does anyone know the height of a big block engine mounting bracket / perch i think that may be why the header will no fit on driver side ?????? but they fit with my 66 with sb perches ??????????????????????????

 

You do realize that the frame mounts are different between a small block and big block?

If I recall right, if you try to use small block frame mounts, it moves the motor back towards the firewall and there is a height difference.

Here is what I found, 67/68 frame mounts, LH 3 11/16", RH 3 15/16".

 

thanks, all that sounds good but when i did the switch in my 66 sb to bb and using same frame mounts the headman type worked fine these flowtec not so good ,i would rather not drill holes in the crossmember for bb frame mounts any thoughts

 

Holes are already in the sub frame, all you need to do is buy the correct frame mounts and bolt them in.
You mention a 66, is that a chevelle, nova, what?

 

called the tec from flowtec give him the demensions from the crossmember to the block he said they are correct that they are bb mounts thought so the guy had a 454 in it before i got it so he said to send them back but thanks again, and my 66 is a impala ss 396

 

well got the bfh out today put 2 dents in two tubes on the header and it went in dont like to do that to new stuff