Slant 6 to 340 swap

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xring

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I thought his topic would have been done to death, but I can't find a thread about it.

What would need to be changed to convert an original slant 6 car to small-block V8? Motor mounts, transmission, rear end, front springs, radiator?

The reason I'm asking is, all along I figured I'd buy either an original V8 car or one that has already had the swap done. But I'm seeing some affordable /6 cars and wondered if it wouldn't be more cost effective to get one and do the conversion myself.

Thanks!
 
Here is what I think I know,
As I am thinking about doing this in a 65 dart.

You can get motor mount brackets, so you dont have to change the K-frame. I am not sure who has them, but I have seen them on ebay.

Your brakes will most likely be 9 inch, so that needs to be upgraded.

A bigger radiator would be nice.

Probably should replace the springs and torsion bars.

If the car has power steering headers are going to be a problem.

Need a bigger rear end. The 7 3/4 will not last too long behind a 340.

You are probably going to replace the rear mount and driveshaft.

So plan on replacing the entire drive train and brakes.

I am sure I am forgetting more than I know.
 
PLAN ON SPENDING A BOAT LOAD OF $$$$$$$$$$$$$$$$$$$$$$$$$$$$.
your best bet is to find a 318 car.
that way you have all the brackets ,etc
then all you will have to swap is the block and rear.
 
Don't have the car yet...I'm building the engine first, will get a car later.

Hoping to find a 70-72 Duster, or a Demon.

I can get a 8.75 rear and 727 pretty cheap locally. I figured torsion bars and radiator, too. Do you have to change the K-frame?

I'm kind of surprised it would be real expensive...since I don't care about a numbers-matching car I thought it might be cheaper to find a not-too-rusty /6 car and convert it myself, given the current market prices.
 
I went from a \6 to a 360. I did it in stages;

1. Swapped the rear end which also required shortening the drive shaft. The rear end was a freebee that I spent about $300 rebuilding first. The drive shaft was $75 for a cut balance and new u-joints.
2. Most \6 cars have 9" drum brakes which are altogether inadequate if you plan to drive on the street. I swapped in 73+ A-body disk brakes. I picked up a doner car for the spindles and control arms and used the rotors and calipers for cores on rebuilts. The new rotors, bearings, hoses, calipers was about $200. The doner cost me a case of beer and the time to hall it out of a co-workers back yard.
3. Built a stout 360. Picked up the 360 core for $50 and spend another $2500 on machining and parts.
4. Picked up a sb bell housing off the internet for $75. New flywheel and clutch was about $300
5. Picked up a new 22" heavy duty radiator for $150. and a set of hedman headers. I had headers and dual exhaust on the \6 that I purposely bent up so that I could easily adapt them to the v8 headers.
6. Cleaned up the v8 k-member from the doner car.
7. Swapped in the 360 using the accessory brackets from the 318 in the doner.

My recommendation is to keep your eyes out for parts that are a deal. There is always a deal to be had, you just need to keep your eyes open and jump when the opportunity presents it self. I just picked up a 340 long block that has less than 2500 miles on the rebuild for zip, another guy just wanting it out of his garage.
 
Hey I really need some help.
I have a 74 dart sport i'm converting to a 340 car. I have already got the motor mounts i need in order to swap out without changing the k memeber, i have the 727 tranny and the bigger 8 3/4 rear end. I am rebuilding the rear end now and the question i have about this rear end is that i was told i had to change the axles from a 5x4 bolt pattern to the big bolt pattern of a 5x4.5. obviously this will make it a little stronger, but i dont understand why i have to swap. If i put in the bigger bolt axles in the bigger rear end then i am just looking for more change in wheels and drums and brakes etc. I just need some direction in this it would be very much appreciated. do i have to change to bigger bolt pattern or will i be safe with the one thats already in it? Thanks! :)
 
Your 74 model came with the large bolt pattern on front and rear. To put small bolt pattern on the rear means different wheels, 2 spares, etc..
 
acouple local wrecking yards could have the treasures you seek. i recently aquired a 72 dart which already has a V-8. they have a 74 valiant in there with BBP disc brake set up on it i got the complete front set up for a 100 bucks all of which is in great working order im also getting the rear even though its a /6 rear it has the BBP aswell. im not planing on tearin up the nieghborhood with it atleast all the rims will be the same. if i was you when you get this plan going i would get the brakes done 1st disc,BBP if you chose to go that route then start on the driveline /6 to V-8 motor mounts would be your cheapest route. the torsion bars can be upgraded after the swap keep in mind that you might have alittle more body roll driving around
 
I totally agree with dgc333. I swapped my '71 Duster from a slant 6 to 360/414 stroker. Most parts came from the junkyard. Just cleaned them up and painted. I hit Ebay, craigslist, local newspaper, car show/swap meets and found everything I needed. It can be done without lots of money. Just be patient. I'd get a B-body 8.75 rear and move the spring perches. A-body rears are too damn expensive!
 
Hey I really need some help.
I have a 74 dart sport i'm converting to a 340 car. I have already got the motor mounts i need in order to swap out without changing the k memeber, i have the 727 tranny and the bigger 8 3/4 rear end. I am rebuilding the rear end now and the question i have about this rear end is that i was told i had to change the axles from a 5x4 bolt pattern to the big bolt pattern of a 5x4.5. obviously this will make it a little stronger, but i dont understand why i have to swap. If i put in the bigger bolt axles in the bigger rear end then i am just looking for more change in wheels and drums and brakes etc. I just need some direction in this it would be very much appreciated. do i have to change to bigger bolt pattern or will i be safe with the one thats already in it? Thanks! :)

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First I think it's great that you are doing your own work.

