[KJ223]

Hi everyone, I just swapped my cam out in my Pontiac 350, (as some of you may know from helping me in my previous forum post) and I also ended up swapping out valve springs with the heads on and the engine in the car for peace of mind. Anyway, while changing the springs I noticed each valve had a hard brittle o ring that cracked and fell off each valve, at the time I had no idea what this did, and assumed that the valve seal was the actual seal on the head at the base of the valve. After breaking in the cam I’ve been driving the car and notice blue smoke on start up, and after idling for about a minute. I realize now that those o rings that I brushed off as nothing somehow play a role in preventing this. Please try not to think I’m too big of an idiot. My question is how does this o ring do anything to seal the oil, and what is the purpose of it and the bigger seal at the bottom, (I guess it’s called an umbrella?). Why are both of these used? Also how hard is it to replace these seals with the engine all assembled now. I know it’s basically what I just did with changing the valve springs, but now I’ll just be working with the valve covers off, rather than the intake and valley pan. One last thing, I’m seeing those umbrella seals are sold as sets of 8 instead of 16, is there a reason for this or do I just need two sets? Other than some blue smoke, the engine runs great.
Thanks

[Half-Inch Stud]

O-ring alone didn't work so good.

Umbrella work IF THEY ALL stay on the Valveguide. Some will ride up if not a tight fit. pop vavlecovers and look through the Spring to verify each umbrella is down.

You could use both, but the umbrella does all the work.

[steve25]

Your heads have been apart at least once before because your era motor never came with umbrella seals.

A umbrella seal is not firmly attached to the guide , they ride up & down with the valve, this is what you have?

These added umbrella seals are a attempt to make up for the need for new guides and or valves I would have to guess.

What is strange is that the last time the heads where put together the umbrella and stem seals should have both been new, but the fact that your O-ring crumbled would indicate that they where reused when the umbrellas where installed.

[KJ223]

Interesting, I honestly have no idea if they’ve ever been disassembled, I’m certainly not discounting that they have been but they look like they’ve been on the car a long time. All the paint had flakes off. From the story I was told by the previous owner the car had sat for a long time, before he bought it and then it sat in his garage for 12 years etc. I wonder who would’ve been the one to dissemble anything. But anyway, since I have both types this would mean I need to replace both?

[steve25]

What valve springs are you using?

When you run just the O-ring, you need to run the stock set up.
If the springs do not allow the use of these oil splash shields like in my photo then you need to run a positive valve guide mounted seal which is in my photo also.

Of course if you have too much slop allowing the valves to rock around too much then even a positive type seal will not be of much use.

[KJ223]

I am using Comp 988-16 springs. I believe these are basically stock spring rate, or maybe just a slight amount more. They do use the splash shield on the outside and the inside piece that the keepers sit in.

[KJ223]

Just wanted to update, just finished getting all 16 o rings installed, as someone said this era of engine didn’t come with any other seal besides the o rings. 14/16 were completely missing. After replacing all these it no longer smokes like a freight train.

[Cliff R]

The "O" rings don't work without the factory oil shields. They seal the top of the retainer under the keep to prevent oil from running directly down the valve stems. The entire assembly then acts like a large umbrella seal.

Umbrella seals weren't used with the factory oil shields and "O" rings.

If unmbrella seals were added, and they aren't loose on the valve stems it wouldn't have been using oil in the first place and the "O" rings and shields wouldn't have been needed right to start with.

I suspect your troubles aren't over as about all you did was to keep oil from running directly down the valve stems past the split valve locks..........

[Kenth]

No RamAir engine uses the oil shields due to stronger valve springs, still used the O-rings in all retainers plus PC-seals on intake guides.

[KJ223]

So i was incorrect about what type of seals I had, I thought there was a large rubber seal at the bottom of the valve, but once I got the spring off I found it to just be metal, I guess you could say it was unmachined for any seals. I am still using the oil shields, but I guess according to the butler performance webpage this is the only seal on my motor. I attached a picture of one of my intake valves along with a screen shot of the butler performance article. Also, the heads are 6X-4 if I forgot to mention it. I think I misread what an umbrella seal actually is, umbrella means it just sits on the valve and rides up and down with it right? Because I was under the impression that umbrella was the kind that had a metal lock ring and snapped onto the valve guide, however my valve guides were too large in diameter to accept these seals positive style seals. Not the metal viton type but the fel pro SS-13360

[Cliff R]

The "O" rings require stock retainers AND oil shields. If not you will need to use another type of seal to keep oil from running down the guides.

It's not complicated. For decades now we have been machining the tops of the guides for PC seals and using valves that aren't even machined for the "O" rings. In addition I grind off some material from the bottoms of the stock retainers to provide additional clearance as they will hit to tops of the PC seals with higher lift camshafts. This also lightens the retainers some making them even better high performance parts and doesn't effect strength as long as you stay BELOW where the keepers sit.

Here I prefer using stock retainers for most of these builds as they are really light and very strong. You still reach a point even using better springs with thinner wire diameter and more room to coil bind to move up to .100" longer valves and 1.700" installed height. It just makes everything easier all the way around with builds leaning more toward "high performance" that street/daily drivers.

Of course when you take the plunge for aftermarket heads everything changes.

For stock type "D" port iron heads most are 1.586" installed height. So tossing the oil shields and seat grinding quickly puts you at 1.600". .100" longer valves puts you to 1.700". More room is better with these things as very few folks build these engines with stock low-lift cams and I don't know too many machine shops or engine builders than don't upgrade to PC seals. Not meaning to get too far off track here just throwing out some info.

For what's going on here I would have kept the oil shields, a stock type replacment or stock springs, and put new "O" rings under the keepers..........

