Hello all, I have a small block and when I bought it the guy said that it was starting to smoke. He said mostly when it started it smoked. So I bought a set of valve seals and pulled the valve springs. When I pulled off the spring caps and retainers on the first cylinder, I noticed that this engine already had a set of hard umbrella seals on intake and exaust valves (old or original). So I pulled the rigid plastic cups, which I assume are factory? and I put on the soft form fitting new umbrella seals from moroso. The thing that bothers me is there is also the small, flat little o-rings, but the new kit does not have them -only the umbrellas. So I ask- do you need to replace these as well or will just the umbrellas work. Also, are the new umbrellas supposed to be really tight or slightly loose like the old? I assumme that since morisi didn't give both types, that the umbrellas are fine, but wanted help. All comments aappreciated Pork
Honestly, i really dont' know what purpose the little flat O-rings purpose is....HOWEVER 99% of the SBC's I've taken apart had them and I put new ones back in...Look em up on Summit to see what they are called and pick up a set for a buck or two at your local parts store......hey your already in there right?
The hard plastic seals are used on the exhaust only. rubber umbrella seals will work well on all stems if you also use the O-rings. Will turn hard with use. The purpose of the O-rings is to seal the stem to the retainer. This keeps oil deflected over the top of the retainer/shield. Keeps oil from running down the stems onto the guide. If you remove the shields (for high lift cams), use the umbrella seals. Better yet is to use the modern Positive seals on the intake and umbrellas, plastic or rubber, on the exhaust. If the guides are any good. Intake side sees vacuum most of the time. Trying to suck oil down the guides. Exhaust sees slight pressure most of the time. Trying to blow oil back up the guide. Umbrella seals keep stem lubricated but won't let oil run down directly into guide. GM stopped using the O-ring seals in the nineties after going to positive seals.
Fel-pro makes a umbrella type seal that has a teflon center that the valve rides on ...they last a little longer.
hey PORKCHOP...the new teflon seals are best, but no seal will help if theres to much clearance between the valve stem and guide. but to answere you question. usually when an engine smokes just after starting, it needs valve seals...POP.
The O was to stop oil dribbling down the stem from the pool atop the spring retainer. "80's Aluminum Corvettes have really nice seals, a little hard shell one for the X and a soft rubber one for the N, reallycompact and dirt cheap.
Thanks gang! I put the whole thing back together with the new umbrellas and I placed the old o-rings back on also. I figure between both, I hope it should do the job. And as someone recomended, if these valves are too badly worn, it wont last too long regardless. It's like everything else in life for me, if I had the money... Thanx for the comments Pork
That should last you a while, I used to get the Fel-Pro ones with head sets, not sure if they still package them that way. Make sure that the drain holes in the rear of the heads are open. You may open another can of worms cleaning them, but do so if they are clogged and change the oil & filter soon after. Bob
The "O"rings are the original Chev valve seals that have been used since 1955 on most small block engines. The umbrella type do work better though as long as they don't get hard. I'll agree that the guides are probably suspect by now and probably were due for replacement. New seals will keep it under control for a while though.
"The hard plastic seals are used on the exhaust only." I thought they were only used on the INTAKE side to prevent the vacuum of the intake from pulling oil into the chambers.
Later GM factory seals are positive viton type seal on the intake and hard plastic on the exhaust. The plastic handles heat better. 11/32" stem uses white umbrella. 3/8" stem uses black . No O-rings since early nineties. Vortec heads use a steel jacket positive seals. Intake and exhaust. Color coded because of different materials.
Great info Bob, any way you can get pic of these? They avail from other than GM? Pioneer part#? I've been using umbrellas on cam & spring swaps with good success but if you say there is something better thats good enough for me, just point me in the right direction. Thanks, oj
Fel-Pro, Victor-Reinz, PEP. Engine Pro. All offer the seals. Intake Fel-Pros are blue for non-Vortec. Victor, Engine Pro and PEP are black with colored band. Exhaust are White or black as stated. If I can remember I will get part nos. tomorrow at the shop. I buy them from engine supply warehouses 100's at a time. But, different part nos.
ive used alot of them rubber umbrella seals with good results, pc's are real good if you have your guides machined for them. those new seals should help.
