Are splash shields on valve springs helpful? - Team Camaro Tech
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post #1 of 12 (permalink) Old Nov 23rd, 05, 11:11 PM Thread Starter
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Jeff
 
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Are splash shields on valve springs helpful?

Im currently replacing the valve seals on my 69 Camaro. This is my first attempt at something like this, and searching through the old posts has given me a lot of great tips already.

The old valve seals (with only 1500 miles on them) are a hard white material like nylon. (Maybe teflon not sure.) While these might work well in some situations, Im pretty sure they are the cause of my oil-fouled spark plugs. With the intake manifold off, I can see a lot of oil buildup on the back of the intake valves inside the intake runners. The intake runners in the heads are dry, and I can't detect any "wobble" between the valve stems and the guides, so Im pretty sure that the valve seals are to blame here.

Im planning to use a set of Dana Clevite positive seals at the bottom of the stems. Theyre a fairly soft black rubber instead of a hard material, so Im hoping for better results from them. (The part number on the box is 216-1067 and I picked them up at a NAPA.)

I also discovered that my heads were reassembled without any O-ring seals the ones that belong in the second groove of the valve stems, up near the spring retainers. Im planning to add the O-rings, but maybe I should go one step further and add the splash shields (or hoods) that fit around the outside of the valve springs near the top. I think theyre made of thin stamped steel but Im not sure because Ive never seen one in person just in photographs.

My impression is that the splash shields are routinely left off during rebuilds. Is that because of the added weight, or because they are ineffective, or to avoid a situation where too little oil reaches the guides?

Right now, Im inclined to add the splash shields. If anyone has any good or bad experience with running them, please let me know what it is. Thank you. -Jeff
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post #2 of 12 (permalink) Old Nov 24th, 05, 12:59 AM
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Re: Are splash shields on valve springs helpful?

Personally, I would leave the splash sheilds off for 2 reasons. Weight, and you want oil on your springs to help cool help them. They will last longer as a result.

The white seals will be teflon. These seals are fine and I use them, but you must take care when installing them. They are easily cut on the keeper grooves. All quality set will come with a sheath to protect them during installation.
Other types of stem seals will work fine, but still be careful when fitting them over the stem's keeper grooves.
The O rings won't be necessary with good stem seals. (If they are the o ring seals I am thinking of.)

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #3 of 12 (permalink) Old Nov 24th, 05, 08:02 AM
 
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Smile Re: Are splash shields on valve springs helpful?

I think I have this right??

You need to use the little plastic "condum" on the end of the valves when installing any seals except the stock o-rings and umbrella's if not mistaken...

It keeps the keeper and o-ring grooves from damaging the seals lips..

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post #4 of 12 (permalink) Old Nov 24th, 05, 09:27 AM
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Re: Are splash shields on valve springs helpful?

The 2nd groove O rings are very helpful when installed properly. They seal between the valve stem and retainer and force oil over the top of the retainer and down the spring instead of running down the guide. The oil cools and extends spring life. I have seen many machine shops install them incorrectly. The O ring should be installed AFTER the spring is compressed just before the keepers (split locks) are installed. You slide the O ring down the guide to the second groove and install the keepers in the top groove. When the spring compressor is released the tapered retainer pulls the O ring up against the bottom of the keepers and seals off the top end of the valve. If you install the O ring before the retainer, the retainer will push it on down the guide where it is useless. Oil will run over it and on down the guide.
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post #5 of 12 (permalink) Old Nov 24th, 05, 11:48 AM Thread Starter
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Re: Are splash shields on valve springs helpful?

Thank you for those tips. I'll be sure to install the O-rings correctly and I'll go without the splash shields on the outsides of the valve springs. Oil passing over the valve springs and cooling them had never occured to me.

New problem today: For some reason, I cannot get the valve stem condom to go over the valve stems. The valve stems have a 0.34" diameter and the condom refuses to fit over them. By the way, even if the condom did go over the tip of the stem, it's not long enough to cover the second groove.

Do I have a non-stock valve stem size that requires a different set of valve seals? The portion of the valve guide that the valve seal will fasten against has a diameter of 0.50" which I believe is typical.
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post #6 of 12 (permalink) Old Nov 24th, 05, 01:55 PM
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Re: Are splash shields on valve springs helpful?

Jeff,
I might be wrong, but I doubt that the seals are causing your plug fouling. Everyone seems to forget that the early small blocks, up until the mid 70's, did not have any valve stem seals other than the o-rings and the splash shields. They certainly did not foul plugs.
As far as the plastic sleeves go, are you sure you got the right seals ? The stems should be .340 or so, so they are correct. Most of the sleeves that I have seen are almost an inch long, you usually have to cut them because they are too long. I think you are right in staying away from the teflon seals on a street engine. I really dont think they work as well in the long run as a good viton seal. The teflon seals are not very flexible, they work fine on race engines but after a while they seem to loosen up on street engines, either way they should not need replacement after only 1500 miles, I think you have other problems. By the way, I have never used a condom on the rubber seals and as far as I know have not had a problem.
Hope this helps,

Bill Koustenis
Owner
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #7 of 12 (permalink) Old Nov 24th, 05, 03:03 PM Thread Starter
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Re: Are splash shields on valve springs helpful?

Thank you for those ideas, Bill. It's becoming obvious that I don't have the right set of replacement valve seals. I just finished inserting one of them onto the stem, and the bottom portion of the seal does not fit snugly to the valve guide. I need to find another set.

