Any feedback on a 518 in a Fusey?

F

feets

New Member
Joined
Nov 25, 2017
Messages
45
Reaction score
106
Location
DFW
I know the 518 is the way I'm going. I already have the transmission and a JW Ultrabell so that is non-negotiable.

What I'm wondering is what kind of fitment issues have been found when installing the transmission in a 69-73 barge?

My 72 Imperial is meant to be a road trip machine and I've already driven it form Dallas to Detroit. It's an awesome ride but I wanted to drop the RPM.

The 440 is currently out so I can go through it with an eye on low to mid rpm torque. The rear is carrying a 3.23 TrueTrac and the car wears 255/70-15 tires that are 29" tall. Toss in the OD and this should become one of the greatest road trip cruisers of all time.

Anyway, have you guys done this swap and if so what problems did you encounter?
 
I personally like the 2.94 gearset in my Imp and I have logged thousands of highway miles with it over the last several years.
How about some pics?
 
The Imps came with 2.94 gears until the power strangle in 1972. To crutch the lower compression motors they got 3.23 gears. Being a California car, it needed the 3.23s. Toss in that OD and they'll run like a 2.19 gear at speed.

My car is nothing to look at. It's just a big old barge badly in need of paint. I put some seats in it shortly after I bought it and went for the later Formal style poofy button cushions.

This old beast has been walloped with the ugly stick but it sure does ride nice!

I plan on another road trip from Dallas to LA. I intend to take the Imperial and leave my Mercedes at home.

Imperial downward angle.jpg
 
I think center tunnel is same on C-B-body. Because center console bases are "same". But crossmember is totally differend with c- and b-body.
Following this, because doing same swap to my car.
Is Imperial and C-body crossmembers same?
 
The Imperial is nothing more than a New Yorker with a 5" stretch on the front end. From the firewall back it completely interchanges with the NY, excluding cosmetic trim, springs, and bolt pattern.

Interesting side note:
As a California car, this thing was equipped with a factory electric fuel pump. There was a rubber fuel line coming out of the tank, over the axle hump, and attaching to the fuel pump. The pressure line went from the pump back over the axle hump and connected to the same fuel line used on all the cars. There was an oil pressure switch that would turn off the pump if the engine died (collision, rollover, etc).
This was all done because the only place to put the smog pump was on the lower right side of the engine and it blocked the mechanical fuel pump mount.
 
You might need some kind of EFI unit. The OD ratio will be right at 2.3, which might mean OD could only be used at higher road speeds. With what you now have, it would be about 25.5mph/1000rpm or so. The 2.94 and P235/75R-15 combination would be close to the normal C-body 2.76 and P225/75R-15 mph/1000rpm situation. About 28-28.5mph/1000rpm. A 3000rpm cruise would basically put the rpm at the rated torque peak for the B/RBs back then.

The issue is not the engine having enough torque at lower rpm, but the efficiency of the fuel metering under the lower rpm/venturi air flow conditions that would occur, it seems.

EFI/TBI uses tps voltage to add additional fuel when the throttle is opened. A carb relies upon increases in air flow through the venturis to get the fuel from the float bowl instead. One reason for the sharper throttle response of the EFI/TBI units, I suspect.

What application 518? Just curious.

CBODY67
 
The body shell might be the same, or very similar, but the position of the engine in relation to the cowl can be different (more forward, from years ago in the OnlineImperialClub thread on such). That's what another posted, back then, claimed.

CBODY67
 
The engine position has got to be the same as the NY or even farther back. You simply can not work on the back half of the engine because you can't get to the stinkin thing! I had to pull the engine to address oil leaks from the sending unit area of the block. From the tip of the bumper to the air cleaner stud is 36 inches. I stand 6 feet tall and can't get the air cleaner off from the front of the car. I have to go around to the side.


As for EFI, that has been part of the plan all along. It was a toss up between reusing my old Electromotive TEC II distributorless EFI system or dropping on a FiTech. So far, it looks like the FiTech is winning the toss up.

The 518 OD is a .68:1 so it will effectively turn the 3.23 into a 2.19 gear.

BTW... you can't always consider the torque peak rpm as the efficiency peak rpm of the engine. That is calculated at wide open throttle. Cruising often uses 15% throttle (it was 12-13% according to the datalogs from my 65 Plymouth). That kind of throttle strangulation really jacks with air flow. It can move the efficiency peak up and down the scale. Add in the load that the engine is carrying from weight, rolling resistance, drag, drivetrain efficiency, and a number of other things and your most efficient rpm can land anywhere in the bottom half of the rpm range.
 
