What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Best way to change valve springs ...?

shady

shady

1 ton status
 Premium
Joined
Jul 31, 2010
Posts
21,201
Reaction score
28,110
Location
iowa
I recently took my truck to the local race shop to have the carb, and timing adjusted. While there I wanted them to check the rockers because it rattles under certain loads.

Turns out that whoever built my engine used some heafty valve springs. Like 175# seat pressure ones. Which aren't working so well with my hydraulic lifters.

The owner talked to me and asked if I could handle changing them because he's got a lot on the plate at the moment. I can do it, but want to know what the best route would be.

I've seen where people have hooked up the air compressor to a cylinder and used that to hold the valves in while they changed springs or seals.

Has anyone done this? If so, is there a tool made? Or do I have to build something?

I'd rather not pull the heads if I can get away with it.
 
Air pressure in cyl. 35 40ish psi. Remove rockers, with deep socket and dead blow give retainer light rap.
Purchase a valve rocker stud spring tool, may need to remove carb on some. Or the screw type spring tool.
Replace the springs. Check your installed hight you might need shims.
 
I just seen that leakdown testers had an air fitting... Never seen that before.

I couldn't think of how I was to get the compressor hooked up to the cylinder lol.
 
Some better quality compression gauges have quick connects. Extra regulator or the main compressor regulator.
You can use a higher psi but motor will turn. So remove rockers to that cyl b4 applying air
 
I did it this past summer, needed to replace the valve stem seals.
I replaced the locking clips while I was there
Like mentioned before air compression tool have the adapter just remember to remove the Schrader valve to allow air to pass through.
I good deep socket to release the tension on them an soft whack.
Keep a magnet handy to catch the retainers.
Took me about 3-4hrs to do all 8 cylinders

download.jpeg
 
I almost ordered the wrong springs. The ones I wanted ended up needing machine work to fit a different type of seal... Only jegs mentioned that. No other place I found them said anything about it.
 
I've always just used the loaner spring compressor from Autozone.
 
I've had a valve drop down into the cylinder once doing a valve spring on a 454,luckily the piston at TDC kept it from going down far enough to "fall in" or go beyond the valve guide..
I was using compressed air to hold the valves closed,and a tool like a gear puller looking valve spring compressor..
After I had the valve drop like that,I assumed the valve or cylinder had enough leakage to let the pressure bleed off ,and the valve to drop..
I then decided to use another backyard mechanic hack that has not failed me yet--I took out the air fitting from the spark plug hole and shoved in about 2 feet of nylon rope about 1/4" in diameter and turned the engine over by hand until the piston contacted the rope..no chance of losing a valve then..
 
I seen that method when I looked on YouTube. Seems like it would work, just take more time.
 
shady said:
I seen that method when I looked on YouTube. Seems like it would work, just take more time.
Click to expand...
Yeah, I know that trick too but as you said too much time. But when you don't have options it's a fail proof option
 
Beats having the engine decide to turn over from the air pressure unexpectedly and watch the valve disappear !..if its not perfectly at TDC or your compressor lets the pressure drop,then kicks back on,it can happen easily..also if carbon deposits on the valve prevent 100% sealing..
 
Definitely not going to pull the heads for springs and seals as a line repair or field repair as i call it unless I have to.
Is possible to drop a valve, and if so it is what it is.
 
Some mechanics put a rubber band around the valve stem as added insurance to prevent it from dropping down too far,should the air pressure fail to keep both valves closed..
A magnet might help hold one or pull one back up too,if the valve isn't stainless steel..
 
I'll add that rotating the crank to get the piston at TDC helps for a couple of reasons. Less volume of space to fill with air. If you do manage to let the valve drop it's not going to drop far enough that you can't just grab the valve stem and pull it back up again.

It's not a tough job to do, just time-consuming. Larry and I did this to the 350 he's prepping for his Blazer project. We got into a pretty good rhythm and knocked it out in a couple of hours.
 
I gotta pull one apart, do some checking and measurements before I can order my springs.. then once I have them I guess I'll just dive in.

May have to use this as a reason to buy a few more tools :thinking:

:D
 
ZooMad75 said:
I'll add that rotating the crank to get the piston at TDC helps for a couple of reasons. Less volume of space to fill with air. If you do manage to let the valve drop it's not going to drop far enough that you can't just grab the valve stem and pull it back up again.
Click to expand...
Are you saying that at exactly TDC the engine won't rotate from the air pressure? It hasn't worked that way for me, so maybe you know another trick. Also, what difference does the volume of air make? Typically you'll have dozens of gallons in the tank. With a good head, the air compressor hardly needs to cycle on.

If you hear tons of hissing when you pressurize that cylinder, that valve isn't fully seated. They seat better with some pressure behind them, so can can whack the top of the valve with a hammer a few times (POP!) until the hissing drops back. Don't pull the retainers until it's a normal amount of leakage.
 
Blue85 said:
Are you saying that at exactly TDC the engine won't rotate from the air pressure? It hasn't worked that way for me, so maybe you know another trick. Also, what difference does the volume of air make? Typically you'll have dozens of gallons in the tank. With a good head, the air compressor hardly needs to cycle on.

If you hear tons of hissing when you pressurize that cylinder, that valve isn't fully seated. They seat better with some pressure behind them, so can can whack the top of the valve with a hammer a few times (POP!) until the hissing drops back. Don't pull the retainers until it's a normal amount of leakage.
Click to expand...
I guess it could rotate with the pressure, but if all the rockers are off, none of the rest of the valves are open either. No place for any of the air to go in the rest of the cylinders so the engine isn't as free to spin over. That's with the spark plugs left in and pulling one at a time to go after the one you are changing springs on.
 
It will rotate with excessive pressure. If rockers are still on motor will rotate till a valve opens. The rope trick is great. Just have to be aware, when you pop the retainer to loosen keepers, not to hit it to hard or you will bend a valve.
 
You must log in or register to reply here.

Latest Posts

Top Bottom