Open vs Quench George? Dan Jones?

Open vs Quench George? Dan Jones?

Joined: June 17th, 2010, 12:57 am

September 11th, 2011, 8:27 pm #1

Hey George
you said something in one of the other post that has me thinking
you said if you mill a set of open chambered heads .060 it would remove 12cc from the chamber with an open chambered head being between 74 78 cc milling the head should bring the cc down to between 62 to 66 which is right in the area of a set of 4v quench heads. so it should be really easy to do a back to back comparision on an engine. as a guy could cc a set of quench heads , then mill a set of open chambered head to match the cc.
the way i see it. there would only be 2 items that would need adjusted
1 the pushrod lenght would need to be shorted the amount of the head milling to make sure rocker alignments is correct.
2 an intake manifold that is milled to correct fitament issue.
Now here is where Dan Jones ? sorry dan if your not interested.
and a guy whos close to dan who has a set of open chambered heads and an intake that matches one of the intake dan has , which can be milled to match his heads
that has a set of heads that he would like to increase his compression ratio.
we could use dan jones test engine , that has the flat top pistons?
sorry dan if i got your combo wrong.
Brent not sure if you can do something like this?
this might help set you apart from the rest of the shops who do cleveland
or anyone building a 351 cleveand who want to find out for himself
as far as Me
I got enought quench heads to last me the rest of my life.
but it might make me look for open chambered heads.
as i have probably passed on 15 sets when maybe i should have bought them
just food for thought
plus i think alot of us on here would really like to know, if
all thinks being equally will an open chambered head make the same power as a quench head
thanks George , for the thoughts
Dan for is dyno testing
andeveryone else who has an idea
later guys
Last edited by pewterboss351 on September 11th, 2011, 8:48 pm, edited 1 time in total.
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Joined: October 1st, 2004, 8:05 pm

September 11th, 2011, 9:46 pm #2

There was a time when combustion chambers were all the talk in the hot rod world, when Chrysler named its motors for the type of combustion chamber they had ... Hemi, Poly Spherical, Wedge, etc. When we pulled a valve cover on a big block chevy or a 351C and saw the valve springs pointing off in those odd-ball angles we knew that meant those motors had poly angle combustion chambers (not just canted valves).

When the 351C was new we considered the open chamber heads just as good as the quench chamber heads, the only difference was chamber volume and compression ratio. If somebody had made the statement back then that the quench chamber heads made more power, we would have rolled our eyes at them, they would be the person having to prove their point with dyno tests. Its funny how today, 40 years later, the tables are turned.

I proved the open heads make as much power as the quench heads back in the 1970s and I've related the story. A former forum member also proved this, he swapped heads and nothing else, compression increased from 10-ish to 13:1 and RWHP increased by 30 (thats about 38 at the crank) which is easily explainable by the increase in compression. There's another former member who says he went faster with open chamber heads and 11:1 compression than he did with quench chamber heads and 13:1 compression. I've provided links to their posts. If Dan were to run a back to back test, I can already tell you what the results will be.

The confusion over this subject really points out how much influence the small block chevy has in the indoctrinization of new gear heads. I realize this can be difficult to accept ... in fact it really rocks some people's world. Which is why the subject has been quietly avoided, not just by me but by many older members here who know better.

There are a few new tricks to explore if we can get people over the hump of thinking the quench heads are superior to the open heads. What you suggest is part of what I had in mind. Any and every 351C can be brought up to 10:1 compression with any set of 351C heads ... and can make equal power all other things being equal. All of a sudden chamber volume becomes more imortant than whether or not the chambers are quench style. All of a sudden guys building up 400 cubic inch motors will want 1971-1972 Cobra Jet heads (75cc chambers) and flat top pistons instead of Australian quench chamber heads and ridiculous dished pistons. All of a sudden, 351C enthusiasts will want a piston with the best possible dome for open chamber heads instead of a dished piston with a dish shaped like the quench chamber. Hopefully Cleveland builders will stop worrying about squish clearance the way Chevy builders do. The value of quench chamber heads and open chamber heads will equalize.

