461 and 462 heads. What is different?
12-09-2009, 04:26 AM
#41
Team Owner
Member Since: Mar 2003
Location: Greenville, Indiana
Posts: 26,118
Received 1,843 Likes
on
1,398 Posts
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..
rustylugnuts
rustylugnuts
Obviously, you're not familiar with the distinctive paint ID markings on the bare cast heads.
12-09-2009, 04:54 AM
#42
Drifting
12-09-2009, 09:19 AM
#43
Race Director
Member Since: Feb 2007
Location: northern california
Posts: 13,613
Received 6,529 Likes
on
3,004 Posts
C2 of Year Finalist (track prepared) 2019
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.
My information, which is considerably newer than yours, comes from sources that include NCRS and others.
Jim
12-09-2009, 01:16 PM
#44
Drifting
A lot of new information has become available in the 30 years since Noland published his first book. It'd be wise to take advantage of it.
I don't post anything that I don't know to be true.
My information, which is considerably newer than yours, comes from sources that include NCRS and others.
Jim
I don't post anything that I don't know to be true.
My information, which is considerably newer than yours, comes from sources that include NCRS and others.
Jim
That's what I originally thought, heresay.
rustylugnuts
12-09-2009, 02:00 PM
#46
Drifting
I see, one ask for proof, one gets proof, now one finds himself in a awkward position because he cannot produce any proof on his behalf. Instead of having the embarrassment of having egg on his face, he answers like a politician. I'm now "The great Oz".....ha ha ha!!!
That's "Mr. Oz"...... and I thank you! This thread is dead, time to unsubscribe, have a good day, and Merry Christmas to all!
PEACE, rustylugnuts
Last edited by rustylugnuts; 12-09-2009 at 04:43 PM.
12-09-2009, 07:47 PM
#47
Race Director
Member Since: Mar 2001
Location: Mustang OK
Posts: 13,852
Received 3,772 Likes
on
1,674 Posts
2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
[QUOTE=65tripleblack;1572365091]
Mmmmmmmmmmmmmmmmm, sorta.
This ONLY applies to the 61-70 heads with 2.02 valves. In 1971, the combustion chambers were increased to ~76cc, thus, the 71-later heads with the bigger chambers and 2.02 valves were NOT unshrouded around the intake valve (because they were already unshrouded by way of the larger chamber).
Tom Parsons
This ONLY applies to the 61-70 heads with 2.02 valves. In 1971, the combustion chambers were increased to ~76cc, thus, the 71-later heads with the bigger chambers and 2.02 valves were NOT unshrouded around the intake valve (because they were already unshrouded by way of the larger chamber).
Tom Parsons
12-09-2009, 08:09 PM
#48
Safety Car
[QUOTE=DZAUTO;1572379932]
Mmmmmmmmmmmmmmmmm, sorta.
This ONLY applies to the 61-70 heads with 2.02 valves. In 1971, the combustion chambers were increased to ~76cc, thus, the 71-later heads with the bigger chambers and 2.02 valves were NOT unshrouded around the intake valve (because they were already unshrouded by way of the larger chamber).
Tom Parsons
2.02/1.60 valves began in 1964
Mmmmmmmmmmmmmmmmm, sorta.
This ONLY applies to the 61-70 heads with 2.02 valves. In 1971, the combustion chambers were increased to ~76cc, thus, the 71-later heads with the bigger chambers and 2.02 valves were NOT unshrouded around the intake valve (because they were already unshrouded by way of the larger chamber).
Tom Parsons
2.02/1.60 valves began in 1964
Last edited by 65tripleblack; 12-09-2009 at 08:18 PM.
12-10-2009, 09:54 AM
#49
I almost feel like apologizing for my query about the physical differences between 461 and 462 heads. It seems that there are a lot of 'opinions', but from what I can determine, very little factual data. I can understand the maching to unshroud the 2.02 intake valve on either a 461 or 462, however a difference in the actual castings is still unknown to me. One post stated that the spark plug hole was 1/8 in lower in the 461x. Hmm. Interesting. That would be a significant casting difference, but still doesn't fully address the issue of my question. I do not have a set of both castings to compare, but I doubt this 'fact'. As cast, my understanding is that BOTH heads had approximately 64CC combustion chambers. Even my machinest claims that 461s had a 62CC combustion chamber and 462's had 67 which I know is NOT true. Intake and/or exhaust runner/port volume remains a mystery. I am beginning to suspect that the ONLY difference is the date of the casting mold itself and that the resulting castings were identical. Is it possible that the actual difference is no longer known?
