Upgrading 73 Challenger with 318.

[Fordication]

So, need some advice. My car presently has a 318 in it. I know the 360 is the more powerful engine with greater ability to increase HP. So I may have to replace my timing chain shortly. I was thinking since I am about to remove a ton of equipment I may go ahead and get a new cam, install a pair of ported and polished 360 heads. I know without new pistons I am not going to get a giant increase in power. What intake and size carb should I go with. What would be a good cam for this upgrade? What is the main differences between a 318 and a 360? Thanks

 

[pschlosser]

How deep do your pockets go? I have this bridge, for sale, in New York...
I think going with the 340 has more (power) upside potential, and a greater industry of parts to choose from, compared to the 360.

 

[HPP]

The 318 is a smaller engine all the way around. Not just in the bore and displacement but also in the heads, in the chambers, in the intake, everywhere.

Not only are you NOT going to get a giant power increase with 360 heads, but using LA 360 heads on a 318 will lead to a power DECREASE due to larger combustion chambers that tend to accompany the 360 head.

The possible exception to this would be using the Engine Quest LA bolt pattern Magnum head that would utilize the smaller Magnum combustion chamber and higher flowing ports that allow it to bolt on to the LA block. Expect to spend about a grand to get this shipped and installed. However, at this point you are another $400-500 away from aluminum heads.

With that, then a duplicate of the 340 4bbl cam would be a good match. You could go maybe a size bigger, but you don't want to go too big and sacrifice cylinder pressure since you aren't changing out pistons to get more squeeze or better quench.

Match it with a RPM Air Gap intake and a 650 carb with headers, and you've got a stout 318. But, its still a 318 popping out 300-325 or so hp.