Valve Springs
07-10-2012, 03:55 PM
#1
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Valve Springs
So I'm looking into changing my valve seals and was planning on swapping out valve springs (never been done according to last owner and has 190k) and spark plugs at the same time.
I was just wondering which valve springs you guys would recommend? I saw different strength springs
Also, since I'm new to mechanical stuff, my old man mentioned that if I use a compressor I'll need to turn the engine depending on firing order, was wondering how one would go about doing that?
Been looking around on search and haven't found my answer so far..
I was just wondering which valve springs you guys would recommend? I saw different strength springs
Also, since I'm new to mechanical stuff, my old man mentioned that if I use a compressor I'll need to turn the engine depending on firing order, was wondering how one would go about doing that?
Been looking around on search and haven't found my answer so far..
07-10-2012, 10:05 PM
#2
Re: Valve Springs
A lot depends upon the year of the engine. Older engines used plain square ring seals which are pretty ineffective at sealing oil and don't seem to have a very long life. Newer engines have retained umbrella type seals which can be more effective but can still fail after a lot of years/mileage.
If you are planning to replace valve seals with the heads on the engine (in car) you will have to retain the valves in order to remove the springs, providing access to the seals. You can use compressed air to hold the valves in place if you have a spark plug hole adapter and constant source of compressed air. Another method is to feed a length of braided nylon rope into the cylinder through the spark plug hole and then turn the engine by hand to compress the rope against the valves. This usually works reasonably well since the limp rope tends to fall downward to the lower (valve) side of the bore.
In either case, a spring compressor will be needed to release the valve keepers and allow the spring cap (retainer) to be removed. Once the spring is removed the seal can be removed and replaced. If you have a newer engine with umbrella seals you might want to find teflon seals designed to replace the stock parts (with the correct guide size).
As for replacing the springs, the year of the engine is again a key factor. Older engines with a flat tappet cam may not tolerate heavier springs very well. Newer engines with roller cams might benefit from upgraded springs but be certain of the compressed height and seat pressure, as well as the inner and outer diameters of the spring sets. Stock spring seats are usually smaller than most aftermarket springs, and aftermarket springs may require machining of the spring pockets and guides to provide adequate clearance.
So, what engine do you have? What head casting numbers?
If you are planning to replace valve seals with the heads on the engine (in car) you will have to retain the valves in order to remove the springs, providing access to the seals. You can use compressed air to hold the valves in place if you have a spark plug hole adapter and constant source of compressed air. Another method is to feed a length of braided nylon rope into the cylinder through the spark plug hole and then turn the engine by hand to compress the rope against the valves. This usually works reasonably well since the limp rope tends to fall downward to the lower (valve) side of the bore.
In either case, a spring compressor will be needed to release the valve keepers and allow the spring cap (retainer) to be removed. Once the spring is removed the seal can be removed and replaced. If you have a newer engine with umbrella seals you might want to find teflon seals designed to replace the stock parts (with the correct guide size).
As for replacing the springs, the year of the engine is again a key factor. Older engines with a flat tappet cam may not tolerate heavier springs very well. Newer engines with roller cams might benefit from upgraded springs but be certain of the compressed height and seat pressure, as well as the inner and outer diameters of the spring sets. Stock spring seats are usually smaller than most aftermarket springs, and aftermarket springs may require machining of the spring pockets and guides to provide adequate clearance.
So, what engine do you have? What head casting numbers?
07-10-2012, 11:16 PM
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Re: Valve Springs
That was one hell of a reply.
I have a 91 305, not sure what the casting numbers are, I'm here to learn and other than an oil or brake change, this is the first thing I'm tackling
I have a 91 305, not sure what the casting numbers are, I'm here to learn and other than an oil or brake change, this is the first thing I'm tackling
07-11-2012, 07:59 AM
#5
Re: Valve Springs
Flat tappet lifters wear into the cam and the cam lobes are not as hard metal as the lobes on a roller cam. Too much spring pressure can push the lifter into the cam lobe too hard and wipe out a cam lobe or lifter itself.
IF its a 91 and a factory roller cam, I'd just drop in a set of comp 981 springs. Basic flat tappet spring that can work on factory rollers just fine too. You dont need much spring for a factory roller cam, they are very mild lobes.
IF its a 91 and a factory roller cam, I'd just drop in a set of comp 981 springs. Basic flat tappet spring that can work on factory rollers just fine too. You dont need much spring for a factory roller cam, they are very mild lobes.
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