Best/ worst experiences with valve spring swap?

[Grand_87_national]

Hello, all. Since there is a good chance my heads are still equipped with stock valve springs (factory cups are still in place), I think I'll swap them out for a set of Comp 981's. Perhaps p.o. left them on for the break-in process with the new Comp 212/212 flat tappet cam? I dunno. My question is: Knowing a lot of you have swapped springs with the heads on, what have you had the best or worst luck with? If I am understanding this correctly, using air pressure could potentially rotate the engine, moving the piston from the top of it's stroke to the bottom? Also, if the valve is bumped open and air is allowed to pass by, the pressure in the combustion chamber will drop, as will the valve, providing the spring/ lock/ retainer have all been removed, correct? It is because of these couple issues that I'm leaning toward the rope method... plus, this being my first time, I feel like I may be less rushed this way? A few questions, though, if I may.... Some folks have said they stuff a few feet of rope in, then rotate the engine to smash the rope (by hand, obviously), while others say it is not necessary, and they just keep stuffing rope in until the chamber is full. Upsides/ downsides to either method? I'm looking to be as fool-proof as possible here, I definitely don't want to drop a valve. I plan on using a magnet for the locks. Also, any reason to replace the locks/ retainers? Any need to shim, or just drop them on and go? Intake valve guide seals? My car has zero smoke at startup. Thanks for any advice!

 

[Charlie Gaudet]

Hello, all. Since there is a good chance my heads are still equipped with stock valve springs (factory cups are still in place), I think I'll swap them out for a set of Comp 981's. Perhaps p.o. left them on for the break-in process with the new Comp 212/212 flat tappet cam? I dunno. My question is: Knowing a lot of you have swapped springs with the heads on, what have you had the best or worst luck with? If I am understanding this correctly, using air pressure could potentially rotate the engine, moving the piston from the top of it's stroke to the bottom? Also, if the valve is bumped open and air is allowed to pass by, the pressure in the combustion chamber will drop, as will the valve, providing the spring/ lock/ retainer have all been removed, correct? It is because of these couple issues that I'm leaning toward the rope method... plus, this being my first time, I feel like I may be less rushed this way? A few questions, though, if I may.... Some folks have said they stuff a few feet of rope in, then rotate the engine to smash the rope (by hand, obviously), while others say it is not necessary, and they just keep stuffing rope in until the chamber is full. Upsides/ downsides to either method? I'm looking to be as fool-proof as possible here, I definitely don't want to drop a valve. I plan on using a magnet for the locks. Also, any reason to replace the locks/ retainers? Any need to shim, or just drop them on and go? Intake valve guide seals? My car has zero smoke at startup. Thanks for any advice!

Use the compressed air method. I did both side in my car in an hour. Used the valve spring compressor tool from kirbans or cottons. Apparently you need to shim to get the correct installed height. To do this you'll need a spring tester to measure the pressures. Also a valve spring height micrometer to measure the installed height and shin accordingly. Easy job. Get a nice magnet to catch the valve spring retainers. Hitting the springs with a dead blow lightly also helps them when you compress the springs with the compressor tool.


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[Grand_87_national]

Use the compressed air method. I did both side in my car in an hour. Used the valve spring compressor tool from kirbans or cottons. Apparently you need to shim to get the correct installed height. To do this you'll need a spring tester to measure the pressures. Also a valve spring height micrometer to measure the installed height and shin accordingly. Easy job. Get a nice magnet to catch the valve spring retainers. Hitting the springs with a dead blow lightly also helps them when you compress the springs with the compressor tool.


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Thanks for the reply! I was wondering about the shims because I always figured the purpose of hydraulic lifters is that they self adjust, however I guess that is just my thinking of how lash would affect (or not affect) seat pressure. When you tap the retainers loose, does that not bump the valve open at the same time?

 

[No disintegrations]

The lifters don't adjust the springs. The spring needs a certain installed height to have the correct seat pressure.

 

[Grand_87_national]

The lifters don't adjust the springs. The spring needs a certain installed height to have the correct seat pressure.

Gotcha... I knew they didn't adjust the springs, just figured the pressure on the rockers pushing against the springs would wash-out any height discrepancies. Do the spring kits come with shims?

 

[Charlie Gaudet]

Thanks for the reply! I was wondering about the shims because I always figured the purpose of hydraulic lifters is that they self adjust, however I guess that is just my thinking of how lash would affect (or not affect) seat pressure. When you tap the retainers loose, does that not bump the valve open at the same time?

Disconnect the battery. With air in the cylinder it'll keep the valve in. Put 100 psi in it. I put 50 in it and no problem. As long as your rings are good it won't leak.


