Best 396 heads?
Moderator: Team
Re: Best 396 heads?
Are the -820 and -241 BBC heads the smog heads with the squared-off side that is inline with the intake valve by the exhaust valves? Almost quenchless...
One head here that is a good head, although a smaller head is the l-29 head that has the heart-shaped chambers with a point that probably would need to be trimmed back a bit and 100 cc chambers.
Although a real large oval head, the intake ports are down around 230 or so cc's vs regular large ovals being like 255 to above 260 cc's.
Might want to watch head gaskets here though?? For possible water leakage due to M IV, Gen V, and Gen VI deck cooling hole configurations is all...
I think Victor Reinz Gaskets has all this covered so please check..
http://www.hotrodders.com/forum/bbc-l29 ... 71714.html ----------
-------- "Victor Reinz has designed two Nitroseal® head gaskets to specifically allow for this conversion. The installation requires Victor Reinz part number 4918 be installed on the right cylinder bank to maintain proper coolant circulation, and part number 4923 to be installed on the left cylinder bank for the correct coolant flow. "
pdq67
One head here that is a good head, although a smaller head is the l-29 head that has the heart-shaped chambers with a point that probably would need to be trimmed back a bit and 100 cc chambers.
Although a real large oval head, the intake ports are down around 230 or so cc's vs regular large ovals being like 255 to above 260 cc's.
Might want to watch head gaskets here though?? For possible water leakage due to M IV, Gen V, and Gen VI deck cooling hole configurations is all...
I think Victor Reinz Gaskets has all this covered so please check..
http://www.hotrodders.com/forum/bbc-l29 ... 71714.html ----------
-------- "Victor Reinz has designed two Nitroseal® head gaskets to specifically allow for this conversion. The installation requires Victor Reinz part number 4918 be installed on the right cylinder bank to maintain proper coolant circulation, and part number 4923 to be installed on the left cylinder bank for the correct coolant flow. "
pdq67
-
- Guru
- Posts: 1481
- Joined: Thu Feb 07, 2008 1:32 pm
- Location:
Re: Best 396 heads?
GOSFAST wrote:Hi Bob, just about all these heads we set up (on these platforms) get a 2.125" SBC intake valve and a 1.810 BBM exhaust valve. These exhaust valves are from the "Indy" heads. If we are "chasing" a bit more HP we will go up to the 2.150" on the intakes and work the (intake) ports over a bit more!Bob Hollinshead wrote:Thanks for the info everybody! Gary, what diameter valves work good? 2.10 intake?
We have on occasion stayed with the .375" stem OEM BBC 1.720" exhaust's but this is our 2nd choice. Takes a bit more port work to get the same numbers as the 1.810" Mopar valves.
With the LS-5 "820" heads ('71 Vettes) we are at 525 HP with the 100% stock-appearing builds with ALL the original components, Q-jet carb, stock exh manifolds, and 9.7:1 C.R. But these are also NOT 396" builds.
Thanks, Gary in N.Y.
P.S. I would add also we use ONLY the Ferrea valves on almost all our builds, occasionally will do Manley's but only when the Ferrea's aren't available. A while back we had a Cloyes BBC "Tru-Roller" literally explode up at about 7000, bent 14 of the 16 Ferrea valves, but not a single one broke!!
Thanks for the info, sounds like you have done a lot of testing on this and feel the stock HP 2.19 intake valve size must be a little too big for the closed chamber? Too much shrouding? I wonder how a 2.15 with 50* seat would do?
Pro question poster.
-
- Guru
- Posts: 1481
- Joined: Thu Feb 07, 2008 1:32 pm
- Location:
Re: Best 396 heads?
I was thinking he may be able to get close to 10-1 compression on a 496 flattop build...Alan Roehrich wrote:Depends on the piston. If you use a flat top, you can't even approach decent compression with any open chamber head. A closed chamber cast iron head yields good compression and good thermal efficiency. They're even good up to a 4.250" stroke 496.
Pro question poster.
-
- Guru
- Posts: 1577
- Joined: Mon Apr 04, 2011 8:54 pm
- Location: central Florida
Re: Best 396 heads?
I was thinking that the 375 HP 396 which was offered in 1969 had rectangular ports, this head was probably too big IMHO for the application, does anybody know what Combustion chamber these heads had? I think this motor was 11 to 1 static compression? Thanks Mark.
Re: Best 396 heads?
Reading right along here...swampbuggy wrote:I was thinking that the 375 HP 396 which was offered in 1969 had rectangular ports, this head was probably too big IMHO for the application, does anybody know what Combustion chamber these heads had? I think this motor was 11 to 1 static compression? Thanks Mark.
