A500 or 727 with GV?

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MoparMark67

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Hey guys,
I have a 67 Dart currently with a 727. I was doing the calculations on RPM's and I'm going to be running too high for highway use unless I'm driving like 55 mph. So I was considering swapping to an A500 however, I read that the 727 was one of the best transmissions ever built and I'm afraid that the 500 wont be able to hold up to the abuse. I plan to have around 400-500 hp. Nothing super crazy, but plenty for street use. So maybe go with a Gear Vendor on the 727 which will reduce my RPM's by almost 1000 at 70 mph. Not to mention give me more gears than the 500. With the cost of finding a 500 and a rebuild on it + the mods that need to be done for it to fit I kinda figure the GV is the way go. What are everyones thoughts on this? Also, does the 500 even bolt up to a 360 motor?

Thanks in advance for the help.

-Mark
 
The A500 is based on a 904 with the OD unit on the back end in place of the tailshaft.

An A518 is based on a 727 with the OD unit on the back end in place of the tailshaft.

The OD unit on either tranny is basically the same and will require the same amount of surgery to the floor of the car to fit in. I would go for the A518 (or as it was later called 46RH, you don't want the 46RE as it is computer controlled). All V8 pickups and vans had the A518 and very few RAM pickups had V6's so it might even be easier to find an A518.

I would think you could pick up an A518 for a $200 at the bone yard and basic rebuild kit is about $300. There are things you could beef up but you wouldn't need to do as much as you would with the A500.

"Not to mention give me more gears than the 500"
While technically you could create 6 different gear ratios with the GV unit for all pratical purposes it's just an OD unit the you engage and disengage on top of 3rd gear.
 
How much beefing would the 518 need you think to handle 400-500 hp? I don't really feel confident yet in doing my own rebuild, I'm currently in school for this stuff, but I'm not there yet. So I would be taking it to a shop for the rebuilt which I was quoted about 1k. Does the Bellhousing bolts line up on the 518 to a 360 motor?

Thanks,
Mark
 
There is no big block version of an A500 either.

Just do some research on what a 727 needs to handle the power and you will know what you should be doing to the A518. Also, it makes a difference in what you plan to do. If weekly trips to the track with slicks and other traction aids it will take a lot more work to get it to handle that. If its just a street car with street tires that might occasionally see a trip to the track a stock rebuild would likely be adequate.
 
I agree, the lock up converter is nicer...helps with about 5% fuel economy and helps keep the tranny cooler which helps your tranny last longer. I'm all for the lock up. I found a place that has rebuilt 518's with the conversion kit and beefed up to handle 500hp easily, comes out to $2550. Cheaper than a GV and has the lock up converter. I may just go this route. They said they did an A body Dart with no tunnel conversion needed for the 518. The body mounts were fresh so there was no need for the tunnel to be touched. The cross member still does need to be modified along with drive shaft of course.

Thanks for the help guys.
-Mark
 
MoparMark67 said:
I agree, the lock up converter is nicer...helps with about 5% fuel economy and helps keep the tranny cooler which helps your tranny last longer. I'm all for the lock up. I found a place that has rebuilt 518's with the conversion kit and beefed up to handle 500hp easily, comes out to $2550. Cheaper than a GV and has the lock up converter. I may just go this route. They said they did an A body Dart with no tunnel conversion needed for the 518. The body mounts were fresh so there was no need for the tunnel to be touched. The cross member still does need to be modified along with drive shaft of course.

Thanks for the help guys.
-Mark
Click to expand...
Body mounts on an A-body??? Hmmmm....don't ever remember seeing any. If you just lower the tailshaft keeep an eye on your driveline angles.....
 
Another thing to consider is the Gear Vendors unit requires a much shorter drive shaft. The unit effectively mounts onto the back of the tail shaft (theirs). I don't know if you could get the drive shaft angles to work with an A body. It would be nice to hear from someone that has one in their car before going that route.
 
the 500/518 is longer then a 727 also...so the driveshaft will needed to be shorten also
 
Thanks guys. I'm going to have to go with something other than a 727 either way...I really dont want to be at 3300 RPM's on the freeway. I think the 518 may be the way to go other wise I have to drive 50 mph or make a trailer queen, LOL.
 
