461 and 462 heads. What is different?
12-08-2009, 12:29 PM
#21
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[QUOTE=JohnZ;1572364234]
I can't speak to the 461 vs. 461X issue, but I know that Tonawanda never built any small-blocks with 2.02/1.60 valves (or solid lifters) - their head machining line didn't have the station for cutting the intake valve unshrouding area in the side of the chamber that was required with the 2.02 valves. That tooling only existed at Flint V-8.
That is a new piece of information to me. Thanks.
I can't speak to the 461 vs. 461X issue, but I know that Tonawanda never built any small-blocks with 2.02/1.60 valves (or solid lifters) - their head machining line didn't have the station for cutting the intake valve unshrouding area in the side of the chamber that was required with the 2.02 valves. That tooling only existed at Flint V-8.
12-08-2009, 12:43 PM
#22
Melting Slicks
[QUOTE=JohnZ;1572364234]
I can't speak to the 461 vs. 461X issue, but I know that Tonawanda never built any small-blocks with 2.02/1.60 valves (or solid lifters) - their head machining line didn't have the station for cutting the intake valve unshrouding area in the side of the chamber that was required with the 2.02 valves. That tooling only existed at Flint V-8.
Did any 462 heads, or later with the small chambers, have the intake valve unshrouding?
I can't speak to the 461 vs. 461X issue, but I know that Tonawanda never built any small-blocks with 2.02/1.60 valves (or solid lifters) - their head machining line didn't have the station for cutting the intake valve unshrouding area in the side of the chamber that was required with the 2.02 valves. That tooling only existed at Flint V-8.
12-08-2009, 01:03 PM
#23
Safety Car
[QUOTE=larrywalk;1572364891]
All heads manufactured by GM with 2.02 intakes were machined especially for them. GM NEVER sent any heads with 2.02 intake valves out the door unless the chambers around the intakes were plunge cut.
That said, by today's standards, GM did a fair job in unshrouding the valves. They still left plenty room for improvement.
That said, by today's standards, GM did a fair job in unshrouding the valves. They still left plenty room for improvement.
12-08-2009, 01:18 PM
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12-08-2009, 02:45 PM
#25
Drifting
[QUOTE=65tripleblack;1572362594]
Mike,
By "large valve head cast", I assume that you mean 1.94/1.50. These were the "big boys" which superseded the 1.72/1.50 power pac heads prior to late '61. Beginning in late 1961, the plain old 461 head, machined for "small valves" (1.94/1.50) was used for all other Corvette engines. The "big valve" (2.02/1.60) 461 head was used beginning in 1964 for the SHP engines.
I thought production 1961 Corvettes used 461X only, starting in September of 1960. the other production engines for 1961 used the same heads as the previous year, "power pac", that hosts the smaller valves. There were no 461's non-X heads used in 1961. The 461's non-X heads were not introduced until the next 1962 model year, and were used on every engine. Both heads are 1.94 int & 1.50 exh. with the exception 327/360 fuelie used the 461X heads. Or maybe we are stating the same thing here!
Your correct the larger 2.02/1.60 461 were first used in 1964.
rustylugnuts
Mike,
By "large valve head cast", I assume that you mean 1.94/1.50. These were the "big boys" which superseded the 1.72/1.50 power pac heads prior to late '61. Beginning in late 1961, the plain old 461 head, machined for "small valves" (1.94/1.50) was used for all other Corvette engines. The "big valve" (2.02/1.60) 461 head was used beginning in 1964 for the SHP engines.
Your correct the larger 2.02/1.60 461 were first used in 1964.
rustylugnuts
Last edited by rustylugnuts; 12-08-2009 at 03:27 PM.
