318 or 360, 727 or 904

[customsportsman]

Hi Everyone,

I am sure this question has been hammered out countless times, however I kinda believe everyones situation is unique. Therefore, forgive me for asking again.

I have a 1969 Fury Convertible with a 318/904 and a 2:76 rear. I picked this rig up in February, and put 4000 miles on it this summer. Motor runs good, but is very very tired. Transmission shifts fine, and when I changed the fluid and filter and drained the torque converter, there were no surprises.

That being said, this winter, the motor comes out. The suspension is getting rebuilt, motor and trans. are getting rebuilt too. I am also adding a completely stock power disc setup from a 72 newport (I cannot WAIT to get rid of the SSBC conversion and LEED booster).

I want to pull my boat on a trip or 2 in the summer next year. The boat and trailer weigh in at a combined weight of about 3200 lbs. Pretty flat terrain also.

So, all this leads to my questions:
1) I am not a speed demon. I am a cruiser, so I don't care about top end. I do want some more low end torque on this rig. I can rebuild the 318, or go find a 360. I know where there is an 84 or 87 360 at a local boneyard. I plan a full rebuild with a camshaft that would help on the low end torque on either engine. Would you all go to the 360, or try to wake up the 318?
2) IF the 360 is the more popular choice, that would mean a 727 and torque converter to match. However, IF the 318 was to stay, is that 904 up to towing the 3500 lbs, plus the weight of this 1969 hunk of beautiful boaty C-body goodness provided a quality cooler is installed? I already have a 26" 3 core radiator, so engine cooling is not an issue.

I am to any information that you all might have. I don't mind getting a 360, provided one can be found and a 727 to go with it.. I would prefer to stay with the LA series rather than a Magnum, so if anybody knows about year-to-year differences, I'm happy to listen.

Thanks for any information that you might have.

 

[Big_John]

IMHO, You have the 318, and it's running. That's a big advantage over the 360 with unknown problems. You also have the 904 trans and it's working, another big advantage over a junkyard trans for the same reason.

You could use the 904 with the 360... It'll bolt up. Switching to the 727 also means another drive shaft. The 904 will last towing, been there... done that with a heavier car trailer. Add a trans cooler and maybe a shift kit and you're done.

What I would do is stay with what you have and maybe switch to a 3.23 rear instead of the 2.76.

 

[413]

For towing get rid of those 2.76 gears. It’s all about torque multiplication. Chrysler put 3.23 gears with the trailer towing package for a reason, even with BB engines.

Remember riding your 10 speed bike and taking off in 10th gear? hard to get going and build any speed, change gears and it was easy to accelerate. Same power, different gearing.

A 360 and 727 will be a big difference / improvement also. You are rebuilding anyway do go bigger. You have a heavy car to start with, then adding 3200 to the rear bumper will be a lot of work.

 

[volksworld]

personally think there's no substitute for cubic inches in a low rpm/ towing /torque situation...between supply chain issues , machine shop jail and other unexpected issues i wound up addressing while the engine was out the rebuild of my 440 took over 2 years...so having the car intact and driveable while building your engine would be a plus...anything done to "wake up" the 318 would either have it still put out less power than the 360 or shift the power band into a spot that wouldn't be ideal for towing...from what i recall of putting the 360 in the 65 fury race car 30 years ago the 360/727 combo wasn't very common in cars...most of them used the 904...and we had to chase down vans to get the stuff we needed...as to which of the 2 trannys is better for your application that i don't know...

 

[CBODY67]

I agree with staying with your existing architecture. Find a good 360 and build a stroker motor. ALSO, you can build the A904 to something akin to 1980 Newport 360HO specs, even possibly adding the 4-pinion 2.7 low gear in the process. 360HO is key as that transmission in non-lockup for trailer towing and such, but was more HD. A good shift kit, for firmer shifts and such. Upgrade the trans cooler, too. 10.75" stock converter.

