after spending some time reading a few engine books im finding that the stock 58cc heads may not be so bad just need a little help. but all i know is they are 58cc. the valve sizes are unknown. is there a chart by casting numbers or whatnot to find out just what my heads are from and what valves are in it?

have you looked at mortec.com to try and find out what you have. 58cc sounds like an early set of 283 heads, or the dreaded 305 heads.

Dreaded?? Some of those 58cc heads make very good hi-perf heads - 416, 081, and 601. They are just as good, or better, than the double humps.

I would love to see some dyno sheets to substantiate that. The 462's and 186's were easily capable of 1HP per cube, and in the case of the 375HP 327 1.15HP per cube. I've never heard of, or seen a 305 head that will hold a candle to that. Most of those small ports were OK on the low demand of a 267 or 305, but fall flat on their face around 4000-4500rpm with 350" motors. Yje small chambers do offer compression increases that add midrange torque and makes the butt-o-meter smiles. Without a lot of work I find it hard to fathom that the little 1.84" valves and small ports of the 601 can hold a candle to the 2.02 / 175cc port of the 186 head.

Marv,

My pair of old 305HO, -601's cc'd at 160.0 and 160.+ cc's intake port size!!

pdq67

the book im reading on small blocks has the same shortblock it have except my cam is slightly bigger. the heads i have come to belive are 58cc with 1.94/1.50 valves. its similar to the tpi corvette aluminum heads just unported. they gained almost 50hp just pocket porting the heads and a 3 angle valve job. if i cant find a decent set of aluminums soon i think i may do the same to these heads and see what happens.

The 601s are the best ones... thick 'HD' castings make them tough, and the 53cc chambers have a very similar 'double quench' chamber design to the old fuellie heads. The 416 and 081s are similar, but with slightly different bigger chambers. The ports are actually quite big for a stock head at 160cc or more. The stock 1.84/1.50 valves are small, yes, but its not hard to change them for 1.94/1.60 valves like I did with mine. The exhaust side on those 305 heads breathes quite well too - on par with stock fuelie castings in stock form, and porting makes them quite a bit better. Theres LOTS of material for porting in these castings.

These heads are a dime-a-dozen because they came on almost every 305 ever made, but they work great on the larger engines like the 327 or 350.

416 and 081 305 heads are good heads after they are ported and throw in some larger vales. The bowls are cast small for the intended 1.72" valves so they really need the bowls opened up, but there is lots of meat there. The 58cc chambers are pretty good also.

The 305HO heads (601 casting) came with 1.84" intake valves and a 53-55cc chamber. They have a bowl that seems to be cast a little larger since they all came with 1.84" valves.

These castings will all CC at over 160 on the intake side, but there is 6cc's of dead space that should be filled under the rocker studs in each port. It actually disrupts flow quite a bit and they flow better with it epoxied up.

The short side radius on teh exhaust ports is pretty good though and they flow well with the stock 1.5 valve.

With filling the hole in the port, going to a 1.94" intake that has been deshrouded in the chamber, and a decent porting job - you end up with 230's in flow on the intake, and 160's on the exhaust, with about a 57-58cc chamber.

The other perimeter bolt 305 castings are garbage - 434, 450, etc.

Rick, what do you charge to take a set of the 601's to the level you describe?

I think the answer to that will express my issue with the 305 heads. In stock form they are pretty lame and a poor choice for a 350 that you want to rev over 4000-4500. Spend $'s (or if you have the expertise and equipment to do the work) on most any head and it 'can be' decent. But is the $'s wisely spent??? If your going to spend $ for valves, seats guides, have the spring pockets / guides cut so you can get some respectable lift, bowl work / porting, decking,, you've spent more then 1/2 the cost of a set of cheepo Chinees clone iron heads that will generally knock the socks off the warmed over 305 head.

I'm not trying to take away from anyone that has done the work and is making good power with them. Not at all. Just commenting that in stock form,, I sure as heck would dread finding a casting number that traces to the 305. To me it would mean I have a lot of work ahead of me, or $'s to spend for something more up to the task.

But then I may be totally out of line. I didn't see where flyboy367 said what motor he had and what he's really looking for.

They are a production line head. The double humps or other similar heads all need the same work as the 305 heads to become real performance heads, or become even remotely competitive with aftermarket stuff.

what air adam said is right. CHP did a comparison a few months back and basically even gm aftermarket heads dwarf anything stock from any age. but for the budget guy you can get things to work. i have a 350 with standard or just above standard pistons. basically your off the shelf 350 shortblock. just so happens to be the same type used in CHP's book the smallblock chevy. the real deal im looking to do is either save up some cash and get some vortec heads or strike a deal in the scrapyard or ebay on some l98 corvette heads. in different ways those heads are close to the same in performance with a base 350. except CHP went carbed with a rpm perfomer manifold and a smaller cam then the performer. i have the performer rpm cam so im a little bigger there and the performer rpm manifold that i want to switch for tpi. as now the engine winds wonderfully just dogs out a bit on the top end cause its a 670 carb and should probably be a 750 like they used in the book.

Mod,

You think this thread is "Sticky" material??

Darn good info here, imho!!

pdq67

416 and 081 305 heads are good heads after they are ported and throw in some larger vales. The bowls are cast small for the intended 1.72" valves so they really need the bowls opened up, but there is lots of meat there. The 58cc chambers are pretty good also.

The 305HO heads (601 casting) came with 1.84" intake valves and a 53-55cc chamber. They have a bowl that seems to be cast a little larger since they all came with 1.84" valves.

These castings will all CC at over 160 on the intake side, but there is 6cc's of dead space that should be filled under the rocker studs in each port. It actually disrupts flow quite a bit and they flow better with it epoxied up.

The short side radius on teh exhaust ports is pretty good though and they flow well with the stock 1.5 valve.

With filling the hole in the port, going to a 1.94" intake that has been deshrouded in the chamber, and a decent porting job - you end up with 230's in flow on the intake, and 160's on the exhaust, with about a 57-58cc chamber.

The other perimeter bolt 305 castings are garbage - 434, 450, etc.
Hey Racer, how do the 601's work with a 1.6 on the exhaust? :)