hey guys/gals, 2 quick questions. 1) do black motor 308 (non-injected) heads fit on a red 253 ? and 2) were the black engines leaded or unleaded from factory? thanks alot for your help.

1, yes & 2, depends on which model, vk's were leaded while vl's were unleaded. Find out which year yours is and that should tell you. cheers

As said above the Vl heads will fit...however, if its an early 253 like say from a hq then you will need the intake manifold that goes with the heads as well. they moved one of the centre manifold bolts later on down the track to either incorporate or move a water jacket...this is why edelbrock torker manifolds dont fit the later model 308 commodore heads. other universal 308 aftermarket manifolds (such as an edelbrock performer) have a blank for you to drill the hole in the location you want for the correct heads. so therefore if it is in a pre commodore and you wanted to just put the heads on and use your existing manifold then you wont be able to bolt it up in the center and you know your gonna get a vacuum leak. And also yes agreed, Vl black motor heads are unleaded and vk's arent. funny though, when we ripped the heads of my vl they dont actually have hardened valve seats. perhaps they cast them in something a little different?

the only difference in leaded to unleaded v8s is that unleaded motors had a bigger bowl in the piston to reduce the comp ratio to suit the lower octane rating of unleaded.

Quote: Originally Posted by hot308vb the only difference in leaded to unleaded v8s is that unleaded motors had a bigger bowl in the piston to reduce the comp ratio to suit the lower octane rating of unleaded. Oh ok, thats interesting. i was always under the impression you needed to have hardened valve seats or the unleaded itself would burn them out?