lost a pound of hair the first time I encountered a cam with eccentric base circles. I was trying to set up the valves at TDC compression because I didn't want to roll the engine over so many times and I kept getting weird readings and I ended up wasting two hours instead of "saving time".Bishop540 wrote: ↑Sat Sep 01, 2018 9:54 pmNo to both, but if I would have checked them the TDC method I assume they would have been a little tighter.Cubic_Cleveland wrote: ↑Sat Sep 01, 2018 9:41 pm Did you check any of the valves using the same method you set them at originally when you found they were loose? Did you check the valves after you re-set them this time using the same method as originally set? That might have provided some answers for you...
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Re: Cold lash after 500 miles, yikes!
It would be easy for a cam grinder to say: "Plus or minus a thous. or so base circle runout on the 0.024"-0.030" lash, what's the big deal?" But when you're monitoring closely for wear and an inconsistent lashing procedure lands you unpredictably on a high or low spot, you could get worried for nothing or worse, miss an important early warning.
The several Jones cams I've measured were all less than 0.001" but with some name brands I've seen 0.003".
A related issue I've run into even with my limited experience is eccentric rocker rollers*. After some perplexing measurements, I marked the suspect parts and found that the lash changed as much as +/- 0.002" as I rotated the wheel against the feeler gauge. I suppose when running it would consistently settle into the "most clearance" position, but... *It just occurred to me that an eccentric lifter roller would mimic base circle runout. Does anyone routinely check same and if so, with what result? Guess I should check my new Isky EZ Rolls before I drop them in.
The several Jones cams I've measured were all less than 0.001" but with some name brands I've seen 0.003".
A related issue I've run into even with my limited experience is eccentric rocker rollers*. After some perplexing measurements, I marked the suspect parts and found that the lash changed as much as +/- 0.002" as I rotated the wheel against the feeler gauge. I suppose when running it would consistently settle into the "most clearance" position, but... *It just occurred to me that an eccentric lifter roller would mimic base circle runout. Does anyone routinely check same and if so, with what result? Guess I should check my new Isky EZ Rolls before I drop them in.
Last edited by MadBill on Sun Sep 02, 2018 1:06 pm, edited 1 time in total.
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Re: Cold lash after 500 miles, yikes!
The most accurate way to set lash, is to set each valve individually. Turn the engine over, until the valve you want to set, is at max lift, then turn the engine over 360 degrees. That would put the lifter on the center of the base circle. Set lash, then go to next lobe.
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Re: Cold lash after 500 miles, yikes!
Maybe I'm just an old b*stard but doesn't the valve lash decrease when the engine is hot not increase? After all the parts expand when hot... I always set the valves when hot at the maximum clearance I want.
When I was a kid with a 30/30 cam in my 283 my boss told me to set the valves at .018/.020 intake/exhaust instead of .030. I thought I burn the engine down. What I got was a better mannered street engine that didn't beat up my valve train.
When I was a kid with a 30/30 cam in my 283 my boss told me to set the valves at .018/.020 intake/exhaust instead of .030. I thought I burn the engine down. What I got was a better mannered street engine that didn't beat up my valve train.
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Re: Cold lash after 500 miles, yikes!
In most cases, no.
The block grows when it gets hot, so now the distance from the cam centerline to the deck has increased. The cylinder head also grows when it gets hot, so now the distance from the deck to the rocker pad has increased. So, when the engine gets hot, the distance from the cam to the rocker increases. The lifter and pushrod also grow when they get hot, but not as much as the block and heads.
Mike Jones
Jones Cam Designs
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jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Jones Cam Designs
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jonescams@bellsouth.net
http://www.jonescams.com
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Re: Cold lash after 500 miles, yikes!
We adjust our valves when the exhaust is almost fully open, and when the intake is almost fully shut.
The difference in lash between a tdc base circle type measurement, the way I mentioned, and even differing places on the base circle, is typically caused by how the spring pressure from other cylinders are effecting cam position in block. This is aggravated by higher rocker ratios.
When running, all bets are off! Hahaha
The difference in lash between a tdc base circle type measurement, the way I mentioned, and even differing places on the base circle, is typically caused by how the spring pressure from other cylinders are effecting cam position in block. This is aggravated by higher rocker ratios.
When running, all bets are off! Hahaha
Re: Cold lash after 500 miles, yikes!
Camking on a iron block and iron heads doesn’t the lash decrease by about .003 when the block and head heat up.
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Re: Cold lash after 500 miles, yikes!
With aluminum rockers it certainly can, depending on the water to oil temp delta. The greater the delta, the less the block and heads will grow, and the more the valvetrain components will.
That is assuming oil temp being greater than water.
Again, aggravated with increased rocker ratios.
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Re: Cold lash after 500 miles, yikes!
I've never seen more than a few thousands difference between initial set and after a while. An extra .020 or so after 500 miles even consistently on all the valves would worry me. I would make sure nothing is wearing prematurely, or athe the very least recheck after a test drive to prove nothing moved.
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Re: Cold lash after 500 miles, yikes!
Yes the OP has some warning signs.rustbucket79 wrote: ↑Sun Sep 02, 2018 5:00 pm I've never seen more than a few thousands difference between initial set and after a while. An extra .020 or so after 500 miles even consistently on all the valves would worry me. I would make sure nothing is wearing prematurely, or athe the very least recheck after a test drive to prove nothing moved.
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Re: Cold lash after 500 miles, yikes!
Hit the wrong button...I meant the valves get tighter not looser. Been a long week!CamKing wrote: ↑Sun Sep 02, 2018 2:20 pmIn most cases, no.
The block grows when it gets hot, so now the distance from the cam centerline to the deck has increased. The cylinder head also grows when it gets hot, so now the distance from the deck to the rocker pad has increased. So, when the engine gets hot, the distance from the cam to the rocker increases. The lifter and pushrod also grow when they get hot, but not as much as the block and heads.
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Re: Cold lash after 500 miles, yikes!
Assuming no deflection from assembled engine spring pressure, if there is base circle runout on the bare cam itself, the entire lobe is off center.