Hey all,
So I am at a crossroads with my truck where I have to make some decisions on how to proceed with the powerplant. I've gotten the old girl running good with all your help (lean burn conversion, HEI) but she's now showing signs of tired valve guides and seals (puffing smoke after a long downhill) as well as a questionable rear main. Knowing I am going to need some head work done and then knowing that I should go ahead and pull the engine and deal with that rear main, and clutchpack, and pilot bearing, I start thinking about whether its worth cleaning it up for my application. I've been reading threads on whether to go big valve or not go big valve, the issues/caveats with hydraulic heads and I'm still on the fence.

Driving terrain: Hilly where I live, but not interstate hilly (all two lane with 55mph max speed limit).

Things I need her to do:
Be reliable
Haul her weight around with an occasional load in the bed without being a slow moving hazard.
Pull small trailers once in a blue moon (boat, uhaul, etc. Not fifth wheel)
handle your basic Oregon fire road.

Things I don't care about:
1/4 mile time
doing mad skids
0-60 time
Throwing 42" swampers on her and ripping up some mud pits

She's got 3.55 gears and an NP435. The PO stuck 33's on her which I am sure isn't helping overall, but until they're worn out I don't have any plans on sticking stock size wheels back on.

So far on pros to keeping the slant is that its a (mostly) known quantity and I have it on hand. I guess the big question I have is that after getting her all refreshed will she be able to accomplish what I need?

Current Engine setup:
1 barrel 1945
stock exhaust manifold
stock valves

I guess what I'm looking for is advice from people with similar rigs and their experiences with a good running slant in them. What upgrades are required and what can be ignored (say, dutra duals vs stock, or 2 barrel vs single; big valves vs stock; bottom end/piston choices).

Thanks!

As long as you aren't planning on going fast or hauling heavy loads or doing serious off roading, the slant will probably be enough. I would go back to stock size tires, though.

The most bang for your buck would be rebuilding the head with bigger valves and increasing the dynamic compression to around 8.1:1. Dynamic compression calculations require careful measurement of the camshaft and engine and doing some math.

A larger exhaust and a two barrel carb would also help.

I had a similar setup to yours with slightly smaller tires. It was a real dog, especially with the air conditioner on and hills were a nightmare on the interstate. All the mods you've done can only help, and like Reed said, spend some money on a good cylinder head since your valve guides are suspect. The best bang for the buck on a slant is the cylinder head. IMHO, you will never have a fast machine. That's a lot of weight and parasitic drag for a slant to haul, and it will consume copious amounts of fuel. Off road, however, it will do great things. Mine could climb like a goat. OK, a goat that was in no hurry. But it was at least equal to the trucks with a stock 318, and got better mileage (if you can call 14 MPG "better").

_________________
If it was easy, everybody would be doing it.

I have the same set-up, 33's and all. I'm wrestling with the same decision. I have a 318, 318 magnum, 383 and a 440 available to me but I like the slant. I think one can be built to acceptable power level but not overwhelming level. I you build a slant, build it for good torque and fuel economy. If you are not concerned about fuel economy then go V8.

_________________
1976 Feather Duster /6 4sp
1984 W100 318 727 np241
1972 'Cuda 340 4sp
1985 D250 360 46RH

I have a 1980 D150 2wd, 225, 4spd OD truck. Based on the mods I have done to the engine in my '63 dart the first thing I would do is recurve the distributor and do the HEI mod. You will feel the difference. Then a larger exhaust pipe and muffler. Next I would bump my compression up, then add a small 2V.
Brad

_________________
“Buy the ticket, take the ride.”
― Hunter S. Thompson

I have an 87 4x4 with the 318/auto. When I switched from the 30 inch tall tire to a 33 inch tall tire it made a very noticeable difference (in a bad way) on the acceleration of the truck. I wanted the wider 11.50 tire and was stuck with the 33 inch height. I'm stuck with the factory 3.2 gears. Anyway, my point is that the factory engine (318) is only rated at 150 HP and I don't recall the torque, I believe it was in the 180-220 range. With this in mind, the slant is not that far behind in the power department. You will notice if/when you switch to a shorter tire. Bump the compression up closer to the 9:1 static, go with a 2bbl setup and bigger exhaust. You can't go wrong with any of those mods, and you'll feel the difference.
-Matt

_________________
-MattMan
LEANED & MEAN

Note in the responses...... those that compared a small block to the slant.

I was unhappy with my small block (with 4 speed) capability at pulling a trailer loaded with firewood from a dead stop so I pulled the small block and put in a slant....everything else remained the same.
Based on the difference in pulling the trailer from a dead stop I felt the slant must have a better torque curve ....ie. it seems comes in stronger at a lower rpm than a small block.

But pulling that same loaded trailer up a hill at cruising speed the slant would lose speed more easily than the small block.

So in my case it appeared for the low speed efforts the slant was a better choice than the small block.
I agree with everyone that a decent head job could give you a new slant if the bottom end is decent,

_________________
1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Ive had the opportunity to drive a stock 80's slant truck with the OD, and a 70's D-150 with the NP, and the AW... along with
having owned a 5.2 Magnum AW-150 Ramcharger...

The parasitic drag with the 4x4 assembly is very noticeable compared to the 2wd version, the 70's D-150 with 1.5 yards of barkdust
and the 1 barrel was fun to try and motivate from a stop (traffic hazard is what it became...).

I did like my Ramcharger even hauling a couple slant six engines to the machine shop in the back the Magnum engine wasn't put down
by the extra weight even from a stop and an uphill drive, the magnum engine is a better workhorse than the original 318. I think using
an older 318 vs a slant six with improvements will be fairly dead even, but in Don's scenario, with the lack of off the line gruntability,
I would have probably pulled the timing cover and advanced the cam centerline to 102 for better low end response (I might have also been
temped to install an RV cam, and use the set of 1991 quench heads my uncle has sitting in the back of his shop, to boost performace).