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SBC Heads interchange

7K views 5 replies 4 participants last post by  JasonKyle 
#1 ·
Hey, I have a question..... I bought a remanufactured small block chevy 400 from Advance (yeah, yeah.... I know) a couple years ago.... I recently messed the engines heads up by showing off the other day..... now, I have what I thought was a spare 350 engine sitting in my garage..... on a whim I thought I would see if the heads were interchangable.... I took down the casting numbers and found that the "supposed" 400 C.I. heads casting number was actually for a 350! and to top that the 350's heads were for supposedly for a 400 C.I. engine. All this information was per Mor- Tech.com.
The casting number for the 400s' heads is 3998993, and the 350s' is 3973493.... so.... am I wrong? or can I swap these heads?
I hope you will forgive my ignorance if I have mis- quoted anything here, but the numbers are as I have written them here, and the heads are still on both engines, I have not pulled either set yet. Any information would be greatly appreciated. I am new to this site so if it wouldn't be too much trouble, could you send any replies to:
jasonkyle454@hotmail.com
Thanks
 
#4 ·
Both heads are probably 1.94/1.50. I haven't seen a 1.94/1.60 combination.

Any Gen I SBC head will fit the 283, 327, 350 or 400. The only difference is, as stated, the steam holes for the 400. Both the head #s you mentioned are 76cc chambers.

If you're not confident with drilling the holes, I would take them to a machine shop...probably about $30. Also, I believe some of the holes should be drilled at an angle.
 
#6 ·
SBC Head Interchange

Thanks MI2600,
I am not sure what these "steam holes" are or where they are located on either of these heads.... I took new gaskets and placed it over both heads and all holes match up.... is there something I am missing?... where do I look for them? there are "holes"... fairly small ones drilled, lets say.... at the "top" of the head as you are looking at the valves themselves.... they are drilled at an angle, I think..... at least as far as I can tell.
Am I supposed to drill these holes through the gasket too? if so... where? I have no technical manual to speak of to look at that would show me where these holes are... and what's making the matter worse is I am trying to do all this before Monday morning rolls around... and where I live there is no such thing as a machine shop.... let alone any being open on a weekend. Best thing I have here is a NAPA store that sends stuff out every so often, and it ususally takes at least a week to get stuff back. I am in a crunch here.... so any help on this matter would be super cool.
Again, I thank all that has responded to my query(s).
Is it possible that these holes would already be drilled?

JasonKyle
 
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