140 Head Differences

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billb1561
Posts: 3
Joined: Sat Jul 16, 2016 6:41 pm

140 Head Differences

Post by billb1561 »

whats the difference between a 65 and 66 140 head?
Clarks has a used part listing and they are listed separately.
Bill Blanchard
Marietta GA
65 Monza Converible
skipvair
Posts: 248
Joined: Sun Apr 30, 2017 8:17 pm

Re: 140 Head Differences

Post by skipvair »

Probably shouldn’t pretend to know for sure, but I understand a large part was upsizing yapped holes on the top to accommodate the air conditioner option offered on 66 but not available on 65.


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Frank Metasavage

65 Corsa 140 4 speed with Weber IDAs
66 Corsa 140 4 speed Stock
Jerry Whitt
Posts: 887
Joined: Thu Sep 26, 2013 2:42 pm

Re: 140 Head Differences

Post by Jerry Whitt »

What is a "yapped hole"? Or do you mean "tapped hole" and just hit the wrong key?
Jerry Whitt
ASE CERTIFIED MASTER TECHNICIAN
Retired
Hemet, Callifornia
65 Monza, purchased new
65 Corsa convertible
66vairguy
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Joined: Tue Dec 21, 2010 3:44 pm

Re: 140 Head Differences

Post by 66vairguy »

billb1561 wrote: Wed Jan 31, 2018 8:27 pm whats the difference between a 65 and 66 140 head?
Clarks has a used part listing and they are listed separately.
The 65 model year 140HP heads are a one year only and have a different casting number. The 66 model year casting was revised to add material were the 66 model year A/C bracket bolted to the head. A/C was NOT available on any 140HP engine during the 65 model year.

For years the head change was speculated about, but finally it was linked to the addition of A/C to the 140HP engine. To clear the carburetors the A/C compressor bracket was unique to the 140HP engine and moved the compressor further away from the engine block increasing the leverage force of the compressor on the head.
skipvair
Posts: 248
Joined: Sun Apr 30, 2017 8:17 pm

Re: 140 Head Differences

Post by skipvair »

"Yapped" holes is obviously the Iphone auto-correct version of the word "up-sized" I believe several of the tapped holes went from 5/16" to 3/8" for '66. I apologize for not editing my previous post.
Frank Metasavage

65 Corsa 140 4 speed with Weber IDAs
66 Corsa 140 4 speed Stock
notched
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Location: Southern New Jersey

Re: 140 Head Differences

Post by notched »

The 65 heads have a casting # that ends in 728. These can be identified by the 1/4-20 bolts retaining the fan shroud to the top with one 3/8-16 at the rear end on the left side and front end on the right side.
The 66 heads have a casting# that ends in 570. I have seen service replacements for these heads with 864 stamped on the ends. These can be identified by all 3/8-16 bolts retaining the fan shroud.
Also there were reinforcements added around 3 of the 4 head stud holes in the heads. You can see this easily with the end shrouds removed by looking at the front of the left side head or the rear of the right side head. The 728 heads will have the upper head stud visible. The 570 heads the upper stud would be enclosed by the additional material.
There are also revisions to all of the head castings using numbers for example 70A, 71A, 72A, etc. The higher the number, the later the casting and of course and update to the original casting.
1966 Corsa turbo
1969 Monza convertible
1987 Buick Grand National
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