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351c Open Chamber Build?

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74GranTorino4dr View Drop Down
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    Posted: 23-September-2019 at 11:05AM
In my quest for power I've recently purchased a nice set of 4v heads for my Torino. My cars a factory 2v and I'm just starting to get the whole puzzle together but the 4v heads i felt were necessary. I know the open chamber heads arent as desireable as the closed chambers for a few reasons but thats not why im here. I was wondering has anyone here had success with the open chamber heads when it comes to power. I daily drive my car so 500+  horsepowers probably too much but id like to smoke some mustangs and the local old guys. So my question is did anyone use open chambers on their build? And what other parts would you reccommend? Im thinking headers and maybe a single plane intake. And id like a cam that youd feel in  your heart hahah. Long story short any build success with open chambers? And what type of power do you have going with them? Pros cons? Etc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gregaba Quote  Post ReplyReply Direct Link To This Post Posted: 23-September-2019 at 12:05PM
I have built several open chamber headed 351c for customers.
You can make them a nice daily driver.
The standard mods work good with this engine, I used a comp cams 264H to 282H  for daily drivers with Hooker super comp headers. Electronic ignition but not MSD, and for daily driver all around smoothness with a little power I used the Wieland Stealth intake.
Don't expect to knock off very many other cars on the street without changing the rear end ratio. Most of the Rancheros came with a 2.73 to 3.08 rear. For good off the line take off and decent MPG I would suggest a 3.25 rear.
Greg

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 23-September-2019 at 12:11PM
I am sure Rockatansky will chime in with some more detailed advice, but I'd suggest start doing some reading before you decide on your build  George Pence has tons of info on these engines, in particular on those using factory Ford parts.  Check out some of his best articles here on the forum:
 
 
 
As for the open chambers being second class heads, that is not the case.  While many think that the open chambers lack "quench" and are prone to detonation, this is not true.  The Ford engineers themselves indicated that the open chamber heads are no more prone to detonation than the close chambers.  They also stated that a performance build could be had with open chambers, but pop up style pistons are required to get the higher compression ratios.  On the quench thing, that really applies more to wedge combustion chambers, like a small block Chevy or Ford.  The 335 series engines use shallow poly angle combustion chambers that don't need quench like a wedge chamber.
 
Here is some brief info I highlighted for you:
 
The D1ZE open chamber cylinder head went into production about May 1971. Ford engineering promoted the D1ZE cylinder head for racing in the Off Highway Parts manual of 1972. They claimed the heads flowed better, but they also advised using the D1ZE heads would require the development of custom pop-up dome pistons to raise compression. Ford engineering was no longer as closely involved with the race teams as it had been, because Ford pulled financial support from the entirety of their racing operation at the end of the 1970 season. The Off Highway Parts operation was shut-down too, in February 1973. Development of the open chamber heads for racing fell by the way-side.

I have known people racing the 351C in competition who have preferred the open chamber D3ZE cylinder heads as far back as the 1980s. Each of them had developed their own custom pop-up dome piston to build compression. They could have used any factory cylinder head they chose, and they were adamant that their race car was fastest using the D3ZE cylinder heads.
 
He Goes on to say:
 
There are no bad production Cleveland heads, they all have their merits. They all share the same excellent "shallow poly-angle" combustion chamber design and canted-valve geometry. The 2V (low port) heads are tuned for lower rpm, they can be fitted with 2.12 intake valves (as advised for the D3ZE heads), and their open combustion chambers have the advantages of improved low-lift air flow. Although their air flow flattens out at 0.500" lift due to their "low port" design, they are still capable of supporting over 400 horsepower. The D0AE and D1AE quench chamber 4V heads offer excellent air flow capabilities due to their big valves and high ports, their reduced chamber volumes make it easier to achieve 10:1 static compression with a standard displacement engine, and the small amount of quench provides good low rpm torque. The D1ZE open chamber 4V head castings have the same big valves and high ports, but they trade the low rpm torque of the quench chamber heads for improved low-lift air flow at ALL rpm. The D3ZE castings have the same port height as all 4V heads, they have the open chambers which promote better low-lift air flow, and they have chambers and valves sized properly for a 4" bore thus un-shrouding the valves even better than the D1ZE heads.
 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gregaba Quote  Post ReplyReply Direct Link To This Post Posted: 23-September-2019 at 12:25PM
That is some good info.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 23-September-2019 at 7:26PM
the key to a successful open chamber build is getting the dynamic compression ratio (DCR) up into the 'the alive' range as described in this article by George. the same results can be achieved with a flat tappet hydraulic cam or a flat tappet mechanical. the more radical the cam, the more static compression ratio you need to compensate and maintain DCR


