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tbrown8338 02-12-2012 03:11 PM

valve seals
 
can someone tell me how to replace the valve seals (umbrella) on a chevy 350 engine. where does the o ring goes top or bottom of the unbrella seal.

techinspector1 02-12-2012 06:22 PM

http://www.ehow.com/how_5374175_inst...ls-engine.html

skip99 02-12-2012 06:33 PM

use one or the other.....and I always used air with a scrrew in fitttng into the sparkplug hole, remove all the plugs apply air and the air will spin the motor, piston down and hold valves closed while you change them..

tbrown8338 02-13-2012 08:47 PM

Quote:

Originally Posted by skip99
use one or the other.....and I always used air with a scrrew in fitttng into the sparkplug hole, remove all the plugs apply air and the air will spin the motor, piston down and hold valves closed while you change them..

will hurt if i used both

oldbogie 02-14-2012 10:14 AM

Quote:

Originally Posted by tbrown8338
will hurt if i used both

The O ring is used on the stem when the valve assembly includes a stamped metal shroud under the retainer, covering the top of the spring and a coil or two on the side, it diverts oil away from the guide. The purpose of the O ring is to keep oil that puddles in the locks and retainer doesn't run down the stem.

The umbrella seal replaces both the metal shield and the O ring providing both the functions of diverting the oil away from the guide and stopping its flow down the stem.

There is no need for both the O ring and the umbrella seal.

If you're running a higher lift cam or 1.6 rockers check the clearance with the valve fully open between the bottom of the retainer and top of the seal. If the seal gets squished in there it function is lost.

Bogie

tbrown8338 02-15-2012 03:47 AM

valve seals
 
Quote:

Originally Posted by oldbogie
The O ring is used on the stem when the valve assembly includes a stamped metal shroud under the retainer, covering the top of the spring and a coil or two on the side, it diverts oil away from the guide. The purpose of the O ring is to keep oil that puddles in the locks and retainer doesn't run down the stem.

The umbrella seal replaces both the metal shield and the O ring providing both the functions of diverting the oil away from the guide and stopping its flow down the stem.

There is no need for both the O ring and the umbrella seal.

If you're running a higher lift cam or 1.6 rockers check the clearance with the valve fully open between the bottom of the retainer and top of the seal. If the seal gets squished in there it function is lost.

Bogie

i had already put both the oring and the umberalla on before i read this. would it cause any problems

spikebot 81 02-15-2012 05:12 AM

I have both seals on some old GM 882 smog heads. These where installed 2 yrs ago. I had some oil consumtion issues and found the valve guides to be worn sucking oil into the cylinder heads. My temp fix was to install both seals to cut down on the oil use. Some prev. owner installed 1.6 roller tip rockers. This fix did cure my oil use. Hope this helps

oldbogie 02-15-2012 09:59 AM

Quote:

Originally Posted by tbrown8338
i had already put both the oring and the umberalla on before i read this. would it cause any problems

The big issue with both is to be sure when the valve is at the peak open position the seals aren't being squished between the top of the valve guide and the bottom of the spring retainer. If the seal and O ring do get squished it will do nothing more than ruin the sealing capabilities, hard parts will NOT suddenly come flying out.

If the heads are on the bench this is easy to check with the valve spring removal tool, by putting a thick spacer over the installed retainer and valve stem so when you compress the spring the valve opens instead of the retaining being depressed to release the locks. Then with a machinists rule little 6 inch stainless job measure the height till you get to where the rocker would have the valve fully open. Then observe the clearance of the seal and O ring as it rests between the guide and retainer. Anything equal or greater than .050 inch is plenty.

Bogie


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