Mopar B block open chamber heads

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Truckedup
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Mopar B block open chamber heads

Post by Truckedup »

The only new vehicle I ever had was a 69 Dodge SB 383 4 speed...This engine had open chamber heads...I was told back then the 67 closed chamber heads could make more power. I assume the closed chamber had more squish? Was the change made to meet emissions?
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Re: Mopar B block open chamber heads

Post by pdq67 »

Waiting to find out too!!

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Re: Mopar B block open chamber heads

Post by Truckedup »

Poking around the Mopar sites it seems the open chamber lowered Nox emissions without other tricks. There's some disagreement about which head flows better, but the closed chamber makes higher compression without bigger piston domes...And better squish for detonation control on lower octane gas...
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Re: Mopar B block open chamber heads

Post by falcongeorge »

The runners in the #906 and #915 were the same, both can go 300+ IF you know what you are doing, and fully ported PROPERLY (this is the key word here) will outflow fully ported #452's, contrary to popular internet myth. But porting the #906/#915 runner PROPERLY is counter-intuitive to a lot of guys. The most critical part to making this port work is probably the floor as it approaches the short side, and it is SENSITIVE. If the floor isn't right, the port will stall around .550.
If your intent is to just port them per the Mopar Performance templates, and you don't have a flowbench, bypass the #915/#906, and use a #452, you get a much better result. You will never get the early port to work well just by guess and by god, porting them successfully is a touchy job.
FWIW, you can also get fair results with the '66 and earlier closed chamber #516 by bigger valves and rudimentary pocket porting, and the #516's are MUCH cheaper and easier to find than the sought after #915, which is a rare, one year only head. I still have a pair of untouched #915 castings, but I am in Canada, you don't even want to think about paying the shipping.
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Re: Mopar B block open chamber heads

Post by Truckedup »

Thanks.......
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Re: Mopar B block open chamber heads

Post by pdq67 »

I guess that I wouldn't even bother because I would go HEMI..

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Re: Mopar B block open chamber heads

Post by Truckedup »

pdq67 wrote: Thu Jul 30, 2020 1:25 am I guess that I wouldn't even bother because I would go HEMI..

pdq67
Over priced and bulky...For street use I believe a properly built Wedge is all that's realistically needed needed
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Re: Mopar B block open chamber heads

Post by pdq67 »

Say that little bitty 241" Dodge hemi and put a 177 mini blower on it to make up for it being small.

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Re: Mopar B block open chamber heads

Post by Truckedup »

pdq67 wrote: Thu Jul 30, 2020 10:16 pm Say that little bitty 241" Dodge hemi and put a 177 mini blower on it to make up for it being small.

pdq67
Expensive horse power.....And just how much power on pump gas?
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Re: Mopar B block open chamber heads

Post by pdq67 »

Max 177 mini roots blower boost and water/alcohol inject it to hold detonation at bay.

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Re: Mopar B block open chamber heads

Post by Truckedup »

pdq67 wrote: Fri Jul 31, 2020 9:34 am Max 177 mini roots blower boost and water/alcohol inject it to hold detonation at bay.

pdq67
Other than eye candy with a hoodless vehicle, it has zero advantage and sure costs more than a N/A build..Of course it's going to be more fun to build...
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Re: Mopar B block open chamber heads

Post by Ron E »

'010 - up 5.7 hemis more HP than a stock 440, same width, shorter, and a lot lighter. carb intakes and stand alone ignitions available.
6.1 or 6.4 hemis. Both strong outa the box. 425, and 485 net HP. Carb'ed 6.4 crate engine 540 crank HP.
never burn another sparkplug wire.
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Re: Mopar B block open chamber heads

Post by pdq67 »

I am back and will be serious here!

I seem to recall an old mag article where CR was tested using the totally open chambered 400 MOPAR heads like being discussed here.

The article started at something like 12 to 1 or maybe even 13 to 1.

Then the article went down hill using a bunch of different thickness STACKED head gaskets until the engine was down around 8 or so to 1.

I want to say like from 12 or so, then 11 or so, then 10 or so, then 9 or so and finally to 8 CR??? I think they ended up at a head gasket thickness stacked of like .125" or so or more???

They stacked head gaskets to arrive at the low CR they were testing for.

Seems the old open chambered 400 MOPAR heads did quite well even though the drop in CR was quite drastic.

At the top end, they started with high test gas and ended up dropping it down to low test gas and this was the only bad deal they didn't check for.

Anyway, the old engine ran well down in the lower CR range and they showed the drop in Hp due to the drop in CR.

It is very interesting article IF we can hunt it up nowadays??

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Re: Mopar B block open chamber heads

Post by Truckedup »

At 10,000 miles I pulled the heads off my bought new 383 Super B and dropped them off at Tony Feil's speed shop in NJ....I read ina book that a milling and a good valve job would add noticabe power...The head were milled to the maximum and valve work....Wow, on the street it was much faster , the engine had a 413 dual point distributor and carb jetting..In "organized" street racing with 7 inch tires it did very well against similar cars.
But at the Englishtown track it was just a low 14 second car like before the headwork....
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