[72 Chevy Nova]

When setting installed height which is better tighter or looser? Or is the goal to get as close to the target installed height. My springs say 1.7 but on a few I can only get 1.705 or 1.690 with shims. which is the way to go on this, I really don't want to wipe out the cam or suffer valve float. Any help is appreciated!

 

[engineczar]

I would go with the 1.705

To me you're just splitting hairs because of the tolerance of the valve springs. What I would do is if you have a spring that checks out to the high side pressure-wise I would use it on that one.

 

[72 Chevy Nova]

Well thats basicly what I am doing, just wasn't sure if it was better to set them with more pressure or a little less to maintain the .060 clearance for coil bind. The specs for the springs are 105# @ 1.7 with coil bind @ 1.150, cam has lift of .477 I and .480 E. The exhaust is really where the specs are getting tight and I figure it's better to have a little extra for the coil bind spec. Is this the right way to go or should I be going for the higher seat pressure and live with it being right at the .060 minimum for coil bind.

 

[engineczar]

Don't go below the .06, coil bind is much worse then float.

 

[nitro_baller4692]

your not stacking shims to get the height your looking for are you? :nono:

 

[72 Chevy Nova]

Well yeah I can only find shims in.015, .030 and .060. Is it bad to stack them?
The shims are being held in place by the valve guide. Stock 882 heads.

 

[machine shop tom]

Don't forget to figure in the oil shield thickness if you are using them. I also think it's a good idea to shoot for the loose end of the specs. I doubt if you will need to shim much, but stacking them is ok if you put the thinner ones on the bottom. Make sure the shims are hardened.

tom

 

[nitro_baller4692]

if you need more than .060'' you need a cup under the spring,two shims ,you going to have problems with sping walk.i don't do it.

 

[machine shop tom]

if you need more than .060'' you need a cup under the spring,two shims ,you going to have problems with sping walk.i don't do it.

If they need that much shim shimming, there are bigger problems afoot.......

tom

 

[nitro_baller4692]

agree but it sounds like he needs to do things the best he can,or take it to a machine shop.

 

[72 Chevy Nova]

OK fellas please explain. This is my first time doing a valve-train upgrade and I want to get it right or at least well enough to drive it till I get new heads. I figure the comment "more problems afoot" was a nice way of saying the 882 heads I have are junk. Can this be made to work with heads still on the car or do I need to have them in to be machined, really don't want to wast the money these heads as I am saving to upgrade to vortecs. Would it be better to take the extra shim out and use the biggest single shim and less spring pressure? I figure I'd need to limit engine speed to say 4000 max till I get the new heads?? Or is the writing on the wall and I am stuck till I get the new heads? Thanks to all those who take pity on this newbie.

 

[nitro_baller4692]

you said the heads were stock,right.if they have never been worked on the valve seats and guides are probably worn out and need to be addressed.you know vortec heads need to have work done to them to accept a cam with more then .450'' lift.you might want to look at having the guides knurled i don't like liners they can come out.knurl the guides and have your shop put used valves in that have a better margine or grind them out to put in bigger valves,this will get you back in the game with your installed height pressures and last awhile.then save your money to get the vortec heads done cuz your going to have this done on them more then likely.