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Aluminum Cylinders
| From:
Stan Jessup
I just spent an hour on the phone, talking with a fellow who just bought a set of aluminum Chief cylinders. He had been told of "multiple failures" with them by several people. Michael Breeding talked to him at some point and gave him my name since he knew I owned a set. Michael did the smart thing; send the guy to the source. So, since (to my knowledge), I'm the only one in North America that has actually RUN a set of these cylinders, here are the facts, and the myths. The issues to be addressed before installation are: Clean up some of the machine work. Provide clearance sufficient for the valve covers. Install thread inserts for the head bolts. Fit to cases to provide base clearance at the peak of the base deck. Normal hone fitting of pistons. The failures I've had (and haven't had) with them (and the causes): 1) Blown head gasket. Caused by a poorly installed set of bolt inserts coming loose, and use of the wrong style of gasket. I share blame for this with the guy that put the inserts in. 2) One intake seat popped out of the machined recess. The machinist or manufacturer that set it has to take the blame for this one, as it was a poor interference fit originally. The new oversize seat works great (fit properly). 3) They are noisier than iron. This should be expected. Aluminum transmits sound better than dense iron. Normal valve noise is more pronounced than it is with iron cylinders. 4) Valves need constant adjustment because the cylinders will 'grow' when hot. FALSE. I checked them daily on the Century Ride just to make sure this wasn't going to be an issue. 5) They will warp. Can't prove that by me. They have over 5000 miles, and they aren't warped yet. 6) They need to be through bolted. There is no evidence to support this in a low compression flathead. I only blew one gasket (see #1).. Since changing the inserts and repairing the one valve seat, standard fiber gaskets are working just fine. In fact, they also worked with the weak inserts. I bought these as an interesting experiment. As with anything untried, there is a learning curve involved. I've tried it, and although not everyone will want a set, I would never say they were a failure in any way. I hope that will clear up some of the misinformation on this. If no one wanted to try new things, there would be no such thing as reproduction parts. Rob Olsen is currently making aluminum cylinders for Hendersons. I guess he has the vision to understand that, if you don't try it, you can't say it doesn't work. Go for it Rob! ------------------------------------- From: Thomas C. Cotten I would add that the honing step should include bolting on stressplates, at least to the base. If solid cast iron moves from fastener torque, then sleeved aluminum would probably move even more. ------------------------------------- From: Jerry Hatfield (-on the Starklite mailing list, where Stan also posted his initial message above. Peter Arundel is the manufacturer of these cylinders, but only made 5 sets and so far hasn't been interested in making more) My friend Peter Arundel, of Melbourne, Australia, runs a 1936 Chief with aluminum cylinders. He has had either no problems, or, like Stan, has long since ridden out the learning curve. It's amazing to pick up one of these aluminum cylinders right after picking up an iron cylinder. There has to be a performance improvement simply from the weight savings. ------------------------------------- From: Rob Olsen Currently I have a set of aluminum Henderson cylinders running on a bike in NC. These cylinders are certainly differnt in that they have no liner but use a nicasil coating like Porsche and BMW use, I needed to use this method as I wanted the savings in weight, better heat transfer and nicasil provides a surface that is slicker and stronger than any sleeve. In order to hone nicasil one must use a diamond hone. In addition piston skirt coatings, with a cam ground piston I was able to use a wall to piston clearance of only .002". BMW uses .0015" but I thought I would give it an extra .0005" for experimenting. So far I have noticed a minor change in growth, but have been experiencing some difficulties with locknuts on tappetts so I can't tell at the moment if I'm having cylinder growth of .0025" or locknut difficulties. These cylinders cut 26lbs off the engine and change the handling. For some reason the torque reaction seems more pronounced, and when cornering throttle-on, has a gyroscopic effect. I suppose this is due to the loss of weight on the upper part of the motor. The engine runs effortlessly and I have rolled it up to 80 mph and crused between 65 and 80 for 100 miles and about 10 other short trips of about 50 miles each. I'm using Mobil 1 15/50 at the moment and about to change to the new 20/50 I have yet to open it up other than in the shop, on the stand. When I first fired it up I opened the throttle, wide open on the stand for 2 minutes looking for something to blow apart. The original cylinders have a dismal 4.6 to 1 comp ratio and in changing Ricardo's combustion chamber design I managed an almost 6 to 1. I chose a thermal dispersant coating as opposed to paint to dissipate as much heat as possible. These cylinders are about to go on a 3000 mile shakedown cruise in an attempt to look for any weak areas that need to be addressed for longevity aspects. The throttle response is very positive (some of this I'm sure has to do with Cotten's floats) but I did port and polish both the intake area and the exhaust port. My current limitations are the intake manifold but I'll address that sooner or later. I have lots more work and experimenting to do with them to extract more including flow work, and more work on the exhaust port. Currently studying cam design for both Henderson and Indian 4, and am starting some pattern work on Indian 4 cylinders, 38 to 42. Stan is so right in statements about trying new things, There is a huge feeling of satisfaction about trying something and having any type of success, but I'd like to add that the only time you fail is when you quit. I appreciate the encouragement Stan, Ride long and fast eh! |
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¤¤¤ ¤¤¤ Related Links: Stan Jessup's Oregon Vintage site Michael Breeding's Indian Parts site |