I just got a set of 186 heads from my friend (yes, they DO have the accessory holes). They were rebuilt about 150-200 miles ago. i think they wre polished up a bit, nothing major. my question is this: how well do these heads respond to gasket matching, etc. They look like they have 1.94/1.5 valves. is there any benefit in upgrading the vavle size? or at least, the exhaust to 1.6? i plan on running a mild shot of nitrous so i need the exhaust flow.

the rebuild included:
-hot tank
-magnaflux
-new valves, springs, retainers, seals
-Crane 1.5 full roller rockers

 

Yes they are good heads. Yes they will respond to larger valves and porting. Some chamber deshrouding is helpfull. The amount of metal removal for deshrouding for large valves is minor.

 

forgot to ask, how do these compare to 416's and 906's?

 

They are among the best of the old castings to get. They came on the higher-powered 350s in 69 & 70. Not the 302s and LT1s, but the ones just below that.

They are much much better flowing than 416s in stock form, and somewhat better (usually) after both are worked to the max. 906s are much better in stock trim. After porting there's not near as much difference.

I have some sets of them left over from my old building days, that I use on my motors.... they tend to run pretty hard. Here's one set of them.

 

sweet, thanks for the info RB!