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  #1  
Old 12-29-2001, 11:58 PM
Sean C Sean C is offline
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Question Just put a 8 3/4" rear in my '66 cuda, need specific driveshaft info

Hey all my name is Sean and I am a Mopar nut!

I have a '66 Barracuda 273 4 speed (chrysler 4 speed, not the A-833) and after 280,000 miles the pinion gear in my 7 1/4" rear disintegrated.

So......I found a A body 8 3/4" and put it in.


The Driveshaft is now about 2" too long, does anyone know if a driveshaft out of an A body 108" wheelbase,( NOT 111" ) automatic will fit? I just thought I would ask because I can find one about 50 miles away. Otherwise I'll have to have my current driveshaft shortened.

Anyone?
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  #2  
Old 12-30-2001, 12:25 AM
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dschumers dschumers is offline
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Question

Don't know for sure what else will bolt in, but when I put the 8-3/4 in my Duster, I had to have the driveshaft shortened 1-3/4".
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  #3  
Old 12-30-2001, 12:32 AM
Sean C Sean C is offline
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When I put the 8 3/4" in my '69 dart, I was lucky enough to have gotten the rear along with the driveshaft.

Believe it or not, the 8 3/4" I got for my '69 Dart came out of a '70 Swinger 318 with a factory towing package, but the car was trashed and not worth salvaging the body, so it made a most excellent donor!
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Old 12-30-2001, 01:34 AM
swansong swansong is offline
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i had to have the drive shaft in my duster cut when i put in a 727....it only cost like 90 bucks to have it cut welded and balanced.
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Old 12-30-2001, 03:10 AM
barracudadave67 barracudadave67 is offline
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You can find drive shaft spec's in the 66-Plymmouth Service Manuals and Parts Manuals. These will tell you what length it should be when using stock rearends and tranny's of diferent combinations. Get the specs from the book and hit the swap meets or get one made or shortend.You can usually find these books at swap meets or on the internet , parts manuals are harder to find. Repos of service manuals are available from Year One.Theyre about $60.00 Good Luck and Happy new Year!!! Barracudadave67
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Old 12-30-2001, 12:55 PM
jelsr jelsr is offline
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If the donor car has the 8-3/4 rear you might be in business. The difference is the centerline of the axles to the center of the "U" joint. For the 7-1/4 it's 10.09", for the 8-3/4 it's 12.35". Then if the slip yoke is the same your chances are even better. If the yoke is different you can change them if they use the same joint. Good luck!
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Old 12-30-2001, 04:07 PM
Sean C Sean C is offline
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jelsr, I got the rear out of a 111" wheelbase A-Body, so I will probably just have my existing driveshaft shortened. Thanks for the specs.
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  #8  
Old 01-14-2002, 05:40 AM
Sean C Sean C is offline
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Thanks guys.

If anyone is interested, my swap went very well, I had my driveshaft shortened 2 1/4" and it fits perfectly. I had it shortened and balanced with brand new USA U-Joints for $50 by a very good machine shop.

My little 7 1/4" had 3.55 gears, my new 8 3/4" has 2.76 gears right now, however I have complete center sections on standby with ratio's of 2.94, 3.55, 3.91, 4.30.

Right now I can cruise on the highway at 80 mph at around 3000 RPM, my mileage went from 20 MPG @65 MPH to 27 MPG @65 MPH. It is stock 273 2 bbl 4 speed with 280,000 original miles.

I change oil at 1500 mile intervals, the oil always looks like honey and there is no sludge at all.
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  #9  
Old 01-14-2002, 05:52 AM
jelsr jelsr is offline
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It's always nice to hear when things go well. Congrats! With 2.76's your next stop the Salt Flats? Top end would be scary if you could pull enough R's.
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  #10  
Old 01-14-2002, 10:59 AM
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cuda66273 cuda66273 is offline
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Default Drive shaft not required?

I swapped in a 727 into my 66 Cuda and cut the drive shaft....
Then I installed a 8.25 rear and had more cut off.....
I almost put in a 8 3/4 and measured it again for another whack job....
I found a Dana 60 and installed it instead, even more needs to be whacked off....I've had it cut so many times I think it's short enough now I can just bolt the tailshaft to the pinion ....hahhahahha
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  #11  
Old 01-14-2002, 03:23 PM
Sean C Sean C is offline
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Cuda66273: The Dana 60 is quite a huge rear, I take it from your username you are runnng a 273?

