With flat top pistons, the 67 cc (Casting 1557582) will give you about 9.0 compression and the 54 cc's ( Casting 1557570) about 10.25 or with dish 289 pistons about 7.5 and 8.5 respectively with the beaded steel head gaskets.

The 67 cc's ( Casting 1557582) came on some trucks also and the 54 cc's ( Casting 1557570) were on most of the '63, and '64 cars and a few of the '62's.

  Casting 1537555 = 8.0 used on '55-'62 with composition head gasket and about 54.5 cc>

Index

Casting 1557582 = 7.0 supposedly used on some trucks and are also the R 2 with 67.7cc

Casting 1555294 =7.75 used on '62 with the composition head gasket

(Note 1) Casting 1557570 = 8.25 used on very common '63 and '64 with the beaded steel head gasket and also
Used on the R1 engines and have about 54.5 cc but also heard one time they
were 58 CC but I think the 54.5 is closer.
1557570 the '63-'64 Lark, Hawk 259 & 289 and R1 Avanti casting number Head. Ref . (29222107)

Casting 1557581 = 8.0 and also used on '63 and '64 but with the composition gasket

The beaded steel gasket will give almost a half point higher compression
ratio. The beaded steel is about .017" thick and the composition about .045 (compressed).

Ted Harbit (Oct 99)

It can be read without removing anything , except maybe dirt. It is not the part number you find in the books, but it is what most of us use to identify matching pairs of heads.

Except for the very uncommon R2 heads (582, which have big combustion chambers), the uncommon 1951 to 1954 232 heads (really tiny valves), and the super-rare tall-port R3 heads, ALL the rest (976, 570,555,etc) are pretty much the same- mid-50's cc's, same valves, etc. All the different compression ratios in the books were a function of stroke, and different piston dishes as much if not more than the small variances in head cc's.

Index

535976 heads were about 8.0 with beaded steel gaskets. These were used
on the Golden Hawks (exc 56J) (among some other models including Export) and
with the composition gaskets were about 7.5. compression with Composition
gaskets and some trucks and were about 56.5 cc

Index

1557570 heads (used on most '63 and '64 and are R 1 heads) and 1555294 were about 8.25 with the beaded steel gasket. The 1557570 used with flat top pistons in the R 1 give 10.25 with the steel gasket.

1557582 heads were about 7.5 with beaded steel (These are R 2 heads that give 9.0 with flat top pistons).

The 537555 and 1557581 have about 54 cc chambers and the 1557582 heads had the most at 67.7 cc's.

These figures should be about right for all 259 engines and the 289's with dish pistons. And you can vary the compression on the 289 since you can get "cup" pistons that have about half the cc's as the dish pistons (or flat tops if preferred).

I think I have these right. Ted

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Casting # 1557570 is part # 1557571. It was used in most R1's. With the flat top pistons, and head gasket 1545072, it gave a 10.25 : 1 compression ratio. It was the "standard" R1 head in the sense that almost all R1's came with it. It was also used with dished pistons in other engines. Casting # 1557582 is part # 1557580. It is shown in the Dec. '63 Avanti parts book as the R2 head; and also "spec. order" on R1's. As used, R2 or R1, it gave a 9: 1 compression ratio. I've read it was used in lower compression trucks, too.

On some lists of head #'s, (John's, if 1557580 is a part #), the lower compression, (9 : 1), R1 is listed as "standard".
Mike M. Jan 2006

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I only have two different OHV head casting numbers in my files, there may be more that I haven't found yet. The casting numbers are at the rear of the head between two head bolts. One would have to remove the valve cover to see them.
1550582 is the most common and was used from 1961-63. The heater hose outlet is at the left rear on this head. 1560959 is a 1964 head, and has the heater hose outlet at the left front.
The date code is also under the valve cover, but at the very front. The 'P' you saw was probably part of that date code. Should have been a couple numbers there before the letter, but sometimes they get ground down during the machining process.
jdwain@gmail.com Oct 2007)