I went from a 283 to a 454 in my 66 chevelle. One problem I'm having is header alignment.I replaced the small block engine perches to big block ones
but still didn't do the trick.the headers i purchased are headmens that i was told were made for the car.It seems the engine is sitting crooked due to the fact that the turbo 400 trans is not centered in the tunnel.The moroso solid motor mounts are making it difficult to twist the engine.Do I try to loosen the frame to engine mounts to try to staighten everything out,or do I try something else. Your help would be great.

i'm having header problems with my bbc 66 as well. i bought hedman 65002's and they do not fit. what part# did you try? do they clear your steering arm and a arm mounts? what heads do you have ? had to refab my x member by moving the tranny mount to the back for my th 400,but it's centered. i also have the moroso solids. just ordered some mid length headers to try next. i didn't mess with the frame mounts on mine though.

thanks for your reply. I'm not sure the part number on the headers. The heads are stock. The engine is a short deck. to be honest i didn't try the drivers side header yet. The passenger side header is hitting the crossmember. The header is sitting back about a 1/2 inch from bolting up. It seems so close yet so far. I'm at wits end, thanks again for your help.

FYI, I finished putting in a 502/502 into my friend's 66 and I had to perform major surgery to the pass. side forward most header tube to make it fit. They were the Dynomax 1 3/4" set. The driver's side went in perfectly. I assume the cross-member on the older cars is at a different angle, causing the pass. front tube to conflict with the cross-member. The front tube is set too far forward to clear the pieces and parts. Supposedly, some of the Hedmans are a better fit - if you get the right part # for the 66. OLDED

My Hedman Elites (68198) fit my 67 without a problem. Passenger side slide in from th bottom but I had removed the starter prior to installtion. Ditto on removing the oil filter on the drivers side.

I have a 66 also with a 454. Bought a set of hooker's and went through the small blk\big block mounts thing too but it didn't make any difference. Still had to put a significant dent on the #5 tube to clear the steer shaft. Passenger side was ok. Talked to couple of other guys with 66-67's that had the same problem. Its amazing to me that companies like Hedman and Hooker have been around for 40 years and haven't got this right? Or are at least able to advise what part number is correct.