Yes that what I was referring to, in the stock form. But then with what you added to yours it should have picked up something but then so would the earlier version engines with the same amount of mods done to them.
All I added were short tube headers and dual exhaust and the mopar computer would only do the same job as super tuning an older engine i.e. maximizing timing and fuel curves.
For a comparision to your 318 magnum engine in your truck, we have a old version 318 with a standard bore and a .501 comp cams cam and 3675 set of heads with stock valves and a M-1 intake and a set of hedders on pump gas and the car weighs in at 3330 lbs. and just last week even being out of tune ran 7.89 @ 88 mph in the 1/8 which this puts the old style 318 engine in the low 12's or upper 11's. The heads have a good VJ and a 75* bowl cut only and have been gasket matched on the intake side, the exh. was left untouched other than what the machine cut at the VJ. Were looking for some low 7.70's or upper 7.60's this week, with the carb jetting that we did.
I'm sorry Bobby but that's not much of a comparison IMO. Mine had the stock cam which is a bunch smaller than yours. Stock valve job with no bowl work or port matching. Short headers vs. your long tubes. And your M1 will make a ton more upper power than my stock magnum beer barrel that flattens out at 4500 rpm. And my truck weighed nearly 400 lbs more and of course has terrible aerodynamics compared to a car. Also mine had the stock 3.55 geared single leg rearend and a stock converter. Yours certainly should go allot faster.
You also have the advantage of being double quenched in the heads and we have a open style chamber, which this is a advantage for you and for comparision sake would be closer to the 302 heads. So yes I in my own opinion I personnally wouldn't ever use a magnum head on a 318 engine. And my reason for this is too much port volume, too big of intake valve, the bowl in the heads are too large for short stroke and small bore engine. This is where the 5.9/360 engine works much better with the magnum heads. Because they have everything that the 5.2/318 engine doesn't in reguards to bore and stroke. My personal opinion is that they tried to pattern the magnum head after the likes of the 440-1 head when they first came out. The bowls were so large that they wouldn't make any power til you turned the crap out of them. They are also in the 160+ cc range from the factory which doesn't bode well for Tq on a NA engine of this size and bore.
You are correct that a fairer comparison is to the 302 head due to chamber design. You are quite possibly right about them being too large for a small 318 engine but I can't help after seeing many of them easily run mid to low 14's in a truck with the aerodynamics of a brick think their not all that bad.
The reason that they work better on the 360/5.9 engine is the piston speed is much faster and the larger bowl will work better, something along the lines of a BBC engine. Now this isn't to say that they wouldn't work well on a 349 style engine as the stroke would be much longer and could make better use of the larger port volume, and piston speeds. Once again similar to the BBC.
Also to in your comparision to the older version engines that your friends have is that your also fuel injected which should be a gain on any engine. And you never mentioned weather the older engines had small 4 bbl carb or 2 bbl carb on them. So were not really comparing apples to apples here.
Your right about the diff. in intake/carb differences in most cases that the fuel injection did help but to make it honest I'll compare mine against my buddies 78 short bed pickup with a 318 and 72 340 intake and thermoquad. Mine was only 50 lbs. less but yet consistently ran over a full second faster. The only advantage mine had over his was shorty headers and 3.55 gears vs. 3.21 gears which I doubt will make a truck go over a second faster. Please refer to post #6 where I mentioned his truck and you'll see where I said his had the 4 barrel and carb.
Sorry for being so winded but IMO I won't use the magnum head on any 318 that comes from me. Maybe thats why I'm getting the performance that I do. But this is MPO.
