What are "555" heads?

Discussion of the 331-354-392 HEMIs.

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big66440
Posts: 12
Joined: Wed Dec 30, 2009 12:09 pm

What are "555" heads?

Post by big66440 »

Sorry to sound so ignorant,I've read quite a few threads on this forum of people mentioning "555" heads I'm assuming thats the last 3 numbers of the head castings but why are they so sought after,and what makes them so popular?
George
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Location: Fl

Re: What are "555" heads?

Post by George »

They are the '55 331 Chr heads. Those & the 56 354 are considered the best flowing. The 55 heads have 3 5s in the casting number(non consecutive), & are the only ones that do.
big66440
Posts: 12
Joined: Wed Dec 30, 2009 12:09 pm

Re: What are "555" heads?

Post by big66440 »

Cool,I have a pair of 56' 354 heads,do you know if all the 354 heads for that year fall under the "best flowing" category?
johnny5
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Location: St Charles, MO

Re: What are "555" heads?

Post by johnny5 »

big66440 wrote:Cool,I have a pair of 56' 354 heads,do you know if all the 354 heads for that year fall under the "best flowing" category?
The ports in the 1954-1956 passenger Chrysler car and industrial heads are the same, so yes.
oldngood
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Joined: Thu Mar 13, 2008 5:14 pm

Re: What are "555" heads?

Post by oldngood »

big66440 wrote:Cool,I have a pair of 56' 354 heads,do you know if all the 354 heads for that year fall under the "best flowing" category?

'56 is better than '51-'53 heads, and marginally better than '57-'58 heads.

If you had the choice and all were easily obtainable, one would choose the '555" for value.

If you have '56 heads, just run those. Any '54-'56 head will work and have the big ports, but each has little differences like water jackets, dowel pins, etc.
dan miller
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Joined: Wed Dec 27, 2006 5:05 am

Re: What are "555" heads?

Post by dan miller »

The 1954 and 1955 heads are the best, the only difference being the water outlets. The 1956 are just a tick less desirable.

Be careful with industrial heads. Not all have the large ports and valves. Many of the late industrial engines come with passenger car heads (on Windsor blocks), and hydraulic lifters.

Danny
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