69 z/28 valve adjustment - Team Camaro Tech
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post #1 of 10 (permalink) Old Apr 25th, 01, 03:55 PM Thread Starter
 
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on my 69 302- should valves be adjusted hot or cold, and are there any reliable ways or recommended procedures? and what is proper lash? (.30" ?)
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post #2 of 10 (permalink) Old Apr 26th, 01, 02:40 AM
 
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.30" is wright I do it hot. Some do it cold but you have to ajust for the heat up about .02" to .04" I do not like to do it that way. The manul says to do it hot.

TIM

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post #3 of 10 (permalink) Old Apr 26th, 01, 03:22 AM
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If its the stock solid lifter cam then .030'' is correct, intake and exhaust
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post #4 of 10 (permalink) Old Apr 26th, 01, 05:25 AM
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Valve adjustment with the (stock) "30-30" Duntov cam must be done with the engine hot and running - the length of the clearance ramps leaves almost no "base circle" on the cam, so the traditional "hot but static" method that works on most other solid-lifter cams won't work with the "30-30"; that's why the Shop Manual says to do it "hot and running". Just use a partial old valve cover to deflect the oil drippage off the retainers and a set of rocker arm clips to deflect the pushrod oil down into the rocker ball area. Once you get the hang of it, you can do it in about ten minutes. Just let it idle - don't rev it up or you'll have oil spatter everywhere.

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post #5 of 10 (permalink) Old Apr 26th, 01, 05:41 AM
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Adjust a solid cam engine while it's running. WHAT?!!!!!!
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post #6 of 10 (permalink) Old Apr 26th, 01, 12:09 PM
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Thats the only way to do it correctly. 30-30 while hot and running. Had three of them (302). Also you will get very good at engine shampoos as well.

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post #7 of 10 (permalink) Old Apr 27th, 01, 01:57 PM
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<BLOCKQUOTE>quote:</font><HR>Originally posted by Stewie:
Thats the only way to do it correctly. 30-30 while hot and running. Had three of them (302). Also you will get very good at engine shampoos as well.

<HR></BLOCKQUOTE>

The only way to do it correctly? I don't think so. I will continue to do it the other correct way, with out it running. Never had a problem or a mess to clean up. Been to a bunch of races, seen alot of guys adjust the valves on there cars, never once did anyone have the thing running.

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post #8 of 10 (permalink) Old Apr 27th, 01, 04:37 PM
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I would like to take this question a little further backwards. How do you set up this cam after you install it up to the point that you do the adjustments. Need some really good details on this since I will be doing this myself...

Thanks,
Gary
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post #9 of 10 (permalink) Old Apr 27th, 01, 07:21 PM
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Here's my two cents worth.
I started playing with engines in the late 60's, had my Lola T-70 running since 1978 with a roller cam in it.
I've allways set lash cold and had NO valve related problems.
I now have aluminum heads on the engine and set the lash .002" tighter than spec when cold. With iron heads just set at the recomended spec.

Stuff I've read over the years says the block, heads, pushrods etc all heat up the same rate if made of iron and steel.
The aluminum heads expand a little more than the steel pushrods so you need to close it up a little.

Those who lash the cam hot. The engine get's much hotter than that when racing or driving down the road at higher rpm's.
So "hot" is a somewhat relative term.
I just have found that I can pull the valve covers, lash the valves accurately and calmly without rushing, replace the valve covers carefully, get everything properly in place and ready to go out on the track with the engine cold. If I get the valve covers on wrong and get a leak, I'll get black flagged and miss my practice group, so doing it with the engine cold is better for me.

By the way, I'm using an Isky roller cam and it's 640 lift, so if I were very far off in adjusting it, I would be having SOME kind of problems by now!
My engine builder does valve adjustments this way too and has done CanAm, and Southwest Tour engines for years, in addition to drag boat engines.

The 30-30 cam has a LOT of lash, .030" is a lot of lash and I've read where you can close it up 2 or 3 thou when experimenting.
I wonder if the high amount of lash is really there to allow for the guy who just drives the car and never re adjusts the lash. In other words, as a safety margin because this cam is a production vehicle cam. If that's true, there would be a very large range of leeway in lashing the Z/28 cam.
Many aftermarket cams use .008" to .012" clearance.

I'm not trying to put down anyone who likes to hot lash valves, I suppose it's pretty accurate. I just don't like working on hot engines.
David

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[This message has been edited by davidpozzi (edited 04-27-2001).]
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post #10 of 10 (permalink) Old Apr 28th, 01, 02:55 PM
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Either method works with most solid-lifter cams - matter of personal preference; however, the "30-30" grind is a unique animal due to the length of the clearance ramps and is spec'd to be lashed hot and running because the base circle is so short.

I've used the "hot and running" method for over 40 years (personal preference), as it's quick, doesn't require manually cranking the engine over from one group to the next, and I never dribble any oil using the clips and partial rocker cover - ten-minute process at most, and you don't fire it up later and hear one or two that are a tad too loose - you can hear them while you're setting them. I always seal the cover side of the rocker cover gasket to the cover with a bead of RTV (since that's the side that will leak, not the head side), just pop them off and on, don't over-torque the bolts, and have never had a leak. Just depends which method you like (except for the "30-30").

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