12-08-2009, 03:19 PM
#26
Drifting
That is very close, but the original production aluminum heads had the presence of "two large plugs" between the exhaust manifold ports. The part number was 3772894 I know the part number and the casting numbers are last digit increase by one, Ok, then where's the two large plugs? These plugs were larger then the exhaust ports. Like I said Jim, your head is very close, but no cigar!
rustylugnuts
12-08-2009, 05:46 PM
#27
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[QUOTE=rustylugnuts;1572366036]
I thought production 1961 Corvettes used 461X only, starting in September of 1960. the other production engines for 1961 used the same heads as the previous year, "power pac", that hosts the smaller valves. There were no 461's non-X heads used in 1961. The 461's non-X heads were not introduced until the next 1962 model year, and were used on every engine. Both heads are 1.94 int & 1.50 exh. with the exception 327/360 fuelie used the 461X heads. Or maybe we are stating the same thing here!
Your correct the larger 2.02/1.60 461 were first used in 1964.
rustylugnuts
In 1961, ONLY the FI engines used the "X" heads and they had a huge dome on the piston to displace the added CC's over the previous year's head to keep the compression up.
AFAIK, the '62-'63 300, 340 and 360 engines used the SAME head casting. I'm not stating that for a fact, just what I believe from the day. The difference between the assembled heads on the 300 engine and the 340/360 engine was the swirled finished valves that were installed in the SHP heads. I do know I am right about the valves. The head casting number (X), not so sure.
I thought production 1961 Corvettes used 461X only, starting in September of 1960. the other production engines for 1961 used the same heads as the previous year, "power pac", that hosts the smaller valves. There were no 461's non-X heads used in 1961. The 461's non-X heads were not introduced until the next 1962 model year, and were used on every engine. Both heads are 1.94 int & 1.50 exh. with the exception 327/360 fuelie used the 461X heads. Or maybe we are stating the same thing here!
Your correct the larger 2.02/1.60 461 were first used in 1964.
rustylugnuts
In 1961, ONLY the FI engines used the "X" heads and they had a huge dome on the piston to displace the added CC's over the previous year's head to keep the compression up.
AFAIK, the '62-'63 300, 340 and 360 engines used the SAME head casting. I'm not stating that for a fact, just what I believe from the day. The difference between the assembled heads on the 300 engine and the 340/360 engine was the swirled finished valves that were installed in the SHP heads. I do know I am right about the valves. The head casting number (X), not so sure.
12-08-2009, 05:58 PM
#28
POSSE ZR-1 Driver
Just to add some fuel to the fire.....
My numbers matching 64 300hp 327 had one 461 head and one 461X head on it when I purchased the car in 2001.
This doesn't mean it came that way from the factory, but the casting dates of the 2 are the same, and are the same month as the block casting (Nov 63).
I was told that it was not uncommon for the assemblers to just pick up whatever head was next on the line for the engine they were building. I'm not implying that as a fact, it's just what I was told.
My numbers matching 64 300hp 327 had one 461 head and one 461X head on it when I purchased the car in 2001.
This doesn't mean it came that way from the factory, but the casting dates of the 2 are the same, and are the same month as the block casting (Nov 63).
I was told that it was not uncommon for the assemblers to just pick up whatever head was next on the line for the engine they were building. I'm not implying that as a fact, it's just what I was told.
12-08-2009, 06:03 PM
#29
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St. Jude Donor '07
Just to add some fuel to the fire.....
My numbers matching 64 300hp 327 had one 461 head and one 461X head on it when I purchased the car in 2001.
This doesn't mean it came that way from the factory, but the casting dates of the 2 are the same, and are the same month as the block casting (Nov 63).
I was told that it was not uncommon for the assemblers to just pick up whatever head was next on the line for the engine they were building. I'm not implying that as a fact, it's just what I was told.
My numbers matching 64 300hp 327 had one 461 head and one 461X head on it when I purchased the car in 2001.
This doesn't mean it came that way from the factory, but the casting dates of the 2 are the same, and are the same month as the block casting (Nov 63).
I was told that it was not uncommon for the assemblers to just pick up whatever head was next on the line for the engine they were building. I'm not implying that as a fact, it's just what I was told.
Bill
12-08-2009, 06:50 PM
#30
Drifting
I just got off the phone with a senior NCRS guru, he stated: From his knowledge the 461X heads that were introduced Sept, 1960 were for the fuel injection engines only. However originally the 461X heads were "only" to be selected for use on all fuel injection engines, but all the casting numbers was the same for 461X & 461's Because the "X" was not part of the casting number, "located on the opposite side" it was missed in production. So many Corvettes could have two different heads, or a combination of the two scenarios. He claims there was a notice sent out late June 1963 to rectify, but Chevrolet didn't see any real problems and the issue was never really pushed to the forefront.
