Posted 2017-02-09 1:42 PM (#533612 - in reply to #533605) Subject: Re: 301 vs 318
Expert
Posts: 1506
Location: Colo Spgs
Hola John
The first series of the A-277 to A-318 ( 1956 to 1966 ) Engines have a Three Hole Valve Tappet Cover. After a while it was realized that Two Holes would hold the Valve Tappet Cover to the heads and the 3 hole design --- went away.
The bolts used are: 5/16 x 18 x 2 . They all use a little Flat Washer - with a Rubber Seal.
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The "newer cover's" have The Wiring Loom Spot Welded vs being bolted.
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Every set of heads still have The Thread Bolt Holes.
Posted 2017-02-11 11:11 AM (#533750 - in reply to #533747) Subject: Re: 301 vs 318
Expert 5K+
Posts: 9679
Location: So. Cal
I think you have it backwards. The 3 hole is the earlier style. My original '56 Plymouth 277 has 3 bolts, and it was produced only 1/2 year before the 301.
Posted 2017-02-11 2:28 PM (#533764 - in reply to #533605) Subject: Re: 301 vs 318
Veteran
Posts: 100
I that 3 bolt i showed you is a 1962 318 poly. 318 came after 301 right. The 2 bolt is an original 57 301. I think what we are seeing is different factories using up parts.
Posted 2017-05-07 1:56 PM (#539611 - in reply to #539610) Subject: Re: 301 vs 318
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Location: Lower Mainland BC
Powerflite - 2017-05-07 1:39 PM
That's a California pollution control requirement that was installed on it.
Okay. A "C.A.R.B." requirement. Do you know whether that was done at the factory or after the factory? Regardless, I guess only for California-destined cars.
Posted 2017-05-07 7:37 PM (#539633 - in reply to #533605) Subject: Re: 301 vs 318
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Posts: 9679
Location: So. Cal
The PCV system requirement was put into effect in 1963 in California, and the older vehicles were retrofitted with it. PCV systems were required on new cars in the rest of the United States in 1968.
Posted 2017-05-17 4:41 PM (#540259 - in reply to #539608) Subject: Re: 301 vs 318
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Location: Oley, PA
56D500boy - 2017-05-07 1:10 PM
Off-topic but sort of related: When did the valve cover ventilation begin? Seems like 1956 would be too soon. Is this a later retrofit?
PCV valve was first offered by Chrysler for the 1961 model year. It was standard equipment on all new 1961 model cars sold in California and offered as an option in other states. By 1964 it was standard equipment in all 50 states.