What would be the best option to put a OD trans behind my /6
The truck is a 66 D100 with the original /6 & auto trans . I'm planning on making it a daily driver
with power discs , EFI , OD trans, and AC , while keeping its original apperance.
Was there a change made to the bell haousing or flex plate in the late 60's ?
I am new to the forum and hope to get a build thread gowing soon.
Any info would greatly be apriciated
Hello welcome to the site... would love to see some pictures of your truck.
there are later model automatic transmissions with OD that will work but its not that simple of a conversion. Im sure someone will have some details of it on here.
I know Gear vendors make an add on overdrive that splits all three gears on the original transmission. I hear it works really well but is rather pricey.
I'ts going to be a long while before I get pic's up, first I'm going to have to
invest in a real nice & comfortable couch, as I will most likely be spending many nights on it .
Curently the truck is in pieces and I have rust to repair in all the usual places.
The converter hub & spline size changed in 67 I do believe......The register on the back of the crank flange is bigger on 67 up models from what I remember. I put a 65 /6 into a 71 demon and had to have a converter special made for it with the small 1965 register but with the 1971 style spline . Keep this in mind with whatever combo you end up using. There is no bolt on O.D. auto tranny and no adapter available to put one behind the 6 regardless of make of tranny. You could cut the v8 bellhousing off of a 518 and heliarc a /6 bellhousing to the front . This would require precision fit, cutting each with a large band saw and then milling each end on a Bridgeport mill, then precision fitting /welding in place . Very hard job to do and not cheap. Gear Vendors unit installed on the rear of a regular / 6 904 or 727 would be cheaper way out I do believe.
I personally would find the old 4 speed manual overdrive from the late 70's . Its the cheapest way to have overdrive behind a slant 6. In fact the factory built that very combination and it got very good mileage. Basically a 4 speed case with 3 speed gears and 4th being overdriven.
Heres a cheaper alternative if you are set on an automatic.......install late 70's v8 a-999 first gear set into your existing /6 904 tranny and run a 2.76 or 2.45 gear in the rear axle. The a-999 first gear is much lower giving good take off even with that highway gear in the back. Not perfect but better than stock.
If it were possible the best combo you could put together would be a 700R4 gm overdrive which has a deep 3.06 first gear, backed with a 3.55 to 3.91 rear axle ratio. This would give you plenty of low end and top end..the gear spread making life effortless for the motor regardless of speed.
moporridge wrote: There is no bolt on O.D. auto tranny and no adapter available to put one behind the 6 regardless of make of tranny.
So there was never an M body with a slant6 and an A500? I believe the last year for the M body was 1989 and the A500 might have been around then. I'll have to check.
Ok, 1983 was the last year for the slant6 in the M body. Only 318s after that. No overdrives behind the slant6.
If you want to all of that, just get a first or second series Dodge V6 From the Dakota,
Dodge 1500-2500 Van or 1500-2500 Ram Truck. The entry level version has
the A-500 and the more Heavy Duty version will have the A-518.
The 3.9 V6 is lighter than the Slant Six, has more power than Slant Six's
and uses less fuel.
Since the V6 is shorter, you will have less weight on the nose.
The V6 has a Alternator-A/C Bracket that is already there.
As already said, there is no OEM Slant Six with a Automatic O/D, or an
Slant Six with any thing other than a OEM "down-draft" Carb.
You will be able to use your present Shift Linkage to the newer Transmission.
Great idea Roger......the v6 is a much better choice and Mopar makes aluminum carbureted intakes 2 and 4 bbl for those who don't want to mess with EFI...
I wonder how the low end torque would compare to a 2 bbl. super six 225 ? By Low end I mean 2000 rpm on down......Inline Motors usually make better off idle torque...
The first year 3.9 V6 used a 2 bbl Carb and belts. It is after that a TBI,
Sep Belt and all that other stuff was used.
Since this engine is the MoPar replacement for the Slant Six They wanted
this engine to all the Slant Six could do and get the better items already
explained about the Engineering Part of it.
Remember the 3.9 V6 is used up to and including the 2500 Ram Truck's.
The Bell-Housing size and pattern is the same as all the 1962 - 1966
A-318's, any LA-273/ LA-318. LA-340 or LA-360.
