wat are they? do they fit on a 92 305? 64cc is that any better? give me some feed back pleaseeeeeee

 

"Performance" heads from the dark ages, usually without accessory bolt holes. Probably not worth messing with.

 

Casting mark looks like this. These particular ones have the bolt holes.... without which you pretty much can't put them into one of these cars, at least not if you want accessories, little detail creature comfort things, like an alternator.

Not appropriate for a 305, especially not a stock one. You'll end up with way not enough compression.

 

Factory casting cores had markers at the ends of the heads to help identify the core at the factory. The core markers for this family of heads was a pair of semicircular mounds at the lower edges of the head, hence, they were dubbed "Double-Hump" or "Camel-Hump" heads. The inner cores used for these heads had larger, straighter ports than many other factory heads of the era, as well as better chamber designs and often larger valves. They used to be more prized, but mostly because all the other factory head offerings from the late '60s and '70s were really poor by comparison. By even mid-'80s standards, they are little more than collectors' pieces, probably best used to hold open doors or stop cars from rolling while changing tires.

Oddly, people that have them still cling to the hope that they have something of substance, and some people actually pay money for them. If you have some, and can find a potential buyer that doesn't know any better, you might have a cash generator that can afford you some real heads.

 

But it really depends on which double hump heads you are looking at. The casting numbers themselves will help out alot. Such as the 186 heads (these have accessory holes) have 2.02int 1.6 exh valves and are 64cc chambers. This is the exact same head as the 492 (which you can still buy from GM Performance parts) and is a very good head. I helped a buddy build a 350 we put in a Malibu which have these heads and it runs 8.30's in the 1/8th and is a street driven car. Full body, full interior close to 3900 lb car.

These heads flow very well (I don't have the exact numbers) but alot of small block engine builders use these (when aluminum heads aren't affordable) and I just saw a set of 186's going for 550 bucks, a set of 461x for 800 and a set of 492's going for 550. These heads are well worth it if you are on a budget.

Plus the big thing about the 186's are they have screw in rocker studs instead of pressed in

 

The heads in my pic are 186 casting. They came with 1.94" intake valves.

Most of those heads were on 69-70 Impalas and station wagons and Monte Carlos, with 350 4-barrels. Most of the sets I have left over from my motor building days came off of station wagons. Nobody used to look under the hoods of those things in the boneyard; I'd find one of those looking like it had been in a demo derby in the boneyard with an inch of schmutz built up on it from 100,000 miles of cork valve cover gaskets, and buy the whole motor for $50. Bonanza!!! It's getting hard to do that any more. Most of them, people have gone to the local corner parts store and swapped them in as cores, and ended up with a bunch of 882s or 624s or 993s, all cleaned up and shiny, but still worthless as the day is long; and the 186s have all gone circle track racing.

Actual employee evaluation I gave someone one time: "easily distracted by shiny things". OBTW, she didn't get a raise. Let that be a lesson to you to pay attention to what's really under the shine (or lack of it).

They flow 215-220 stock, and 235-240 with a decent port job. People sometimes get them up to 250-255 without hitting water or oil, but it's not a real high probability thing.

 

These particular heads are a very good stock head, but they are old technology. Your 305 will not benefit with them. They also need hardened valve seats installed due to the fact that they are not designed for use with unleaded fuels.

If you know where to look, you can possibly find some that are 58cc closed chamber, originally meant for use on the 327 but ended up being modified with steam holes and used on the 400. These would flow around 240 stock and a lot better with a good porting. I use them on my 327, but I did weld mine full and rework them.

Either build another engine and use them (not a 305), or sell them.

 

That would make one hell of a high compression engine!