[KJ223]

Originally Posted by Cliff R

The "O" rings require stock retainers AND oil shields.

For what's going on here I would have kept the oil shields, a stock type replacment or stock springs, and put new "O" rings under the keepers..........

That basically exactly what I did, so I’m glad to hear that this is what you would have done. The comp 988-16 are not very strong springs from my understanding, which is perfectly fine for me because I have yet to rev the motor up past 4500rpm anyway. I’m really not sure what the safe rpm is for these pontiacs but I don’t want to find out the hard way.

[Cliff R]

I don't use 995 or 998 Comp springs. Every time I check a set of their springs they do NOT show the same specs as the posted literature on them. Matter of fact the last set of 995's I checked were a LOT stronger at every point that what I'd ever want on a flat hydraulic cammed street/strip Pontiac engine, so I used Crower 68405's instead.

Not dogging their product, I'm sure they are excellent quality spring wire, here I don't run a lot of spring pressures on my engines, at least not those with iron heads and not set up for high RPM use.

I will add this about springs. ALWAYS check them with the retainers you plan on using. In addition to the Comp 995's being way off the mark I was hired a few years ago to assemble an SBC 350. The owner supplied some aftermarket iron "high performance" heads. Can't remember now what brand, Iron Eagle or Dart, but not sure. Anyhow I pulled a few springs and checked them and they were WAY WAY WAY too strong and would not have faired well in long term service on the relatively "mild" engine build we were assembling.......

[steve25]

The comp cams spec ( if correct) states 110 psi on the seat @ 1.650” installed height.

The average stock installed height on a 6X head that has NOT had a touched up valve job and is still set at a intake valve seat OD of 2.080 will have a height of 1.586”.
This reduction of installed height of .060” should increase your seat pressure from 110 to 125 or so.

This will leave you safe for running .450” lift without getting into coil bind, and allow you to turn a easy 5000 rpm.

[pfilean]

When I bought my 61 the PO had already had the engine rebuilt. They put on Comp 988. The 988 were larger diameter and they threw the splash shield away and just used the little O ring at the spring retainer. Smoke and 500 miles per quart. I bought different heads that still had splash shields and had a valve job done using correct O rinds on the spring retainer and the splash shields. Much improved and I'm happy for a driver.

I think at one time Comp offered splash shields that fit their springs but that has been discontinued. With no splash shields use the correct O rings at the spring retainer with the umbrella seals.

[KJ223]

They must have changed the diameter, my oil splash shields fit perfectly on the new 988 springs. A problem I did have was getting the completely wrong spring in my box of 16 from comp. I had to drive 4 hours to summit as it was a Friday evening. Not sure how their quality control let that one slip.

[steve25]

In regards to the comment in post #15 you must have had mis-boxed springs because the 988s have always been a smaller OD then the factory springs.

[KJ223]

So after driving it a bit, I picked up a rocker tick on I believe the driver side. I set the lash on these by feeling resistance in the push rod turning the motor a 1/4 turn repeat etc, but I’m reading somewhere that you torque these rocker nuts to 20 ft lbs. is this true? What’s the correct procedure for setting these rockers because I believe one of the nuts backed off.

[KJ223]

I’m getting conflicting results, I read an old service manual which calls for 20 ft lbs on each nut, but some say this can’t be done with an aftermarket cam. I also see others saying that it’s ok with milder cams, and this is my case. I have a summit 2800 which has a duration of 204/214 and lift of .421/.444 with factory rocker arms which I have. Would I be ok in torquing these rocker nuts to 20 ft lbs considering this cam is pretty mild and has less lift/duration than say a Pontiac 068 cam? This is where I’m concerned, I’m worried I’ll make them too tight and mess something up. I can’t see how I’d mess something up as from my understanding these aren’t adjustable rockers like a Chevy motor (i followed the adjustment procedure for a Chevy motor I guess). Do I try loctite on the nuts, and maybe do 10 ft lbs?

[Sirrotica]

Two options, first one is 3/8" polylock jam nuts, with the 7/16" spacer washers:

https://butlerperformance.com/i-2445...tegory:1459541

https://butlerperformance.com/i-3164...tegory:1459541

Second option is 3/8" self locking nuts, with attendant 7/16" washers. These are basically SBC locking nuts, but to use the nuts you also need the washers that go under the nuts to go over the bottleneck step on the rocker arm stud, giving the bottom of the nut enough length to go over the bottele neck step:

https://butlerperformance.com/i-2568...tegory:1459541

https://butlerperformance.com/i-3164...tegory:1459541

Either setup will work with your stock rocker arm studs.

There is a third option if you already have screw in studs in your heads. Butler sells a kit to convert your stock studs to the beefier 7/16" studs and nuts. You have to have screw in studs, which came on most 4bbl cylinder heads after 1966. If you have press in studs the heads need to come off the car to be machined for screw in studs. Kit to convert from stock bottle neck studs to the stronger 7/16" studs, also used on BBC heads:

https://butlerperformance.com/i-3164...tegory:1459541

With your cam, you likely can get away with only converting to either style of nuts, and keep the OEM bottleneck studs.

It's a little bit involved to make a Pontiac valve train adjustable, but it's not overly expensive, or time consuming.

If the base circle on the sftermarket cam is the same as the original cam then you can get away without making the valvetrain adjustable. You likely don't know if they are the same though, unless you measued both out of the engine. In my own cars if I change the cam, I usually make the valve train adjustable while I'm already removing everything anyway. I prefer the polylock nuts on my own engines, and for customer engines, that I built before retirement.

The loctite idea is not worth persuing IMO. Make it adjustable with one of the three options I layed out, and never look back.