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SBC valve seals and retainers

20K views 8 replies 5 participants last post by  cobalt327 
#1 ·
I'm giving the 327 in my Chevelle a mild refresh. One of the tasks is fresh valve seals. Please give me a little advice about what seals to use.

I pulled the springs off #2 to see what seals are currently installed. Here's what I found (trying to attach picture but)

Valves have 2 grooves so I can use o-rings
Valves had crusty remnants of dried up old o-rings
Intake valve also had a black, soft, rubber like positive type seal on the guide
Exhaust only had o-ring
I'm not sure if the guides are properly machined for positive seals.
Intake guide OD = 0.566"
Exhaust guide OD = 0.571"

My Summit valve spring kit included a set of blue viton seals with an ID of 0.500". I can probably get these on the guides with a little convincing, but I think the guides are too big. Am I right?

Should I track down positive seals to fit on my guides? Does such a beast exist?

Should I just use an o-ring and umbrella seal on all 16 valves?

Also, the intake and exhaust valves have different retainer set ups (also in a picture I hope shows up). When I put it back together, do I use this setup or the retainers/locks that came with my spring set?

Thanks for your help - this is the first time I've done this level of work.

A little background if you want it...
Car is a 67 Chevelle wagon that's been in the family since '71

Engine was built in mid-80s and has about 100k on it
Engine sat a lot from mid 90s - mid 00s and smokes because the seals are dry

This project started when my 40+ year old damper separated. I figured, if I had to tear it apart enough to replace the damper (including drilling and tapping the crank), I should put a fresh timing chain in it.

Then, I figured, since I'm in this far, I should do something about the lifter that's been clacking on and off for 10 years so why not put a cam and lifters in it (getting a Summit 1102 204/214 cam and lifters to replace the 929? cam in it now).

This of course made me think a fresh set of springs would be a good idea and since I'm doing that why not put fresh seals in.

I'm really fighting the urge to pull the front sheet metal and paint all the engine bay...

I'm sure some of you can relate...
 

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#2 ·
Before you even worry with the seals, check the valve guide wear. Usually when the older heads reach a 100,000 miles, the guides are shot. If the guides are worn you can replace the valve seals and it`ll stop the smoking.
However, it will still use oil, even so you won`t see it smoke, you`ll be able to smell it. The proof will be on the back side of the valve stem, right before the valve head. Oil will leak down the guide on to the valve, which is hot, and the oil will cake up in a hard crust that`s difficult to get off resulting in hampering the engines air flow.
 
#3 ·
The 0.500" ID seals are made for guides that have been cut down to that size, so using them on an unmachined guide boss won't really work too well.

The choices are using umbrella-type seals and/or the small O-ring seals that fit into the stem groove.

If you opt for the O-rings, be sure they're located in the groove after the spring and retainer/lock is assembled- the O-ring gets easily dislodged from the groove when assembling the valves.

Really, for the best results, the original heads need to be given a standard valve job, w/a three angle cut on the seats. No need to go nuts w/all the bells and whistles- the cost will soon be greater than opting for Vortec or aftermarket heads.

A set of 1-5/8" long tube headers will do wonders (along w/a true dual exhaust, maybe w/an "X" or "H" connecting the two sides), along w/a pair of low restriction mufflers. ;)
 
#8 ·
Hi guys - thanks for the tips.

I figure the engine is worn and my ideal solution would be building a fresh 350 with a late model block, roller cam, and good heads. The next best thing would be a fresh set of good heads. However, that's not happening now.

Interestingly enough, one head is a 624 and the other is an 882. Hmmmm..

Also, both springs are the same length (the same period as far as I can tell) and both seats are the same depth. More hmmmm...

I'll give some thoughts to replacement heads but, honestly, I just want to drive the thing again without a clattering lifter and blue smoke on startup so I'm leaning towards putting it back together with fresh o-rings and umbrella seals.
 
#9 ·
jb2wheels said:
Interestingly enough, one head is a 624 and the other is an 882. Hmmmm..

Also, both springs are the same length (the same period as far as I can tell) and both seats are the same depth. More hmmmm...
The heads were likely put on as an exchange from a supplier of rebuilt heads- they are basically the same head w/slight differences that were enough that GM deemed them a different casting. Performance identical. The 462624 overlapped the 333882 for at least 4 years during production.

As far as the seat depth and spring length being identical, there's really no "hmmm" involved- there were at least three different things that could be found on heads using rotators- changing the spring seat depth (something I've not run across) is one, shorter springs on the rotator is another, same spring on the rotator as the intake is another (last two having the same spring seat depth as the intake side). So don't let the idea that your heads have the same depth bother you at all.

I'll give some thoughts to replacement heads but, honestly, I just want to drive the thing again without a clattering lifter and blue smoke on startup so I'm leaning towards putting it back together with fresh o-rings and umbrella seals.
It is worth a try. Usually, the exhaust side doesn't need an umbrella, but I suppose if the guides are worn quite a bit they may help. Your call on that one, you just don't want to dry up the stem to the point it will gall, but I doubt that will happen w/these 100K heads.

Good luck.
 
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