/6 to V8 questions

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MLC Dodge

MLC Dodge

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I have a 1974 Duster with slant 6, A904 tranny and 7.25 inch rear end. The car runs great and looks great. However, stomping on the accelerator just isn't much fun. So, as a rookie to Mopar, if you had $5000 to add a V8 to this car, how and what should I do? I realize that the tranny and rear end are light duty and would have to replaced too--hopefully later. I was thinking of a crate engine (from whom I don't know). I would prefer an engine type that could be bolted directly to the A904 for the time being to keep modification costs to a minimum. Or, should I find a donor car and pull the V8, tranny and rear end out of it? As I understand it, my stock front suspension will not work with a V8 transplant. Correct? I guess the last alternative is to ditch this car and start over. Thanks for any help here.
 

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The slant six trans will not work on a V8, if you leave that small 7.25 rear in there it won't last long. Find a 8.25 or 8.75 fom an abody or have a 8.75 cut down and buy new axles, new driveshaft will need to be built too. You will need different engine mounts, I think you can get conversion ones for that car, or you could change the k-frame.

What front brakes are you running? If you swap in a V8 you will want discs up front, can use ones from a 73-76 a-body, they will bolt right in. Front sway bar and heavier torsion bars would be smart too. You don't have to do any of this stuff but your car won't handle very good if you don't, and you want it to be fun to drive! Also, by swapping the front discs you will have the larger 5 on 4 1/2 bolt pattern, same on rear if you swap in a 8.25. If you buy new axles for an 8.75 you can get new axles with the same bolt pattern, this will allow you to run several different styles of wheels, including 15" I assume you currently have the small bolt pattern lugs?

Also need to get a bigger radiator, be sure to get a nice set of headers too. I think you could have a 360 built for a decent price, probably alot cheaper than a crate engine. No need to ditch the car, that thing looks great! I think for $5000 you could do everything you want if you take your time and do the work yourself.
 
I've been looking and $5K won't buy much of an engine. With all those changes required it looks like the smart thing to do is sell and start over with a V8 car. The anemic /6 just isn't what I was hoping for. Oh well, live and learn.
 
One thing to consider too is you could always upgrade the rear and front suspension and leave the slant six in there, then if you have enough money to built a new engine go for it! A nice used 318 could be swapped in for now and those make good power in a light a-body as well!
 
The car looks to be in great condition including the /6 in it already.
You can do some fairy inexpensive mods to the engine to make it perform a lot better.
If you must go the V8 route, i would get a donor car and take what you need off of it and rebuild the front suspension etc.
Do you have bbp disc brakes on it now?
If the front and rear are bbp, you are lucky and could get away with just changing the k member to a spool mount V8 one, or get the shumacker conversion mounts.
You would need a small block 904 and the rear end would be good enough for now if you put a mild 318 in it. You also need to upgrade the radiator and torsion bars and hopefully install a front sway bar on it to do it right.
If you decide to do lots of burn outs and want a lot more power, a lot of work to change everything over like the rear diff, torsion bars, etc. would be in the cards.
What amount of power do you need?
You would probably have a hard time selling your /6 and parts you replace for very much money, even if it's in good shape.
So, my suggestion really is to buy a complete parts car and rebuild all of the parts and switch your car over, modify your existing engine, or maybe buy a car that this is already done to and sell yours as is.
Don't buy a piece here and a piece there, it will cost a lot more in the long run.
I hope this helps.
 
I'm not really looking for a whole lot of power, but rather, something that responds to me mashing on the go pedal. The single barrel /6 just has no uuumph! A 318 sounds like plenty for my desires. I will keep my eyes out for a donor V8 car. BTW, I have drum brakes all around.
 
MLC Dodge said:
I'm not really looking for a whole lot of power, but rather, something that responds to me mashing on the go pedal. The single barrel /6 just has no uuumph! A 318 sounds like plenty for my desires. I will keep my eyes out for a donor V8 car. BTW, I have drum brakes all around.
Click to expand...

