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Thanks Ed, I’ll give that a try. Getting everything setup properly is important!

Jim

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“Back in the day’ I have read engineering papers indicating that in the ’30’s engines were re-rung without re-boring and the head “de-carbonized” at 15000 miles. Valves were also ground. Wear from airborn dirt with simple cast iron rings was the biggest contributor, so a city car driving exclusively on pavement would last longer than a car driven on country dirt roads. Tnis doesn’t mean they couldn’t go much longer than that and run okay. Loose, worn rings loose compression and leak more blow-by, make it harder to start, but have less friction at speed, and can still have good power. Full flow oil fltration helped some, but my reading has indicated the biggest improvement to ring/cylinder life was the chrome face top rings after WWII and the paper pleated airfilter in the late ’50’s. Chrome top rings were developed to give WWII tank engines better life in the desert. The dry pleated air filter was possible by the ’50’s because most of the roads were paved and the dust was reduced enough to allow a paper filter to have realistic life before getting plugged.

I find modern airfilters to reversibly retrofit to ’30’s cars to keep the wear down. I’m not into authentic wear.

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Dave, does this mean these are 40 durometer rather than the (very hard) 80 durometer I bought from someone years ago? (my original doughnuts I believe were marked 40 and were definitely softer).

thanks

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Bob Koch has requested by seperate email copies or references of the engineering documents I use to support my assertions regarding valve materials, stating "You adhere to several positions that are at variance with textbook and repair manual literature that I have." The report I refer to cracking valve seats being caused by knock does not address valve temperature directly but is an interesting insight into engines of the 1930’s. It is "Problems in the Development of a High-Speed Engine" by Sparrow in the SAE Journal volume 36, No. 2, 1935. It is available for a copying charge from SAE.

I didn’t intend to make this into a large technical dissertation, I just wanted to highlight the danger of knock being a cause of seat cracking and that the lower conductivity of modern aftermarket valves may contribute to the problem since hot exhaust valves promote knock. However, since questions remain I have written up a response that is too large to post on the forum, so anyone interested in my response as well as the original 1930’s engineering paper on valve seat recession can email me and I will fwd. My email is listed in the roster on this site.

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what part of the country are they located in?

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Curtiss, sorry I haven’t been on the forum for awhile. I haven’t actually tried this myself yet, but a while back I found a company that has convex glass lens’ in graduated sizes intended for clock repair from 2" to 15". The website is timesavers.com.

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