hey guy's, well last year i drove the d150 with the mostly stock 318 beside's the normal bolt on's ( long tube header's, performer intake, 600cfm carb) i want a little more giddy up & go. so im getting a comps XE256H cam (thanks to a member here) I dont want to yank the motor & do a complete rebuild but what else could be done to get a little more power?? i am swapping to 355 gear's which should help.. i am kickin around replacing the head's with a set from areoracing, i dont want to go throuw the hasle of the magnum head swap, i do got a pair of 89-90 tbi head's but last time i checked it was well over $500 to get them rebuilt.. any info would be great guy's

By your screen name, is it fair to say that the truck is 4 wheel drive? If so, you need torque to get the big tires rolling. The 318 isn't the first choice for that but the headers do help as would a full 2 1/4" exhaust system. The cam is borderline for torque in a 318 but it will work. Its certainly a step up. Stock 318 cams had .373 lift! Really.
Engine Quest sells NEW LA and Magnum heads. If you are bucks down, a good rebuild and port job on a set of 1985-91 #302 heads is one option. they are small valve, small port but with bigger valves and porting, they will do.

truck is a 81 d150 2wd... i hate 360's so thats why opted for a 318.. truck has duel 2.5" exhaust along with long tube header's... i got a set of 308/302 head's but like i said the shop wanted well over $500 to just rebuild um.. the onse from areo heads are 1.88-1.60 IIRC

Around here Magnum 5.2's are cheap, picked up my last one for $150

Consider swapping one in with a carb intake.

I would reconsider the mags. JY ones are cheap & you'd just need a mag compatible intake & possibly different pushrods. If you're dead set against them then the 302's with some home porting. You desperately need compression which the closed chambered mags/ 302's would provide. A cam from Hughes and alot of time tweaking the dist subsytems in order: initial/total to 35 (31 if mags)/springs/vac adv. May I ask why you dislike 360's? as you desperately need torque (more cubes) for your app.

I would like to know why you would pass on the 360 too?
Big mistake in my opinion.

spent a fortune a 360 i had built & it was a dog. every 318 i have owned has been good.. like i said i got my mind set on the comp XE256H dont want to go through spending a fortune on a new intake, push rod's, lifters with the mag head swap.. looks like i will pick up a set of areo & do a little porting & call it good....

ya i know they are differnt lol... not a fan of 360s just me... would the #308s be worth rebuilding compared to the areo heads?

Aero heads are Indy's garden variety rebuilt heads & been a few bad reports on them tho probably not any more than anyone else (we're in the business of solving problems here on Moparts) so we get way more bad reports than good but they are open chambered. I would strongly consider finding some 302's (closed chambers) & open em up a bit. FYI 308's are the best of all the iron open chambered heads

i will have to double check but im sure the head's i pulled of my 89-90 w150 318 was 308's.. might have to run to the next town & see what they will charge to rebuild um... whats the normal rate you buy's pay to get them rebuild

Switching from 302s to 308s is a tradeoff. The 308s flow better but they also have larger chambers resulting in a 1/2 point loss in compression.

No 318 ever came with 308 heads, unless it was a factory mistake. If you have heads off a late model 318, they are 302s, or there was another head with different casting number but same heart-shaped combustion chambers.

The 302s I'm running right now are from a 120,000 mile Fifth Avenue and they were not "rebuilt". Guides were still in tolerance and the seats looked good. I did cut down the valveguides so I could run a bigger cam later, and added new valve stem seals and Crane 308 springs which will be okay if I ever get the roller 318 cam reground. Then I did a whole bunch of home porting.
I installed them with Mr Gasket thin head gaskets. I'm still working out the carburetion, but on its first long trip it returned something over 21 mpg.
If you are absolutely bucks-down, find that late-model Fifth Avenue and pirate the heads, or the whole engine if you can. My shortblock had no ridge and the crosshatch still visible in the cylinders. Bearings were OK, too.

R.

318 4BBL M-body cop cars had open chambered 360 heads through 1989, but not 308s AFAIK.

I can understand doing the 318 if that what you own, but you hate 360s? Lets see more stroke, bigger bore. What's not to like? If the 360 was a dog a 318 with the same parts will be worse. The problem using 308 heads on a stock short block is low compression, you'll be lucky to get 8-1. That equals dog. I would mill the heads at least .060". Thermo-quad and a stock intake will improve low end grunt.
Doug

well after dropin ina couple thousand it was a dog.. thats just me... the head's are stamped 714 so iirc they are fast burn head's.. are the 714's any good??

The 714 is a production Magnum truck head. You say it was a "dog". What compression, cam, intake,carb? What vehicle, gear, converter? By all rights this head should easily support 400HP.
Doug