I also have a '69 Dart with the original 273(yes a '69 with a numbers matching 273) and have done some mods like an engine rebuild, 8 3/4" 3.55 rear, MP .450/.455 cam, viscous fan, 4BBL, B&M transpack, battery relocated to trunk, stock manifolds, Flowmaster 40 series. For a 273 it's pretty fast.

jelsr: , I thought I would see how I liked the 2.76, and since I already have a souped up Dart, I am thinking of leaving the 2.76 in there for gas mileage and hwy cruising, I go to Butte a lot(55 miles roundtrip) and it is nice to be able to cruise at 80 around 3000 RPM, before with the 3.55 anything above 65 MPH for extended periods seemed uncomfortable, now the engine can relax and maybe run for another 100 grand! However I do have a 318-2(casting no. Truck block, extra meat in the cylinder area) and have bored it .060 over and am building it according to the MP 12 second quarter mile recipe, I just don't know if it's going in the Dart or the 'Cuda.
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Old 01-14-2002, 05:10 PM
jelsr jelsr is offline
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I believe there is some sort of inverse hookup between the tach and the fuel guage. When the tach goes up the fuel level goes down. Works like that in my stuff too! The Cuda is probably the better of the two for aero figures, small engine compartment no problem for smallblock. If the Dart is the 111 WB size it has large engine compartment but would be a little heavier and have more aero drag. Probably six of one and a half a dozen of the other as to pros and cons.
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  #13  
Old 01-14-2002, 10:49 PM
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cuda66273 cuda66273 is offline
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Default Sean C

No, I dumped the 273 after the 2000 season and built a 318.
It builds over 400 HP at the crank and around 425 on the tork scale ran 12.50's as a street legal 3460# runner.

We've done a long list of changes which include taking a couple of fillets of her and getting her down to under 3000. We're looking at 11.90's still with the 318.

Why haven't I chaged my handle to cuda66318...???? it's a long story........

Don
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  #14  
Old 01-14-2002, 10:59 PM
Karl43 Karl43 is offline
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Sean C: 27 mpg from a v-8 is awesome. I used to have a 2.76 in my 68 Cuda and would get 18.8 MPG with a home brew 318 4-bbl and a 2.76. Blew up the 7 1/4 too many times and swapped in an 8 3/4 with 3.23 sure grip. I miss the 2.76 though, it was a great gear. I am looking for good economy with performance.
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  #15  
Old 01-15-2002, 04:35 AM
Sean C Sean C is offline
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jelsr: The only concern I have with putting the 318 in Cuda is the header situation, TTI makes headers that fit without cutting anything, but they are not equal length, my only other choice is fenderwell headers which require cutting a hole or 2 in the inner fender.

Don: Would you care to elaborate on how you got your '66 cuda to run so fast? What kind of headers did you use? What mods have you done to the engine? Are you using 360 heads with 1.88 valves or 340 1.88 heads? Or 318 heads opened up to 1.88? This is my dilemma right now. I have heard the newer 318 swirl port heads are the way to go with the 318.

Karl: I don't know what it is with this engine/car, gas mileage has always been really good, I know it sounds unbelievable but my little 2 bbl 273 really gets great mileage, my 273 Dart on the other hand when it was stock with 2 bbl and 2.76 gear could only muster 18 MPG, of course with my mods now, I'm getting about 14 MPG HWY and 16 MPG around town if I keep my foot out of it. Wierd.
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  #16  
Old 01-15-2002, 10:50 AM
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cuda66273 cuda66273 is offline
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Default Secrets revealed

I can give you a few of the basics but the fine details are way too extensive to explain here. I think they have a 1500 word limit to a post?

The math....I spent a year doing all the math to obtain the maximum quench, piston design, valve combination, volumetric efficiency etc.

The Basics....
318 truck block 1967 vintage bored to +030

Arias custom pistons using the NASCAR technology of the reverse dome which allows for longer flame travel.

Reduce the rotating mass, SCAT custom light weight billet crank, '66 273 rods they were forged and are far lighter than 67 and up rods, again I referance the ARIAS pistons...as light as they could make them, SS 11/32 chevy type valves-back cut and lightened as far as we dare go, Titanium retainers...basically lighten the whole valve train as much as possible.

Huggins Cam, this was a task, we did the math on so many profiles that I wore out a calculator, we literally spent months designing the cam, we needed to build huge cylinder pressures without huge lift which would cause piston interferance because of the piston design and combustion chamber. We ended up with a .508 lift with a huge split duration and a centerline you've never heard of.

