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Expert
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Location: New Castle PA | Folks, many of you are much more "into" motors than I'll ever be, so I'm asking for help. I received this email, and would like to reply back with an answer. Here it is: All the early Chrysler Corp hemi motors went to a raised block in 56 or 57 for increased displacement. The heads on the Dodge and Chrysler motors changed the intake port location and angle when they went to the raised block. So the port angle on the later heads is at a lower angle than the early heads. It may have had to with maintaining clearance to the hood, not sure. Do you know if this was also the case with DeSoto?
Thanks for any help you can offer. I'll give you credit for the answer, as I'm certainly no motor expert like some of you! |
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Extreme Veteran
Posts: 360
| I know on Chrysler engines this is the way I understand it. The intake port location is for all intents and purposes the same. What occurred with the raised deck is the V became more spread apart. If you put non raised block 354 heads on a raised 392 block you will have a gap when installing the intake because the V is wider. The 392 heads are wider to close the gap. I assume this is the case with all the raised deck hemi engines. heads will interchange but you will need a gap closer if putting 331 or 354 heads on a 392.
On the other hand if you put 392 (raised deck block) heads on a 354 (low deck) block a stock intake wont fit due to the 392 heads being wider. This should apply to all the early hemi engine families.
Think of it as a lower case v and an upper case V. The upper case V has more space between the upper points versus the lower case.
The angle of the intake may have changed slightly for hood clearance but I am more inclined to think the air filter changed to accommodate hood clearance. Earlier it was a large doughnut shape and later it was completely different angled down with the filter hanging lower. Look at the way the filters changed design. The intakes didn't really change, in fact they are interchangeable.
I am sure there are some pictures online of the intake ports on Desoto heads. I bet each year can be found. I know some year Chrysler heads flow better than others as a result of the raised deck and lower deck blocks that were made. The intake ports have extra material on 392 heads (on the top side I think is what I read) and therefore don't flow as well as a certain casting 331 head. So yes the angle of airflow changed.
The amount is negligible unless you are racing. Stock heads that fit without spacers or mods can always be ported if you desire the extra flow. On a driver it just means extra gas money spent.
As far as what heads flow best in the Desoto line I do not know. Someone else will likely add a bit of techy info
Edited by 51coronet 2016-10-06 10:42 PM
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Elite Veteran
Posts: 888
Location: Peoples Republic of Oregon | Close but..... Chrysler changed the heads and the intake manifold will swap between the two deck height engines.
DeSoto and Dodge changed the intake manifold and left the heads/ports alone.
If you need to verify this, try putting a 270 intake on a 325 or a 276 intake on a 341.....
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Extreme Veteran
Posts: 360
| Interesting. Thanks for the info. Hope that answers the OP question |
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Expert
Posts: 1488
Location: New Castle PA | Yes, thank you both! |
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question on DeSoto heads
