Broke a BB Valve Spring Today

[Verne Frantz]

Re: Broke a BB Valve Spring Today

I agree Joe,
I usually try to set it up that way, but sometimes I've done the job with no plugs in the heads, and the air pressure pushes the piston all the way down anyway.
I've never actually "lost" a valve that way, but came close once. Luckily, the rubber seal on the stem stopped the valve on top of the guide. That one would have become particularily ugly, since I was making the repair on the side of the road 5 hours from home. !

Verne

[Joe L.]

Re: Broke a BB Valve Spring Today

Verne-----

Always put the car in first gear with the parking brake on and wheels chocked when pressurizing the cylinders. If the piston goes down (and, consequently, moves the car) under these conditions, then you're using WAY TOO MUCH air pressure. But, at least you've got one hell of a compressor to brag about!

[Verne Frantz]

Re: Broke a BB Valve Spring Today

Well sir, there were a combination of circumstances going on that left me unable to do the right thing at the time. The air came from a portable tank filled as high as it could go (courtesy of the AAA boys). I had to work fast while one fellow was letting me know how fast the pressure was dropping on the tank.
Also, I have metallic brakes on the car. They were cool at the time, so there was no such thing as an emergency brake that would withstand the 175psi in the cylinder. So, I just left it in neutral and let it spin.
Of course, the guys had to go back to the station and refill the tank after the valve dropped. One of those "interesting" roadside experiences.......
Hey, at least I had a new valve spring with me for the trip....... AND I was able to drive it home, rather than having it delivered.

Verne.

[Joe L.]

Re: Broke a BB Valve Spring Today

Verne-----

I was offering the advice primarily for the benefit of others. What occurred in your circumstances so long ago is history, now----we can't change that, one way or the other. Mainly, I was referring to doing the operation in one's driveway or garage. "Field repairs" at roadside are another matter; one has to improvise as conditions require.

Generally speaking, just having the car "in gear" will be enough to prevent the piston from being driven down assuming that one doesn't use very high air pressure. 30 PSI, or so, is all that's really necessary. With the wheels securing chocked, there's no danger of the car moving or the piston being driven down. Even with 90 PSI shop air pressure, I don't think that they'd be any problem. That's what I've used in the past, anyway.

[Peter M.]

Re: Broke a BB Valve Spring Today

Joe - Your advice hit the mark with me as I will be performing this procedure for the first time - I need the benefit of others who have done this so I do not learn from the school of hard knocks - in this case - putting the virgin nose of my all original BB Coupe through the back of the garage!

[William V.]

Re: Broke a BB Valve Spring Today

Has anyone out there used the rope method? This is where rope is inserted into the cylinder through the spark plug hole when at BDC. The engine is then hand cranked to where the piston squeezes the rope against the valves to keep then closed. I never tried this but a guy I know claimed he would fix valve springs on his BB Chevy while he was on the side of the road.

I DO NOT RECOMMENT THIS METHOD. Use the air compressor.

[Clem Z.]

the rope trick works and

you will always have the piston at TDC so dropping the valve into the cylinder can not happen. before you try to pop the retainer to remove the keys use a deep 9/16" socket centered over the retainer and give it a sharp rap with a brass hammer to "break loose" the retainer from the keys. having a pair of tweezers comes in handy to lift the keys from the retainer. i have 3 different shaped lever bars to compress the springs because of different things that get in the way,like the power brake cylinder, when you try to use the lever bar

[Tracy C.]

Good to see you back Jerry! *NM*

[Rich G.]

Re: Broke a BB Valve Spring Today

We always use the "rope trick" on airplane engines. The plug holes are a little bigger and are easier to get to, plus you can feel it contact as you pull the propeller. As I was reading the thread, I wondered if it would work on these motors.

Rich Giannotti

[Bob Simard]

Rope Trick

The rope trick worked very well on my '70 350. To turn the engine, just put it in fourth gear and push on the top of the front tire. Engine turns easily and precisely. One complete revolution takes about 2 feet with 3.70 rear gears.