Lower rpms will always win a fuel mileage war period ( a road trip in any new car will explain this).
The 518 is a piece of crap trans, not a fan of super tall OD and half-breed heritage, but since you went that way it will be okay. I am going to assume you got a non electronic govenor, earlier one. Just make sure you ultimately have manual control over shift points and converter lock up to make it not hunt for gears on a grade. The trans crossmember will need modified for mount and need to keep demensions and structure to for torsion bar crossmember support.
After putting a 4 speed manual OD trans in my Charger the .75od and 3.23 rear and 28" 275/60 15, it is a pleasure on the highway 70-75 mph (normal highway speeds) it is in the low to mid 2k range, very comfy. My Challenger on the other hand with 727/ 3.23 and 26" tall 225/70 14 is at 32-3300 at 75 barely 12 mpg 383 and tiresome. Mileage did go up with 400 and headers/ x-pipe exhaust about 13.5 mpg, going across route 22 at maybe a 60mph average mileage went up to over 15. My Charger with 440 on way to Nats with hardly any tuning, borrowed carburetor, 440 with less than 200 miles on engine netted me almost 14mpg comfortably keeping up with I70 traffic, not sure of exact mpg because speedo reads appox 10% low checked against mile markers. Should get the highway mpg up over 15-16 this summer with some distributor tweaks and a different carb. If you want it, do it. I love blowing by a group of shiny muscle cars on the highway going 60-65 probably spinning 3500 with stupid 3.55 rears with my primered fendered car loafing at 2300@75mph

Yeah I'm "that" guy
 
Last edited:
via a Google search, I found a Hemmings article on conversion, in general. Mentioned "Performance Auto Trans Center" in Bossier City, LA, that has a hydraulic pressure switch item to control OD and TCC lockup.

FWIW,
CBODY67
 
The A518 transmission will have come off the small block V8 engine and as such the bolt pattern will not match the back of the 440. You will have to modify the belhousing to fit the 440.
 
CBODY67 said:
via a Google search, I found a Hemmings article on conversion, in general. Mentioned "Performance Auto Trans Center" in Bossier City, LA, that has a hydraulic pressure switch item to control OD and TCC lockup.

FWIW,
CBODY67
Click to expand...
That the name, thank you. Use their switch system but as I mentioned I would wire for manual override to make it stay in a gear and/or locked up, on a pull/grade
 
I have the same transmission in my 92 D250 diesel. Those things use the TPS to control the OD and nothing else. They also have a habit of eating expensive TPS sensors. I put the truck on a hydraulic switch using governor pressure (with a manual override) over 100,000 miles ago.

I know how to make these transmissions work.

This thread was all about fitment issues in a 72 Imperial.
 
feets said:
I have the same transmission in my 92 D250 diesel. Those things use the TPS to control the OD and nothing else. They also have a habit of eating expensive TPS sensors. I put the truck on a hydraulic switch using governor pressure (with a manual override) over 100,000 miles ago.

I know how to make these transmissions work.

This thread was all about fitment issues in a 72 Imperial.
Click to expand...
I think you have to tell us. I think i have never seen A518/A618 swap to fusie c-body.
 
I would keep my 727 someplace handy. The A518 in question was designed for a relatively low torque small block engine (based on the small block 727 or 904 transmission). I think it will be unlikely to live very long behind a high torque big block pushing around a 4000lb car. Let us know how this conversion works out. Hot Rod magazine did an article on this conversion a while back. You will need to fabricate a new rear cross member and cut out part of the drive line tunnel and fabricate a new one. Drive line will need to be modified to fit the longer transmission. Article is at:
www.hotrod.com/articles/43323-mopar-overdrive-transmission-swap/

Dave
 
Last edited:
I did a bunch of math on this to see what the rear end ratios should be. One of the other things you might consider is he stall on your torque converter. It might act weird if you’re asking it to lock up below the natural stall.

Anyway, with the .68 OD, it still had lower revs than stock (2.94 on my ‘67) with 3.55 gears. If budget permits, that’s the combo I’ll use: 518, PATC kit, 3.55 sure grip.
 
You should not have any tunnel fitment issues. Most guys only have to remove the ribs on the top of the overdrive section to clear on B & E bodies torsion bar crossmember (piece welded to the floor), not there on a C body.
We were just trying to help. Thanks for the condescending attitude and thread redirect, though we might have learned something from you maybe Moparts might be more your style. Fair warning we do not always stay on topic. Good luck with your conversion, hope to follow along if you will post thread on conversion.
 
You must log in or register to reply here.
Back
Top