Heads...this is the strangest part of the whole combo..the original 273 head castings were used, ported and cut to obtain the max flow and most important the highest velocity that we could create. I was a little disappointed here , after we ported the heads as far as we dare go and then a little more we couldn't get the runner volume up to our target, so next year I'll build the set of 915J heads that I have under my bench. That should get the HP up at least another 30 and the tork up another 20.

There is no secrets here, just basics exploited to the max.....rotating wieght, fuel intake balance between volume and velocity, combustion chamber efficiency, oil system control, optimum exhust back pressures....you all know what the object is it just takes alot of time and research to make all the combined parts work together to max.

We still have a long way to go....sometimes what works on paper and the dyno doesn't work that well on the track...the head castings were a mistake, the J heads will get the RPM range up from a current max efficiency RPM of 62-6300 to around 6800, but the combustion chambers will require alot of work to balance them to the piston configuration.....next winters project, it'll take me 3 months of grinding to get them just right.

I tried the motor at a 7000 RPM shift and it slowed down to 12.98 and I could feel the engine just flat run out of air and nose over.

Compression ratio is 11.2:1 on EVERY cylinder, combustion chamber are 53.3 CC's on every cylinder, valves are 1.94/1.60, Hooker Super Comps, Demon 750cfm, MSD, 108 fuel, BG fuel pump@7 pounds, 727 with a DYNAMIC convertor....cause there is no other PERIOD

The car weighed 3460 last year and we couldn't get it over 5500 at the stripe with the 3.91's. So this year we took a filet knife to the fish and cut nearly 400#'s off her, added a dana 60 and 4.56 gear and added a little more tire to get it to the 6200 stripe RPM we're looking for, this should give us 11.90's.

If you follow everyone else and buy catalog parts...you'll do just that....follow everyone else...."Dare to Be Differant"

There ya go...more information than you probably needed.

Don
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  #17  
Old 01-15-2002, 07:33 PM
Sean C Sean C is offline
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Thanks cuda66, I think I have a good formula going right now, What I really want to know is, did you have to cut up the 'Cuda to fit the headers? Did you have to notch the cylinder wall to clear the 1.94 intake valves? Also I may use a Hughes .508 cam. KB pistons (11:1). The 318-2 block came with a forged crank, so I'm good there. Let me know on those headers and valves.

Thanks
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  #18  
Old 01-15-2002, 09:09 PM
Thunderstruck Thunderstruck is offline
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Default Re: Just put a 8 3/4" rear in my '66 cuda, need specific driveshaft info

Quote:
Originally posted by Sean C
I have a '66 Barracuda 273 4 speed (chrysler 4 speed, not the A-833)
I hate to disappoint you but the A833 is the chrysler 4 speed in 1966, unless you have a truck with the NP435 in it. In fact I believe the A833 is the only non-truck 4 speed that was Chrysler built, ever.

Steve
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  #19  
Old 01-15-2002, 09:46 PM
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cuda66273 cuda66273 is offline
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Default Sean C

Yes I had to cut holes in the fenders for the headers...I drew a line about 3 inches back from the radiator support then along the seam where the innner fender makes the 90 and bolts to the outer skin and down the back about 1" from the fire wall make a 90 towards the front and be careful not to whack off the shock tower...makes a nice hole and you can service the brakes without taking the tire off hahahahaaaa. hey! and it cut 36#'s off the front end!

The valves cleared fine no notch required on the 318....273 I believe would need to be notched.

I'm not really sold on the KB Hyperutechtic deal...I guess there OK for street app's but for all out power I would have to stay with the forged aluminum.

Be sure and use your 273 rods and hook 'em up with a GOOD set of ARP bolts, they make 2 differant grades be sure and spend the extra $10.00 and get the good ones...I doubt Smummit even carries them.

Have a look at the Racer Brown or Huggins line of cams before making a decision on a cam, give them a call and see what they have to offer, there top notch Mopar racer type Guys.

Remember what I said about following what everyone else does......you follow everyone else, me, I prefer to lead...the view is better.

If you call Huggins tell them that Drummond Machine from Oregon referred you.

Good Luck with your project.

Don
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Old 01-17-2002, 02:45 AM
Sean C Sean C is offline
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Thanks cuda66, I will look into your suggestions, in fact I'm doing a lot of research before I make any final decisions.
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  #21  
Old 01-17-2002, 02:49 AM
Sean C Sean C is offline
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Quote:
I hate to disappoint you but the A833 is the chrysler 4 speed in 1966,
Ok Thunderstruck, I'll take your word on that. It's just that my 4 speed seems smaller than whats behind the 340's and such.

Can you tell me the best way to get a 10.5" clutch behind the 273/318? My 'Cuda came stock with the 9.5"
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