The Stovebolt Site Forums The Shop Area Engine Shop SBC assistance, please...

I looked up the casting numbers on the heads on my old 327 to verify what appears to be the "camel humps". Now, I'd like to find out more about these 'legendary' heads. What makes them so special? 160cc intake and 62cc exhaust ports, with 62cc chambers...is this good? What's the significance of these volumes?

You might want to check your info, I believe that the chamber size is 64cc

Just going by the info. from the castingnumbers.info link, above.

if you're asking about why camel hump heads are better than any other head, they had larger valves to improve breathing. I can't recall if they had smaller combustion chambers to bump compression some, but guess they do.

Well, curiosity got the better of me and I popped one head off to measure the valves. 1.94" intake and 1.50" exhaust. Are these larger than on any other head?
My book says the C.R. on this engine was 10.5:1.

2.02" intake valve heads were the ones guys would fight over, used to hear them called "fuelie" heads. compression is good for power, but with todays crappy gas, and lower octanes, not so good. There were single hump (power pack) and double hump (camel back), and I think at least 2 versions of the latter? I'm sorry, going only from memory, likely wrong on all of my thoughts and need to leave comments to others who definately know before I muddy your water any....

Unless you do most of your driving at wide open throttle I wouldn't get too wrapped up in valve diameter. 327 is a fun little motor

The "double hump" or "camel hump" heads were used on a number of 327 engines in various horsepowers. Some had 1.94 intake valves and some had 2.02 intake valves. I know that there are 2 castings for sure, one ends in 461 and another 462. The combustion chambers are 64cc.

They're worth quite a bit I know that. Old school muscle

The main drawback to the 327 "double hump" heads was the lack of any bolt holes for mounting accessories on the ends of the heads. Later model 64CC heads have the accessory mounting holes if you're not building a concours restoration that requires a specific casting number. 64 CC heads on a 350 engine bumps the compression high enough that a really radical cam grind is required to keep the actual compression ratio (not the theoretical) down low enough to run on currently available pump premium gasoline. Otherwise there's a major risk of destructive detonation.

76 CC low compression 350 heads can be angle milled .100" and the combustion chamber volume goes down to 60CC. We used to build "cheater" engines with those heads for the "stock" division at the local round track with 2.02" intakes, 1.6" exhausts, and 60CC heads - - - - -more compression and bigger valves than a camel hump engine. The tech inspectors didn't look past the casting numbers.

"Camel hump" heads are only good for bragging to folks who don't know any better, like a lot of other stuff that's done to old muscle cars.
Jerry

283 crank and rods with those heads and you got a nice breathing high rpm 302.

A 3.1" stroke crankshaft from a 262 V8 in a 4-bolt main bearing 350 block works out to 311 cubic inches. That setup with a set of 58CC heads off a 305 will run 8K RPM all day and stay together!
Jerry

Thanks for the replies...helps me decide what to do.
I drove my truck with this engine in it for quite a few years, but it was a quick swap in...I didn't even notice the humps on the heads. It was a great engine with the 3-speed.
Now, I envision a vintage-looking 331...accessory holes are on the ends of my exhaust manifolds. I guess my toughest choice is whether to put this engine back in the '65, or go with the 400 I just finished.
Then there's the '65 283 out in the barn...

cm

400 is a nice motor as well. Since it's a fresh rebuild I take it the cylinder walls are in good shape. Those are my only concerns with a 400. Sounds like you have a fun project no matter which drivetrain you choose.

CM,

Have you tried INDY CYLINDER HEADS? I purchased a set of cast iron heads from them back in the late '90's for the 383 stroker I built for my '58 Biscayne. They were very accommodating and worked with me on the type of engine I was building to get the best performance and efficiency. I was very pleased. That 383 was a BEAST!! There prices were the BEST I I could find at the time. I believe they have a website. If not, check any high performance Chevrolet magazine and they usually have an ad listed.

Tim

Hotrod, you're driving me to drinkin. Anyone can figure out the static, mathematical compression ratio. Can you share with us how the actual compression ratio is measured? I am assuming that the cam profile, lift, duration, and over-lap have something to do with it, but what do I know? (I will answer that: not much at all.)
Carl

Check out Cochise.uia.com

They have a formula. You need cam specs. It's complicated as heck. Lsa, cam degree, pistons, volume at bottom of stroke, volume at tdc, the list goes on and on. Quench is a big deal on a racing engine also. Not so much on a stock motor that doesn't see wot. More info than most people care to think about.

Pretty much your static is compression at idle or lower rpm. Actual compression will increase over the rpm range. The piston is traveling so fast your volumetric efficency can't keep up. That's on a stock/mild motor. With milled heads and valve jobs and domed Pistons and cam lsa, lift, duration and all that fun stuff, your VE increases but rarely to 100%. Boosted engines with VE of 100% or more gain almost 50% more compression at rpm. My motor goes from 8:1 static to 15:1 actual @ 12# of boost and 7200rpm. Anything over 9.5-10:1 needs more than today's pump gas.

Carl, it's a lot of guesswork unless some pretty sophisticated higher math gets involved, and that's a job for my aerospace engineer brother- - - - -way above my pay grade! Not much, if any cylinder pressure is going to be developed until the intake valve closes, so if a radical-grind cam keeps the valve open partway up the compression stroke, simple logic demands that the remaining cylinder volume needs a tighter squeeze to get the pressure back up to where it used to be when the valves were operating normally. As speed increases, the velocity of the incoming fuel charge keeps exhaust gas from entering the intake manifold when the valve opens before the end of the exhaust stroke. That's why over-cammed engines idle rough, or not at all at low speeds. I remember one 355 cubic inch round track engine we built with a roller cam, a rev kit, and altered rocker arm geometry that simply quit running below 2200 RPM, and didn't run smooth below 3,000. From 3,000 to 7,500, it produced awesome power- - - -enough to get wheelspin off the turns of a 5/8 mile high banked asphalt track if we chose the wrong rear end ratio. As speed increases, the efficiency gets better, so just figuring straight volumes gets into too many variables to be even close to exact.

Bottom line- - - -nothing much beats a few decades of engine building experience to get it right, and taking advantage of the technical assistance provided by the cam grinders, carburetor, intake and exhaust manifold manufacturers can provide definitely helps. Just beware of somebody who promises to solve all your problems with some expensive product that they just happen to have on sale!
Jerry

Those heads won't have 'hardened valve seats', you might want to factor that into your calculations.
If you go with later heads that have the accessory bolt holes then you'll need to go with a long waterpump & pulleys etc to use the newer bracketry.

If you want to get stupid with oldschool trick heads, I have a pristine set of 292 heads I'd cut loose for a price.