For the 360+CID . . . Cam in the 216 degrees at .050" range, Edelbrock Performer 318/360 intake, AVS2 600cfm or similar, plus a good undercar exhaust system (2.5" pipes, typically).

We KNOW the 318 is stout, basically. No issues there, just that it is the size it is. With nothing else done to the motor, at least a rebuild and shift kit in the A904, plus an aux trans fluid cooler would be good to do anyway. The A904-family automatics also take less power to work, so that is a plus and reason to beef it up internally. Remember, too, that other than the weight of the boat, there will also be wind resistance of the boat which must be overcome, which can take power.

To me, I'd put the rear axle ratio off to last. See how the new powertrain works out. Perhaps it will have sufficient torque to do what you want to do, with the existing ratio (in what possibly is not an 8.75" rear axle). Doing the 2.7 low gear planetary in the transmission can help compensate for the existing ratio a bit. 3.23 would be preferable, but if the existing ratio does what you want to do, that's good enough. Main thing is having the guts to pull the boat out of the water on steep boat ramps! Road driving is another matter, which should be less taxing, unless you want to drag race with the boat from red lights.

Just some thoughts on how to spend YOUR money,
CBODY67

 

[413]

Do the gears first! Drive it with the existing 318 and see the difference it makes. You won’t be disappointed.
2.76 gears just kill the torque, and with a small block you don’t have enough to waste.

It’s most likely a 8 3/4 and easy to swap a third member, buy a good used one, plenty of guys wanting to “upgrade” from a 3.23

have fun pulling a boat up the ramp with 2.76. Again there is a GOOD reason trailer towing package cars had 3.23 as standard.

and you will need to think about rear springs with a 3200 lb trailer. The 55 year old 318 leaf springs are tired also.

 

[57fury440]

I agree with 413. Change those gears. Going to 3:23 gears will make a big difference, then you can decide if you want to stay with the 318 or go with a 360.

 

[66l78rat]

FYI there is a 360/727 on Facebook in Warren Mi.that got listed yesterday. Sorry i dont know how to link it here and I do not know the seller

 

[customsportsman]

Thanks for the info., fellas.
I have made the decision to stay with the 318. Being a 69, the unit has closed combustion chambers, I own it already, I'm not driving the car over the winter (so hopefully machine shop jail will be a short stint), and changing out the chunk in the rear end (provided I can find a 3.23) is easy. Gonna go forward and see if I can build this guy to increase low end torque. I don't care about the upper end, so whatever I can do to increase that air mixture velocity at the low end is gonna be my way.
BTW...Anyone have a good camshaft recommendation? I have been out of the building engines so long, I don't know who makes junk anymore, and whom to stay with.
I have never built a transmission before, so I'm gonna try my hand at rebuilding the 904 with any recommended upgrades (anybody got any recommendations in addition to the large cooler, and a shift kit?). I will add a transmission temp gauge (which will be very indescreet; I like the original look) also.
If, after the rebuild I'm not happy (though I am sure that I will be), then the 360 and a 727
will get looked at.

Regards,

 

[MoparapoM]

Glad to hear you are going the 'run what ya brung' route! I woiuld do a couple of stealth conversions, during the rebuild that will not decrease reliability or driveability.

A) Substitute a set of late 80's 318 heads. The Combustion chambers are upgraded to a what folks refer to as a 'swirl' style. In addition, the Valve Seats are already Hardened to withstand UNleaded fuel. These heads are commonly referred to as '302' heads due to the casting number/part number ending in 302. Here's a short quote from a write up I found.