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[Grand_87_national]

Disconnect the battery. With air in the cylinder it'll keep the valve in. Put 100 psi in it. I put 50 in it and no problem. As long as your rings are good it won't leak.


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Will do, any need to rotate to tdc, or will the pressure just push the pistons back down anyway?

 

[turbo nasty]

Will do, any need to rotate to tdc, or will the pressure just push the pistons back down anyway?

Many times the psi will move the piston to BDC. And you will hear some air leaking into the crankcase dont be alarmed. Verify all install heights and shim the rest to the shallowest. You can pull all the springs and put tie wraps around the valve stems to keep them from falling in the cylinders.

 

[Charlie Gaudet]

Will do, any need to rotate to tdc, or will the pressure just push the pistons back down anyway?

When you put air to the cylinder it will crank the motor automatically to its position. But if not you will hear air pissing a little. Don't worry. It's normal. Make sure your hoses don't leak, then the compressor will be cycling all the time. You'll be fine


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[Grand_87_national]

Many times the psi will move the piston to BDC. And you will hear some air leaking into the crankcase dont be alarmed. Verify all install heights and shim the rest to the shallowest. You can pull all the springs and put tie wraps around the valve stems to keep them from falling in the cylinders.

Verify install heights with what tool? Also, where do the shims come from?

 

[Charlie Gaudet]

Verify install heights with what tool? Also, where do the shims come from?

Valve spring micrometer. Order from summit or Amazon. Order the shims according to springs I believe.


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[SCOOBY DOO]

We've done a gazillion sets. Compressed air. One person compress the spring from one side of the car...and the other person on the other side to re and re the springs. Removing the coil pack/ignition module makes life easier. Drop the bottom retainer in first...then the top. 981's are fine. I use 130 lb valve springs with my CC's 212/212...but I've been at this for awhile.

 

[Jerryl]

Seat/open pressure is an important performance aspect of spring installation. You simply have to take the writing on the box for granted, or you *may* end up doing it again, or worst . . . . .

To correctly install springs, you will need to know exactly how much the spring needs to be compressed to get the pressures you are shooting for on both sides of the operating conditions. I am sure there are Youtube videos explaining this, but still need springs that is tested. Of course, you can always perform testing after it's installed on the car, which will require add/remove shims each time . . . . . if you have the correct measuring equipment. Sounds like a PITA to me.

If I was doing this in the car, I would purchase a measured spring set from Bison. That will ensure you are making informed decisions on shims that will be needed based on installed height. (Not going to mention "engine oil for FT cam" and turn this thread into a 15 page what oil to use B*** session. )

 

[Grand_87_national]

The stock cups just press in? Just a little wiggle to remove, then throw them in the lake? New springs use internal dampers, it looks like.

 

[dank GN]

Here Is a couple pics of a iorn head setup I was doing

 

[Grand_87_national]

Seat/open pressure is an important performance aspect of spring installation. You simply have to take the writing on the box for granted, or you *may* end up doing it again, or worst . . . . .

To correctly install springs, you will need to know exactly how much the spring needs to be compressed to get the pressures you are shooting for on both sides of the operating conditions. I am sure there are Youtube videos explaining this, but still need springs that is tested. Of course, you can always perform testing after it's installed on the car, which will require add/remove shims each time . . . . . if you have the correct measuring equipment. Sounds like a PITA to me.

If I was doing this in the car, I would purchase a measured spring set from Bison. That will ensure you are making informed decisions on shims that will be needed based on installed height. (Not going to mention "engine oil for FT cam" and turn this thread into a 15 page what oil to use B*** session. )

I will contact bison... I was planning on hitting him up about springs, anyhow. Thanks!

 

[turbo nasty]

Verify install heights with what tool? Also, where do the shims come from?

Get a spring micrometer and shims....Get them from Jegs, etc.

 

[Grand_87_national]

Get a spring micrometer and shims....Get them from Jegs, etc.

Thank you!

 

[1986 Buick GX1]

Worst part was getting the passenger side valve cover off.
I wish I had found this info beforehand, offered by Bison, who else. Lol

 

[Grand_87_national]

Worst part was getting the passenger side valve cover off.
I wish I had found this info beforehand, offered by Bison, who else. Lol

View attachment 307989

Oh, I hope you're right! If that's the worst part, I'm golden. Taking the valve cover off wasn't terrible once I removed the small bolt that holds the lower side of the wire harness clip/ bracket and rotated it out of the way. Just swapped them last weekend for the TA Performance, low profile pieces. I may not have had to even mess with the harness or bracket had I known this! Lol, freaking Bison.... that dude makes me feel like a complete fool every time he types something.