QuestionI have an original 78 CJ w the AMC 304. I would like greater performance and am considering porting the heads and possibly enlarging the valves. This probably would cost more than new performance heads except I don't know where I can acquire any. I would like to add a 4 barrel intake %26 carb... any advice.
AnswerDon't know how much more power you want from your 304, but porting & polishing the heads and installing larger valves seems pretty extreme.
There are a number of things you can do to increase performance, without going to extremes.
1) Install a quality dual plane 4 barrel manifold. i.e. Edelbrock Performer.
2) Install a 600-650 cfm carburetor. i.e. Edelbrock Performer w/vacuum secondaries or a Holley.
3) Install a set of quality 1 5/8" diameter headers.
4) Dual exhaust with low restriction mufflers. It will have to be custom built because of the chassis layout. It has been done.
5) Install a mild cam. i.e. Edelbrock 2132 or Crane 863904.
You will be pleasantly surprised with the performance you gain by properly matching components. I doubt you'll be revving over 5800 RPM, polishing & porting your heads will be over kill. Matching ports is good, but a lot of work.
Keep It Simple.