-G
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Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
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Joined: June 14th, 2006, 2:29 am

September 11th, 2011, 10:46 pm #3

I have a simple question:

Why doesn't anybody in the aftermarket make them?
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Joined: February 13th, 2006, 4:59 am

September 11th, 2011, 11:08 pm #4

Yes Tim that's a good question ? In theory it's all about getting the most airfuel into the cylinder,one would think that seeing you have the bigger combustion chambers the open would be the way to go. That's ofcourse everything else is equal?Where are all the old pro-stockers I'm sure they have done some dyno work in this area trying to find hp?
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Joined: July 21st, 2005, 12:13 am

September 11th, 2011, 11:25 pm #5

I have a simple question:

Why doesn't anybody in the aftermarket make them?
.. but the question was ignored. Maybe you'll get a response.
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Joined: July 24th, 2008, 10:06 pm

September 12th, 2011, 12:56 am #6

True 4v heads have neen the hot setup for 40 years and no one makes them eather. that don't mean much!
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Joined: December 16th, 2003, 11:56 pm

September 12th, 2011, 1:32 am #7

There was a time when combustion chambers were all the talk in the hot rod world, when Chrysler named its motors for the type of combustion chamber they had ... Hemi, Poly Spherical, Wedge, etc. When we pulled a valve cover on a big block chevy or a 351C and saw the valve springs pointing off in those odd-ball angles we knew that meant those motors had poly angle combustion chambers (not just canted valves).

When the 351C was new we considered the open chamber heads just as good as the quench chamber heads, the only difference was chamber volume and compression ratio. If somebody had made the statement back then that the quench chamber heads made more power, we would have rolled our eyes at them, they would be the person having to prove their point with dyno tests. Its funny how today, 40 years later, the tables are turned.

I proved the open heads make as much power as the quench heads back in the 1970s and I've related the story. A former forum member also proved this, he swapped heads and nothing else, compression increased from 10-ish to 13:1 and RWHP increased by 30 (thats about 38 at the crank) which is easily explainable by the increase in compression. There's another former member who says he went faster with open chamber heads and 11:1 compression than he did with quench chamber heads and 13:1 compression. I've provided links to their posts. If Dan were to run a back to back test, I can already tell you what the results will be.

The confusion over this subject really points out how much influence the small block chevy has in the indoctrinization of new gear heads. I realize this can be difficult to accept ... in fact it really rocks some people's world. Which is why the subject has been quietly avoided, not just by me but by many older members here who know better.

There are a few new tricks to explore if we can get people over the hump of thinking the quench heads are superior to the open heads. What you suggest is part of what I had in mind. Any and every 351C can be brought up to 10:1 compression with any set of 351C heads ... and can make equal power all other things being equal. All of a sudden chamber volume becomes more imortant than whether or not the chambers are quench style. All of a sudden guys building up 400 cubic inch motors will want 1971-1972 Cobra Jet heads (75cc chambers) and flat top pistons instead of Australian quench chamber heads and ridiculous dished pistons. All of a sudden, 351C enthusiasts will want a piston with the best possible dome for open chamber heads instead of a dished piston with a dish shaped like the quench chamber. Hopefully Cleveland builders will stop worrying about squish clearance the way Chevy builders do. The value of quench chamber heads and open chamber heads will equalize.

-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
Now, there's a dog that just won't hunt.
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Joined: February 13th, 2006, 4:59 am

September 12th, 2011, 1:50 am #8

What about the c3 high port yates heads that have a starting cc 0f 40 in combustion chambers?They make a ton of power??
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Joined: August 23rd, 2003, 12:49 pm

September 12th, 2011, 2:38 am #9

http://speedtalk.com/forum/viewtopic.php?f=15&t=23564

Have a read of the thread above and the nuances of the newer style chambers become pretty obvious. Chamber shape can greatly influence the way air and fuel flows into the cylinder.
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Joined: June 17th, 2010, 12:57 am

September 12th, 2011, 3:33 am #10

There was a time when combustion chambers were all the talk in the hot rod world, when Chrysler named its motors for the type of combustion chamber they had ... Hemi, Poly Spherical, Wedge, etc. When we pulled a valve cover on a big block chevy or a 351C and saw the valve springs pointing off in those odd-ball angles we knew that meant those motors had poly angle combustion chambers (not just canted valves).

When the 351C was new we considered the open chamber heads just as good as the quench chamber heads, the only difference was chamber volume and compression ratio. If somebody had made the statement back then that the quench chamber heads made more power, we would have rolled our eyes at them, they would be the person having to prove their point with dyno tests. Its funny how today, 40 years later, the tables are turned.

