Do you know how many miles are on the motor? If it's in that good of shape I would leave the bottom end alone and focus on the top. $3k budget?

440 Source heads: $1k
Used dual plane: $120
Headers: $150
Used Holley: $150
Cam set: $150
Rear sump pan: $150
Mounts: $100
Gaskets: $100

I know you said you weren't considering aluminum heads, but after freshening up a set of irons you're halfway there and you still need to deal with the compression issue.

I had the same experience with the 284/484 hydraulic cam that I put in my '64 Polara with a fresh 440. You need a looser than stock converter to take advantage of the cam off the line and my converter was stock '64 and tight. It had a great top end once you got over 60, but below that DOGGY

Have the bores checked with a dial bore gauge for wear and taper before deciding to re-use the stock pistons. How do the main and rod bearings look, how much clearance? Do the rings rotate freely in the piston, or are they all carbon up?
Are you re-using the stock rod bolts, or replacing them and having the rods resized?
Inspect crank journals and crank run out and straightness in case the crank needs re-ground and bearings to match.
What condition are the cylinder heads seats, valves and valve guides?

I guess if it was me, and had a good short block, then I would leave the short block alone and put smaller chamber heads on the engine.
If you used something like the 78cc Trick flow heads, that should put compression around 9.5:1, already have new everything new including springs for aftermarket cam. That would kill your budget because of the cost of the aftermarket rockers arms, and hardware, but give you room to make alot more power later when you can afford to build a stronger short block.

I wasn't recommending to follow that exact build, was just pointing out to show that low compression isn't that big of a power killer in a bottom end
power build. But the cam choice is critical, though.

Listen to what fast68plymouth is telling you.

I would opt for the regular performer or a CH4B if you can find it .

The original compression ratio for that engine is right at 7.2:1. It's been calculated a zillion times here. The piston is down in the hole about 0.180".

Increasing the comp ratio from the original honest 7.2:1, to 9.5:1 increases power output by 8.7%. So a 350 hp engine turns into a 380 hp engine with no other changes.

The original 440s were dynoed and at the standard conditions of that test procedure they would make 335 hp. That is per an interview with an old Chrysler guy in Mopar Action years ago.

I agree with whoever said first thing is to buy a new set of Stealth heads. 440Source has one pair in their clearance section for $750 delivered. Those heads are worth up to 90 hp over stock cast iron heads.

Now that flow is taken care of, compression is next. The Six Pack pistons will get you to about 9.5:1 compression, maybe a little bit less. But they will also give you squish which will help by reducing negative work.

If you cant find a set of those then using the data from another post, look for original pistons for a 1967 or 1968 HP 440, they'll at least get you into the mid 8s.

With a heavy truck and low compression you need a short duration cam that closes the intake valve early. Either the .484 or .509 cam is way too big. XE262 Comp is as big as I'd go.

R.

PS: Thanks to Polyspheric (I think) for this useful page:
http://victorylibrary.com/mopar/otto-c.htm

Stick with the 262 - 268 cams, Performer (not RPM) intake, and put it back together.
Save your pennies for a set of pistons and heads.

That will get you by and give you a significant torque increase over that gutless 318.


Just for giggles, I dynoed my 72 Imperial with it's bone stock California spec 440. Popping off the factory air cleaner pushed me up to a whopping 199 rear wheel hp and 294 lb/ft.

It was rated at 225 hp and 345 lb/ft so I think it was doing pretty good.

Sliding in a cam perked it up but the timing gear let go before I got it back on the dyno.

You can make 375hp with that 440 but you won't like the way it runs in your truck.

I've built a smogger 440 just like yours. I put a mild cam in it and a set of 440 source heads. It still didn't have the bottom end power I wanted and that's in a car, not a truck. To get the smogger 440's to haul you need a decent torque converter and some aggressive rear gears. I started with a 3.55 gear and a stock converter and it was not near enough. And your truck is probably 1000lbs more than my car was.

I would clean up the engine, regasket it, install a new timing chain set if it needs it and run it. Recurve the distributor and dial in the carb of your choice. It won't have 375hp but it will run, tow and 4x4 well.

I built and dyno'd the 440 engine that kowalski440 referenced you to. There is no way I would suggest you run the 509 cam we used. The best truck engine I ever had was a bone stock 440 out of a 1973 Chrysler New Yorker. I used it in a 1 ton welding truck and towed some big trailers with it at the same time. Don't use the 250 heads as the 452s are a better head, clean them up and run them. The 452 heads are easier to get flowing for the amateur porter and will get better flows than the 250 heads. Keeping the stock pistons I definitely wouldn't run a cam any bigger than 220 @ .050". A stock cast iron 4bbl intake manifold from 1968-1970 works fine in a truck application. Use the CH4B, or the Performer RPM if you must.