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Old 02-24-2014, 11:21 AM   #21
Ski in NC's Avatar
City: Wilmington, NC
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True, bolt torquing is a complicated topic. I've done some calculations when I was in industry, and what seems simple on the outset can blossom into complexity. No need to go into that here!!

A few more details: A bolt can be examined for stretch (yield) using a simple (yet crude) technique. Mesh the threads of subject bolt with a new bolt- if light is seen through the threads, there is yield. Since most bolts do not engage all their threads, the yield will be above the engaged threads. On that Lehman, the bolts showed no evidence of yield, so they were re-used.

Another trick I used was to measure valve lash before I started. After retorque, the valve lash was reduced significantly (don't remember how much) so that indicated the head was pulled down. Note that valve lash changes as a multiple of head movement, depending on rocker arm ratio.

Need to reinforce that valve lash does need to be checked after retorque, as lash does tighten up. Some manuals are not explicit in that.

Thread lube is super critical. Follow those instructions. If manual specs oil, use oil. If it specs moly lube, use it. But DON'T use moly if oil is spec'd!! If lube is not discussed in manual, I use engine oil. I don't remember what the Ford specs were.

Dry threads are near impossible to get in a head job. There will always be a trace of oil in the bolt hole unless heroic steps are taken to clean it out. It takes just a trace of lube to change the friction coefficient.

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Old 02-24-2014, 11:39 AM   #22
psneeld's Avatar
City: Avalon, NJ
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Thanks again..will keep it all in mind...pretty aware of the lubed/non lube torques but will have to look them up/call around I guess...

Correct about the "dryness" of anything but a boiled block..but I'm sure somewheres close is the best many of us do anyway.

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