318's are cheap and easy to find, could even go used, tear it down and put in new gaskets, paint it and go! The suspension stuff is easy to find too. For the front brakes you will need (from a 73-76 a-body) the spindles, upper control arms, brake proportioning valve...that's really it, the calipers, rotors, hoses, can all be bought at the local parts store yet.

Forgot on the rear that a leaf spring change would be good too, or could have a shop install another leaf or 2 and they should be good to go. I think if you can buy smart and can settle for some used parts along the way, this can easily be done in your $5000 budget!
 
O.k.
What you are looking for is a '73 to '76 318 auto a body complete as possible, preferably running and driving but a little rusty for under a grand. I would get a 4 door so you can to keep costs down. Hopefully it will have a 8 1/4'' rear diff in it too!
Refurbish everything and re and re.
Good luck.
 
That looks too pretty to do any swapping on. But so was mine and a 360 roller now sits where my slant did. Got a 727 behind it and just got a long legged 8.25 to go out back. It's not done yet but so far didn't hurt that bad financially. 250 for an 5.9 out of a rollover pickup. 200 for the trans from Craigslist. Schumacher spool mounts , crosswind intake and carter carb, I think I'm under a grand. With 5 grand you can do better than I did.
 
Thanks for the guidance. I'm guessing my car, while very nice, is only worth about $4500 as it sits. Since the body is excellent without any rust, it looks cost effective to modify what I have as opposed to selling and buying again. Correct assessment? I'm not following the lingo for the rear end (long legged) or the engine mounts (spool mount V8). Could someone school me on those. I found a 318/904 car local on CL. It's a runner too. Do all V8 cars have disc brakes?
 
My car was originally a /6 car. But the V8 was already slapped in when I bought it. If I had a choice in the matter I think a built up /6 with a turbo added would have been cooler, more unique, and could manage the same power of the V8 cars if built too.

So if I was in your shoes I would consider messaging the motor, adding the turbo, throw on some fuel injection. Then surprise some of these V8 guys.
 
71swing,
I hear you. I worry about dumping more money into a slant 6. In the end, it will still be a 6 cylinder. I thought about this too, but can't seem to locate a super six setup. Any leads would be appreciated.
 
my 73 duster was a six car, i picked up a 67 318/727 for 400 bucks , a set of conversion mounts , headers, radiator and had my driveshaft shortened and never looked back. i still retain all my slant suspension and i drive the car everyday. i am completely happy with it and it sounds/runs great. i have less than 800 in the entire swap. not to mention i got 200 back out of the 6 and trans.
 
I'm in your shoes. I've had Mopars for year but never did any of the work. I have a 68 Barracuda that had a slant six. If it was me, I'd keep the car you have because it is super clean. You don't have to do all the sheet metal work that can turn this into a much bigger project than you want to deal with. Schumacher engine mounts allow a direct bolt in for a SB V8. I've checked around on this forum and you will find members who have everything from 273s through 360s that they will sell and the deals are usually pretty good. Some come with a tranny. All you have to do is have it rebuilt to your specs, add the radiator and rear end, upgrade wheels and brakes, and you will have an awesome car. The more work you can do yourself, obviously the less it will cost. Keep checking with forum members here because many of them have already done what you're going to do, know the ins and outs and what not to do, and I have found they are happy to help other members. I like your car.
 
Thanks everyone for the help and kind words about my Duster. I love this car and the Forum is a blast. The forced induction is beyond my capability. I know how to wrench--but that work is above my payscale. I noticed that Clifford offers a kit to replace the intake with one that will accomodate a 2 or 4 barrel carb. They also provide an exhaust header set and Weber carb. The kit is $1300 and they say it improves power by 60%! Wouldn't this be the easiest and least expensive fix? Anybody gone this route? If so, what is the maximum flow rate carb you could put on this intake/engine combination? Thanks again.
 
You can get a magnum 360 or magnum 318 for just over 1k including shipping. Then you just need a different manifold if your going to run a carb.
southwestengines I do believe, haven't used them but I'm thinking about it.

Oh and don't ditch the car just cause it's got a /6 and you want a V8, it looks great
 
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