I got my hands on a '55 331 Hemi. I'm going to build a pretty basic motor--stock compression with a little cam. A few guys have told me I absolutely have to have hardened valve seats installed. A couple others have said absolutely not. What do some of you hemi builders out there think?
I don' have any hemi specific knowledge, but I can tell you that non hardened seats will wear out at an acclerated rate with unleaded gas. (The Lead was a lubricant) If you drive it 100 miles a year its probably not a problem - but if it's gonna be a driver it certainly will.
Ummmmm..... I thought they came with "hardened seats",or inserts of a different metal than the parent metal.
I believe they had some hardended seats, or at least most did. Check the link to the HEMI Tech stuff in my signature. There is some discussion there. Maybe check the heads section or the section talking valve train components. Good luck! Keep us posted on the build and take some pictures. I'll included it in the Hemi section. Scooter
I wouldn't use hardened valve seats unless I found out that I had to. They DO come loose sometimes, and will usually destroy an engine when they do. ALL GASOLINE was Unleaded gas for many years in the early days. There was a time when ALL engines had to run on unleaded without seat inserts. Not all cast iron heads are equal. I have run tens of thousands of miles per year for decades without using seat inserts in my Studebaker and Packard engines. I do my own valve jobs every dozen years and never had any problem. Believe me, I am very rough on them. I run them hard, rev them high and tow a lot. Those are exactly the situations where the experts say I MUST use seat inserts. nope.. If you had a later Ford, or a Chevy soft-block, or any of the newer engines, I would understand and recommend hardened exhaust seats for sure, but if you find out that your engine was built with the old-style ways, I wouldn't hurt the heads by cutting into them for seats until I found out that I absolutely had to. Long ago, the car manufacturers used a harder, tougher cast iron that was harder to machine than later iron. They used to set the castings outside to season a bit before machining. Later when the machining started, the tools were sharpened regularly during the production process. Years later, the common practice was to skip the seasoning, make the iron softer (and the castings thinner at the same time) simply for making the production lines run better, and to get longer tool life between sharpenings. The softer iron didn't matter all that much because of Tetra Ethyl Lead, the new chemical that was being used in fuel to raise octane ratings. The lead additives helped softer iron seats survive, so cast iron hardness wasn't as important anymore. Now we must go back to the days before Tetra Ethyl Lead was introduced. If your engine was made with the old school thinking of more nickel in the iron, higher quality even if it cost more, and all gas was unleaded, then seat inserts are not needed. If your engine was made with the more "modern" philosophy of easy production-line machining, then you probably have a softer iron and will need seat inserts. I would suggst you do some research with some Early Hemi guys. I have the impression that the early Hemis were made with the old school design thinking, and had the harder cast iron just like older Chrysler, Packard, Stude, and many others used before the days of leaded gas. Others may argue, but this is my thought on the matter.
I was just back home and chatting with a dyed-in-the-wool HEMI guy, has had them all from 241's in 54 Royals to 71 426 HEmi Challenger....I mentioned that I was going to look into a 3 angle and hardened insterts on my 55 270 HEMI. HE emphatically said NO ! He has built or worked almost every engine that anyone on this board would drool over... Just as previously mentioned, the seats can work loose, and cause major damage. As well, he said the metal was much much better and I could sleep peacefully. I trust his advice. I'm not cutting them out. My 2 cents, Derek
'55 chrysler 331 hemi heads (the 1556157 "triple five" castings)should have hardened seat inserts in them from the factory.
NO you DO NOT need hardened seats in ALL old cylinder heads. A lot of heads are not thick enough inside to handle the seat insert. If you are lugging the engine it makes a bunch of exhaust heat. If you were buildin' an old MGB 4cyl then I'd use seats. Like "dare" said in his post "I would not cut for seat inserts until I had to" Have fun,Smokey
If it's got the original heads on it, it's already got factory hardened seats. At least that's what the books say, and what I found when I pulled the heads on mine....
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