Swirl Port Heads Chrysler's small-block cylinder head design changed very little until 1987 when the 302 casting (last three digits of the casting number), commonly known as the swirl port, was introduced. While the 302 casting, as well as the later 308 casting, were most commonly found on low-performance 318s, they shouldn't be overlooked for a performance build. Even with small 1.75-inch intake and 1.50-inch exhaust valves, the design of this head's heart-shaped quench-style combustion chamber makes it a good choice for mild to moderate performance. An engine with these heads in stock form will outperform an engine with stock X or J castings simply due to the improved combustion chamber design. Additionally, these heads have hardened valve seats, which make them compatible with unleaded fuel. The swirl port heads were utilized through 1991 and respond well to port and bowl work, offering better power potential than all of the earlier small-block heads. Another nice feature of these heads is they utilize valvetrain and intake manifolds common to early small-blocks, so parts are readily available. Simply bolt these heads to your small-block and enjoy the extra power they provide.

B) Substitute a Torque Convertor designed for Towing. Call these folks and get their advice, but just ONE step over Stock will make a huge difference and will extend the life of your Transmission. The 904 is ...plenty... tough enough for the task, don't change it.

Welcome to Hughes Performance - Hughes Performance

Hughes Performance specializes in rebuilding and repairing transmissions and torque converters. Call today and talk with our knowledgeable sales staff.

www.hughesperformance.com

602-257-9591

Bruce

 

[413]

Find and use steel shim head gaskets.

are you boring the block and getting new oversized pistons, or re-ringing it? Don’t get 8:1 Smogger pistons, it will not have any power.

 

[Just Carbs]

3500 pounds is heavy enough to need a posi rear at a lot of ramps with sand, weeds, old worn wet concrete.
I like a 3.55 gear in that car with the 318. Or you will be in second gear more often and longer than you want to be.
A known good 360 and using the 904 with a VERY good trans cooler would be much more appealing to me than rebuilding the 318.

 

[Knebel]

I have a little souped up 360. The thing is a gas guzzler lol. But its what was there....

If I had the 318, I'd soup that up. Intake, cam, heads...

 

[57fury440]

My son's 74 Barracuda has a 318 in it. To get a little more power we put a 340 intake manifold and a Street Demon carb on it. We also put in a 340 cam and lifters along with dual exhausts. It made a lot of difference in the performance. A 3:55 sure grip was added and that also made quite a difference. 3:55 gears would be better for off line performance but if you do a lot of highway driving I would go with a 3:23 set.

 

[fury fan]

I'll admit I haven't read all the other comments fully.

But for towing, I'd look for a good used 5.2 Magnum, add a carb intake and 600cfm carb, and 3.23 gears.
The 5.2 will add an easy 70 hp over a stock 318 and is somewhat of a bolt-in. It will get better mpg, too.
There are posts on here about the parts swaps that are needed, and some of it can come from your 318.
If you add a small cam, I've read reports that a mildly-cammed 5.2 Magnum will be comparable to a similarly-cammed LA360 due to the superior Magnum heads. FWIW.

@Big_John mentioned the A904 would be OK for towing. I wouldn't have thought so, but I'll defer to his experience.
But in that case, I would recommend an 80s and newer A999 (copcar?) that has more HD parts, or at least a standard one from that era - they have a 2.74 1st gear and 1.54 2nd gear, and that will help with towing vs the A904 you have.

If the Magnum would interest you, I could try to dig up some of the parts swapping that is needed.

 

[3175375]

Thanks for the info., fellas.
I have made the decision to stay with the 318. Being a 69, the unit has closed combustion chambers, I own it already, I'm not driving the car over the winter (so hopefully machine shop jail will be a short stint), and changing out the chunk in the rear end (provided I can find a 3.23) is easy. Gonna go forward and see if I can build this guy to increase low end torque. I don't care about the upper end, so whatever I can do to increase that air mixture velocity at the low end is gonna be my way.
BTW...Anyone have a good camshaft recommendation? I have been out of the building engines so long, I don't know who makes junk anymore, and whom to stay with.
I have never built a transmission before, so I'm gonna try my hand at rebuilding the 904 with any recommended upgrades (anybody got any recommendations in addition to the large cooler, and a shift kit?). I will add a transmission temp gauge (which will be very indescreet; I like the original look) also.
If, after the rebuild I'm not happy (though I am sure that I will be), then the 360 and a 727
will get looked at.

