318 Torque Build

-
superdart

superdart

Shade Tree Tinker Gnome.....
Joined
Aug 26, 2004
Messages
1,146
Reaction score
28
Location
DFW, Texas
Just getting some input. I've got a '77 M880 (W200 Power Wagon) with a 318, 727/NP203 (full time 4wd) and 4.10s on 33" tires. The engine is original, under 100k miles, but a bit of idle time after belonging to a narcotics task force.

For now I'm doing some maintenance and running the engine with some upgrades:

625 Carter AFB
Wiend Stealth dual plane
MSD Streetfire, Pertronix distributor, wires
1-5/8" block huggers

What I'm thinking of is what I want to do long term. Being a truck I'm looking for torque, and an RPM range to go with the tires and gearing. In the future it may get a 518 to knock the highway RPMs down...but even that will still turn 2k+ at 65mph.

Yeah, I know...do a 360....but I also might have access to a NIB Mopar 3.58" stroker crank (ironically one I sold, but my friend never used). I'm thinking do that with the right cam and moderate compression, revalve and port the heads.

Thoughts? Cam and compression ideas?
 
Great carb.
Cam? It would be different if you stroke the engine, so you should decide yay or nay on the crank, & then a more accurate cam selection can be made.
 
I ran the carb on my Dart for many years before I converted it to EFI. It's been sitting on the shelf for 5 years, so this seems like a good way to use it. The Wieand and distributor were awesome deals from the discount shelf at Summit.

For argument sake, lets say I stick with either the 318 or go with the 346 stroker. I would do a minimum bore to clean it up in either case. I have the heads off now and the cylinder walls look great. Interestingly, at TDC the piston is only about .08 in the hole. I expected it to be a bit deeper.

I'm not trying to make it a power house...but I'd like it to have some grunt if I needed to put a car trailer behind it (Texas, so pretty flat around here).
 
Piss on the 360 the 318 is a fantastic low rpm torque truck engine. Along with the other mods you've already done, a good mild cam choice will really shine.
 
Another member here has an 886 (ambulance version) with an Offenhauser dual port, Edelbrock 1406, an Isky 3901M Mile-A-More, and a mild distributor recurve.
Isky Racing Cams 3901M Mile-A-Mor Cam | Creative Motoring, LLC

He says the torque is worlds away from stock. I do recommend a pair of magnum exhaust manifolds (they’ll clear the column shift setup nicely) and a pair of 2-1/2 inch pipes to a Jones Racing dual in & out motorhome muffler
on the right side.
Jones Exhaust SD726-3F Jones Exhaust Full Boar Round Super Duty Mufflers | Summit Racing
I like the Lunati high efficiency grind better, but if you can’t find one, summit shows comp has this similar grind in stock.
DODGE COMP Cams 20-220-3 COMP Cams Xtreme Energy Camshafts | Summit Racing
 
Last edited:
superdart said:
Just getting some input. I've got a '77 M880 (W200 Power Wagon) with a 318, 727/NP203 (full time 4wd) and 4.10s on 33" tires. The engine is original, under 100k miles, but a bit of idle time after belonging to a narcotics task force.

For now I'm doing some maintenance and running the engine with some upgrades:

625 Carter AFB
Wiend Stealth dual plane
MSD Streetfire, Pertronix distributor, wires
1-5/8" block huggers

What I'm thinking of is what I want to do long term. Being a truck I'm looking for torque, and an RPM range to go with the tires and gearing. In the future it may get a 518 to knock the highway RPMs down...but even that will still turn 2k+ at 65mph.

Yeah, I know...do a 360....but I also might have access to a NIB Mopar 3.58" stroker crank (ironically one I sold, but my friend never used). I'm thinking do that with the right cam and moderate compression, revalve and port the heads.

Thoughts? Cam and compression ideas?
Click to expand...


Get some 10.5 compression 318 pistons and then put a set of 340/360 heads on it... Mild port the heads and install hardened seats in the exhaust side...