12-10-2009, 11:02 AM
#50
OOPs and hold on. Post #11 seems to quite possibly have the most correct answer. Upon closer inspection, the combustion chamber immediately below the spark plug in the 462 head is relieved as a quench area. In the 461 this area in not relieved and is an obvious squish area. ....and it 'appears' that the spark plug hole is somewhat lower. This would indicate that the cumbustion chabber capacity may be smaller in the 461, possibly as much as a couple CCs. (62CCs vs 64)
12-10-2009, 12:23 PM
#51
OK, so now that the little known difference between 461 aand 462 heads (intake runner/port capacity aside) may be known the question as to 'why' the change. The 461 head, with it's squish area immediately below the spark plug and subsequent increased combustion chamber turbulence would seem to be superior in performance, but because of post-war automotive fuel (with the exception of avgas and Amoco Superior Premium, both of which NEVER contained tetraethylead), the build up of carbon and ESPECIALLY lead fouling in that area of the head and on the piston may have promoted detonation initiated within that (tight) squish area. The increased volume and reduction of size of the squish area in the 462 head could/would(?) have reduced that problem in higher mileage engines. Today's non-leaded fuel would most likely negate the necessity of that casting change.
12-10-2009, 01:32 PM
#52
Race Director
Member Since: Mar 2001
Location: Mustang OK
Posts: 13,852
Received 3,772 Likes
on
1,674 Posts
2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
12-10-2009, 01:36 PM
#53
Le Mans Master
I almost feel like apologizing for my query about the physical differences between 461 and 462 heads. It seems that there are a lot of 'opinions', but from what I can determine, very little factual data. I can understand the maching to unshroud the 2.02 intake valve on either a 461 or 462, however a difference in the actual castings is still unknown to me. One post stated that the spark plug hole was 1/8 in lower in the 461x. Hmm. Interesting. That would be a significant casting difference, but still doesn't fully address the issue of my question. I do not have a set of both castings to compare, but I doubt this 'fact'. As cast, my understanding is that BOTH heads had approximately 64CC combustion chambers. Even my machinest claims that 461s had a 62CC combustion chamber and 462's had 67 which I know is NOT true. Intake and/or exhaust runner/port volume remains a mystery. I am beginning to suspect that the ONLY difference is the date of the casting mold itself and that the resulting castings were identical. Is it possible that the actual difference is no longer known?
In the end, most opinions were right. You have to pick and choose the info sometimes. Given that, I think you would be hard pressed to find a better source of Corvette info than the forum. If you really want the true details, do a bit of google surfing. Most if not all of this information is available in many,many articles. It's all there. Just spend the time to browse. I found it. I just don't have the desire or energy to repeat it all here.too much typing and my hard drives crashed wiping out my favorites menu. (Therefore no links available)
Last edited by MiguelsC2; 12-10-2009 at 01:48 PM.
The following users liked this post:
OLDED (08-14-2018)
12-10-2009, 02:41 PM
#54
The more time you spend on the forum. The more you will see these kinds of disagreements on all kinds of issues. Thats what happens with so many "experts". They can't handle being told or challenged that they are wrong.Then it becomes personal. And their little feelings get hurt. Losing the original intent of the post.
In the end, most opinions were right. You have to pick and choose the info sometimes. Given that, I think you would be hard pressed to find a better source of Corvette info than the forum. If you really want the true details, do a bit of google surfing. Most if not all of this information is available in many,many articles. It's all there. Just spend the time to browse. I found it. I just don't have the desire or energy to repeat it all here.too much typing and my hard drives crashed wiping out my favorites menu. (Therefore no links available)
In the end, most opinions were right. You have to pick and choose the info sometimes. Given that, I think you would be hard pressed to find a better source of Corvette info than the forum. If you really want the true details, do a bit of google surfing. Most if not all of this information is available in many,many articles. It's all there. Just spend the time to browse. I found it. I just don't have the desire or energy to repeat it all here.too much typing and my hard drives crashed wiping out my favorites menu. (Therefore no links available)
All that was required was for me to take a GOOD look at and compare the combustion chambers of a 461 to those of a 462 and the solution to the mystery became apparent.
12-10-2009, 03:50 PM
#55
Team Owner
Member Since: Mar 2003
Location: Greenville, Indiana
Posts: 26,118
Received 1,843 Likes
on
1,398 Posts
I thoroughly agree. It seems that there are quite a lot of shall we say, misinformed 'experts' that tend to have their 'knowlege' or expetise challenged. I have put together more than a couple 327's (and other 'small block' 1st gen engines), but hardly consider myself an expert. Seemed to me that my 461 462 query was simple enough and it was ....interesting(?) to see so many posts that were so far off my initial post and all of the misinformation that was subsequently posted.