Here is some more background information on this motor:

The heads are a pair of 186 camel humps that were rebuilt about 1500 miles ago along with the rest of the engine. That was about 6 years ago if you can believe it. (Yes, I know that I need to get out and DRIVE this car!)

I have heard that old gas can contribute to visible exhaust smoke, so I drained out the old gas and added new. That didn't help.

The cylinders and pistons were taken up to .040" over during the rebuild. A recent compression test while the starter turned the motor showed very close to 145 psi in all cylinders. There is no oil getting into my coolant, and no coolant getting into my oil. The carb is a fresh Holley 4150 with size 68 jets on the primary side and size 76 on the secondaries. I've experimented with primary jets all the way down to size 64 but the spark plugs were still wet with oil. I have been running Delco R45S plugs with .035" gap.

The threads on the spark plugs are always soaking wet with oil when I pull them out of the heads. This condition is perfectly consistent on all 8 cylinders. The outside of the heads are clean, so the oil on the threads is definitely from an internal source. I pulled the intake off, and the intake runners inside the heads are dry. However, I can see that the back side of every intake valve has a thick layer of oily crud on it. It's not a wet layer of oil but it's not completely dry either. (I grabbed a sample on a wood dowel.)

I have only disassembled the valve springs on one cylinder so far and I used the rope method to prevent the valves from dropping. The rope method has allowed me to release the pressure on the valves slightly and slide the valves up and down in their guides. I can't detect any wobble between the stems and the guides when I do that. I'm hoping that the stem/guide clearance is also good on the other valves when I get around to doing them.

I'm still blaming the valve seals right now, but I would appreciate other ideas too.
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post #8 of 12 (permalink) Old Nov 24th, 05, 03:53 PM
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Re: Are splash shields on valve springs helpful?

I just went thru the same thing as you. I had the same symptoms. After removing the heads it was the guides. Too much clearance. Don't count this out yet. The machine shop some how forgot to sleeve the guides even though it was on my bill.

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post #9 of 12 (permalink) Old Nov 24th, 05, 04:18 PM
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Re: Are splash shields on valve springs helpful?

Jeff,
You dont give your location, but your local machine shop should be able to tell you which seals are correct. I am not sure if I am going to the shop on Friday or not, we are officially closed but I may sneak in and try to get some work done with no interuptions ... if I do, I will get you a seal part number that should work. I want to say a Pioneer OS450 is the one, but dont hold me to it !

Bill Koustenis
Owner
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #10 of 12 (permalink) Old Nov 24th, 05, 08:56 PM Thread Starter
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Re: Are splash shields on valve springs helpful?

I'm living in Durango, Colorado now, but the engine work was done by a shop in Florida. I haven't found a good local machine shop here yet, but I haven't started looking either. Bill - if you happen to find the correct Pioneer part number, I would really appreciate it. If you know of a supplier for them, that would help too because I haven't found one yet.

I have not ruled out the guides as a possible problem either, Gary. They were replaced during the rebuild but they're not above suspicion. I plan to check each valve stem carefully for any wobble inside the guides as I replace each valve seal. (Just wiggling the stems with my hand to see if there's any noticeable movement side to side.) If I don't find any wobble along the way, then I'll go ahead and reassemble the complete motor, cross my fingers, and run it again.

If the exhaust smoke and the wet plugs persist at that point, then I guess the heads will need to come off.
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post #11 of 12 (permalink) Old Apr 6th, 06, 12:29 AM Thread Starter
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Re: Are splash shields on valve springs helpful?

I began this thread and I'll post a wrap-up in hopes that this information is helpful to somebody sifting through these postings in the future.

Good news: After replacing the valve seals and driving a bit, the exhaust smoke and the wet-fouled spark plug symptoms are completely gone. I'm 100% happy with how this engine is running now. I should have posted these follow-up notes sooner but I've been using all my spare time to get out and drive this car again. Feels great!

When I had the valve springs off, I noticed that none of the small rubber O-rings had been installed at the tops of the valve stems. That may have been contributing to the problem as much or more than the valve seals themselves. The new parts that I installed are:

Pioneer OS-1090-16 teflon valve seals (I discovered that the O.D. of my valve guides are smaller than stock where the valve seals attach. I'm pretty sure this was done to make room for the double valve springs on these heads.)

Pioneer OS-240-B-1000 rubber O-rings for the tops of the valves (A box of 1000 is the smallest quantity that Pioneer sells, so I've got a lifetime supply now.)

I ordered these parts through a local Checker Auto Parts store and everything went together without incident. By the way, I went with the "rope technique" for keeping the valves from dropping while the springs were off, even though I had everything needed to do the compressed air technique. I opted for the rope technique because it allowed me to make an informal check of the valve guide clearances by rotating the engine backwards a few degrees after taking the valve springs off. That released some of the pressure on the valves and allowed me to lift and depress each valve about half an inch and feel for any side to side "wobble" against the guides. I could just barely perceive a trace of wobble in a few valves but nothing that made me want to remove the heads and redo the guides. I suppose that the same kind of test could be done by uncompressing and recompressing each cylinder with air, but with my luck I'd probably let a valve slip through my fingers.

So all's well that ends well. Thanks to everyone who helped me along the way. -Jeff
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post #12 of 12 (permalink) Old Apr 6th, 06, 02:43 AM
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Re: Are splash shields on valve springs helpful?

Well done..

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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