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Post Info TOPIC: Replacing Valve seals with Heads on
BLyke


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Replacing Valve seals with Heads on
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Getting ready to install the new set of Umbrella seals that came with the 52 Pontiac parts

The man who built the 350 was in decline and suspect that they were omitted accidently

Here are the questions for those of you that have performed this task using air pressure to hold the valves in place with the springs off

  • What PSI of compressed air did you used (have seen anywhere from 20-40 to 120+ online)?
  • What position do you have the piston at (up or down)?
  • Did the air cause the engine to rotate??

 

Thanks in advance for those who have been down this path before and are willing to share their successful tales or cautionary warningsthumbsup



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Bruce L. - Lakeville MN

1971 Malibu Convert

 
Lost in the 60s


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Your springs require a lot of leverage to compress enough to get the lock keys out. I always use 120 lbs pressure to hold them shut.
I always have the pistons at TDC, in case you drop a valve. It can usually be saved with it on the piston. If at the bottom of the cylinder ???
You should have a method of holding the crankshaft from turning while doing this. I use a 24" 1/2" drive breaker bar with socket on the balancer bolt. It doesn't take a lot to hold if the piston is truly at TDC. Having a degree wheel on the crank will help with this. I happen to have one. Use the wheel and a wooden dowel to determine TDC before inserting the air hose adapter in the plug hole.
You sure you don't want to hold off and make this a tech session, but probably in March ? I think this would be very interesting to members....stirpot

P.S. I, also, have the lever to install on the rocker stud to compress the springs too.



-- Edited by Lost in the 60s on Tuesday 27th of December 2022 12:06:47 PM

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Mitch D.   River Falls, WI

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Some Assembly Required

1966 Chevelle SS 396 M20

1970 Chevelle SS 396 M20

1967 Camaro SS 350 rs
John D


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All of the above, or...

(this may need a helper)
I've done it (when I didn't have air available) by threading about 2 feet of oil-soaked cotton clothesline through the spark plug hole.
Use a breaker bar on the balancer, and bring the piston around to where it's coming up on TDC, stop about 1/2-way there. Thread in the rope LEAVING A GOOD TAIL HANGING OUT (!).
Carefully bring the piston up toward TDC. When the resistance gets tight stop.
Have the helper hold a bit of force on the breaker bar, and use your lever-action compressor to free the keepers. Install your seals.
Reinstall the springs/retainers/keepers, and gently reverse direction on the breaker bar.
Carefully pull the rope out of the cylinder.
Rinse & Repeat.

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John D. - St. Louis Park, MN.

1965 El Camino - LT-1, 4L60e, 4wh discs, SC&C susp.
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Bobs_Place


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I have always just plugged in the the air to the cyl, let the piston go to BDC, with a 1.5" exhaust valve and 120PSI, you would need about 200lbs of force to unseat the valve, I have not lost any valves.

If you do go the TDC route you can do 2 cylinders at a time, so if you start with #1 than #6 will also be at TDC, than crank to #8TDC and 5 will be ready when done with #8, than #4 and #7 and last #3 and #2. This will save you having to do 1 complete turn and a line the crank on TDC for the second 4 cylinders. Your simply doing the second half of the firing order along with the first half.

Before you try to compress the valve spring, tap on the spring retainer, use a piece pipe, pvc tubing or a socket as the valve/keepers get wedged into the retainer, as you tap you'll hear a pop of air until the keepers free up.

I would also find a piece of rubber hose that fits just tight enough on the valve stem to retain the valve if needed, keep it handy, put on the stem for when you drop a keeper or some other emergency or excitement happens.



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Bob W.

Lino Lakes
BLyke


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Thanks for the feedback, Guys.
I have been putting this off for a while and think it is needed.
Great to hear from those who have done this before.

Mitch,
let me consider the March tech session option, maybe i will work on some other items first.


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Bruce L. - Lakeville MN

1971 Malibu Convert

 
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