Good write up on valve spring shimming?
10-17-2011, 02:43 PM
#1
Good write up on valve spring shimming? I searched here and with google and didn't find quite what I was looking for.
I have some 799 heads going on with a new EPS 230/238 .600/.615 cam and some Patriot duals, stock rockers.
Anyone have any good instructions on how to measure and setup using snap gauges/calipers/ other standard tools. I do not have a valve height micrometer and was told it is not necessary as there are other ways to measure and set them up.
I can get shims locally, but the guy always sets things up based on spring pressure alone, doesn't check height or shim to within certain specs of coil bind like I was told needed to be done.
I have some 799 heads going on with a new EPS 230/238 .600/.615 cam and some Patriot duals, stock rockers.
Anyone have any good instructions on how to measure and setup using snap gauges/calipers/ other standard tools. I do not have a valve height micrometer and was told it is not necessary as there are other ways to measure and set them up.
I can get shims locally, but the guy always sets things up based on spring pressure alone, doesn't check height or shim to within certain specs of coil bind like I was told needed to be done.
10-17-2011, 11:21 PM
#4
if you don't have a valve spring micrometer you can use an inside caliper to check spring installed height (takes a little getting used to but it will work) you still need a dial caliper to measure the inside spring caliper though.
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as far as coil bind, open pressure, seat pressure (LBS at installed height) you really need a nice heavy duty spring checker machine ($1,000+) most engine builders/machine shops will have one and alot will check all your springs specs for free or a slight nominal fee. As far as how much seat pressure you need depends on your cam. keep in mind the more you shim your springs the closer you get to coil bind i think you need a min. of .060" clearance before coil bind (i think its .060" not positive though).
i know that doesn't really answer all your questions but i hope it helps.
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as far as coil bind, open pressure, seat pressure (LBS at installed height) you really need a nice heavy duty spring checker machine ($1,000+) most engine builders/machine shops will have one and alot will check all your springs specs for free or a slight nominal fee. As far as how much seat pressure you need depends on your cam. keep in mind the more you shim your springs the closer you get to coil bind i think you need a min. of .060" clearance before coil bind (i think its .060" not positive though).
i know that doesn't really answer all your questions but i hope it helps.
10-17-2011, 11:31 PM
#5
Well the problem is last time I did a cam I did PAC 1218 springs on a comp 230/224 with .57x/.56x lift and the car has been floating the valves at 6000rpm. Should have been fine but they weren't 
Don't want to repeat that.
I do have the tools you mentioned though I'll see what I can get
Don't want to repeat that.
I do have the tools you mentioned though I'll see what I can get
10-18-2011, 08:29 AM
#7
Need to measure and shim today so heads can go on tomorrow. Any more opinions and advice needed.
I won't be running the car hard for a few weeks when I can get injectors and do some tuning anyway, but changing springs on the car to shim would be a huge pain in the ***. I'd rather set it up right while they're off.
I won't be running the car hard for a few weeks when I can get injectors and do some tuning anyway, but changing springs on the car to shim would be a huge pain in the ***. I'd rather set it up right while they're off.
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10-18-2011, 09:41 AM
#10
If you are going to be a real hot rodder get the correct tool to do the job. You can purchase a valve spring height micrometer for $39.95 from Summit Racing. You need one in your tool box if you are going to do the install/mods yourself. Other wise find a shop that will do it for you. Beleive me they will use a valve spring height micrometer to do it. Trying to use the wrong tools to do the job is going about it in a halfass manner. It is way too
EZ to do when you have the right tool. If I were you I would just go a head and break down and spend the 40 bucks and be done with it and do the work yourself.
EZ to do when you have the right tool. If I were you I would just go a head and break down and spend the 40 bucks and be done with it and do the work yourself.
10-18-2011, 09:52 AM
#11
Well that won't help me much today, Summit takes 4 days to deliver here and this car has to be on the road ready to go 250miles by the weekend. None of the machine shops here use them, already asked.
A very well respected engine builder told me not to bother ordering one for 1 install since install height could be checked with calipers, with snap gauges, or other tools. He said it was a convenience tool.
Disregard the fact I don't have the tool...assume I used it to measure install height. Knowing the install height, what is the correct process for shimming?
A very well respected engine builder told me not to bother ordering one for 1 install since install height could be checked with calipers, with snap gauges, or other tools. He said it was a convenience tool.
Disregard the fact I don't have the tool...assume I used it to measure install height. Knowing the install height, what is the correct process for shimming?
10-18-2011, 10:15 AM
#12
You don't want to shim unless you know the actual installed height and actual coil bind distance. If you have valve seals on the heads already, you will need a new set because the shims go under them and you will destroy them taking them off. Chances are you will be just fine without shimming since you likely have almost 100lbs more open pressure than the beehives as they sit now.
, i like the creativity
10-18-2011, 12:34 PM
#15
I have been hot rodding now for over 50 years and have watched many big time engine builders use this tool while setting up heads. The reason that it is called a convience tool because it does such a great job doing it right. It does what it was designed to do very well and makes it very ez to do the job. Like I said using the correct tool always makes whatever the job that you are trying to do so much easier. I have used mine many times and loaned it out many times. You cannot wear one out. It will last you a life time. There always ways to "rig" up something but if you are a serious hot rodder your tool box wil have one it.
10-18-2011, 04:41 PM
#16
It's just a matter of adding or subtracting shims to obtain the correct installed spring height. For instance, if you measured 1.815", then you'd need a 0.015" seat shim to make the new installed height 1.800".
10-18-2011, 04:56 PM
#17
So what I'm coming up under...just playing around before lapping valves I did a couple and both were in the 1.7s. Going to get a better measurement after the valves are good to go to make sure I didn't make a mistake.
I measured my old head and they were 1.8 (stock 853s with stock retainers and seals/seats). Which makes me wonder why I was floating valves at 6000rpm with PAC 1218s on a .57x/.56x cam...
Thanks guys, stress is getting to me so I apologize if I come off as a stubborn ***. But right now I have to work with what's here and try to get it together.
I measured my old head and they were 1.8 (stock 853s with stock retainers and seals/seats). Which makes me wonder why I was floating valves at 6000rpm with PAC 1218s on a .57x/.56x cam...
Thanks guys, stress is getting to me so I apologize if I come off as a stubborn ***. But right now I have to work with what's here and try to get it together.
