I saw an article that mentioned using double springs, Chevy valves and hardened seats on an 1800 head. I have a 122 with a B18 engine and wonder if there are any advantages to this? What valves, seats, and springs are used? My engine has no compression on the first cylinder, and 150 lbs. on the other cylinders.
Kim Kepchar
kkepchar@davidson.alumlink.com

Phil says: I've heard of Chevy valves being used in Volvo motors in racing applications, but I don't know the specifics of it, so we'll put this down as a "no clue." Let's accept the idea, though, that any valves of the desired dimensions and material could be used. I doubt that the valves currently in your motor say Volvo on them. I imagine that valves suitable for a custom-built racing motor just happen to coincide dimensionally with one of the large variety of valves used in Chevy motors; ergo that terminology.

Hardened seats are a must whenever valves are replaced or ground if one intends to use unleaded fuel. Double-wound springs may be useful in conjunction with a steep cam grind at high RPM, such as those supplied with ipd's cam kits (Iskenderian springs originally intended to fit a Buick V-6, I believe, and solid lifters common to a number of GM motors).

The simplest and most economical course is to rebuild your motor to stock condition. If you'd like more power -- and less economy, both during and after the rebuild -- there are many other things you should do before resorting to changing valve size.

David suggests that you start off by having a leakdown test performed to find out why there's no compression on one cylinder. Simply taking a look under the valve cover may also be revealing.

Answer from a Swedish expert: Valve spring force, as in required, is mainly a cam design issue! Any cam profile is normally designed with a specific valve opening / closing motion in a certain RPM range and, epecially, with a certain valvetrain mass / weight in mind. More valvetrain mass creates more valvetrain inertia, i.e. [it becomes] more difficult for the complete valvetrain to follow the intended valve motion. Thus, adding more mass is a "no go" alternative.

If the valvetrain does not need more spring force, added spring force just adds unnecessary valve train wear. Double valve springs do typically also add mass to the valvetrain...

There is no need to introduce US-oriented parts -- there are proper and well-engineered purpose-made aftermarket parts available which will [give you] the desired performance.

A sad thing with some of the well-known "race" cam kits is that they suggest heavier valvetrain parts than OEM, typically concerning the lifter. I suggest this is very poor engineering...

The obvious and best [solution] is to have a lighter valvetrain if increased RPM as well as valve acceleration is intended! By the way, the OEM valvetrain does have some margins in this department, as well.
M.Aaro
m.aaro@mail.bip.net