Hot Rod Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
1,684 Posts
Head casting numbers

3927186 heads originally came on:

1969 Z-28 302 (2.02's, guide plates, screwed studs)

1970 LT-1 350 (2.02's, guide plates, screwed studs)

1970-1975 350 (1.94's, NO guide plates or screwed studs)
These were mostly used on 1 and 2-ton 'fleet sales' trucks with motors designed for using propane. On some of thes heads, one of the accessory bolt holes is 7/16" thread instead of 3/8".

Also used on appx. 10,000 "CE" long blocks and complete engines.
The engines were either 327HiPo or LT1 350's. (possibly 302's)
(all these had 2.02's, guide plates and screw-in studs)

These are GOOD PERFORMING HEADS...
Highly valued by the 69-Z28 crowd, especially w/late 68 date.
Yenko and Baldwin's cars received these heads.

2.02 heads are easy to spot off the engine without measuring. Look on the combustion chamber side and you'll notice that the valves look like they're nearly touching each other.

On 1.94 heads the valves are about 1/8" apart.

*edit*
3927185 are the low performance 327 and 307 heads used 1969-1973
__________________
 

·
Registered
Joined
·
11 Posts
The heads that came out of the late 60's were great for thier time. But,even a set of stock iron vortec heads will give you better performance now.
 

·
Registered
Joined
·
25 Posts
For what im running they are good heads... small (64cc) chambered heads. !86's are double humps that DO have accesseory holes. Granted you can buy better flowing heads, but im running a 68 SBC 350 and really like my set up.
when I ran dirt track, they were the heads of choice... what im trying to say is they run great for the right set up, but there are better heads on the market. but they are far from trash, there is a market for them!:welcome:
 

·
Hotrodders.com Moderator
Joined
·
2,100 Posts
As the poster above just stated while there is better stuff out there the 186's are not junk like California Kid would lead you to believe. Having the accessory holes in them in a bonus. A lot of the other double humps don't have them which makes things like power steering and alternators a real hassle to hook up.

As long as the exhaust seats are in good shape an not receded and With the right cam those heads will support 375+hp all day long. Plus you already have them. lol
 

·
Administrator
Joined
·
18,646 Posts

·
Registered
Joined
·
9,050 Posts
Biggest problem with old heads is they are worn out. Cracked, guides worn out, exhaust seats shot, warped or have been manipulated by many previous owners. Many who don't have any idea/clue.

MOST are not compatible with modern fuel.

Example that just happened last week..and I get similar all the time. Customer brings in a set of painted up 186 heads. Says he bought them a few years ago. Been setting on the shelf waiting for project. SUPPOSED to be fresh.. Just check for rusty seat area, seals and valve spring pressure.

On the first head.. Warped .005" Cracked from spark plug hole to edge of chamber. center exh seats about 1/4" wide, sunk about .060" and .006" valve stem/guide clearance. Guides had been knurled TWICE. Two distinct patterns. Valves had no margin and major stem wear, thru the plating, at top of travel. Hard wafer trimmed off end to eqalize stem height..Double .060 shims in center valve springs, Fresh valve job??

Second head. Cracked in both center chambers. Again .006+ stem clearance, same double knurl on guides. All exhaust seats sunk. Plus most of the previous heads valve job?

Did the customer get his "great deal" of $400.00 from seller?
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top