So after measuring all the valve springs, this is what I am looking at. All of my intake springs are within .010, except one on #4 which is .030 off.

Exhaust side, looks like 6 of the springs are .030 off.

Well, now I guess I have to wait for the high rev springs to get here tomorrow. Is it safe for me to assume the new springs will come in about the same measurements being .030 off on the exhaust side? Or can the new springs make things better or worse?

 

My dyno sheet showed a sudden drop in power and tq at about 7900rpms.

AS for feeling it, anytime I revved the car out to its redline, the car would fall on its face, and then continue to run with a bad hesitation feel for a few seconds, then just magically go away. All would be good, until I would try and rev it out again.

 

Ok will keep in mind

 

My numbers might be a little skewed too. The caliper that I am using, I am using the metric side, then transferring millimeters to inches by dividing by 25.4. 1mm difference in the measurements is around .030 inches. So a mm really throws the number off.

I know now where an actual spring height tool would be great, but I dont have the resources to get one or make one.

Im happy that I didnt have any numbers just way off, out of a shim range lol.

 

You should be able to see a shim, but most "Local" shops do not stock the import small ones.

Now from what I have seen, and measured. On the 1g and 2g DSM heads, what the FSM says, and what I have found are 2 totally different spring installed specs.

It looks like that GSC has used real world numbers, and not the engineering specs from the FSM.




Yes, shims need to be used to correct for the tolerances used in factory machining. Factory machining is normally sloppy, as long as it falls into range it is good. Keep in mind that the factory is slamming hundreds of heads together in a day.

It is not all hand checked and assembled like you get from a decent machine shop.

Good choice on springs for the Kelford 272 cams.


Any time you move from a stock set up, check the valve spring installed height. Setting up a head to run right, you do not guess, you know.

Assume is not the way to go. Some shops just do not fully understand how to set up a head fully.

They have the thought process of "It ran before, It will run again" This thought process leaves a lot on the table and costs you HP and money.

This thread will make that point clear.
https://www.evolutionm.net/forums/ev...tion-10-a.html

A spring tester is what is used.
https://www.evolutionm.net/forums/ev...e-springs.html

Yes that is a very good write up, even tho it is based more towards the domestics.
The only part that really does not apply is the section on rocker arm to retainer clearance.

What you have to be aware of instead is follower to valve lock/retainer clearance. But that has to do with the valve tip above the retainer, and how much the valve tip has been ground down.


Yes, if the springs you have in now are that far off, the new ones will be too.

What are the actual measurements you took?

Now what I want to know is why, those valves are so much more than the others. .030 is a good amount.
Were the seats cut that much deeper?
Did they correct the valve tip height?
Were the valves unshrouded on those seats?


1mm=.03937 (.040)

So 1mm is closer to .040 than .030


I multiply instead of divide when I have to convert from metric to SAE

I have had to add as much as .120 worth of shims on some applications to get the springs to be correct.


The Tomi shims you spoke of earlier wold work out to be

.2mm x .03937 = .007874
.3mm x .03937 = .011811
.5mm x .03937 = .019685

The shims I use are

.015 x 25.4 = 0.381mm
.030 x 25.4 = 0.762mm
.060 x 25.4 = 1.524mm



From what I am picking up from reading this thread, is your willing to do the wrench time and go to the expense of getting it right.

I would suggest you find a shop that understands your head and has a solid understanding of how to set up springs and have them do it. The right shop will have the right tools and equipment and parts in stock.

I can understand the DIY attitude, and wanting to learn. Nothing at all wrong with that.
I also understand it it would be more wrench time to R&R the head, and more expense in gaskets and shop labor.

But trying to do this balancing act with makeshift tooling may cost you more in the long run.

If the head is in good shape, a spring install, with a handful of shims, and maybe some new (vition blue) seals, should be around $100 and take an hour or so.

 

Thank you bogusevo for taking the time to address what are probably dumb questions. I will def make sure to check specs when I'm doing the head. And I would love to be able to take the car to a professional shop but unfortunately I don't trust a single shop up here there's maybe 6 or 7 evos in all of alaska and the shops would rather race um than work on um. And one more dumb question where can I order these shims from?

 

I am gonna pick up a digital caliper today. I am gonna try a different way of measuring the springs. I am gonna measure the thickness of the stock seats, then the thickness of the new titanium retainters. Then I can actually use the digital caliper and just measure from the very bottom where the seat contacts the head, to the top of the retainer. Then just subtract the retainer and seat thickness. I read on another forum this is how a lot of guys do it in the garage that dont have the exact tools the machine shop does.

I will take some meaurements tonight when I get the new springs in.

I am the same way, the local machine shop around here, I hate to take my stuff to them. ive heard they do good work with the domestics, but i feel like sometimes they just throw stuff together and get paid.

 

I can understand how you both are sketchy on shops. I have just wored through a pile of heads that were horrid done.

"just get paid " builds, the head inspection 10 is one

Another was ported so poorly, you could feel every snail trail, and burr mark.

here is a true horror story, guy had the head built, and bought new Ferrea +1mm valves, we all know thats about $400 on the valves.
Apparently the the shop did not have the equipment, or did not want to cut the seats for +1mm valves. so they ground down the valve heads back to std dia !

 

Thats what I am talking about lol. Some of the shops I feel just have old school techniques still. Which work great for some applications but on newer stuff, might not cut it.

Ill tell ya, I feel better about the way that I measured tonight. With measuring the thickness of the spring seats and retainers, and then using a digital caliper and measuring from the bottom to the top of the spring retainer, then subtracting the seat and retainer.

My springs fell in the 1.55-1.56 range. Gsc recommends a 1.55 on their website. Travis from GSC told me to do 1.56 on the intake and 1.54 on the exhaust, so it sounds like .010 either way is tolerable. So I felt comfortable enough to put the cams back in.

Im gonna finish it up this morning and fire it up.