I proved the open heads make as much power as the quench heads back in the 1970s and I've related the story. A former forum member also proved this, he swapped heads and nothing else, compression increased from 10-ish to 13:1 and RWHP increased by 30 (thats about 38 at the crank) which is easily explainable by the increase in compression. There's another former member who says he went faster with open chamber heads and 11:1 compression than he did with quench chamber heads and 13:1 compression. I've provided links to their posts. If Dan were to run a back to back test, I can already tell you what the results will be.

The confusion over this subject really points out how much influence the small block chevy has in the indoctrinization of new gear heads. I realize this can be difficult to accept ... in fact it really rocks some people's world. Which is why the subject has been quietly avoided, not just by me but by many older members here who know better.

There are a few new tricks to explore if we can get people over the hump of thinking the quench heads are superior to the open heads. What you suggest is part of what I had in mind. Any and every 351C can be brought up to 10:1 compression with any set of 351C heads ... and can make equal power all other things being equal. All of a sudden chamber volume becomes more imortant than whether or not the chambers are quench style. All of a sudden guys building up 400 cubic inch motors will want 1971-1972 Cobra Jet heads (75cc chambers) and flat top pistons instead of Australian quench chamber heads and ridiculous dished pistons. All of a sudden, 351C enthusiasts will want a piston with the best possible dome for open chamber heads instead of a dished piston with a dish shaped like the quench chamber. Hopefully Cleveland builders will stop worrying about squish clearance the way Chevy builders do. The value of quench chamber heads and open chamber heads will equalize.

-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
George
not to doubt you, you list a couple of example where they made the same power or similar power with open chamber heads. A car could run faster going from 13 to 1 down to 10 or 11 to 1 , and that could be the cam in his car works better with the lower compression. Like you say all the time , its about the cam timing.
I can personally tell you from my experances,
and it alot. I have been messing with 351 clevelands for over 30 years.
I AM BY NO MEANS A NEWBY
around here, north platte nebraska. I am known for making ford run. And if you want a fast ford to go see Bill Binegar ( thats me) around here theres has not been an open chambered head 351 400 or what ever that could run with any of the 4v quench headed motors i put together.
I have had a 73 and a 74 torino , that recieved quench heads, and i can tell you they made a big differance.
Granted i added compression to the engine when i chaged heads
but theres no way i added 3 full points of compression. by installing a head with 12 15 cc less combustion chamber volume.
A freind of mine has a 351 cleveland in a 72 mustang its built with open chambered heads, and 12.5 open chamber trw pistons.
His car is fast no doubt about it.
But i can tell you my 71 mustang with quench chamber heads with flat top piston will walk all over it
and his car has 4.10 gears and mine has 3.50.
You said someone picked up 38 horse by swithing to closed chamber heads
but their compression ratio went up 3 points.
I know every combo is different
but i always figured it was more like 1.5 to maybe 2 points going from an open chambered to a quench chambered head.
George your a smart man , no doubt about it, and your experiance is vast.
I am not doubting what your have experance is true.
But i feel a few cases where an open chamber head matched a closed chambered head,
does not mean in all case it would be true.
Plus you said an open chambered head makes as much power as a quench.
i do not recall you saying as making more power?
which goes back to you saying back then
when they said a quech head make more power we would roll our eyes at them?
they would be the one having to prove themselves with dyno testing
well just like you i have read alot of information on 351 cleveland in the last 30 plus years
and i dont ever remember anyone recomending an open chambered head
for any performance build.
I do how ever remember a few where it was recomended to lower the compression ratio, to run on today pump gas .
Funny thing I never had a problem running pump gas with a quench chambered headed engine.
And if fact I beleive almost every performance build 351 cleveland built by any knowledgeable ford engine builder on the national stage ( ie in the performance mags) have been built with either 4v quench heads or
aussie heads.
I dont every remember a 351 cleveland built in a national magazine to have been built with a set of 4v open chambered heads.
Granted I may have missed 1
but if they are as good ,(which they maybe) why havent we seen engine built with them?
A more scientific test one like dan did would be more inforative
sorry not tring to beat up on you george
as i have read and read what you have wrote
and it has me thinking.
and now i want to know
and once again thanks
Last edited by pewterboss351 on September 12th, 2011, 4:25 am, edited 1 time in total.
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