The Stovebolt Site Forums The Shop Area Engine Shop Intake valves all stuck?

Hey yall, recently got a 235 from a 57 truck and the bottom end has already been rebuilt and seems to be up to snuff, but the valve head needs some work. The exhaust valves all moved and came out without any issue but all the intake valves were very stuck, took a lot of hammering to get them out. I know that some years use the umbrella seals and some dont, only the intake valves had the umbrella seals. Could it have something to do with that?

The engine may have run with old gasoline, the gas starts to varnish as some of the more volatile vapors evaporate and leaves behind a sticky mess. if the engine ran on old gas, the valve stems and guides collect the varnish and it seizes the stem in the guide.

Yep, most likely varnish from stale gas. Never, ever, pour fresh gas into a tank that's been empty for a long time, as the residue will dissolve and deposit itself on the intake valve stems. Wake up a long-dormant engine with fresh gasoline from a clean tank, like a plastic carry jug or an outboard motor tank. Steam clean or replace the onboard tank before using it.
Jerry

A gas tank I had years ago had about a 1" thick layer of basically tar in the bottom of it. It took a gallon of solvent and quite a bit of time to dissolve that crap to be able to reuse the tank.

Hope you didn't ruin the valves and/or guides when you "took a lot of hammering to get them out". If not, try cleaning the valves and guides with solvent and check them for fit and clearance, they might be saved.

Theyre not original valves so im not too worried about saving em, they are most definitely ruined lol. Plan on taking the head to the machine shop to get new valve guides and hardened valve seats anyway

You might want to reconsider going to the expense of installing hardened valve seats??? I think Jerry (Hotrod Lincoln) will offer some previously provided "great" recommendations on why hardened valve seats aren't really necessary in respect to your 235.

Jerry - Care to offer the new guy some wisdom?

Back in the dark ages when leaded gasoline was available, the tetraethyl lead anti-knock additives had the added benefit of leaving deposits on the valve seats that minimized valve and seat wear. As the lead compounds were gradually reduced, and finally eliminated altogether, valve seats began to wear, and the valves slowly sunk themselves into the cylinder head. The fix was to install Stellite valve seats that didn't wear as quickly. That practice these days is about as obsolete as starting engines with a hand crank. It's much more effective (and less expensive) to simply install stainless steel exhaust valves. Fortunately, the same exhaust valves that fit small block Chevy V8s are a drop-in fit for stovebolt sixes. Nothing needs to be done to the intakes, as they're constantly being cooled by the incoming fuel/air mixture, and there's no need to use hard seats, or special alloy valves. I just fitted a set of new valves to a 261 head yesterday, using the commonly available stainless V8 exhausts. Instead of the original O ring seals on the valve stems below the split locks, I use positive stem seals that clamp onto the top of the valve guides on the intakes, and "umbrella" seals on the exhaust valves. DO NOT double up on stem seals- - - -use either the O rings, or the positive seals, not both. Running the valves with too much sealing causes rapid valve guide wear. They need a tiny bit of leakage to stay lubricated.

www.ebay.com/itm/156769335932

www.ebay.com/itm/122009255781

Don't get robbed on the cost of the guides- - - - -I use these frequently:

www.ebay.com/itm/153212646674?

Jerry

All I've ever owned are cars built before 1972 and trucks built before 1980. I've never used lead additives and have never had hardened seats installed on any engine when a valve job was required.

Unless you're auto-crossing your truck, you will never experience premature exhaust valve wear with standard valve seats.

The Bismarck has 200,000 miles on it running unleaded fuel only for more than 2/3rds of its life with absolutely no problems. I just filled it up today with unleaded. 15.6 mpg.

The only machine shop around me that can confidently say they can work on my engine wont use customer provided parts. But yeah it seems what you're talking about with the double seals is what happened to my engine. The previous owner said it was hydrolocked but i think it may have been this. Every intake valve had the o ring and the umbrella seal.

Let's be clear on this, o-rings and umbrella seals are not seals, they are oil deflectors. The only true valve stem seal is a positive type with spring wire holding them tight to the guide with a semi tight fitting lip seal.

The o-rings keep the oil that runs down through the valve keepers off the stems. Most valve keepers butt right up to the o-rings.
The umbrella seal does just like an umbrella does, it deflects the oil ( or rain ) out away from the stem but doesn't actually seal to anything. Oil mist and splash still reaches the stem. If the umbrella seal sticks to the stem and rides up and down with the valve, they can cause more oil to enter the guide because the umbrella is catching and funneling the oil right to the guide.

A positive seal meters the amount of oil to the stem as long as it's in good shape, but like all seals in an engine, they loosen up with age.

The stem to guide clearance is way more important than the seal type.

65+ years of building engines from stock to all-out competition has made me an opinionated old fart- - - - -but my competition engines win races, and the street engines I build usually last about three days past forever. No, I don't do race engine stuff on street engines- - - - -that's stupid squared!
Jerry