| |
Click on image for the lowdown. 
====
| | | Forums66 Topics128,035 Posts1,055,445 Members48,422 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | 
#83504 09/28/2007 4:50 AM | Joined: Sep 2007 Posts: 33 Wrench Fetcher | | Wrench Fetcher Joined: Sep 2007 Posts: 33 | Anyone know if the valves/runners are any bigger on a 261 head, versus a 235 head? I am aware of the main differences in the 2 engines. I also understand that the 261 head uses steam holes and such, which would require one to drill-out the 235 head.
The combustion chamber on the 235 is obviously smaller, since the compression ratio is higher.
Also, what's the likely hood of finding a good 235 head that is not cracked. I hear this is a common problem.
Thanks a lot,
G | | |
#83505 09/28/2007 4:54 AM | Joined: Jan 2005 Posts: 1,602 Shop Shark | | Shop Shark Joined: Jan 2005 Posts: 1,602 | There are plenty of heads on this web site. Look in parts wanted or parts for sale. I found several in a matter of three days. Good luck!
| | |
#83506 09/28/2007 7:19 PM | Joined: Oct 2001 Posts: 3,458 Extreme Gabster | | Extreme Gabster Joined: Oct 2001 Posts: 3,458 | The passages of the 850 261 head are exactly the same as the 848 head of the 235. The 261 uses stellite exhaust valves but I don't remember if there is a size difference. The rocker arms are not the same.
Paint & Body Shop moderator
A lone amateur built the Ark. A large group of professionals built the Titanic. | | |
#83507 09/28/2007 9:49 PM | Joined: May 2004 Posts: 920 'Bolter | | 'Bolter Joined: May 2004 Posts: 920 | I've always wondered about the differences between the 848 head and the 850 head. There are those here that have said the 848 head will give more compression. Is that true? Reading the shop manual, the only difference I can see is the hardened exhaust valves and stiffer springs. And of course the steam holes. Can 235 rocker arms be used in a 850 head? I have one NOS 850 head and one good 848 head for the 261 stroker I'm building. I'm undecided on which one I'll use. Maybe someone can push me over to one side of the fence? | | |
#83508 09/28/2007 9:57 PM | Joined: Aug 2002 Posts: 455 Shop Shark | | Shop Shark Joined: Aug 2002 Posts: 455 | If you visually compare the combustion chambers you can see the smaller volume of the 848 head. It has the highest stock compression ratio of all 235/261 heads.
Rocker arms are the same for late 235 and 261 heads, according to the shop manual. | | |
#83509 09/29/2007 1:05 AM | Joined: Sep 2007 Posts: 33 Wrench Fetcher | | Wrench Fetcher Joined: Sep 2007 Posts: 33 | Thanks a lot for the good info. Sounds like a good idea just to use the 235 head then. | | |
#83510 09/29/2007 1:19 AM | Joined: Jan 2005 Posts: 1,602 Shop Shark | | Shop Shark Joined: Jan 2005 Posts: 1,602 | I came the the same conclusion and I'm using a 235 848 head.
| | |
#83511 09/29/2007 1:48 AM | Joined: Aug 2002 Posts: 455 Shop Shark | | Shop Shark Joined: Aug 2002 Posts: 455 | Chevy 6 rodders have used the 848 head with 235/261 blocks ever since they first were introduced with trucks in 1954....
I got a 1962 and 1954 dated 848 head on both my late 235 and 261 blocks.
Funny and kind a cool - the first and last year of production. | | |
|
|
| |