"does anybody know what Combustion chamber these heads had?"
pdq67
-
- Expert
- Posts: 934
- Joined: Mon Jan 23, 2006 10:50 pm
- Location:
-
- Guru
- Posts: 5566
- Joined: Sun Feb 19, 2006 10:19 am
- Location: MA
Re: Best 396 heads?
Most of the time I buy in that flat top is better than a dome.
With the BBC engine, open chamber heads and a domed piston makes great power and torque. I think the chamber shape and increase in compression with a dome more than makes up for any possible loss in airflow because of the dome. Maybe the dome actually helps promote turbulence/burn in the chamber. You don't see evidence of a poor burn even with a large dome.
I also find more power in the BBC increasing compression with a dome VS milling the heads to get to the same comp ratio.
I use the open chamber (454)heads on the 396 (with the 2.19" int valve) . I use a dome piston and shift the head over with offset dowels. These engines perform very well!
With the BBC engine, open chamber heads and a domed piston makes great power and torque. I think the chamber shape and increase in compression with a dome more than makes up for any possible loss in airflow because of the dome. Maybe the dome actually helps promote turbulence/burn in the chamber. You don't see evidence of a poor burn even with a large dome.
I also find more power in the BBC increasing compression with a dome VS milling the heads to get to the same comp ratio.
I use the open chamber (454)heads on the 396 (with the 2.19" int valve) . I use a dome piston and shift the head over with offset dowels. These engines perform very well!
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit
Re: Best 396 heads?
With the BBC engine, open chamber heads and a domed piston makes great power and torque. I think the chamber shape and increase in compression with a dome more than makes up for any possible loss in airflow because of the dome. Maybe the dome actually helps promote turbulence/burn in the chamber. You don't see evidence of a poor burn even with a large dome.
I also find more power in the BBC increasing compression with a dome VS milling the heads to get to the same comp ratio.
I use the open chamber (454)heads on the 396 (with the 2.19" int valve) . I use a dome piston and shift the head over with offset dowels. These engines perform very well!
I couldn't agree more!
I also find more power in the BBC increasing compression with a dome VS milling the heads to get to the same comp ratio.
I use the open chamber (454)heads on the 396 (with the 2.19" int valve) . I use a dome piston and shift the head over with offset dowels. These engines perform very well!
I couldn't agree more!
Racing a NA NHRA stocker should be mandatory before any posting.
-
- Pro
- Posts: 461
- Joined: Sun Feb 13, 2005 11:27 am
- Location:
Re: Best 396 heads?
How much offset do you use on the dowel? Do you have to modify the head bolt holes in the head?Keith Morganstein wrote:Most of the time I buy in that flat top is better than a dome.
With the BBC engine, open chamber heads and a domed piston makes great power and torque. I think the chamber shape and increase in compression with a dome more than makes up for any possible loss in airflow because of the dome. Maybe the dome actually helps promote turbulence/burn in the chamber. You don't see evidence of a poor burn even with a large dome.
I also find more power in the BBC increasing compression with a dome VS milling the heads to get to the same comp ratio.
I use the open chamber (454)heads on the 396 (with the 2.19" int valve) . I use a dome piston and shift the head over with offset dowels. These engines perform very well!
Re: Best 396 heads?
Gary,
What are your thoughts on mildly worked over -206's, the way early, 96.7 to 98 cc true bathtub chambered heads?
I know they will shroud the valves some, but still due to the small chamber's, use flat-top pistons and .020" thick or so steel shim head gaskets here.
pdq67
What are your thoughts on mildly worked over -206's, the way early, 96.7 to 98 cc true bathtub chambered heads?
I know they will shroud the valves some, but still due to the small chamber's, use flat-top pistons and .020" thick or so steel shim head gaskets here.
pdq67
-
- Guru
- Posts: 5566
- Joined: Sun Feb 19, 2006 10:19 am
- Location: MA
Re: Best 396 heads?
Depends on the "mock-up" but always at least the .030" and sometimes the .050". I set the head on parallels in my Bridgeport and plunge mill the head bolt holes. Pretty easy, only about 30 min a head.Old School wrote:
How much offset do you use on the dowel? Do you have to modify the head bolt holes in the head?
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit
-
- Pro
- Posts: 482
- Joined: Tue May 06, 2008 9:59 pm
- Location: kansas city mo
Re: Best 396 heads?
does the 2.19 in intake help that much for performance on a 396 even when you offset it?
Re: Best 396 heads?
The offset is done on a NHRA stocker build (375 HP 396) the offset is done by moving the bore over. There is a power increase, I believe it to be around 10 HP.gnicholson wrote:does the 2.19 in intake help that much for performance on a 396 even when you offset it?
Racing a NA NHRA stocker should be mandatory before any posting.