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 Hydraulic 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.

340292 "Turbo" Over Counter Angle Plug, 64cc, 2.02-1.6 valves
3767462 327, 62-67, 161/65cc ports
3782461 327, 64-66 Double humpers or Camel hump 161/62cc port
3782461X 60-63, Larger intake runners, 172/64cc port
3991492 350 LT1, 70, 64cc, straight plug, camel hump
3991492 Over counter, strt or angle plug, 64cc, 157/62cc ports

Courtesy of this site;
http://www.kendrick-auto.com/chevrolet_head_casting_number_re.htm

There isn't much difference between any of the heads you mentioned. The 461X heads have bigger ports and the earlier heads have slightly smaller chambers, but other than that you wouldn't see any difference between them.

Is the lack of accessory holes going to be an issue? If so, go with 186 heads. Still old school but with accessory holes.

http://www.chevytech.com/3c3917291.html

http://www.chevytech.com/3c3782461.html

http://www.chevytech.com/3c3890462.html

http://www.chevytech.com/3c3927186.html

Mark

Camaros-n-Chevelles
What are the differences between the 291, 461 and 462 Castings?

Very little.Minor differences in port volumes and combustion chamber but not enough to matter on a street car.Find a good matched set and use them.

Personally, since he's putting it into a '55 and if he wants it to look more authentic/retro, I would suggest the 461X's, bigger ports for 383, and no accessory holes for the '55 era.

Otherwise, I'd run either the 292 or 186.

I agree.
I have a set of 291s, 461s and 462s and was hoping to use one of those sets. However, after looking at the numbers, the 461X Castings are the sensible choice. Now I have to find a set.
Thank You for the Input.

Be aware that one of the most common 'fakes' when it comes to heads are the "X's" ;)
Don't pay $$$ unless you can confirm the markings.
The port was nominally @12~15cc larger - depending on what valves and who measured them.

You can achieve the same flow results with a well machined and pocket ported set or 291's or 461/462's ... so no need to pay more $ for a casting mark you can't see vs. the same performance - IMHO of course.
Make sure if you're looking at a set of 'factory' "2.02's" that the shroud cut is there and looks correct - or their not 'factory'.

Your 383 will not run very well with any of those heads IMHO. Those heads can not handle the port velocity that today's new cams produce. They also can't handle 383 cubic inches or a 750cc carburetor. Those heads were designed for 327 cubic inch engines with a 600 CFM carburetor and relatively small, old school cams. Get a set of RHS Pro-lightnings in cast steel and paint them orange. Get a head with 180cc ports minimum. With a 383 you really will want 190-200cc ports.

You can achieve the same flow results with a well machined and pocket ported set or 291's or 461/462's ... so no need to pay more $ for a casting mark you can't see vs. the same performance - IMHO of course.


X2 and they will work fine on a 383.

If the casting symbol on the end of the head doesn't bother you, why not run vortecs.

Better hp and gas mileage. :beers:

The camel humps were used with some pretty gnarly cams back in the day.
My friends 362" motor made 550hp on a set of worked castings, don't remember which of the humps.
The small runners will choke the rpm band down, but it will still make good power if built right.
I suggest not using a single pattern cam, and the Comp 270H-10 is pretty small.
Remember when calculating compression it's not only the head volume and piston dome, flat top or dish, you need to factor in the cc's of valve relief, deck height, and gasket thickness. Just something to remember when building.

http://www.chevytech.com/3c3917291.html

http://www.chevytech.com/3c3782461.html

http://www.chevytech.com/3c3890462.html

http://www.chevytech.com/3c3927186.html





These links have been referenced before but I believe there are several inaccuracies in these links.

Specifically they state that '67 462's used on 327/275hp had 2.02's which is wrong, they are 1.94's. Also, I wouldn't call them large ports. I've CC'd my originals and they come out right about 155 cc's.

Also, on the 461's they state the '64 327/300 was 2.02 which it was not, as evidenced by my Dad's bought-new '64 vette.

They further state that 461's on '67 327/210 were 1.94's which they are not. I'm not sure 461's were even used on 210 hp cars but the valve size on 327/210hp is 1.72's.

These are just the ones that jump out at me. There may be more...

Tom, I think you're right, I remembered a link posted a while back similar to that and it said the 327/210 head was a camel hump, which it is far from. You are correct in saying the 210's used 1.72 valves, and also had huge 75cc chambers. The camel humps were never used on 327/210's, and probably not even on the 275hp version.
The 327/210 head casting # is 3917293

Tom, I think you're right, I remembered a link posted a while back similar to that and it said the 327/210 head was a camel hump, which it is far from. You are correct in saying the 210's used 1.72 valves, and also had huge 75cc chambers. The camel humps were never used on 327/210's, and probably not even on the 275hp version.
The 327/210 head casting # is 3917293

Thanks. For sure, my '67 327/275hp 462's are camel humps, though. :thumbsup:

The 327/275 motors in 1968 used the 291 Castings.

