trans_am_racing

i have an 86 ta w/a mid 70's 350 take to a 355, my question is which heads would get get the best overall performance from

A: 87-91 1.84/1.5 58 cc chambers

or

B: 72-73 1.74/1.5 76 cc chambers

five7kid

iTrader: (14)

A.

trans_am_racing

thanks, thats what i have on now, just wanted a second opinion

kfoley

A's ported and with a larger intake valve (1.94).

trans_am_racing

A: has 1.84/1.5 according to the casting numbers i got off the heads, also their 305 heads.

Cronic3rd

what are the casting #'s?

CaddiBird

Personally in my opinion neither one of the heads are good. If your using a stock cam the 305 head would be better cause you would pick up some power with the smaller chamber raising the compression. But for the record the ports in a 305 head sucks. Now days the better heads to get are Vortecs, yes you have to run a diffrent intake and yes the springs aren't good for more than around .450 lift but they'll out flow a old iron head with 2.02 1.60 valves.

Cronic3rd

Take a grinder to the ports and stuff in some bigger valves and some 305 heads will flow pretty good... on the lines of a vortec head.

kfoley

I was meaning add the larger intake valve, it adds a lot more flow potential.

CaddiBird

I sorta doubt that considering a Vortec head has raised and much bigger intake ports which keep the fuel atomized better and they also use a diffrent designed chamber to give more power.

Cronic3rd

I didn't say that they were better heads just that with porting they could put up the same flow #'s. Do a search on f-bird'88 he is the one that posted the numbers.

Cronic3rd

It is a moot point if those heads are swirlports though.

Arctic White 91 RS

I wouldn't spend one cent on either of those two castings if you looking for power. I think the Vortecs would be the better choice.

trans_am_racing

14102187 is the casting # on 305 58 cc heads

Cronic3rd

icky icky icky swirlports. baaaaaaddddd swirlports. use the 350 head.

Air_Adam

Those 305 heads would probably need the centerbolt valve covers too I bet.

The better 305 heads to look for are the #416's.. they have the same 58cc chambers and same size valves, but are not swirl port heads. These are the heads used on the L69 (HO) engine, but was used on many other 305s too, I'm sure.

Cronic3rd

601, 801, and 081 are other good casting 305 heads.

Spectre

I guess it would be more cost effective to
get vortecs with matching intake.
Or just get s/r torquers.. and be happy.

scottland

yeah $469 and some change for a pair of complete vortec's, they will flow much better than either one of those, i'll bet on it.

www.gmpartsdirect.com

part # 12558060

and 305 heads would have to be THROUGHLY worked to ever match the flow #'s of vortec heads.

five7kid

iTrader: (14)

Even swirlports would be better than those 70's smog heads. There would be no point in trying to port either one, though.