Check to see if the valve lift is causing the spring retainers to hit the stem seals. On a high lift cam, it's usually necessary to shorten the top of the guides a little to avoid retainer to seal contact. You'll need about 1/16" (.060) clearance at max valve lift. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thanks Jerry. Truck was running 7 years ago with no issues. I replaced the valve covers before firing it up with the sniper, there were no "vortec worms" found. The cam is an Isky 270 mega cam. 0.465 int/ex lif so not a real high lift. Have used this cam before with no issues. Cutting the seals at the top would not work as there is a small wrap around spring at the top of the seals.
Buddy and I think that from sitting the seals might have dried out and stuck to the valve stem.
Used a part from a leak down test. Put each cylinder at tdc, screwed in fitting from leak down apparatus into the spark plug hole. Used a ratchet strap from frame to dampner to keep engine from rotation. Used 35 psi to each cylinder. Used a spring compressor, pulled the keepers, spring and retainer washer. Removed buggered seal. Seal kit comes with a short straw, use it, protects the seals from damage from the spring retainer detent on the valve stem. Apply oil to new seal, slide on, set seal in place with a 1/2 in deep well socket and small hammer.
There's a blurb on valve seals replacement without pulling heads. Tedious project.
Yes it does, screw on to rocker stud. More tips... use an extendo magnet from Harbor Fright and a dental pick, and another set of hands. One person to depress valve spring and another fishing out the retainer clips using magnet and pick. Once spring, retainer and push rods are pulled plug push rod holes, oil galley holes with pieces of blue shop towells to prevent any flying retainer clips
Just some tips
Last edited by Canine man; 04/15/20251:15 AM. Reason: More info
No, you don't cut the seal- - - -shorten the top of the valve guide so the seal sits lower on the guide and the valve has more room to move up and down. I've had to do that on lots of guides when I went to the positive style seal instead of the O ring on the valve stem. I always check that dimension when setting up a set of HI-PO heads. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
It does appear that the seals were brittle, certainly age can play a big part in that. Do you think the engine was running too hot or the possibility of some aggressive chemicals were introduced in the oil? just thinking outside the box a little.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
I think the rubber tops on the seals dried out, and stuck to the valve stem, thus pulling the entire seal off the seat/boss. Then the valve spring retaining washer smashed the seals. Some of them look really hammered. After all seals were installed, we turned the engine over with the starter only. Everything worked so far. Buttoning things up for full start.
Use either O rings, OR positive stem seals- - - - -never both. It's possible to run valve guides "too dry" and wear them out.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
A little late to this thread, but if you do not have an air compressor you can do the job with parachute cord. Pull all the sparkplugs and using a breaker bar and socket on the crankshaft bolt, bring each piston on the compression stroke as you want to work on it. At the bottom of the compression stroke, feed about 18" of cord into the cylinder. Using the breaker bar, bring the piston up until it stops without applying too much force. The valves springs can now be removed without worry of dropping a valve. After the seal is replaced, simply turn the crankshaft bolt counterclockwise to relieve the force on the valves and remove the cord. Proceed to the next cylinder and repeat the procedure. Use parachute or multistrand nylon cord with the end melted to prevent loose strands from contaminating the cylinder.
Last edited by 1955 1 Series; 04/29/20252:04 AM. Reason: Clarity
... and don't forget to remove that cord from the cylinder after. Ask me how I know
They shoot out pretty far!!
1949 Chevrolet 3/4 Ton - Still Solid. Regular Driver OT Vehicles: 1950 Chevrolet Styline (Parts) 1952 Canuck Pontiac Sedan Delivery (Well Underway) 1973 F250 4x4 Highboy 1977 F250 4x4 Lowboy
