Whats the difference between the tbi and tpi heads or is there any? I've been searching the posts but can't find any reference. I'm probably gonna do a tbi to tpi swap and my "local" dealer sais my heads won't do. Ofcourse I'm gonna port then if they fit. If there is a difference what is it. The chilton manual didn't help either... help please. I gotta know by friday do i need new heads.

 

There is a HUGE difference.

The TBI heads have the "swirl-port" design, which is this giant fin or vane sort of thing in the intake port around the valve. It is a major flow impediment and will prevent the engine from even producing as much power as a stock 305 TPI, let alone having any chance of doing better than that.

They'll fit and work, as far as just working goes; but the engine will be weak, especially at higher RPMs, just like a TBI motor is.

The exhaust manifolds are similarly different. TBIs have the same drinking-straw size exhaust that the LG4 had. To get the benefit of all the expense and trouble you are about to put yourself through, it needs to be upgraded as well.

 

Thx... maybe i'll have to get a pair of used heads off a tpi .port and pollish..

 

That would be The Thing To Do.