I have been reviewing the small block chevy heads and cannot determine for sure what the correct casting is for 1969 z/28 correct heads?? The books i have read show several different casting codes: 3932386, 3956618, 3970010, 3927186, 3947041
3947041x.

any help or thoughts?

Todd Miller

Almost sure that it's 3927186. Note "almost"!

The 618 / 386 / 010 numbers you entered are all for engine blocks! The casting numbers and heads you want for the Z28 are the 186 numbers you mentioned. They will also have a julian date code below the casting numbers (under valve covers) and should be matched to your motor if thats what you are trying to do.

3927186 (DZ 302 Heads)The other 041 numbers you entered are for other small block applications and and are not correct for the 69 Z28 motor. They only used the one 3927186 casting in a 202 / 160 design. Keep in mind that there are 2 designs in that casting. This one above is right for the Z28 and has the large valves, and there is another version with smaller 194/150 valves for the low performance engines.


Hopefully that is what you wanted to know.

Hugger_sixty_nine since were on the subject... I have a pair of the 186 heads that have the 194/150 valves. Are these heads identicle to the 202/160 valve heads in every other way?

Yes they are identical except for the size of the valves. You can have them machined for larger valves at almost any machine shop and can install the 202/160 valves into them without any trouble. A good head guy can spot them when they are done, but most could not. Performance gain in a valve change is quite noticeable and will likely give you 20 or so horsepower. Some bowl porting or blending at the same time will add another 20 or so to that. While having them machined for bigger valves, it is also common to add machining for screw in studs. Then you can rebuilt the heads and add guide plates when your done.

The big valve double-hump heads have a plunge-cut done to them around each intake valve that you can see and feel!

This opens up the chambers anywhere from 62/64 to 66.+..

My virgin -461's are big valve and measure right at 66 to 66.3cc's and you can see and feel the stock plunge cut.

pdq67

I guess a virgin wouldn't be using screw-in studs...

I have put screw-in studs, plus have pinned them,

To me virgin means they have NEVER been ground on anywhere, which mine haven't. Ports and bowls just like they came from GM...

pdq67

thanks guys for the info. what is on my car currently is the 492 angle plug double hump heads. they have roller rockers. Would you leave as is or get the "correct' 186 heads?? what kind of performance diff. would l see? if any?

3927186 is the only head casting any one has ever been able to determine is correct. The date code is month day year, ie A319 (January 31, 1969). If you have an original 1969 Z28 with a DZ engine then get the correct heads, IMHO. Hope this helps. smile.gif
Gary
P.S.
Other posts on the subject:http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=9;t=011565

If you currently have stock GM heads, I see no point in putting on another set of stock heads except for Vortecs. As much as we all love the Z/28, by todays standards the 186 heads are low performance. And I mean LOW. For the price of a set of 186's, you could buy some real nice aftermarket heads.

IMHO, leave the camel humps for the resto people.

GM still sells them heads bare, but dollar for dollar, vortecs are the way to go unless you need it to be "correct".