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By PF Arcand - 10 Years Ago
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Have others found the following problem? I have here two sets of 1956-57 ECG rocker arms c/w the later one piece interference type adjusters. One set was a swap meet item & basically the rockers were worn out, and the adjusters were frozen in them. The 2nd set came off a set of ECZ-G heads that were stored in doors for years & were still oily & not rusty. But, the adjusters in them are also almost impossible to turn. Even using penitrating oil & holding them in a vice, they barely turn with an 8" spanner. So, I referred to Eickman's Y-Block book, & am now totally confused!. His illistration shows the early 1.43 rockers c/w the one piece adjusters & the ECG's with the jamb nut style! And makes various references to part #s but not to casting numbers, which isn't too helpful. Further, is there any way to I.D. the oversize thread adjusters that were available at one time? Is this a common problem?
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By Ted - 10 Years Ago
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Here are some general guidelines I use for the 1.54:1 ECG rockers. The 1956 rockers had the locking jam nuts along with the conventional 7/16-20 free moving threads. The tops of the rockers around the adjuster will be spot faced or machined flat for the jam nuts. For 1957, the rockers went with the interference fit thread design and did away with the locking jam nut. The tops of those rockers do not have that machined flat spot. Converting the later model interference thread design rocker to the jam nut design is as simple as rethreading the later model rocker with a 7/16-20 tap and using the earlier model jam nut style adjuster.
The interference threaded adjusters requiring a ½” wrench are the standard threaded diameter while the adjusters taking a 7/16” wrench would be the oversized units. 0.003” seems to be the number most often referred to as to the amount of oversize for the replacement adjusters.
Here are some past threads on the subject.
http://forums.y-blocksforever.com/FindPost47371.aspx
http://forums.y-blocksforever.com/FindPost98318.aspx
http://forums.y-blocksforever.com/FindPost106489.aspx
http://forums.y-blocksforever.com/FindPost107597.aspx
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By PF Arcand - 10 Years Ago
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Ted, thanks for the information.- A somewhat confusing subject to say the least.. It would appear that I've had the bad luck to end up with two ECG rocker sets, that are 1956 vintage, (the adjuster ends all appear to have machined tops) but someone has tried to convert both to the interference fit adjusters, which would have been nice, but the threads are wrong & they are virtually impossible to adjust.. It goes back to that old saying, "If anything can go wrong it will "...
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By DANIEL TINDER - 10 Years Ago
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Unless the added weight is an issue, in my opinion the best configuration is a combo of jamb nut AND interference thread type hex adjuster, since the action of tightening the nut always seems to change the lash setting on earlier rockers (time consuming, especially with the slotted screw head), and frequent adjusting of those without the jamb nut will eventually wear out the threads, making it impossible to maintain the clearance setting.
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By PF Arcand - 10 Years Ago
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Daniel: Interesting idea, but in this case it won't work, because the rockers are apparently early 56s & the fitted interference adjusters simply will not turn, period..
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By 57RancheroJim - 10 Years Ago
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I may be wrong but I thought the interference thread was in the rocker arm not the adjuster? I would try adding a little heat like a small propane torch to the rocker and use a longer then 8" wrench and try to break it loose.
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By Ted - 10 Years Ago
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57RancheroJim (6/16/2015)
I may be wrong but I thought the interference thread was in the rocker arm not the adjuster? ...
The interference thread design is in both the rocker arm and the adjuster. It takes a 7/16-20NF tap to clean up the interference threads in the ’57 and up rockers so that an early locknut style adjuster can be used.
Here’s some technical information on the interference threads as there are different amounts of friction that can be built into the threads.
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By PF Arcand - 10 Years Ago
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Just to clarify, I have set of 1956 ECG rockers that have been retrofitted by someone with the later interference fit adjusters (I didn't realize this when I bought them). Doing that has rendered them unuseable as they are essentially jambed. Apparently, my options are to buy another set of complete 1957 ECG rockers & likely rebuild them, or buy & refit the existing earlier rockers with the proper 2 piece adjusters. "If" I had a complete set of 1957s in good working order, I wouldn't be trying to refit them with the early more awkward to use, 2 pce adjuster setup. It was my intention to have a rebuilt set of 1957 rockers available to use on replacement 1957- G heads that I plan to have rebuilt soon for my car's engine.. (my 57 car has 1956 heads on it that are apparently not in good shape) Best layed plans go astray. My 3rd option I guess, is to take my car's engine out of service for a period & have it's existing 1957 rockers refurbished & use them...Anyway, thanks for everyones input on this somewhat confusing situation.
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