On the page for 291's the chamber view photo (76cc) seems to show holes for 1.72/1.50 valves. So something doesn't jive there also.:confused:

[QUOTE=

You can achieve the same flow results with a well machined and pocket ported set or 291's or 461/462's ... so no need to pay more $ for a casting mark you can't see vs. the same performance.[/QUOTE]
X3
Stock, they are barely outflowed by Vortec heads. Something overlooked is that smaller ports can generate a quicker flow velocity that will make up for size. Definitely want the bigger valves though with a good backcut.

There is no discernible difference between a 291 and a 462 head. The 461 head had no chamber below the spark plug, it was machined flat when the head was made.

The 461x heads though desirable for their bigger ports are basically all gone, used up and expensive. Class racers had used up most of them.

Aftermarket heads are a better value.

From my experience there is not much difference between the 291, 461 and 462 Castings from a performance view; however, the 291 with considerable expense fitted with 2.02/1.6's, screw in studs, widened spring pocket to 1.439", pocketing and porting ...etc are excellent for a 327. Take in mind these heads where designed for the smaller displacement 302 and 327 engines. The Best head in this class was the later 292 Castings with larger runners, advantageous Port and Chamber Wall angles and favored by Jenkins running a 331ci SBC. I would think, if you intend to rev up any SBC over 350ci, especially the 383, would benefit from aftermarket heads having bigger runners to handle the Port Flow and much cheaper in the long run then working a set of any of them old castings.

From what I understand the Vortec do have larger runners but are limited to Valve Size and the Guides do not permit Hi-Lift cams without extensive shortening which is detrimental for wear.

You have to remember that 383 by nature are lower reving torque engines – the use of ultra trick high flowing heads is great for some applications where you’re trying to extend the upper RPM range (and have built a stout forged bottom end) but … for most street/performance applications, the larger valved and pocket ported ‘Camel Hump’ style heads are just fine.
I’ve seen lots of dyno fiqures for mild performance 383 using slightly improved stock GM heads giving HP/Torque outputs in the upper 300~400Hp/400~450Tq range with a dual-plane intake and @750~800 cfm carb.s.
These are very streetable and produce plenty of torque for tire-smoke demonstrations as needed …
I’ve built a couple following this formula, one for a boat and one for a SUV, and they are still in service and doing great!
As stated, these engines will perform just fine with a well prepared stock style head for most street uses. You will only be giving away a few upper RPM HP with larger flowing heads in most cases.
Building an “Olds-Cool” ‘327-looking’ assembly would be easy and quite a sleeper … specially once that little added extra torque kicks in off the line :D

If you want high-end HP build a shorter stroke 355~370 - if you want streetable torque build a mild longer stroke 383 and you'll be very happy ;)

As always JMHO’s

...
From what I understand the Vortec do have larger runners but are limited to Valve Size and the Guides do not permit Hi-Lift cams without extensive shortening which is detrimental for wear.

:yes: using a cam with more than @.420" lift requires cutting down the guide boss to allow for retainer clearance.
If combined with 1.6:1 rockers and effective guide seals guide wear can be an issue for long service lifes.

Right on John - I'm in total agreement - If you not building an 8000rpm 383 screamer and satisfied with a 6000rpm torquer (Cam Specific) the old Turbo Flow or Camels on a 383 should be just fine keeping in mind they don't flow much above a .520" lift unless you do some Bowl Radiusing, widen the area of the intake runner opposite the Push Rods and slightly widen the Floor of the Exhaust Port Heel. On the other hand they are capable of revving a 302 or 327 to well over 8 Grand when Jenkinized - LOST ART ToDay.

It's just not worth doing this today considering whats available aftermarket for Small displacement SBC Screamers:

My 8000+ rpm 327 Jenkins Spec'd 281 Heads:

http://farm4.static.flickr.com/3407/3638727769_c0a7fedc8a.jpg

http://farm4.static.flickr.com/3333/3639537426_38b7d8b068.jpg

http://farm4.static.flickr.com/3406/3638727897_57368a58a6.jpg

Humm - That looks like a Stock 68 327 - Who is that Guy - LOL

492's!

All them Camel Hump and Turbo Flow head fall pretty well into the same Category but the 292's where the BEST - Bar NONE. Considering he uses one of these heads for a 383 build he would not require a Forged Crank; however, I recommend Hypertech Pistons, Sir Rods, Machine for Screw in Studs. 7/16" Roller Rockers (Harland Sharp or Pro-Mags with a Quality Isky Push Rods and ARP Studs) Definitely machine the Spring Pockets for 1.439" Dia Springs (now you're looking at aftermarket heads due to COSTS) - No need for a Girdle or Shaft Rockers - NICE Economical 425 to 450 Hp build with tons of Torque @ under 6000rpm.

I was thinking of using a Comp Cams Magnum 270 Hydraulic 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.

Lets see 55 Nomad STREET car .470 lift cam, A/C, 2004R OD with 3.64 gears.

A set of Double heads no matter what the casting number will be more than enough for his engine.With that cam he doesn't even need screw in studs. A set of Z28 springs and stock rockers would be fine.These threads seem to spiral out of control and skyrocket in the money department fast.

Building an “Olds-Cool” ‘327-looking’ assembly would be easy and quite a sleeper … specially once that little added extra torque kicks in off the line

Especially if you do it with a 400.Watch the videos in my sig.