4006452
- Thread starter dodgepaul
- Start date
65 Plymouth Satellite 426
Well-Known Member
The #4006452 Or #452 Open Chambered Heads Were Used On '76 To'78 Mopar Vehicles With The 400/440 Engines. As Far As What They Were Cast Of, I'd Say Steel Like Everything Else Ma Mopar Built! But I Remember Discussions Of A Set Of Aluminum 452's That Either Mopar Cast Or Perhaps Were After Market Units With The 452 Numbers On. I Think What You May Be Thinking About Is These Heads With The 81.5cc Combustion Chambers Have Hardened Valve Seats. There Always Has Been Arguments To Whether Or Not These 452's Were As Good Or Better Than The 915, 906, And 346 Heads.
Meep-Meep
дворянин
There is an aluminum set of "452" heads that are cast by Edelbrock - basically the Performer heads with a MoPar logo. The old iron 452's are as it says above, late model hard seat stuff. One of the big differences is the flat intake port floor similar to the old 516 closed chamber and the famous early max wedge heads. As I understand this flat intake port floor was found to be inferior and the answer was to rely on expertise from Harry Weslake to develop a more contoured port as found on the 915 and 906 heads. Why they went back to the flat floor I have no idea but can guess it may have been emissions related.
Perhaps the flat port floor put more of a swirl into the chamber as opposed to improved basic wet flow, since the target was a more complete burn of the mixture thus reducing HC emissions. Think about when these heads were used in production. I'll add that the huge bore chamfer on my 78 440 block may very well be for the same reason - to allow the flame front to burn the gases trapped in that space. Later piston design aims to reduce the annular space above the top ring by placing the top ring higher on the piston in an effort to have less unburned gas after the combustion cycle. Bringing the top ring closer to the chamber and keeping that gap tight also requires a stronger piston with different thermal properties and that brings us the hypereutectic alloy.
I think plenty of folks had good success using the iron 452 heads for a street motor, but I bet their popularity was due only to availability and not because they are better than the 915 or 906 heads. 915 heads are nearly gone (except in my shop) followed closely by the 906 head. Then you factor in adding hard seats to the early stuff and you are money ahead. For a basic street motor that you want to build on the cheap you may get more bang for the buck by focusing on cam, compression, a free flowing exhaust and gearing. You don't even need an aftermarket intake but I do recommend a good exhaust.
Perhaps the flat port floor put more of a swirl into the chamber as opposed to improved basic wet flow, since the target was a more complete burn of the mixture thus reducing HC emissions. Think about when these heads were used in production. I'll add that the huge bore chamfer on my 78 440 block may very well be for the same reason - to allow the flame front to burn the gases trapped in that space. Later piston design aims to reduce the annular space above the top ring by placing the top ring higher on the piston in an effort to have less unburned gas after the combustion cycle. Bringing the top ring closer to the chamber and keeping that gap tight also requires a stronger piston with different thermal properties and that brings us the hypereutectic alloy.
I think plenty of folks had good success using the iron 452 heads for a street motor, but I bet their popularity was due only to availability and not because they are better than the 915 or 906 heads. 915 heads are nearly gone (except in my shop) followed closely by the 906 head. Then you factor in adding hard seats to the early stuff and you are money ahead. For a basic street motor that you want to build on the cheap you may get more bang for the buck by focusing on cam, compression, a free flowing exhaust and gearing. You don't even need an aftermarket intake but I do recommend a good exhaust.
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