The larger combustion chambers of the 340/360 heads will get you back down to the 9.2 compression range - perfect for a street driver on pump gas... And the ports of the 340/360 heads flow better...
 
4.10s and 33s are the equivalent of 3.23s with 26" tires. So I imagine, if it still has the stock lo-stall TC in it, that she's a bit of a slug on take-off.
Normally aspirated there are only three ways to get off the start-line quicker;
1) is a higher stall, and
2) is more cylinder pressure.
3) is more cubic inches.

> if the 318 has to stay, then more stall is usually the best choice. Going from say 2000 to 3000, your 318 could be 100 ftlbs stronger, which could translate to more than 100 horsepower.
> if you stroke it to 349; this is a change of ~10%.. With no other changes and a stock stall (guessing 2000 or less), 10% is not a very significant change. I mean at WOT and 2000 rpm, you might be looking at 10horsepower difference.
> if the 4.10s have to stay, more cubes at same stall will help. But cubes, compression AND stall would of course, be the cat's meow. This gear/tire combo will force your engine, into a low-rpm situation until about 3300rpm/30mph; so no matter what you do to the engine in terms of bolt-ons, nothing will make a significant improvement. Only the Higher-stall will get you moving quicker.
>A bigger cam usually has a later-closing intake valve, and so, with no other changes, will lose cylinder pressure, making the zero MPH take-off yet softer.
> if you install a 4bbl the power does not begin increasing until the capacity of the current carb is exceeded, which could be around 3000 rpm. With no tirespin and your current 4.10s/33s, this could be 27mph. If you make the secondaries open at zero mph, chances are very good with a 2000TC that she will just bog.
IMO
Of all these options; the higher-stall TC should be the very first Go-To. After that should be gears; but to be significant, it would need to be at the very least 10%, so 4.56s. But this only brings your speed down at 3300 from 30 to 27mph, so not the best idea. You can get the same 10% with the 3.58 crank. And then you also get the opportunity to increase the cylinder pressure. That's a 3-fer; More displacement/more low-rpm torque, plus more pressure, plus a slightly higher stall on the stock TC.
But since the engine is out, now's the perfect time to up the stall. And since the engine is completely torn down, now is the perfect time to up-cam, and optimize the pressure to it.

Now;
since you already have the 4bbl, do yourself a favor; With whatever is currently on it, do some time-trials to 27 or so mph, and average them out.
Then after you get the 4bbl on and working, do the time-trials again to 27mph; no cheating, cuz you'd only be cheating yourself. Now calculate the difference and convert it to a percent decrease in time, if any......... You don't have to publish it, this is just for your own satisfaction.

In any case; Happy HotRodding.
 
With the pistons.080 down hole, I would probably look at a set of sealed power four relief cast pistons and getting the block decked to zero, too. But if I went that far into it I would do the extra stroke (if you can find the pistons) if that crank has the smaller 318 main size. If they weren’t so expensive, an NV4500 out of a magnum powered later truck with the married 205 ( 3/4 ton HD or full ton) or 238 (1/2 ton or regular duty 3/4 ton) transfer case and installing locking hubs would be fantastic. If you can find one, a 1981-1985 non CAD 3/4 ton axle with manual hubs is a good upgrade, too. If not, be sure to keep your hub bearings greased, especially with a lot of highway usage. I’ve been in enough NV swaps and can tell you that you’ll have to convert to the factory hydraulic slave cylinder clutch setup but no automatic comes close for the performance in a heavy truck, especially when towing.
 
Last edited:
superdart said:
Just getting some input. I've got a '77 M880 (W200 Power Wagon) with a 318, 727/NP203 (full time 4wd) and 4.10s on 33" tires. The engine is original, under 100k miles, but a bit of idle time after belonging to a narcotics task force.