A GV unit might seem expensive until you add up the costs involved with converting to an OD trans. A 727 will fit in a Stock A body tunnel so no surgery is needed. You might need to hammer the metal in a few places for the GV unit but I believe it is the way to go if your looking for an OD.
 
lets get real if you are going to run a 400 to 500 hp. 360 eng. on the freeway you would want it to run 2800 to 3400 rpm's to keep it clean, Run it at 20 or 2300 and it will carbon up in 500 miles, save your money and keep the 727. a 400 + hp 360 will idle very rough I would say about 1500 rpms min. so you will need at least a 3500 stall converter. gas mileage is going to be low so if you can'nt afford a engine that gets 8 to 12 mpg. only build it to 275 hp. good luck Gary
 
flboatman1 said:
lets get real if you are going to run a 400 to 500 hp. 360 eng. on the freeway you would want it to run 2800 to 3400 rpm's to keep it clean, Run it at 20 or 2300 and it will carbon up in 500 miles, save your money and keep the 727. a 400 + hp 360 will idle very rough I would say about 1500 rpms min. so you will need at least a 3500 stall converter. gas mileage is going to be low so if you can'nt afford a engine that gets 8 to 12 mpg. only build it to 275 hp. good luck Gary
Click to expand...

Gary,
I didn't think of that. I think I read a different post on the board where someone had 350 hp 360 motor and was getting 22 mpg. Would you say that it's probable? I was thinking closer to 400 than 500....
Another question..How much HP can a 727 handle anyway?

thanks for the help.

Mark

Thanks to everyone else that answered as well.
 
My 360 is making approximately 370 HP and gets 22 mpg on the hiway with an A833OD tranny, 3.55 gears and a 27" tall rear tire. It turns just a tick over 2000 rpm at 65 mph.

This engine idles almost as smooth as a stocker at 700 rpm and pulls cleanly from 1100 rpm to 6000+. To get my engine over 400 HP would only take a better set of heads than my stock magnum heads.

I drive my car almost daily between Marh and the first salting of the roads in the late fall and the tranny will typically be in the OD 4th gear anytime I am at or above 40 mph. It is not unusual for me to drive it for a number of miles at a time with the rpm in the 1200-1300 rpm range. I have spent a fair amount of time dialing in the carb and the engine does not load or carbon up.

I can't see why you can't build for 400-450 and still be able to run down the hiway in the low 2000's without loading up.
 
dgc333 said:
My 360 is making approximately 370 HP and gets 22 mpg on the hiway with an A833OD tranny, 3.55 gears and a 27" tall rear tire. It turns just a tick over 2000 rpm at 65 mph.

This engine idles almost as smooth as a stocker at 700 rpm and pulls cleanly from 1100 rpm to 6000+. To get my engine over 400 HP would only take a better set of heads than my stock magnum heads.

I drive my car almost daily between Marh and the first salting of the roads in the late fall and the tranny will typically be in the OD 4th gear anytime I am at or above 40 mph. It is not unusual for me to drive it for a number of miles at a time with the rpm in the 1200-1300 rpm range. I have spent a fair amount of time dialing in the carb and the engine does not load or carbon up.QUOTE]

holy crap! what are your engine specs?? i like the sound of that for my dart! do you suppose id get about the same mileage running an a500 unit or a GV? i am on the fence for the same swap haha
Click to expand...
 
The engine is a 30 over 360LA block with zero decked KB107 pistons. I have magnum heads with an 0.040 compressed head gasket for a measured 10.6:1 compression. The cam is a Comp XE268H (224/[email protected]", .509/.512 with the magnum 1.7 ratio rockers). Induction is a Crosswind intake and Holley Street Avenger 670 carb. 1 5/8" headers with 2.5" mandrel bent exhaust. The tranny is the mentioned A833OD with 3.55 gears and 27" tall tires.

You likely won't get quite that mileage with an auto. NOTE: I tried a lot of different carbs before settling on the 670 Street Avenger, just switching to a Holley 3310 750 and I loose 5 mpg and gain no noticeable power. Double pumper carbs won't do as well either.
 
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