Differences Between 291, 461 and 462 Heads - Chevelle Tech
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post #1 of 20 (permalink) Old Jun 27th, 10, 9:52 AM Thread Starter
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Differences Between 291, 461 and 462 Heads

Hi Guys,
I am building a 383 for my 55 Chevy Nomad. I want to keep it looking old school and am starting with a 1970 4 Bolt Main Block (3970010). I am using an Eagle Forged Rotating Assembly.
What are the differences between the 291, 461 and 462 Castings? Which set of heads will work best? I was thinking of using a Comp Cams Magnum 270 Cam and Lifter Set.
The car will be street driven and will have a Vintage A/C System.
I have a modified 200 4R and a 1957 Olds Super 88 Posi with a 3.64 gear.
Any suggestions, advice and information is greatly appreciated.
Thank You.

Tory
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post #2 of 20 (permalink) Old Jun 27th, 10, 10:09 AM
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Re: Differences Between 291, 461 and 462 Heads

I'd personally use Votec Heads that were drilled for the early valve covers and intake...

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post #3 of 20 (permalink) Old Jun 27th, 10, 11:24 AM
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Re: Differences Between 291, 461 and 462 Heads

Tory,

All those heads are small chamber, does your 383 kit have dished or flattop pistons? You know, right, that those 60's heads are obsolete as far as ports and making power go?

If you're going to use a non-roller cam be sure to understand the stuff in the oil topics at the top of Perf and engine sections. Any error on the oil type will result in a flat cam.

Tom
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post #4 of 20 (permalink) Old Jun 27th, 10, 11:47 AM
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Re: Differences Between 291, 461 and 462 Heads

Tory,

Old school engine? Cool. That thing sounds like it will definitely go for sure.

I found this looking for some good info to post for you regarding old school chevy heads...


This is from a waaaay old thread that google found for me. It is actually from TC...

A good post:

Quote:
Originally Posted by Tero Topilla View Post
I got to tell you this: Iīve measured most of these camel hump heads (#186, #291, #461, #461x...) intake ports myself last winter, and they really were all the same. ALL OF THOSE CASTINGS MEASURED 165cc, INCLUDING THAT #461x.

I located tens of pairs of these old camel hump heads just by accident from a wrecking yard, and I was wery eager to return there again and measure them to find a superior head for few dollars. You can imagine my disappointment when I finally got to measure the intake ports, and they all were the same! Really! The intake port from a #461x is just as small (approx. 165cc) as from a #291, for example.

I had read from Hot Rodding magazines that there are some superior big intake port camel hump and fuelie heads cast by GM, and I thought they were either #461x, #292 or both. So now I know the superior head definetely is not the #461x...

On the latest Chevy High Performance Magazine there are quite many SB Chevy heads measured (both the intake ports and combustion chambers), and they even flowed them on a flowbench. Itīs a VERY good article! One camel hump head was there, namely the #492. Their measurement did not end up as big as mine, I think they got 159cc, but Iīm not sure. Gotta check that article again. Anyway my measurements are from stock heads, not ported, so what could be the difference between the magazineīs and my measurements? My measurements may be off by 1-2cc, but no more.

That wrecking yard I visited has got various types of those camel hump heads lying around. Ported, stock, with valve seats installed and without, small and big valves, screw and pressed studs, complete and bare, some cracked, some not... They cost less than $300 a pair. That may sound like cheap, but I wouldnīt install any of those heads straight without first checking (and maybe machining and fixing) them.

And to answer Bryans question: the main difference (in my opinion) between a #462 and a #461 (x or not) is the combustion chamber size. The #462 has got the normal approx. 64cc chamber and the #461(x) has got a bit smaller one with approx. 60,5cc. Just as Scooter said. So with the same pistons you get more compression (=power or problems... with the #461(x) heads.

Bryan, you said youīve got #292 heads there. PLEASE VERIFY THE INTAKE PORTS OF THOSE AND THE #461(x). Put an intake valve in itīs place in both heads and check which headīs intake port will swallow more water. By doing that you could end this never-ending debate about mystery GM SB heads! Please do that and try to be accurate. No accurate cc number is necessary, just the fact whether they are the same size or not.

