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A-518 Overdrive swap - Big Block

57K views 131 replies 21 participants last post by  s ǝoɾ 
#1 ·
Well.... after a little bit of serendipity, I've decided to swap out my busted 727 for a more "modern" A518. With the 4.10 gears I have in the rear, the 31% overdrive will be a welcomed addition to the drivetrain.

Currently, 65mph brings the engine to about 3100rpm. To pass someone at 75mph, the engine is humming around 3600rpm. With the A518, the RPM's will drop to 2100 at 65mph, and 2500 at 75mph. This will be very much enjoyed by my wife, my wallet, and myself. I love how the big-block sounds, but damn - it gets old quickly when you're trying to talk to someone at cruising speeds. I am hoping to break 15mpg as well, but we'll see about that.

Since I'm doing to swap in a big-block truck, I had to order the bellhousing adapter from PATC. I got a re-manufactured trans from "Phoenix Re Trans". I also ordered a Trans-Dapt universal transmission crossmember, as I didn't feel like hacking/welding the existing crossmember. The only thing I'll need to do (other than put it all in and drill the holes for the new mounts), is to have my driveshaft chopped down about 3.5". Currently, I'm looking around for local shops to do it.

I'll keep everyone posted and will maybe do a write-up on it when I'm done.

Check out the progress --> http://www.cardomain.com/ride/2834477/9
 
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#2 ·
Let us know how the adapter works.  Most guys are using the trans pump located bellhousing, which requires cutting and grinding the integral bellhousing off the small block 518.  How thick is the adapter?
 
#3 ·
cragdweller said:
 How thick is the adapter?
I just called PATC - they said it was drop-shipped for their vendor so I should be getting it soon (within the next 2 days). I'll post some pics to my cardomain page and I'll even try to get it installed on the engine, along with the new flywheel and spacer.
 
#4 ·
Well - all of the parts finally arrived, including the transmission adapter. I ordered everything from PATC racing; however, I've come to find out that they use http://www.smrtrans.com/ as their supplier for the trans adapters.

To answer cragdweller, the adapter plate is about 1/4" thick, so the flywheel adapter is roughly of the same thickness.

The instruction sheet says that I will need to grind off the "dog ear off the lower half of the engine block - directly below the factory starter mounting location". This is supposed to allow you to run the stock style starter. I'm using a more modern "mini-starter", so I will see if I can make it all fit before grinding.

Currently, my headers are at Jet-Hot getting the "extreme sterling" coating. When they are finished, and I finally get the trans dropped off, I'm going to bolt it all together to see how it all fits and to see if I need to "clearance" anything again.

I'll post some pictures this weekend!
 
#5 ·
I've looked at the SMR adapter plate, but haven't had any feedback on how well it works.  Thanks a lot for reporting back to us on this, and good luck with the project.  Hopefully you don't have to grind or cut anything off your block, that would make it a less desirable method.  I think the mini-starter will help with that...
 
#6 ·
Took advantage of the "down time" and had my headers Jet-Hot coated with their Extreme Sterling finish (1700F).

 
#7 ·
79 D200 Sleeper said:
The only thing I'll need to do (other than put it all in and drill the holes for the new mounts), is to have my driveshaft chopped down about 3.5". Currently, I'm looking around for local shops to do it.
just had some driveshaft work done at Arizona Drivelines -> Drive Shaft Superstore

It's right off I-17, south of Van Buren, if your still looking.

Good luck - that 440 looks sweet :)
 
#8 ·
DoomsdayJesus said:
just had some driveshaft work done at Arizona Drivelines -> Drive Shaft Superstore

It's right off I-17, south of Van Buren, if your still looking.

Good luck - that 440 looks sweet :)
Sweet tip! Thanks for the help - I much prefer going to a shop that has "good karma".
 
#10 ·
jungle said:
Headers look great! Whats it cost to have done?
$320 - if you decide to do this, first get an "online quote" - then wait 5 days and they'll send you a package in the mail with a 10% off coupon.
 
#11 ·
OK - I've hit some issues in this swap, time to ask some questions...

