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PostPosted: Sun Nov 25, 2018 12:41 pm 
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Cory said the mid-lift design was the issue.

The main bearing clearances will grow. There's just no way around it with two different materials composing the housing bore. You wouldn't know that anything would be wrong unless your clearances were too small....kinda like a cast iron block deal. If your bearing clearances were correct when the block got up to operating temperature, then you won't notice any issues. If you set them as you would with a cast iron block, then if anything they would be a little loose with the aluminum block.

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PostPosted: Sun Nov 25, 2018 12:54 pm 
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Thats not the case Brent. The mid lift principle was not used they were setup up as a standard 1.8 rocker. You cannot set them up with midlift principal on cleveland. If
You set a midlift rocker beside a crane very little difference. They are basically the same as a crane gold so im not exactly sure what he talking about. I noticed zero difference in valve setting compared to any other alloy rocker.


Last edited by Steve.k on Sun Nov 25, 2018 12:58 pm, edited 1 time in total.

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PostPosted: Sun Nov 25, 2018 12:55 pm 
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Not sure either, but he told me that he wouldn't rely on the valve lash to tell any stories, because they were hard to get an accurate lash setting with them.

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PostPosted: Sun Nov 25, 2018 1:08 pm 
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blykins wrote:
Not sure either, but he told me that he wouldn't rely on the valve lash to tell any stories, because they were hard to get an accurate lash setting with them.

The only thing there is cause stud girdle. You do see cool down if you remove girdle. However Tim and I checked lash with out moving girdle. Just a quick check to see where we at, thats what we saw. On a cast motor with same setup i see less than a thousand usually nothing with alloy heads on engine. The Cleveland motors themselves in design use part of the midlift therory already which most do not know. This I found out when i decided to use rockers, you cannot use the setup theory on a cleveland. The rocker is basically made the same as any bbf or cleveland rocker with the exception of maybe being stronger than same era alloy rockers.


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PostPosted: Sun Nov 25, 2018 1:14 pm 
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On my SBF/Cleveland/FE engines, I can almost bet my paycheck on the lash increasing .006" from cold to hot with a cast iron block and aluminum heads. Cast iron blocks with cast iron heads, I usually don't see any change from cold to hot. On my all-aluminum engines, it's usually right at .014".

I also set the valves with the EVO method. Setting them at TDC with a big cam can introduce error.

Stud girdles won't change lash in and of themselves, but the initial adjustment takes a little longer because when you tighten up the set screws it usually skews the geometry a little bit.

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PostPosted: Sun Nov 25, 2018 2:10 pm 
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Never seen it that high. Set the same way as you. Once valves are set from engine stand to dyno or car never checked again cold. I never kept real close attention on 436 of my own as after break in we set valves to where we wanted them. Some did not require adjustment once so ever. Chi 4v head.


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PostPosted: Sun Nov 25, 2018 2:24 pm 
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I always set them cold on the stand, roll the engine over through a complete cycle of all the rockers and check them again/adjust. I use the above rules of thumb, then I check on the dyno with them hot and rarely have to reset anything else.

Looks like same for these guys:

http://www.speedtalk.com/forum/viewtopic.php?t=21953

Look at post by madscientist.

Also see here:

https://www.enginebuildermag.com/2011/0 ... alve-lash/

That's why I'm saying that a cold/hot variation of just .004" just isn't logical.

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PostPosted: Sun Nov 25, 2018 2:47 pm 
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Well i have never seen .006 On alloy heads to iron. However i set pretty much same as you on stand. Check twice. Then dyno and break in or vehicle whatever it is we are doing, like i said usually iron needs no adjustment but on alloy heads I'll see some loose. Usually just adjust to spec where necessary. I will say on my own 436 the ones that needed adjustments I never noted how much only set. The tb however we made a point of it cause no one has ever used supracast alloy which expands less and takes more heat to expand.


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PostPosted: Sun Nov 25, 2018 2:49 pm 
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I'm a big stickler on setting valve lash. Once it's set correctly it should stay set, but you can change the effective duration of the camshaft by changing the lash spec....plus setting it correctly will let you know if there's any issues with the cam/lifters later on.

Maybe check it again when you get it running...

I agree, the Supracast stuff is supposed to be higher tensile/yield with a lower rate of expansion, but it still has over twice the rate of expansion as cast iron.

The expansion rate of ductile cast iron is 5*10^-6 in/in/°F. Supracast is 11.4*10^-6 in/in/°F.

Theoretically speaking, say for the length of a block deck height, 9.200", 150°F would make a cast iron block grow .006". The Supracast alloy would grow almost .016".

Now, obviously, that is a very watered down, by the book calculation that doesn't take into account a lot of things, but if you had a piece of cast iron and a piece of Supracast aluminum out in the open being heated up, that's what you should see based on the thermal coefficient of expansion. That statement doesn't have anything to do with valve lash, just a comparison between cast iron and aluminum.

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Last edited by blykins on Sun Nov 25, 2018 2:59 pm, edited 1 time in total.

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PostPosted: Sun Nov 25, 2018 2:57 pm 
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I'll double check that when back together but we didn't see anything much different on it as a alloy headed iron motor which we attribute to supracast. I typically set my valve lash tight, meaning it takes good amount of effort to get guage in. I know a lot of guys don't like this way and neither way is wrong its just preference. I could be very well setting tight and do not see as much variance. But it works for me,and like you see little movement after running awhile. I'll make a point of checking again when we resume dynoing.


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