swapping valve springs while the engines in the car

[grumpyvette]

BTW if you go to change the valve springs with the heads still on the engine, most guys use the hose they use to do a compression check and the spark plug adapter and pump the cylinder up with about 125 psi of air to hold the valves shut while they do it, yeah it usually works just fine.

(yeah theres a differant method)
(1)disconnect the battery
(2) remove the spark plugs, and rocker arms
(3)turn the first cylinder to BDC BYE HAND or someplace close to that
(4) insert one end of 5 ft of 3/8" rope into the cylinder thru the sparkplug hole and be sure you tie a KNOT in the other end
(5) rotate BYE HAND,the engine until the rope compresses against the valves holding them in place
(6)REPLACE THE SPRINGS on that cylinder while the valves are held to the combustion chamber roof
(7)rotate the cylinder back to BDC
(8)pull out the rope
(repeat 7 more times)sup: :laughing:
yeah! the air USUALLY works but I don,t trust it EITHER, I want those valves locked from falling into the cylinder PHYSICALLY sup:
BTW youll want one of these or something similar

http://store.summitracing.com/partdetail.asp?part=SUM-906784&autoview=sku
IVE done it both ways many times, Ive never trusted the air alone but Ive used it without problems in the past, the ropes usually not a problem,, and yeah theres the potential for it to tangle but I have not had that happen either

 

[oldskool79]

Great post...and quite timely for me.

 

[Bob Chadwick]

Is it even necessary to rotate the engine? Once you remove the rocker arms the valves will be seated by the springs.

 

[USA-1]

I've done several spring changes with the head still on the motor and never used a rope. some were at the track with a hot motor.

when you sock the air to the cylinder the piston is going to go down. when the rockers are removed the valves will seat. with hydraulic lifters you will have to count revolutions when removing the rocker nut so you can get the lash close when reinstalling. providing you don't loose your air source the valves will stay up. a hose is available with a check valve that will hold pressure.

there's a very simple tool available that has no moving parts and is much cheaper than those illustrated, made by KD tools.

this can be a little intimidating the first time. hint: don't drop the keepers!! :L

 

[SpryGeezer]

Many years ago I changed a few intake valve springs on a '69 427/390 with engine-in by propping the valve up thru the spark plug hole using a whittled drumstick. Had I known I would have used the knotted rope trick described above, much less chance of an OOOOPS! or damage to the piston.