Issue #1:
Apparently, Mopar changed the torque converter (TC) bolt pattern in the middle of the 46RE/46RH run. Later models got a "90-degree" bolt pattern, meaning that the mounting holes in the TC are symmetrically spaced. Earlier models used the "old school" pattern, where one of the TC mounting holes was offset. Of course, I got a TC from a later model so it won't match up to my adapter flexplate.

Issue #2:
With doing the above research, I got to thinking about my engine. The block is a 1978 6-bolt crank. Can someone verify that I have an INTERNALLY balanced crankshaft and do not need TC/flywheel weights like the 360 or 440-6pack crankshafts? This is actually causing me some grief. I figured that I can just run an earlier model TC and the bolt holes will line right up. However, when looking around - all of the earlier model TC's have "butter fly weights (whatever those are) and are designed for 5.9L Magnum engines (I think so at least). The 727 that I took out does not have flywheel weights, so I assume that I do not need them here.

I've emailed SMR to ask them what model+year A518 TC they designed the adapter for. Of course, I have a feeling that they're going to tell me that it's for the earlier model "offset" mounting hole TC. This is fine and dandy, but I am unable to do so since my engine is internally balanced (I think).

Issue #3:
When I try to line up the TC and flexplate holes, they are only off about 1/4" when I rotate the flexplate the right way. This has me wondering - wouldn't an "offset" mounting pattern be much more offset than 1/4"? To be honest - it's more like an 1/8" off. I wonder if SMR didn't drill the holes in the exact location. Has anyone "clearanced" flexplate holes before to fit better?
 
#12 ·
I just elongated one of the holes on my flex plate.  I have yet to experience any vibration or any ill effects.  This is with a 98 5.9 Magnum to a 93 2wd 518 that originally sat behind a 5.2   
 
#13 ·
russellmopar said:
I just elongated one of the holes on my flex plate. I have yet to experience any vibration or any ill effects. This is with a 98 5.9 Magnum to a 93 2wd 518 that originally sat behind a 5.2 Â
Anyone else ever elongate a hole in a flexplate on a BB/SB Mopar? I did it before on a SB-Ford and never had an issue.

It turns out that I have a rare 1977 440. In the late 60's, Dodge put forged cranks in "heavy duty big blocks", starting with the 413. They continued this until the big-block production ended. They built these heavy-duty big-blocks for RV's, Motorhomes, and "international support vehicles" (whatever that means).

This means I can use the converter that I have since it doesn't have a balance weight.
 
#14 ·
For those wondering - yes, you will need to grind the "ear" on the block where the starter goes. With the new A518, it just doesn't bolt up. The ear sticks out dead center of where the starter is supposed to go into the transmission.

Looks like I'll be making a trip to Home Depot for some new cut off wheels!
 
#15 ·
What did that 440 come out of?  What do the stampings on the ID pad say (flat spot on the block, just in front of the driver's side cylinder head)?  Its pretty rare for a '76 vintage 440 to have a forged crank (internally balanced).  But it looks like yours has the forged crank balancer, so its possible.  Maybe the motor was rebuilt?  Have you had the pan off to verify whether its a forged or cast crank?  The cast crank motors are externally balanced and need a weighted torque converter or a weighted flexplate.
 
#16 ·
cragdweller said:
What did that 440 come out of? What do the stampings on the ID pad say (flat spot on the block, just in front of the driver's side cylinder head)? Its pretty rare for a '76 vintage 440 to have a forged crank (internally balanced). But it looks like yours has the forged crank balancer, so its possible. Maybe the motor was rebuilt? Have you had the pan off to verify whether its a forged or cast crank? The cast crank motors are externally balanced and need a weighted torque converter or a weighted flexplate.
I bought it from a guy who had it in a Belvedere (I think that's spelled correctly!). He pulled it from a wrecked 77 or 78 Motorhome and had it rebuilt using cleaned-up 906 heads, a Mopar Performance camshaft, and some other basic upgrades. I have taken the oil pan off so I could install a truck-type oil pan (rear sump). It didn't even dawn on me to look at what type of crank it was. Brad - the gentlemen I bought this block from and who is also going to sell me a 400-BB (for a 451 stroker), says the balancer was the one that came with the engine. Neither the TC or flexplate had balance weights on it.

I'll check the ID pad this weekend...
 
#17 ·
Here are some pics...

Here's the adapter plate installed...

Engine and trans mounted...