You learn something new everyday......
rustylugnuts
You learn something new everyday......
rustylugnuts
12-08-2009, 07:45 PM
#31
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Different day, slightly different story. I wouldn't take it to the bank. I doubt the engine plants haphazardly threw different head castings in a pile and expected the assembler to pick/sort out the correct head.
In addition, Alan Colvin lists the 461X head as spec'd for the '62-'63 300/327 engine. He's not perfect but he doesn't make too many errors.
The 461X head was a take-off of the aluminum head. The 461 was a make-over of a 283 head. Again, according to Colvin's book, the 461 wasn't released until 1964 so how could it be on a 1962-63 engine? Anybody have a 461 head date prior to late '63? If the "X" head wasn[t used on the '62-'63 300, what head was used?
In addition, Alan Colvin lists the 461X head as spec'd for the '62-'63 300/327 engine. He's not perfect but he doesn't make too many errors.
The 461X head was a take-off of the aluminum head. The 461 was a make-over of a 283 head. Again, according to Colvin's book, the 461 wasn't released until 1964 so how could it be on a 1962-63 engine? Anybody have a 461 head date prior to late '63? If the "X" head wasn[t used on the '62-'63 300, what head was used?
Last edited by MikeM; 12-08-2009 at 07:47 PM.
12-08-2009, 08:18 PM
#32
Drifting
Different day, slightly different story. I wouldn't take it to the bank. I doubt the engine plants haphazardly threw different head castings in a pile and expected the assembler to pick/sort out the correct head.
In addition, Alan Colvin lists the 461X head as spec'd for the '62-'63 300/327 engine. He's not perfect but he doesn't make too many errors.
The 461X head was a take-off of the aluminum head. The 461 was a make-over of a 283 head. Again, according to Colvin's book, the 461 wasn't released until 1964 so how could it be on a 1962-63 engine? Anybody have a 461 head date prior to late '63? If the "X" head wasn[t used on the '62-'63 300, what head was used?
In addition, Alan Colvin lists the 461X head as spec'd for the '62-'63 300/327 engine. He's not perfect but he doesn't make too many errors.
The 461X head was a take-off of the aluminum head. The 461 was a make-over of a 283 head. Again, according to Colvin's book, the 461 wasn't released until 1964 so how could it be on a 1962-63 engine? Anybody have a 461 head date prior to late '63? If the "X" head wasn[t used on the '62-'63 300, what head was used?
rustylugnuts
12-08-2009, 08:46 PM
#33
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That is very close, but the original production aluminum heads had the presence of "two large plugs" between the exhaust manifold ports. The part number was 3772894 I know the part number and the casting numbers are last digit increase by one, Ok, then where's the two large plugs? These plugs were larger then the exhaust ports. Like I said Jim, your head is very close, but no cigar!
rustylugnuts
rustylugnuts
Jim
12-08-2009, 08:47 PM
#34
Drifting
Different day, slightly different story. I wouldn't take it to the bank. I doubt the engine plants haphazardly threw different head castings in a pile and expected the assembler to pick/sort out the correct head.
No, but with a open mind, one can easily see if the casting numbers are all the same and this is how to identify different heads, it would be easy to grab a "X" head by habit. Production has done it the same way for years! Remember this was the "first year" there was an additional marking with the same casting number, and the identifier was located on the "opposite side". It would be extremely easy to miss..
If you don't agree, no problem! PEACE....
rustylugnuts
No, but with a open mind, one can easily see if the casting numbers are all the same and this is how to identify different heads, it would be easy to grab a "X" head by habit. Production has done it the same way for years! Remember this was the "first year" there was an additional marking with the same casting number, and the identifier was located on the "opposite side". It would be extremely easy to miss..
If you don't agree, no problem! PEACE....
rustylugnuts
Last edited by rustylugnuts; 12-08-2009 at 10:20 PM.
