VALVE CLEARANCE HELP!!!!!!!!! - Performance Forum

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VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 4:31 PM
Ok so you all know that im putting my engine back together. Well i ran into a problem. I got the pistons in and bolted on the head to check the valve clearance and i rotated the engine over and what not and there really wasnt any resistance doing so. Well when i took the head back off the pistons had a little (and i mean little) mark on them where the valves come down. Now heres what i was thinking. Could i shim up the rocker arm stud to make them sit higher and compensate for this? That really the only thing I can do at this point. I got a remanufactured head from ebay and i think it was deacked a little bit thats what might be making this problem.


http://www.cardomain.com/ride/2090440



Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 4:45 PM
All you can do is to cut reliefs in the pistons or use a thicker head gasket. You need to maintain atleast .100" VtP clearance. Your best bet is to talk to your machine shop, and see what they'll need to get the proper depth and angle for the reliefs.





Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 5:04 PM
I really think that raising up the rocker arm is the best fix for it. The marks on top of the piston are so small that you cant even feel them with your finger but you can see them. If i get a washer thats like 1mm thick then i think that would be perfect for this fix.


http://www.cardomain.com/ride/2090440


Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 5:05 PM
are you sure its timed right?



Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 5:13 PM
yea i mean everything is lined up right as far as i know. I read and re-read that part in the shop manual just to make sure... I mean correct me if im wrong but this is a pic of it and the 2 marks are supposed to be lined up with the 2 tabs on the tensioner...



This pic is kinda at an angle so it may look like there off but i assure you there right on the mark...


http://www.cardomain.com/ride/2090440


Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 5:14 PM
$hit wrong pic...




http://www.cardomain.com/ride/2090440


Re: VALVE CLEARANCE HELP!!!!!!!!!
Monday, February 27, 2006 5:49 PM
Yeah, your timed correctly.

Raising the rocker arm will do nothing but throw your geometry off. Push rods, valve stem lengths and rocker arm hight only change the geometry of the valve train, not the amount of lift. Changing the rocker arm ratio will change the amount of lift, as will the camshaft.





Re: VALVE CLEARANCE HELP!!!!!!!!!
Tuesday, February 28, 2006 3:49 AM
Quote:

I really think that raising up the rocker arm is the best fix for it.

I'm sure you're saying this because you're not looking forward to pulling the pistons. But you should listen to Madjack's advice here. Think hard about how the valvetrain works, and about what raising the rocker arm will do, and you should be able to see how it's not a good fix.

The reason for the .100" minimum is (that's a measly tenth of an inch, btw) is to make up for changes in dimensions of all the parts in the engine due to temperature and inertia.

You didn't mention whether or not you had a head gasket on the engine when you did this. Most gaskets have a compressed thickness somewhere between .020" and .040" which isn't enough to provide the minimum clearance, but it can help your machinist determine where to make the changes needed.

You should also check that rebuilt head to make sure it isn't machined too much. The minimum spec is 5.305" If it's substantially less than that, you might want to look for a head that hasn't been butchered.

-->Slow
Re: VALVE CLEARANCE HELP!!!!!!!!!
Tuesday, February 28, 2006 5:45 PM
Hey Nitrous Nate AEM makes a slave cylinder bracket for use when you remove the factory airbox, and it like $30, in case you didn't know. I got one for my Z24 when I put the short ram on.


2000 Z24 5spd header & catback for now.
Re: VALVE CLEARANCE HELP!!!!!!!!!
Sunday, March 05, 2006 4:23 PM
ok ok ok i found out what the problem was... my dumb @ss totally forgot about THE PUSH ROD GUIDE PLATES!! which take up space under the rocker arm stud. everythings fixed now lol thanks for the advice...


http://www.cardomain.com/ride/2090440


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