I'm thinking of building a cheap 318 to throw in my duster while I'm saving for the 340 or 360. Can someone tell me why all of these people are putting magnum heads on LA blocks instead of building magnum 5.2's? My idea is to get a 5.2 magnum from a running truck, regrind the stock roller cam, crosswinds intake, 800 TQ, 3100 springs, and headers. I'm mainly just curious why there aren't as many 5.2's being built as LA's. Also, I'm choosing the 5.2 because they're internally balanced so I could just leave the bottom end alone and work on the top end although I may put in ARP rod bolts.

ALL 318s includeing the old poly 318s all the way to the last 01 318 magnum are ALL internally balanced. The entire rotateing assembly is the same, same crank, same rods(except machined a hair skinner at the small end), same pistons... as the LA and the block is no more weak or strong, I think the only reason people put the mag heads on the older ones is a doller saveing move. If they already have a good motor and want to bolt on a few hp then the mag heads make great sense. On the other hand if you are buying a motor from a JY to throw in your ride the 5.9 is the same price and a lot of people do throw those in old cars.

The 318 mag is a great swap also it should be an easy 300 hp with out pulling the valve covers, just add a RPM air gap intake and some decent headers and there you are.

The 3100 springs are a good upgrade though as the stock 318 cam witch is a better cam the the 5.9 cam is already on the verge of loseing control of the valves around 5000 RPM. If you are planning on useing the mag heads on the 340-360 later then it is not even a waste of $$$, same thing with the intake. The cam is going to be a little different from the magnum to the bigger motors so I woudn't bother unless I was buying the cam for the bigger motor and just live with a little less tq from the 318. Might be just me but I hate buying stuff twice

Thanks for the response. I found someone selling a 5.2 with 88k on it from a 99 ram that was rolled I think I'll pick this up and finally put together a car that rolls on it's own. I'm running a manual trans and have everything set up for a neutral balance that's why I'm looking at the 5.2 for now and not a 5.9.

Go with the Crosswind. Check out the port matching on an Air-Gap and tell me which one you think is a better intake. Yeah... I think the Crosswind is beter too. And you can use it on your magnum motor if you go that route too, dual bolt pattern.

I had a good '86 roller cam short block, and picked up some mag heads for a good price (free), so I used them.

anyway, yes, use a mag 5.2...the shortblock is essentially the same between a roller LA and a magnum.

here's my combo: stock '86 short block (pistons are .055" in the hole), Mr. gasket thin gaskets, magnum heads (671 castings), redrilled for LA intake pattern, LA RPM air gap, eddie 600 carb, headers, and a reground cam by bullet cams, stock rockers, pushrods, and lifters.

the cam uses their HR259/316 lobes for intake and exhaust, and are 259* adv, 208* @.050, 127*@.200, .316 lobe lift, .506 valve lift, ground on the factory 112LSA/108ICL.

I did some porting on the heads, opening up the pushrod pinch, profiling the guide bosses, and opening up the bowls a little bit. I also had the valve job opened up, as they are way undersized from the factory. I basically followed dulcich's article in I think the may '05 issue of mopar muscle for magnum head porting.

this motor runs VERY strong, as least as strong as my old motor, which was a a stock long block 360, comp XE262, with the same carb, intake, and headers. low speed drivability and idle quality are better than the 360. I strongly recommend doing a mag 318 with the cam listed above. it has great midrange and pulls hard to 5500 RPM, and makes a superb street engine.

for valve springs, the GM3100's are a good, cheap alternative, but they don't have enough spring travel or seat pressure for the fast ramps on the lobe I used (it has 10 degrees less .050 duration than my old XE262, but only 3 degrees less .2" duration, and .008" more lobe lift). I used hughes 1110 springs, they're ~$0.40 each more expensive than most places than the GM springs, have a similar rate (~345 lb/in), but have 135lbs of seat pressure installed at 1.66", and a coil bind height of 1.04" (so installed at 1.66", they're good for .550-.560" valve lift). with the heavy roller lifters, lots of seat pressure is needed. I used some junkyard retainers off of a dodge shadow and omni with 2.2L motors. my heads stock, with the factory valve job, the magnum keepers, and these retainers had a installed height of 1.6" even, YMMV. when I had the valve job done, I had them sink the valves .030" to get me an installed height of 1.63", which gave me a safe operating range of up to ~.530" lift.

I'm running the engine in a ~3900 lb 5th avenue, 3.55 gears, A500, and 27" tires. a lighter car and a 4 speed, you could probably go with a little bigger lobe, maybe their HR266/325 or HR270/330, but that's about the biggest I'd go in a 'teen for a street car. it'll cost less than $200 round trip with shipping for them to regrind the cam.

I wouldn't go with a crosswind, because I prefer to buy american made products when possible, not chinese knockoffs.

I'm pretty set on the crosswind. I can't justify paying the extra $ for the edelbrock. I know the eddy is probably a better made manifold but the magnum air gap is about $200 more and the crosswind has close to the same performance.

it's your money. I guess I have personal reasons (working in engineering & manufacturing, it's not fun to see your design copied offshore and undercutting you after you put a lot of R&D time and $$ into it) for not buying the PP/summit part.

hughes sells the magnum air gap for $269. the summit version of the P-P air gap isn't listed on their website anymore? and the fleabag P-P air gaps go for ~ $189....that's $80 difference, not $200.

Well, for an EFI motor, the 5.2 does have a couple minor differences though doesn't it. Like the crank sensor mounting spot? not that it's a huge difference.

true, it also has both the older mount ears and the newer truck mounts. but it will fit where an LA 318 once resided.

I wondered where you were hiding out, Patrick.

Your springs sound very much like my Crane 833s, same spring rate.

I had the 360 roller cam already, it's a new Sealed Power or Clevite piece, so that's what I'm running. It's got a bit more lift and duration on a 114 LSA and because it was designed for the 308 heads it actually has a shorter exhaust duration tha n the intake, although both are around 200 degrees and 04 lift with the 1.5 rockers.

I spent a weekend on my 302s and took out a lot of material in the bowl roof /valve guide area, also the pushrod pinch. I am running the stock valve sizes and stock valvejob, which stinks.

With the same exact carb I increased mileage from 15 with the Poly to 20 with the 1986 engine.

I'm working on saving money for a regrind, I think I'll use a slightly smaller lobe, although the 259 looks very nice. Maybe one at around 206 degrees, but because of my installed height I can't use any lift over 0.474.

I thank you for all your posts on this subject, if the 302 head is good, the 5.2 must be even better!

For those who are hung up on the "notch for crank sensor" this is only if you're planning to run the stock Mag fuel injection. If you're going carbureted, it doesn't make any difference at all. It's just another red herring.

For those searching for Mag motors, be on the lookout for those advertised in Craigslist as "1995 318" or similar. Sometimes the wrong name and pricetag is applied.

R.