The Crank Shaft Flange is the same as any of the above ( the 360's are
balanced different, but use the same bolt pattern ).
Not a big fan of the 3.9 had a few, To be fair the trucks they were in had their own problems like wiring, weight & lots of miles. I'd probably go with a poly 318 sooner than a 3.9 or a magnum just because. Does mopar or anyone else make an electronic ignition for the poly 318 ?
Thanks for all the input I'm thinking sereously aboyt cuting some bellhousings though.
I've had numerous /6's and numerous 273 -318's... Polys and Wedges......To be perfectly honest....the smallblocks got better mileage.....Its hard to beat a 318.....There is a point where the 318 low end torque helps more so than smaller cubic inches. Experience has shown me that a 318 will get better mileage than a LA 273 .....its because the engine doesn't work as hard......Less throttle opening required...equals high vacuum....equals great mileage. Hard to believe that a bigger piston used less gas.........273 - 180 h.p. 275 tq. 318 - 230 h.p. 340 tq............ The larger cylinder bore area around the valves probably makes the engine a little more efficient as well. 318's make gobs of torque for their size.... way more than Fords 302 and the same tq. as Chevys 327 2bbl.....
On another note thats not Mopar oriented....
How does a 5000 lb. 75 Oldsmobile 98 with the 455 4bbl get 20 mpg on the freeway ? Gobs of low end torque and a 2.41 axle ratio.....
My grandpa owned this car and then my dad and then me.....tuned up with fresh oil and filters ...the car once got 22 mpg on a trip to Austin....Motor had over 300,000 on it and still ran like new when i traded it off....Oldsmobile was the only GM product worth owning in my opinion. Great engine....would have been an even better truck engine. They do well in Jet boats....all that brute low end power....
http://slantsix.org/articles/4-speeds/O ... speed1.htm Check that out. Several people here on the forum have put an A 833 OD behind the slant six with good results. You'll prob have to switch to using a mechanical clutch with the "Z" bar setup. Talk to "cowboy" on the forum. He has given me a good bit of insight on this as I was/is thinking about this swap. Let us know what you decide.
2bluesweptlines wrote:http://slantsix.org/articles/4-speeds/O ... speed1.htm Check that out. Several people here on the forum have put an A 833 OD behind the slant six with good results. You'll prob have to switch to using a mechanical clutch with the "Z" bar setup. Talk to "cowboy" on the forum. He has given me a good bit of insight on this as I was/is thinking about this swap. Let us know what you decide.
The truck is a factory auto and that kick @$$ shifter on the dash takes me back to my childhood in Grandpas ole Dodge
I'd hate to part with it. May be going to a poly 318, has anyone seen any EFI tech on them ? As for OD its the A518
Cool...glad you are deciding on a poly maybe.....I've seen a Holley projection on a polyhead before on top of the Weiand intake......It worked real well....responsive and torquey......
moporridge wrote:Cool...glad you are deciding on a poly maybe.....I've seen a Holley projection on a polyhead before on top of the Weiand intake......It worked real well....responsive and torquey......
I'm of the understanding that weiand is the only manuf. curently offering an intake for a poly. Would it be possiable to somehow install fuel rails and injectors on the weiand or other intake ? I'm all about some redneck engineering, and dont much like the price (broke tight wad) of the holly TBI. As far as the computer and electronics, I would'nt mind non mopar peices All that stuff is from China, Japan, or Mexico anyway
The TBI and whatever is just a 2 bbl Electronic Montering fuel delievery
system. Part of this "package" is a Cam spec'd to the driving speeds
of today ( good lift and very low to no over-lap ).
The first LA-318's of the Electronic Era are labeled as 5.2L's. Look into
the TBI Unit used on them to be used on your OEM A-318 2 bbl Manifold.
The newest Weiland ( 4 bbl & single plane ) is a unit that has poor
low end abilities is as old as a GTX or RoadRunner.
The best aftermarket manifold for today's world is the very hard to find
Offenhauser Dual Port.
For all you guys running /6 a out there cheek out the /6 forum. There are a couple of tech write ups for running MPFI
using mid 80's 3.8 liter (GM ) parts. It was these articles that got me thinking the same could be done with a poly.
/6 with OD
) parts. It was these articles that got me thinking the same could be done with a poly.