1957 Intake Gasket Followup

[Jimmy G.]

After doing some research I need some confirmation or denial of my theory. In 1957 all heads had small port heads that used a gasket that is approximately 1.75 x 1.087 on the intake runners. Later cars in 1958 used larger port heads and used a gasket that is approximately 2.0 x 1.275. It is possible that the later 1957 FI heads were large ports, I think but most 1957 heads are small.

Gasket sets with no ID bump and a square bump are small port gaskets. Gaskets with a round or triangle are the large port design.

Let me know your thoughtsIntake Port Size Drawing.jpg

[William C.]

Re: 1957 Intake Gasket Followup

Jim, the GM parts books call for the same part number for the intake gasket set from 1957-1963 except for the SHP 327 engines I checked references from 1957, 1963, and 1965. No indication of the 283 ever having "big port" heads until 315 hp in '61 with the introduction of the '461 series heads. At least based on a few sets I've owned, '57-58 intake runners were visually the same. NHRA may have a reference for total port volumes but I don't know that for certain, not do I believe it is accessable to the public. There was a noticable change in the intake runner starting in '57 when the 265 became a 283, coinciding with the introduction of the 3734115 (square protrusion) gasket set.

[William C.]

Re: 1957 Intake Gasket Followup

To add to the confusion, some pass cars had a 2bbl carb 265 inch engine installed. I think it was a 162 hp configuration. Seldom seen, but the only use of a small port (56-style) head in 1957. Might cause some confusion, but did not carry the pyramid on the front of the casting as I remember. Been over 45 years since I saw one...

[Gary C.]

Re: 1957 Intake Gasket Followup

Bill,

FWIW, the '57 265 was a regular 283 block with smaller bore IIRC. Don't recall the head configuration. Had several many moons ago and they were painted yellow.

Gary
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[Jim L.]

Re: 1957 Intake Gasket Followup

Bill,

FWIW, the '57 265 was a regular 283 block with smaller bore IIRC. Don't recall the head configuration. Had several many moons ago and they were painted yellow.

Gary
....

Yep, the '57 265 was made from the same "548" block as the 283, just a smaller bore.

Although there were a lot of yellowish and greenish '57 265s, not all of them were painted those putrid colors. This photo below is of a never-rebuilt, never-re-painted '57 265 made very late in the model year:


The heads have the plain rectangle symbol, as on previous 2bbl engines. However, the casting number was unique to '57 and my ( frequently untrustworthy) memory is the casting number ends in "554".

Jim