For now I'm doing some maintenance and running the engine with some upgrades:

625 Carter AFB
Wiend Stealth dual plane
MSD Streetfire, Pertronix distributor, wires
1-5/8" block huggers

What I'm thinking of is what I want to do long term. Being a truck I'm looking for torque, and an RPM range to go with the tires and gearing. In the future it may get a 518 to knock the highway RPMs down...but even that will still turn 2k+ at 65mph.

Yeah, I know...do a 360....but I also might have access to a NIB Mopar 3.58" stroker crank (ironically one I sold, but my friend never used). I'm thinking do that with the right cam and moderate compression, revalve and port the heads.

Thoughts? Cam and compression ideas?
Click to expand...

Thoughts….

Decide up front on engine size. Like Bewy said, the engine size will dictate the cam to use.
Your block hugging headers need to go. The longer the tube for the header (within reason) will provide more torque over a shorter tube. Then run a collector extension between 16 & 18 inches into a pressure wave cancellation box. This helps produce maximum torque. Exhaust tube should be 2-1/2 inches. Use a X or H pipe after the cancellation boxes.

Cam, should not be a split pattern. A single pattern cam makes more low end torque. Just a few foot pounds, but everything adds up to something so keep piling the little things up.

Compression and heads.

If you rebuild it, add some hood compression to it. Iron heads at 9.5-1 and a max of 10-1 if you can get 93 octane. Aluminum can be a good help as well and can add a little more compression. (About 1 point more.)

Have your heads well prepped with a good racing valve job. A bigger set of valves (2.02-1.60) are good to use for this. A bowl porting is a big plus.

Research your cam carefully!
 
Last edited:
What intake to run? Assuming he stays SB. Torquer or Airgap or other?

Edit: I see he has an intake. What if he didnt have an intake, what would be a good intake? I might be in the same boat soon.
 
69valiant21 said:
What if he didnt have an intake, what would be a good intake? I might be in the same boat soon.
Click to expand...
In order-ish, build dependent, goal dependent…

OE iron/Performer/MP dual plane = equal.
A step upwards in order of power RPM capabilities;
Weiand Action plus, Weiand Stealth, RPM, RPM-AG.
All the above except the OE & MP dual plane are available new.

Edelbrock’s older intakes are also very good.

The above intakes are the only ones I’d consider using. The Weiands are turning up with some pretty bad core shift on there divider walls for the ports. It is easily correctable, but it’s just the annoyance of it being so bad. Each intake above would do better with some work, so it is not just a Weiand issue but a problem with Weiand. All intakes can and could use a matching to the head. If it is the gasket size you choose, then there isn’t an intake ever made that gets it done bang dead bulls eye on casting after casting.

Other older used intakes that have been discontinued have been for a good reason. You probably don’t want to mess with some of the other makes and wacky designs. The above are the best and still currently a available.

IF you need instant off idle torque, like for a truck that is pulling a load, skip the Edelbrock RPM’s.
 
Last edited:
superdart said:
I ran the carb on my Dart for many years before I converted it to EFI. It's been sitting on the shelf for 5 years, so this seems like a good way to use it. The Wieand and distributor were awesome deals from the discount shelf at Summit.

For argument sake, lets say I stick with either the 318 or go with the 346 stroker. I would do a minimum bore to clean it up in either case. I have the heads off now and the cylinder walls look great. Interestingly, at TDC the piston is only about .08 in the hole. I expected it to be a bit deeper.

I'm not trying to make it a power house...but I'd like it to have some grunt if I needed to put a car trailer behind it (Texas, so pretty flat around here).
Click to expand...
Spend a sat install a GOOD cam and lifters and some added torque could be had
check Isky towing / rv cam selection out I had the exact issue with my 886.
 
1Badcolt said:
Spend a sat install a GOOD cam and lifters and some added torque could be had
check Isky towing / rv cam selection out I had the exact issue with my 886.
Click to expand...
That Offy Dual Port that the RV folks seek out probably helped quite a bit, too. The heavier the vehicle, the better those work.
 
