Page 289 of High Performance Parts for American V-Twins 2008 by S&S Cycle

1958-2008 50th ann iversary s&s® performance replacement cylinder heads for stock displacement 1984 99 big twin engines put some snort back in that old hog sometimes in our quest for more and more performance we don t pay enough attention to the guys who for one reason of another don t feel the need to go extremely fast and are satisfied just going very fast we re talking about the kind of riders who think a few more horsepower would be cool but not at the expense of reliability or engine life in the past the most compelling reason to install s&s heads was to increase performance more power but today there are a lot of high mileage stock harley-davidson® evolution® engines out there that are in need of some tlc the owners of these machines are faced with the prospect of an engine overhaul and like everyone they want to get the most for their money more than likely they re thinking that while they re rejuvenating the old hog they might as well build in a little extra performance at the same time it might make sense to install a stroker kit instead of rebuilding the stock lower end maybe now is the time to put on a set of s&s heads instead of having the stockers rebuilt and ported stealth s&s performance replacement cylinder heads sport only one s&s logo perfect for a sleeper hog tailored for stock displacement engines to satisfy the needs of these riders s&s offers performance replacement cylinder heads for 1984 99 big twins these new s&s heads were designed specifically to be an out of the box replacement part for smaller displacement engines and to provide a significant performance increase to boot applications include stock displacement engines stock bore strokers and big bore engines up to 96 valves and ports intake valves in the performance replacement heads are smaller than those in s&s super stock® heads but slightly larger than stock intake valves this results in better than stock flow but maintains intake velocity for good low rpm and midrange performance the exhaust valves are actually smaller than stock but the port design allows these heads to out-flow stock heads by a wide margin see the flow comparison chart on the next page the intake ports are the same size as the ports on stock evolution® engines so the original manifold bolts right on needless to say it works even better when an s&s high flow manifold is installed the exhaust ports are also stock diameter and are compatible with stock or aftermarket exhaust systems the advanced design of the intake and exhaust ports allows these stock diameter ports to flow significantly better than the ports in a stock cylinder head and nearly as well as the larger ports in the s&s super stock cylinder heads see the flow comparison chart good flow in a smaller port results in higher port velocity this results in better torque in the all-important low and midrange rpm all in all we feel that is the perfect set up for the vast majority of street riding applications combustion chamber the most noticeable feature of the s&s performance replacement heads is that the combustion chamber is designed to be used with stock and other flat topped pistons this allows them to be used in stock rebuilds as well as in a number of performance applications using flat topped pistons the 76.5cc combustion chamber volume is slightly smaller than stock which gives a slight compression increase from the stock 8.5:1 to 8.8:1 in an 80 engine a 96 engine with performance replacement heads will have a healthy but manageable compression ratio of 10:1 the slight increase in compression gives the engine a little more attitude and improves the effectiveness of most performance cams if even higher compression is desired the heads can be decked an additional .060 which will reduce chamber volume to about 73.6cc this translates into 9.5:1 compression ratio in an 80 engine and about 11:1 in a 96 order toll free 866-244-2673 8-6

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