The ground off "ear"...

And the modified dipstick tube - since I'm using headers
 
#18 ·
Nice to see this since I was thinking of trying to put one in the Warlock when the time came.
 
#20 ·
Finally! I got a chance to work on the truck for more than 15 minutes at one time!

I got the x-member fully installed and the driveline angles look like they're matching up (and hence cancelling out). I left about -0.5 degrees on the pinion angle to account for the fact that when driving and under load the rear will "point" upwards.

Drilling through the frame was rough, in more ways that one. First - it was physically rough, causing me to resharpen my bit every second hole. Secondly, I was drilling through my frame so I took MANY MANY measurements and double checked everything. It looks like it turned out just fine... then again, those are the famous last words of many blown-up projects.

The good news is that I think my exhaust will clear the new crossmember easily. The bad news is that hooking up the pressure switches will require some effort. The pressure port on the side of the case is pretty tucked away in the transmission hump. I may have to check my options here, but I think I'm going to run a steel tube (brake line with the proper fitting) and then connect it to a 1/4" tee.

I'll post some more pics of the trans x-member.
 
#21 ·
CRAP! What an idiot I am! I installed the engine back in the wrong location! Just another example of why I need it to cool down outside so I can install my shop lights. I should have noticed it though, I set the engine down a long time ago.

Anywho - I did have some luck. It turned out that the distance between the engine mounting holes is the same distance between the Trans-Dapt crossmember mounting holes, so I only needed to redrill 2 holes for each crossmember. I had to remeasure (and remeasure and remeasure and remeasure) the driveline angles, but everything worked out just fine.

The engine mount fiasco killed about 3 hours, and trying to get the starter to clear the headers took about 3 more. Regardless of what is said elsewhere - THE STOCK MOPAR STARTER WILL NOT WORK WITH AN A518 SWAP. You will need the mini starter - and in the case of Mopar trucks with headers, you'll need to clearance them with a ball pen hammer. This usually isn't an issue, but I made the mistake of having my headers Jet-Hot coated before getting them to fit. I didn't mess up the finish too bad, it just was painful having to bang a spot flat.

This weekend I'll move on to installing the new plugs, carb, linkage, and OD switches. I already modified the BB trans dipstick to fit, along with the engine oil dipstick. Once I get my driveshaft back, I should be running in no time!
 
#23 ·
ramitupurs84 said:
So you started banging before the mini starter?
No - I was installing the mini-starter before banging. The old starter is, well, old - and dirty and grimy and heavy. Plus, the headers need to be unbolted when you want to replace the starter. Now, after clearing, I can remove either the header OR the starter individually.
 
#24 ·
Updates!!

The engine/trans are fully installed. I got the engine started to make sure there weren't any TC/flywheel issues. Everything sounded great and she started after about 30 seconds of cranking she started right up. The gas from the carb was drained and even though it was capped, the gas from the lines had evaporated. I was seeing pressure on the gauge while cranking so the delayed start helped prime the pump since I dropped the pan while the engine was out (installed a new "crush proof" gasket).

I only let her run for about 20 seconds since the radiator isn't installed and there wasn't any fluid in the block. It was more of a sanity check than anything. Probably not the best thing to do to an engine, but it was worth it to me before putting everything back on only to have to take everything off again.

On a side note: I've always been a big fan of the "whiny" new Dodge starters. Not only did I get the wonderful "wheee whee whee" noise by switching to the mini-starter, it also made the engine spin much faster than before.

I have to pick up my driveshaft today from Mesa Driveline. Apparently, my old shaft was bent beyond their comfort level so I have them build me a new one. It was pricey, about $270, but in reality it was only $140 more than having them cut and balance my old shaft.

If I can find some time tonight, I'll get the radiator back in and the shifter/kickdown linkage hooked up. With any luck, I'll be able to hook up the OD switches by the weekend and I'll take this bad girl for a cruise on Sunday!

Would anyone be interested in an A-518 write-up for the How-To section? I have a few pictures and can add them to a simple word document for anyone thinking about it.
 
#26 ·
79 D200 Sleeper said:
Would anyone be interested in an A-518 write-up for the How-To section? I have a few pictures and can add them to a simple word document for anyone thinking about it.
ABSOLUTELY!!
 
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