All that was required was for me to take a GOOD look at and compare the combustion chambers of a 461 to those of a 462 and the solution to the mystery became apparent.
All that was required was for me to take a GOOD look at and compare the combustion chambers of a 461 to those of a 462 and the solution to the mystery became apparent.
And you still don't have the rest of the story on comparing those two heads.
As far as discussing any given subject at length with differing opinions of what's right, what's not so right, I've never met the guy that knows it all and that goes for those involved in this thread.
12-10-2009, 04:54 PM
#56
Le Mans Master
I agree too. By the way, how did you determine what was correct and what wasn't?
And you still don't have the rest of the story on comparing those two heads.
As far as discussing any given subject at length with differing opinions of what's right, what's not so right, I've never met the guy that knows it all and that goes for those involved in this thread.
And you still don't have the rest of the story on comparing those two heads.
As far as discussing any given subject at length with differing opinions of what's right, what's not so right, I've never met the guy that knows it all and that goes for those involved in this thread.
So far JohnZ would be top dog in the knowledge dept.
Last edited by MiguelsC2; 12-10-2009 at 05:01 PM.
12-10-2009, 05:10 PM
#57
Safety Car
OOPs and hold on. Post #11 seems to quite possibly have the most correct answer. Upon closer inspection, the combustion chamber immediately below the spark plug in the 462 head is relieved as a quench area. In the 461 this area in not relieved and is an obvious squish area. ....and it 'appears' that the spark plug hole is somewhat lower. This would indicate that the cumbustion chabber capacity may be smaller in the 461, possibly as much as a couple CCs. (62CCs vs 64)
BTW: That information, along with photos and explanations is contained in what I consider the Bible, for porting SBC heads: David Vizard's "How to Build and Modify Chevrolet Small-Block V-8 Cylinder Heads"
http://books.google.com/books?id=mm8...age&q=&f=false
SEE page 10 of the above. If you would like pictures of 461 v 462 chambers, I'll see if I can find some.
Because of his good advice, and with much practice, I have been able to safely achieve inlet flows of 250 cfm and exhaust flows of close to 200 cfm (verified on SuperFlow 1020/1200 flow benches)out of a good set of 461 heads.
A link to one of my flow tests:
http://img.photobucket.com/albums/v2...FlowData_1.jpg
Last edited by 65tripleblack; 12-10-2009 at 07:11 PM.
12-10-2009, 05:33 PM
#58
I agree too. By the way, how did you determine what was correct and what wasn't?
And you still don't have the rest of the story on comparing those two heads.
As far as discussing any given subject at length with differing opinions of what's right, what's not so right, I've never met the guy that knows it all and that goes for those involved in this thread.
And you still don't have the rest of the story on comparing those two heads.
As far as discussing any given subject at length with differing opinions of what's right, what's not so right, I've never met the guy that knows it all and that goes for those involved in this thread.
12-10-2009, 05:34 PM
#59
12-10-2009, 05:49 PM
#60
And who was the genius who contributed post #11? What the hell does he know, anyway?
BTW: That information, along with photos and explanations is contained in what I consider the Bible, for porting SBC heads: David Vizard's "How to Build and Modify Chevrolet Small-Block V-8 Cylinder Heads"
http://books.google.com/books?id=mm8...age&q=&f=false
SEE page 10 of the above. If you would like pictures of 461 v 462 chambers, I'll see if I can find some.
Because of his good advice, and with much practice, I have been able to safely achieve inlet flows of 250 cfm and exhaust flows of close to 200 cfm (verified on SuperFlow 1020/1200 flow benches)out of a good set of 461 heads.
A link to one of my flow tests:
http://img.photobucket.com/albums/v2...FlowData_1.jpg
BTW: That information, along with photos and explanations is contained in what I consider the Bible, for porting SBC heads: David Vizard's "How to Build and Modify Chevrolet Small-Block V-8 Cylinder Heads"
http://books.google.com/books?id=mm8...age&q=&f=false
SEE page 10 of the above. If you would like pictures of 461 v 462 chambers, I'll see if I can find some.
Because of his good advice, and with much practice, I have been able to safely achieve inlet flows of 250 cfm and exhaust flows of close to 200 cfm (verified on SuperFlow 1020/1200 flow benches)out of a good set of 461 heads.
A link to one of my flow tests:
http://img.photobucket.com/albums/v2...FlowData_1.jpg
All the documentation, opinions, published numbers etc. are good for a start, however nothing is more definitive than looking at the casting numbers of a 461 AND a 462 then and turning each one over and actually looking at combustion chambers of both. I did not verify the port/runner volumes, but #11 was and is spot on. My eyes EASILY saw the difference between the two once that post indicated what I should have seen earlier.