12-08-2009, 09:02 PM
#35
Drifting
First, it's not what I say! It's what's stated from what was read. It's not made up, it's fact. My information was retrieved from: The complete Corvette Restoration & Technical Guide - Vol. 1 1953 - 1962 First Edition Revised Updated Edition. Forth Printing 1980 page 293, 294. There is also a photo of Zora holding this head on page 293, on page 294 there is a another photo showing this head with "two large plugs" between the exhaust manifold ports. There are other original black & white photos of complete engine bucks showing this same aluminum head.
I cannot state what you have, only what it isn't.
rustylugnuts, sorry: PEACE!
Last edited by rustylugnuts; 12-08-2009 at 10:23 PM.
12-08-2009, 10:54 PM
#36
Advanced
Someone said that 61 model year production was introduced in September 1960. While that may be true, the engine in my real early 61 fuel car was cast and assembled in July 1960. I have VIN 095 and the engine is original. If these engines were assembled with 461x castings that would put any head date earlier than September.
My car came with 0-191598 heads when the second owner purchased the car in 1961. They are prototype heads for the 461x castings, dated May 1960. Sorry the webmaster says I can't post pictures. Don't know why.
I know this doesn't answer the question about the differences between 461 & 462, but I thought it would be of interest.
My car came with 0-191598 heads when the second owner purchased the car in 1961. They are prototype heads for the 461x castings, dated May 1960. Sorry the webmaster says I can't post pictures. Don't know why.
I know this doesn't answer the question about the differences between 461 & 462, but I thought it would be of interest.
12-08-2009, 11:33 PM
#37
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That much is very clear.
This, less so.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
only what it isn't.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
12-09-2009, 02:05 AM
#38
Drifting
That much is very clear.
This, less so.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
This, less so.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
Jim, I'm only quoting from the source from what was previously stated.
Page 294 quotes: There are some owners who feel 1960 Corvettes were never produced with aluminum heads. One enthusiast has gone to considerable lengths to track down one or more of the aluminum heads, but to date he has located none. His logical conclusion is that none exist. Yet, there is some evidence that such heads were used by the engine plant. No one possesses better information on this subject than Zora Arkus Duntov, and he recalls that they were installed on fuel injection Corvettes during the first three months of production. There was a problem in manufacturing the heads without defects; Zora recalled the reject rate was approximately one-third of production, pushing the manufacturing cost past the point of reason. After AIM date 3-17-60, cast iron heads were installed on RPO 579 engines with and without the high lift cam. :unquote
This book can be purchased for around 70.00
If what your saying is true, reveal your source publication and we will ask for the NCRS, SACC historians to get involved. After this is verified to be authentic, Producing times dates, etc. this indicates changing the Corvette "Bible" into a new revision. You will be credited in the revised publication by name for your findings.
rustylugnuts
12-09-2009, 02:41 AM
#39
Drifting
bertbrown, might be able to help. Send me an email through this site. Giving me you serial number off your steering colum, and your front engine pad numbers. These numbers are located passengers engine side front of engine, between the front of the head there is a flat 3/4'' pad. But you already know this. Also give me casting number and date from your heads. Will get back to you in a few hours after reading. You might have something very rare here. It needs to be verified.
rustylugnuts
rustylugnuts
12-09-2009, 04:19 AM
#40
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That much is very clear.
This, less so.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
This, less so.
There were two aluminum head castings in 1959, the earlier was 3767466 and the later was 3772895. The early head was released in late 1959 and replaced in February '60 by the later head. However, paradoxically, all known examples of the "later" head were actually cast in mid '59.
Now, I'm not exactly sure what your point is when you refer to "original production heads" since there were no production engines that used either head. You seem to be implying that the head in the picture I posted couldn't be an aluminum head from GM from the 1960 era. I say "seem" because you haven't come right out and said what your claim is.
However, the head in the photo is the Real Deal. You can believe it or not. I don't care.
This is its casting and part number:
Jim
Jim:
What you're posting here is what I've been led to believe from a number of sources over the years.