1Badcolt said:
Spend a sat install a GOOD cam and lifters and some added torque could be had
check Isky towing / rv cam selection out I had the exact issue with my 886.
Click to expand...

Thanks for the info. I'm not swapping the cam just yet as I have more pressing things I need to focus on (getting my shop enclosed). For now it's just fixing some things and making it run decent until I verify everything else is functional condition. Later I plan to pull the engine and do a complete build.

I did end up with the Wieand Stealth Intake (Summit bargain bin) and I can confirm that there is a bit of shift. Some intake mount holes were a pain to get lined up, and the back of the intake manifold is really tight on the base of the distributor housing.
 
superdart said:
Thanks for the info. I'm not swapping the cam just yet as I have more pressing things I need to focus on (getting my shop enclosed). For now it's just fixing some things and making it run decent until I verify everything else is functional condition. Later I plan to pull the engine and do a complete build.

I did end up with the Wieand Stealth Intake (Summit bargain bin) and I can confirm that there is a bit of shift. Some intake mount holes were a pain to get lined up, and the back of the intake manifold is really tight on the base of the distributor housing.
Click to expand...
Common problem with their items today my buddy had the same issue most be poured across the pond now.
 
if it's torque you're after i'm surprised nobody suggested a 4" stroker kit to give you 390 cu in's. you said you may get a 3.58 stroker crank, by the time you source the other parts needed it'd be easier to get a complete kit and bigger's better of course. you wouldn't need a full forged kit by the sounds of it so the kit's aren't expensive either.
neil.
 
A 360 based 318 stroker isn’t too expensive to do if you get low compression TRW forged 318 pistons off of eBay. They only require less than a .060 mill off the head after widening the chamfer above the top ring to put the top back below deck.
 
I did a 3.58 stroker 318 for a friend a couple years ago. Only thing new was the crank. One thing about using the 318 pistons with this, you need to clearance the skirts. The pistons we had were low hour marine deal. They were flat, four valve relief. I want to say they had the early compression height. We basically made a 5.7 hemi piston out of them. Flat skirt on the bottom, he was super worried about compression. This was in a Magnum block, Magnum heads. The piston come up out of the deck just a few thou. I told him with the thick Magnum gasket and the old school purple shaft, he'd be ok. Wound up taking some off the top of the pistons to get zero deck. It was a lot of work for a slap together, **** ball engine. He ran an Air Gap and 750. Long tubes. Actually ran pretty well. If a guy would **** can the cam for a torque cam.
 
mygasser said:
if it's torque you're after i'm surprised nobody suggested a 4" stroker kit to give you 390 cu in's. you said you may get a 3.58 stroker crank, by the time you source the other parts needed it'd be easier to get a complete kit and bigger's better of course. you wouldn't need a full forged kit by the sounds of it so the kit's aren't expensive either.
neil.
Click to expand...

Yes, I have been eyeing the 4" kits, especially after realizing the PITA it will be to come up with decent pistons for the 3.58 crank (assuming he would even part with it). Right now it's either a budget 318 rebuild with a cam, KB167s 1.81s and cleaned up heads, or go with the 390 and get significant low end. I have a year or two to make that decision.

Here's where we are for now...so much going on I can't get a solid day to wrench on it....but we are getting close. Ignition, carb, cooling system...then I'll get an exhaust under it. For the record.....the Lokar return spring setup does not work with the Stealth, so I had to make my own bracket. Also have a 6 blade clutch fan to replace the fixed 4 blade, and I stumbled on an aluminum radiator. Also using a Flowkooler water pump and Carter street fuel pump.

Did I mention I don't have a shop yet? (Well, I have an RV carport that I will be enclosing soon).
W200.jpg

2021-12-05 15.25.32.jpg

2021-12-10 20.49.19.jpg
 
You must log in or register to reply here.
-

Back
Top