Fel-Pro. Premium seals. = SS 72877 exh. SS 72527 intake. Umbrella (use with O-ring) SS 10058 and the latest positive sets are SS 72861
I realize this post is 10 years old. Just adding this for some additional info and for those who search this website for the amazing amount of "old engine wisdom" that it holds. My comment pertains to the “basic small block Chevy (non-vortec). I knew an old engine machinist back in the day. This man really new his stuff. Back when I rebuilt my first small block, I wanted to go with the umbrella seals. He told me that the basic GM o-ring was one of the best designs ever made and he would not recommend using the umbrella seals. His thoughts: if it smokes because of the valve stem seals being worn, hard or missing then replacing the o-rings will be all that it needs. If it’s not because of any of these 3 things, then your guides have excessive wear and will require your heads to be reworked. Today there are some that might consider it unimaginable to run only the thin o-rings and others who think they’re not needed if you use umbrella type seals or the newer progressive type. I appreciate everyone has their opinion and use what they feel works best. My own experience lends to the answer that the old machinist gave me: The simple o-ring works best if your guides are not worn. And further to my own thoughts, the umbrella seals will harden over time, break and fall into your engine. I wouldn’t use them. And the use of newer progressive seals on anything other than vortec heads, this was a design that was intended more for modern emission issues. Many of us who’ve worked on old engines will tell you that a bit of oil will make it past the guides as the engine wears. It's ok. And unless it’s noticeable on the dipstick and it doesn’t appear that you're mosquito fogging as you drive,..a bit of oil past the guides is no big deal. Some would even say it makes your heads last longer if you do have a bit of oil going by the guides. Extra lubrication. ;-) The machinist that once gave me the advice is gone now. We’ll miss you old Abe. I’ll pass on his wisdom here for those interested.
Hey there, very good read thnx. I'm new the car world and have some little experience. I have a 77 Firebird with a 350 and after market World S/R heads. In the last years i was noticing a puff of smoke every now and then when i started up. Buddy of mine said its most likely the valve stem seals, so last night we opened up one of the heads and took apart the rocker and spring and too our amazement there was no stem seal only a small plastic ring on top of the stem.. any information would be much appreciated thnx!
that is the original Chevy seal design, it needs a cup over the valve spring, under the retainer, to do any good. Looks like whoever put the heads together didn't know what they were doing. But you probably want to use aftermarket valve stem seals. Measure the outside diameter of the valve guide. Find seals that will fit the that size, and work with the valve stem diameter you have (probably 11/32").
Amazing thnx for the information. Is it possible the cups are not needed? I know that the car has a small comp cam and comp cam rockers What do the cups do? How could there be no stem seals on these stem? I've had this car for 5 years now and have not had any issues with the start up puff of smoke. Thnk alot!
The O ring seals the retainer to the valve stem. The cup keeps oil from being splashed onto the valve stem. It's not a perfect system, but it works well enough. The idea is kind of like an umbrella. Also, there are umbrella seals used as original design on Chevy big blocks, they do the same thing, but with one rubber part that fits on the valve stem, and covers the top of the guide, but is not attached to the guide. More modern designs fit tightly on the guide, and fit the stem so the stem slides up and down in the seal. This is what you probably want to use. No need for a cup with this design.
Ok i understand..I'm going to measure these seals my friend gave me. He said they might fit. He had them for his 69 elcamino, but he has a 401. He told me to check em.
Those are umbrella seals, they are designed to fit on the valve stem, and not fit tightly to the guide. If they're for a 396 or 402, they will be too large, as the big blocks have a 3/8" stem.
ok thnx.. so moving on haha..and another friend recommended these https://www.summitracing.com/parts/FEL-SS72527
I've used the seals for late 80's SBC. They press on to the factory machined guide. Have used them on a 65 283 for the intake. The black plastic umbrella is for the exhaust. GM has a set that includes both car and truck sizes. This was a factory fix for smoke on start up. Believe it or not it was the exhaust seal causing the smoke. Using these the o-ring and shield can be eliminated. GM part number for the kit 12511890
Another often skipped process in installing valve seals is not using the supplied cap that protects the new seal when going over the top of the valve and past the keeper groves, destroying the new seals
Thnx for all your help guys. I will make sure to take care installing the new seals. will keep you posted.
In the end i'm going to remove the heads and cut down the valve guides to fit positive stop valve stem seals..
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