here's a chart George put together showing DCR's for various factory Clevelands


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Post Options Post Options   Thanks (0) Thanks(0)   Quote gregaba Quote  Post ReplyReply Direct Link To This Post Posted: 24-September-2019 at 3:37AM
One thing the OP might consider since his car is a daily driver and it will need some low end power is to use the 2V heads and not the 4V heads.
The 4V heads were developed by Ford for high RPM use and as they found out with the 69 Boss 302 the 4V heads just didn't work out good on the street. Not to say you cant make them street able  but might cost more then you want to spend on a daily driver.
If you want and have the money you can build a 351 with as much HP as any new engine.
The 70 Boss switched to the 2V heads for a lot more low end response.
Just a thought.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 24-September-2019 at 6:26PM
1969 & 1970 Boss 302, and 1971 Boss 351 all used large port large valve 4V head castings

as long as you don't over-cam 4V heads they'll run fine on the street / low end with a reasonable gear
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74GranTorino4dr Quote  Post ReplyReply Direct Link To This Post Posted: 25-September-2019 at 1:04AM
Ill see if i can find the casting number on the heads. It might be easy to start there to determine what limits ill have. Ill get back to everyone on that. There's alot to consider for sure and the wealth of knowledge here is greatly appreciated. Id like to have a bulletproof engine overall. But my intentions will be 4v all the way. The camshaft and the gearing are my next thoughts. Id like maybe 3:73s out back and a cam for mid to high rpm. I drive no more than 5 miles a day between work and home so im fortunate in that regard. The cars been to philidelphia from the shenandoah valley and a few other places. I rarely go on the freeway and almost never go more than 50 miles from home in the torino. All that being said if i had a performance cam and the 4v heads etc i imagine i wouldn't have driveability issues. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 25-September-2019 at 6:19PM
it's very easy to over-cam a 4V into a major driveability issue condition

60*-65* total overlap is about the limit for a mannered street driver with stock converter
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74GranTorino4dr Quote  Post ReplyReply Direct Link To This Post Posted: 26-September-2019 at 12:31AM
Has anyone seen this thread about the cam?
 
This sounds like about what im looking for but thoights? Would this be too much?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 26-September-2019 at 4:35AM
Yup, seen it Wink

too much? not all. it's rather conservative actually and that's why it's a good recipe. my 1st thought went to What Static CR To Make Effective DCR ? if you build the engine to a static CR of 10:1 it makes 7.69:1, very safe for pump premium

Static compression ratio of 10:1
Effective stroke is 2.60 inches
Your dynamic compression ratio is 7.69:1
Your dynamic cranking pressure is 155.29 PSI

if you build the engine to have 10.5:1 static CR it makes 8.06:1 DCR, that's pushing the limit recommended for pump premium and on the verge of tuning issues unless you're at high altitude?

Static compression ratio of 10.5:1
Effective stroke is 2.60 inches
Your dynamic compression ratio is 8.06:1
Your dynamic cranking pressure is 165.15 PSI

back it down to a 10.25:1 build and it makes 7.87:1 DCR, at the high limit of the recommended safety margin for pump premium fuel. for Georges '275/285 Custom Street Cam'  i would build the engine to have a static CR of between 10:1 and 10.25:1 at sea level for best results

Static compression ratio of 10.25:1
Effective stroke is 2.60 inches
Your dynamic compression ratio is 7.87:1
Your dynamic cranking pressure is 160.08 PSI

with a chamber volume of 76cc's, depending upon head gasket thickness between .038"(Edelbrock) and .047"(Fel-Pro 8347) compressed thickness, a piston with a dome of 10cc-13cc is needed to make the target CR window. the Edelbrock gasket can go 11cc's and make 10.21:1, the Fel-Pro gasket can go 13cc's and make 10.21:1. there's about a 2cc difference between the 2 gaskets that can be used to final tune the CR

compare these projected DCR's to those on George's chart up above, the pathetic cylinder pressures generated by those open chamber engines are why the open chambers got their poor reputation in the 1st place. cylinder pressure is needed to control the burn characteristic of any grade fuel, even 87 octane regular just burns uncontrollably like a hay fire at 5 & 6 DCR



Edited by Rockatansky - 26-September-2019 at 4:48AM
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 27-September-2019 at 3:44AM
Originally posted by 74GranTorino4dr 74GranTorino4dr wrote:

Has anyone seen this thread about the cam?
 
This sounds like about what im looking for but thoights? Would this be too much?
 
I am not any expert on engine buidling, so I didn't want to recommend any cam specifically.  However, reading George Pences info, this cam sounds like it'd be perfect.  If I were building a 351C, I'd use that came without a second thought.
 
Don't forget that you'll need to replace the crappy factory two-piece valves!
 
Rock's info above is great as always.  He wouldn't steer you wrong.
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