Check out these
https://www.ebay.com/itm/26455...

...hmmph...

Notice the INSTR read 1954-1955 and for use on intakes only. Could have been released in 1955.

NOTE TO SELF - huKt oN fONIx - Wurx 4 mEE
Text reads if used on intake only -




FORD racing teams of that era must have known the quality problems and had to use performance rockers.

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Here is a post excerpt I saved some time ago. I believe it was TED EATON who posted it. I usually source them but I seemed to have not on this one -

... we have been led to believe ECG 6564-A2 rockers were all 1.54 ratio. Usually they are, but as Ted points out & also John Mummert in an article in issue # 83 of YBM, a few aren't. According to John, another way to confirm the difference on the similarly marked rockers, is to note that the 1.54 s have a small 3-digit number near the adjusting screw. The 1.43 impostors have a single digit number. Just another nuance to try and remember.

Also, I believe the numbers being referred to are CASTING MOLD ID NOS.

Rocker Arm Comparison - 5751066 @ TOP - ECG-6564-B2 @ BOTTOM

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Check out these

https://www.ebay.com/itm/264559710542

I have a number of rockers simply marked " made in USA" on one side and a letter on the other with interference type adjusters that measure .250 on the adjuster side. No Ford script, no part numbers that appear to be high ratio by our measuring standard (.250) and later model by our interference adjuster. Is anyone aware of high ratio after market rocker arms?? This has become progressively more intriguing and my A2s are 1.43s by the .320 or so measurement by me. So I I fact seem to have all the 1.53s I need! Who knew??? MIKE

Mike, still lovin his 57 t'bird after 53 years!

Kultulz, I picked a random A-2 rocker arm out of my stash.  The OAL length is 2.950" and a 15/64" drill bit is a tight fit between the rocker body and the ball on the adjuster screw.  I guess I should have compared it to a B-2, wasn't thinking.

I really appreciate that!

Do you have a B2 arm to compare? Can you lay them A2 top and B2 bottom to photo to make a eye comparison? Was the adj screw two piece? If you have a B2, two piece or one piece? The change(s) may have been gradual.

Rocker Arm- Casting ID No _3 - ECG-6564-B2 - 5751066


I believe this comparison photo is TED's.

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Kultulz, I picked a random A-2 rocker arm out of my stash.  The OAL length is 2.950" and a 15/64" drill bit is a tight fit between the rocker body and the ball on the adjuster screw.  I guess I should have compared it to a B-2, wasn't thinking.

John - "The Hoosier Hurricane"

If that's the case, then the article in Y Block Magazine is wrong.  The later 1.43 rockers (after 58 I guess) started with or had  575

I am not privy to the magazine and cannot read that tech article.

What I am going by is that during the 1956 production run, a lot of modifying was done on the valve-train. It seems to be around when FORD  put the 312 in the PASS CAR. One was the change in rocker arm ratio and adjustment screw design.

Going by SERVICE PN only in the period MPC and chassis catalogs, the first PN was B6A 6564-A and the later B6A 6564-C. The MPC also shows the B6A-A was the service replacement for the 54/55 EAN which is 1.43. The late 56 and 57 engine had the 1.54 ratio and the ratio went back to 1.43 in 1958.

The seven numeric character you see on the later arms are part of a PN System used briefly 1958/59. The Service PN was changed again in 1960 (C0AZ 6564-A) which was a 1.43 retro-fit for all FYB.

Without the SERVICE BULLETINS and PRODUCTION LETTERS of the period most info is incomplete and/or conjecture. This is also why one engine will have a multi-use of rocker designs on it.

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If that's the case, then the article in Y Block Magazine is wrong.  The later 1.43 rockers (after 58 I guess) started with or had  575





54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

EAN rockers are 1.43 ratio rockers.  The ECG  rockers are the 1.54, either lock nut (A2) or interference (B-2)

Someone who actually has an ECG-6564-A2  rocker arm needs to measure the OL and drill bit size as described by Ted to nail this down. I think A2 is going to be 1.43 while the B2 is 1.54.

____________________________

So the saga continues. With Ted's help another member of this site was generous enough to try to send me the rocker arm I need only to be foiled by the ineptitude of our U.S Pistal Service. Yes the envelope arrived tracking number and all but EMPTY! The shipping envelope had opened in transport and they delivered an empty envelope! Maybe this is just not meant to be. Mike

Mike, still lovin his 57 t'bird after 53 years!