Via3d

Are there any spec/charts for the flow or port sizes on the various SBO heads?

I have seen some experienced Olds enthusiasts suggest both the #4 and 5's ... probably the 5's suggested most as best flowing. I haven't seen any data are specs regarding....

joe_padavano

First, all of these "head flow" charts are typically based only on measurements of one or two heads. The manufacturing tolerances are greater than the differences you find in these tables. Bottom line is that any SBO head prior to the no. 8 smog heads will flow about the same as any other, given the same valve sizes. People loose WAAAAY too much sleep agonizing over this.

olds 307 and 403

Yes and #8's with a bowl hog on the exhaust bowl match early heads for flow. The later number then large "A" heads, all suck and need port work to flow as much as earlier heads.