My target height is 1.790, I keep geeting 1.800, if I leave alone it's .010 too high, if I add a .015 shim it's .005 too low. Which option is better? I'm trying to get my heads assembled tonight.

Thanks

 

How much margin did your target height of 1.790 leave you to coil bind? You can run within .050" of coil bind. Are you anywhere close to bottoming the retainer on the valve seal?
And what is your seat pressure at 1.790?

 

That's less than the thickness of a business card. Acoupla sheets of paper.

"Measure with micrometer, mark with chalk, cut with axe".

There's a reason shims only come in increments down to .015"... and that is, once you get within that tight of a tolerance, you're as close as you need to get. As long as you aren't into coil bind, you're fine.

As to which side you'd rather put the error on, consider (a) the positives of erring in that direction - increased seat pressure, increased clearance, etc.; vs (b) the negative consequences of a given error - coil bind, valve float, parts interference, etc.

If you're building a motor to where .005" or .010" actually matters to the outcome of the project, you don't need to be building the motor tonight. The race just finished a few minutes ago, so you have the rest of the week to work that out.

 

Are these stock Vortecs?

 

Sorry guys, I responded last night but must have forgot to hit "reply" after typing.

I ended up going with the Vortec Alex spring kit that was a little more cost effective. I believe that kit allows me up to .550 lift. Max lift on my cam is .530. I'm running 1.52 rockers. That gives me wiggle room on maximum allowed. Coil bind is listed @1.145.

If I can go up to .550 lift and I'm .020 under on that measure alone and running stock ratio rockers based on that figure I should be good.

Just wanted to make sure I wasn't doing a big "no no" by opting to go a smidge on the tight side ( -0.005) of the target spring height.

 

Good decision. When you have that much room to play with, it's best to err on the tight side.
There's nothing magic about that recommended installed height; it's just a reference point.

 

What I'll be interested in seeing is your approach in determining the proper push rod length. Some here will be familiar with the epic failure I experienced when I neglected to double check pushrod length after I swapped engine components around. I'd hate to see your valve guides wiped out after a few thousand miles.
I had planned a pictorial essay of my approach and invite comment from the "pros" however it looks like you may beat me to it.

 

As soon as I get my heads bolted on I was just going to pop on my "pushrod length checker" I bought off ebay. I assume stock length pushrods will work but I got the checker anyways to be safe. I'll stick it on a stock pushrod and see what it tells me.

 

What checker did you get? Far and away the best I've used is the Comp Hi-Tech tool.
http://www.summitracing.com/dom/part...02-1/overview/.
No measuring involved. Just extend or retract to an appropriate length and run a pattern.
That's how I produced the patterns in the above pictures. The picture of the ruined valve guide is the result if you don't have precise measurements. Very often there's a difference between the intake and the exhaust depending on the cam profile. Different cylinders may yield different results too (no I'm not suggesting that each valve gets it's own unique pushrod!). It pays to check thoroughly or you may pay the price down the road.
Pushrods are available in .050" increments so there's one that's just right for you.
I'll be interested to see how you make out and what the replies are.