I mean you could do me a BIG favor. Iīve been searching those "mystery" big port heads for some five years every time I went to a swap meet or wrecking yard, and Iīve already given up because I thought the best ones were the #461x castings. But what if the #292 is the one? You would send me on a mission again by telling me that #292 intake port is clearly bigger. I donīt care how much bigger, just the fact would put me on the road again.....

Million thanks already.
Discussion here


I'd be looking for the most runner volume you can get with that stroker.

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post #5 of 20 (permalink) Old Jun 27th, 10, 12:22 PM Thread Starter
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Re: Differences Between 291, 461 and 462 Heads

Quote:
Originally Posted by Tom Mobley View Post
Tory,

All those heads are small chamber, does your 383 kit have dished or flattop pistons? You know, right, that those 60's heads are obsolete as far as ports and making power go?

If you're going to use a non-roller cam be sure to understand the stuff in the oil topics at the top of Perf and engine sections. Any error on the oil type will result in a flat cam.
Hi Tom,
The pistons are dished. Which Roller Cam is comparable to a Comp Magnum 270 Hydraulic Cam?
Thank You for your help.

Tory
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post #6 of 20 (permalink) Old Jun 27th, 10, 12:27 PM Thread Starter
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Re: Differences Between 291, 461 and 462 Heads

Hi Jake,
Thank You for the post. It was very helpful.

Tory
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1968 Camaro
1968 Malibu L-79, 1 of 4082 ~ SOLD
1984 Hurst Olds w/ Factory Sunroof, 1 of 99 ~ SOLD
1985 442 White / Grey w/ Factory Sunroof ~ SOLD
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post #7 of 20 (permalink) Old Jun 27th, 10, 12:48 PM
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Re: Differences Between 291, 461 and 462 Heads

Comp makes a retro-fit hyd roller 270 magnum, but I don't know if you can get it on a billet core.

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post #8 of 20 (permalink) Old Jun 27th, 10, 1:12 PM
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Re: Differences Between 291, 461 and 462 Heads

Quote:
Originally Posted by Highway Star View Post
Tory,

Old school engine? Cool. That thing sounds like it will definitely go for sure.

I found this looking for some good info to post for you regarding old school chevy heads...


This is from a waaaay old thread that google found for me. It is actually from TC...

A good post:



Discussion here


I'd be looking for the most runner volume you can get with that stroker.

Pretty good info except the part about the 461x
They were in fact 170-175cc not 162-165 which is what I have measured the other heads at & they are pretty rare
There are heads with an "X" on them that are not 461x heads & this is where people get confused
The "desirable" X head will have the casting number as 461X
Others will have 461 with an X divorced from the actual 461 casting number

Be advised all of these heads do not have hardened ex seats & which can be an issue with todays fuels unless you use an additive especially if you are going to drive this hard, haul a load or put a lot of miles on it.

For what you are doing the differences between the heads except for chamber sizes as noted are not worth mentioning
Just realize that you can most likely build a brand new set of the "Street Replacement" aftermarket heads for less money which will have many advantages & be reasonably hard to detect except for the "purists" once installed

Id's
http://www.fastnuf.com/Headguide.html

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post #9 of 20 (permalink) Old Jun 27th, 10, 7:00 PM
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Re: Differences Between 291, 461 and 462 Heads

Quote:
Originally Posted by Lionel-n-Chevelles View Post
Hi Guys,
I am building a 383 for my 55 Chevy Nomad. I want to keep it looking old school and am starting with a 1970 4 Bolt Main Block (3970010). I am using an Eagle Forged Rotating Assembly.
What are the differences between the 291, 461 and 462 Castings? Which set of heads will work best? I was thinking of using a Comp Cams Magnum 270 Cam and Lifter Set.
The car will be street driven and will have a Vintage A/C System.
I have a modified 200 4R and a 1957 Olds Super 88 Posi with a 3.64 gear.
Any suggestions, advice and information is greatly appreciated.
Thank You.
The combustion chamber. Use the 291s, there better.
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post #10 of 20 (permalink) Old Jun 27th, 10, 9:49 PM Thread Starter
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Re: Differences Between 291, 461 and 462 Heads

