round or square ports?

[dirtydon]

How can I tell what ports my 521 with an l18 has without removing the ex manifold?

Thanks in advance for any info.

Dan

[Pac. coast Datsun]

Dan different heads had different sized ports [round or square] . Im not really sure what head is on yours but that will tell you. My 620 had a L 18 in it when i bought it, heres a pic of the head w/ manifold off...i've since put in a new motor but i believe that head was a U 67...