Heads/intake manifold question 454

[cooter55]

I have a '73 C20 with the original 454 and am looking for a square bore intake manifold for a fuel system change. The question is were the intake ports round or rectangular in '73? Is there any way of telling by part numbers or such without tearing it apart?

 

[nvrenuf]

True rectangular port bbc heads only came on the highest hp motors, your '73 truck motor will without a doubt have oval port heads.

If you pull a valve cover the identifying casting number will be visible between the rockers. Most likely your truck motor will have either '781 or '049 casting heads which are very desirable for builds running 6k rpm and under.

 

[cooter55]

Thank you for the info