Quote:
Originally Posted by VORTECPRO View Post
The combustion chamber. Use the 291s, there better.
Hi Mark,
Thank You Very Much.
What are the sizes of the Combustion Chambers for 291, 461 and 462 Heads? I have a set of each and will use one of the sets on the 383.

Tory
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1955 Chevrolet Nomad
1964 Malibu SS Unrestored 36,000 Mile Survivor
1964 Malibu SS
1966 Chevelle SS 396 Unrestored 76,000 Mile Survivor
1968 Camaro
1968 Malibu L-79, 1 of 4082 ~ SOLD
1984 Hurst Olds w/ Factory Sunroof, 1 of 99 ~ SOLD
1985 442 White / Grey w/ Factory Sunroof ~ SOLD
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post #11 of 20 (permalink) Old Jun 27th, 10, 10:40 PM
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Re: Differences Between 291, 461 and 462 Heads

I cant help you with what the cc of the heads are but if you get a piece of plexie glass/some vasoline and a syringe that has cc readings you can check yourself easly.
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post #12 of 20 (permalink) Old Jun 28th, 10, 10:44 AM
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Re: Differences Between 291, 461 and 462 Heads

Quote:
Originally Posted by Wolfplace View Post
Pretty good info except the part about the 461x
They were in fact 170-175cc not 162-165 which is what I have measured the other heads at & they are pretty rare
There are heads with an "X" on them that are not 461x heads & this is where people get confused
The "desirable" X head will have the casting number as 461X
Others will have 461 with an X divorced from the actual 461 casting number

Be advised all of these heads do not have hardened ex seats & which can be an issue with todays fuels unless you use an additive especially if you are going to drive this hard, haul a load or put a lot of miles on it.

For what you are doing the differences between the heads except for chamber sizes as noted are not worth mentioning
Just realize that you can most likely build a brand new set of the "Street Replacement" aftermarket heads for less money which will have many advantages & be reasonably hard to detect except for the "purists" once installed

Id's
http://www.fastnuf.com/Headguide.html

I remember reading somewhere that the 461X wasn't really a production head, more like a "bowtie" racing head. I have read that they had much bigger runners, closer to 175. Seems that there is a lot of conflicting info out there. Even your link, Mike had a bad piece of info in it...claiming that the 624 smogger head is actually a 305 head with 1.84/1.50 valves.

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post #13 of 20 (permalink) Old Jun 28th, 10, 1:47 PM
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Re: Differences Between 291, 461 and 462 Heads

the old info was that the 461X was bigger, but there's no X on the casting number, it's xisible through a water jacket hole in the deck. I remember seeing pics of this back in the early 80s but I've never seen a head like that.

Tom
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post #14 of 20 (permalink) Old Jun 29th, 10, 10:05 AM Thread Starter
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Re: Differences Between 291, 461 and 462 Heads

3782461X 60-63, Larger intake runners, 172/64cc port
3782461 327, 64-66 Double humpers or Camel hump 161/62cc port
3767462 327, 62-67, 161/65cc ports
3917291 302, 327, 350, camel hump, 161/65cc ports


Courtesy of:

http://www.kendrick-auto.com/chevrol..._number_re.htm

Are the 462 and 291 Castings Identical?
I know that the 291s have a provision for the Temperature Sending Unit. Does the 462 Casting have the same provision?

Tory
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post #15 of 20 (permalink) Old Jun 29th, 10, 10:56 AM
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Re: Differences Between 291, 461 and 462 Heads

the only difference between the 461 and 462 is more meat in the valve spring area on 462, which allows machining for oversize valve springs...not familiar with the 291...try to find a set of 492's...angle plugs, best of the camelhumps...

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