Regards,

They’re a lot of fun with a 318 and 904!

 

[volaredon]

Many Dodge trucks and vans had the 318 and alot of those people towed with them.
The 69 318 was the highest compression ratio of the bunch, which is great for torque. which is more important than HP for a heavy vehicle and then ad towing to it.
EVERY 360 I have opened up has been cursed with dished compression robbing pistons. Most 360s I have had have been a dog. Mid to late 80s were the worst as far as low CR. The "heaviest duty" 360s were even advertiesed with compression in the 7s to 1... and when Ive built engines, and actually measured combustion chamber CCs, piston "in the hole" at TDC, etc most I have fall short of "advertised" CR as originally built/
You know the 318 runs, and most likely doesnt have a cracked block etc. Dont do a 360 unless you plan to build it up... flat top pistons, solid RV cam, (a COMP 252 is exact dead nuts identical to stock 360-2 barrel cam. except a few thiousandths in lift/ Duration, overlap, etc are IDENTICAL. If you do a 252, go with a Melling SPD 25. Again same cam (that IS Melling's stock 360-2 cam. Good upgrade for 318 though. If I did do a 360 Id start with a 260H cam at least. That's "1 step over stock".
but Id stay with what I know is good (albeit tired) Rebuild your 318. go with a slight upgrade to cam and a small 4 barrel.

 

[volaredon]

I'll admit I haven't read all the other comments fully.

But for towing, I'd look for a good used 5.2 Magnum, add a carb intake and 600cfm carb, and 3.23 gears.
The 5.2 will add an easy 70 hp over a stock 318 and is somewhat of a bolt-in. It will get better mpg, too.
There are posts on here about the parts swaps that are needed, and some of it can come from your 318.
If you add a small cam, I've read reports that a mildly-cammed 5.2 Magnum will be comparable to a similarly-cammed LA360 due to the superior Magnum heads. FWIW.

@Big_John mentioned the A904 would be OK for towing. I wouldn't have thought so, but I'll defer to his experience.
But in that case, I would recommend an 80s and newer A999 (copcar?) that has more HD parts, or at least a standard one from that era - they have a 2.74 1st gear and 1.54 2nd gear, and that will help with towing vs the A904 you have.

If the Magnum would interest you, I could try to dig up some of the parts swapping that is needed.

not over a 68-79-70 318. and the "5.2 is still a "318". and for my money if you do in fact have a 904 Id be swapping it out for a 727....

 

[fury fan]

Yes, the 5.2 is still a 318, but it has numerous internal advantages that reduce friction and increase fuel efficiency, both of which give more torque for the driver.
And the Magnum has dramatically better cylinder heads.

'71-older 318s are rated at 230 hp GROSS, even though CR started dropping in 71 (8.6:1).
5.2 Magnums are rated at 220-230 hp NET. (common '72-newer 318-2 are rated at 150hp net)

Perhaps the difference isn't as great between a '70-older 318 and a 5.2, but it would be a noticeable difference nonetheless.
There's 30 years of technological improvements between the 2 engines...

 

[Dads300]

My thought would be as volaredon suggested. Keep it mild. Get a 360 2 barrel cam and build it otherwise stock, 68-69 318s run really good. As said, be sure the pistons aren’t later model low comp units. If you wanted to run an adapter and use the larger 2 barrel that came on a 360, that would help too. Or as suggested a small dual plane intake and a 500 cfm 4 barrel to keep it crisp down low. The 318 will have zero problem toting your boat down the highway, but I would focus on getting it moving. 3.23 gears and maybe the later 904 2.74 gesrset along with a cooler. The info I found says all 81-up 904s have these ratios. Your rebuilder can likely just add these parts to your trans during rebuild. Keep it simple, it will do the job.
Travis..