Don't if I should port and polish my stock heads off a 1973 350 . Or buy some new or rebuilt ones.The sock heads are 1.94s. Also how do you decide what cc runners you need. And what size combustion chamber. This is going to be a street car. But I want some power.

That's alot of questions in one post, i'll try to answer them in order.

Porting can provide excellent gains however it requires specialized tools (die grinder, carbide burrs ..) and good machining skills along with some experience. If you heads are 1973 originals they are absolutely going to need a rebuild (valve job, valve guides, stem seals, resurfacing). In my opinion the money you will spend to rebuild your current heads would be MUCH better spent rebuilding a set of iron Vortecs (062 or 906 castings). The Vortecs will yield much higher flow in their stock condition, and can be ported to improve flow further if your engine's power necessitates it. Vortec cores can be found at your local wrecker or here on TGO, and the matching intake manifolds are offered by all the big names (edelbrock, weiand, summit, holley). The chamber size of a head primarily determines the static/dynamic compression ratio of the engine. The runner volume effects the power/torque distribution of an engine, it is always a compromise between intake charge velocity and ultimate breathing ability.

If you provide us with more information regarding your engine combo, or the combo you wish to build, along with its intended application you may get more useful replies.

-Zander

Thanks. Zander You answered all the questions. That was pretty good. As for porting them I think I can do it my self. I will check into those vortec heads.

If your heads are stock 1973 they absolutely aren't worth spending any time or money trying to improve.

Stock Vortecs are valve-lift limited. Poor valve springs as well.

An excellent value:
http://www.sdparts.com/product/SD806...formerRPM.aspx
Takes care of the valve lift and valve spring problems, includes everything you need to install them.

I agree stock vortecs are lift limited, and do have awful springs from the factory. However if you find some cores to rebuild, the rebuild will include new valve springs, if you go with comp beehive springs your good to 0.550 lift which is more than vortec heads will ever need.

Go vortec, thats my vote.

-Z

The nice things about the SD kits:

- New heads
- New intake manifold (which you'd have to buy if you go to Vortecs)
- Upgraded valve springs
- Self-aligning rocker arms (required with Vortecs, unless you convert to screw-in rocker studs and guide plates)
- All the gaskets are included (again, you'd have to buy them anyway)

You also get new head and intake bolts.

Rebuilt cores rarely include new valve springs. That's a special order, extra cost option in a rebuild. Nor would you get the "good" stem seals without specifying them (again, at extra cost).

The sdparts kit is a bang-up deal. Don't even have to go to a junk yard.

my apologies for the confusion, your correct five7kid. I was suggesting that regardless of the heads he was gong to rebuild, valve springs should be replaced. I failed to word it very well though.

Just a quick related question, are the stock stem seals o-rings, or positive stop?

-Z

Is there any years that there were good stock heads . Besides the vortecs I already have an intake for the other heads dont wan to buy another one.

I actually like the mid & late 80's H.O. heads for the 305cid and 350cid engines.
Like any stock iron head they will require porting, a good valvejob, better springs/retainers, and either some machining or parts swapping to get more than about .470" lift. Valve upgrades are helpful especially if you start out with the 305 heads.

Normally old stock heads need the guides freshened up in which case you could use guide inserts to convert to the thinner 8mm LS1 style valves. You can find the valves, retainers, and locks used for around $50, and stock Z06 valvesprings also cost about $50. Some stock heads are great performers for street use with the right modifications.
You do quickly approach a point where the money invested comes close to what you would spend on aftermarket heads though.

Yep, Im with 305sbc.

I am a fan of the #081 58cc 305 heads, and the 416's, the perimeter
bolt valve cover pattern counter part. Ive used both with good success
on both the 305, and 350!

I have a 305 in my car that I'm replacing with a 350. Dont have the motor out yet to tell what heads they are. My heads for the 350 are 993 casting id.

993's - good for low RPM fuel economy and reduced emissions. That's about it (unless you need a door held open or a boat kept in place).

Good 350 heads: 083, 113 (aluminum).

Good 305 heads: 081, 416, 601.

I would never recommend building an engine around an intake manifold, though. It would be quite easy to spend more money fixing up/building & installing the heads above, even if you already have an intake manifold, than the SD kit would cost you.

I am not sure exactly how much it cost to replace guides on an iron head, but after you find non cracked cores, magnuflux and clean them, then machine them and outfit them with new valves, are they much cheaper than a new set of vortecs?
EDIT
Man. I have got to start reading all the posts more clearly, I just repeated the last post!

Buddy of mine says he knows a guy that has some 113 heads that he wants a 100.00 for.

Not bad. Have them checked over very carefully, though. In order to stay up with Vortecs, they'd have to be carefully ported.

hey 57 - how goes it?
picking up a zz4 cam and have a change to get two 601 heads for 230.00. completely rebuilt. will they work well with the cam if I put on stronger springs to handle the cam?
i dont want to go to the 113's or anything else that requires such open evidence of a modification when I see the smog people.
anything else you might think i need to do to keep them running at peak performance with that cam?
rockers, springs, anything? for that price i can spend a few bucks to do it.
i dont think my stock tbi 305 came with these heads, they are ho's unless i am mistaken.