You do not HAVE to swap to the big bolt pattern right away. All 340 a-body cars were built with the 4" bolt pattern rear end from 68 through 72. (as were the 383 and 440 factory cars) The wheel selection is MUCH better with the BBP though.

You have a few options here.
1. You could stay with the rear end you have and run the car with it. If you have a 4" bolt pattern on the front, everything would match, if it's BBP in the front, you would have 2 different bolt patterns on the same car. (BTDT) If your car really is 4" pattern on the front, you probably need to upgrade your brakes to be safe.

2. You could sell your SBP a-body rear and use the money to obtain an 8-1/4' a-body rear or another 8-3/4 w/ the BBP. The 8-1/4 rear was used on 340 cars starting in 73.My friend has an original 73 Dart Sport, 340 4 speed w/ the 8-1/4.

3. You could convert your present rear end to BBP by getting brand new axles for about $300 but you will have to convert to BBP brakes in the rear. It looks like most of the common new axles require the green bearings unless you specifically request the tapered bearing style that the factory used.

4. You could source 70's era C body or truck 8-3/4" axles and have them shortened to fit your a-body width rear and change the brakes. IIRC, The source axles must have at least 28" straight length from the brake drum flange to the area on the axle where it starts to neck down.

I did option 4 and this is what was involved:
Bought a pair of early 70's C-body axles (deal at $35/pr) and sent them UPS to Moser Engineering in Indiana. They called me the very next morning (!) to confirm what I needed before they started cutting. Including shipping it only took about 4 days and about $110. I told them what brakes I was using and that they were going into an a-body width 8-3/4 rear. I had already sourced new backing plates ($20/pr), and 10 x 2-1/2 drums from various mopar swap meets. Bought new hardware and wheel cylinders from Rockauto. Using the big axles results in the rear track being 3/8" wider per side for a total increase of 3/4". Seeing the old SBP side-by-side with the larger axles is pretty impressive. Not only is the axle itself bigger, but the wheel studs went from 7/16" diameter to 1/2" on a 4-1/2" bolt circle.

So I probably spent about $200 for the rear BBP conversion by careful shopping and now have Road Runner sized brakes on my a-body with the 73-76 a-body front discs, adj prop valve, and run them w/o power. Another expense was different wheels. Personally, I think using 11" rear drum brakes is a waste on an a-body as they aren't needed and the extra inertial weight only makes the car slower.
 
Your 74 model came with the large bolt pattern on front and rear. To put small bolt pattern on the rear means different wheels, 2 spares, etc..

If the car is a \6 with drum brakes they are still small bolt pattern. The \6 drum cars stayed small bolt pattern to the end of the a-body production.
 
thanks to you guys here on FABO the smallblock conversion in my 66 went much easier than it honestly should have. It was an original 225 hoppin half dozen, 904, 7.25 w/ 2.90s on wheel peel monster. it seems like theres a lot of people on here that have the mentality that theres only one way to do things. honestly it depends on what you want to do with the car. I built mine to be a cruiser, but dont forget, theres always room for improvement, and it does NOT have to all be done at once. for my swap i started with an 87 vin M 4-barrel gran fury. Zero decked 318 short block with 360 heads and intake, and this was factory. luckily this car came with a TF999 with lockup. other tidbits that came with the fury and were helpful was the oil filter adapter, mostly correct oil pan (ill explain later) three piece kickdown linkage, 8.25 posi diff, remote engine and trans coolers, and the more common aluminum water pump. I also got lucky that someone swapped a posi 3.23:1 7.25 in long before i got the car. (I flog that rear end regularly, and it hasnt given me a lick of trouble):burnout: One of the local junkyards here has two early barracudas. (65 273 2 barrel console auto and a 66 formula S) To my advantage they were v8 cars, so the drop drag link (unknown to me at the time my 66 already had one factory, its a late 66 build) and gas pedal assembly were easily located. I also snagged some alternator brackets and pulleys from a 70s pickup. Schumacher supplied the motor mounts wich worked 95% flawlessly (they make the engine sit approx 1 inch higher in the engine bay, making the transmission kickdown/governor lever eat the floorpan, requiring a BFH for floor mods in my case) and exhaust clearance becomes an issue. i used a 70s truck dizzy to work an "old" analog MSD 6A box (i ordered it from napa, where i work) since the original dizzy in 87 didnt have mechanical advance weights, it was designed for an ECM. the TF999 is dimentionally 100% the same as the original 904 and in 1966 dodge went to a splined yoke for the output, previous years used a ball and trunnion setup, not cool. I happened to get lucky. not all smallblock oil pans that claim they fit early a bodies will. some custom mods are required on most to clear the drag link on the drivers side, this is one thing no one seems to tell you, and a little time with a torch, a ball peen hammer, and some finess will solve this issue. or just make sure theres a dimple on the drivers side right behind the sump, if not, hammer time! that modification, if done right, will clear windage trays too. my engine being a cop setup had one factory. as for steering and exhaust, the flaming river coupler is too damn expensive, and is a joke in my opinion. me being mr. budget ordered a sweet mfg. 3/4 DD x 3/4-36 spline steering coupler from speedway motors (90 dollars), requiring some steering shaft mods as follows: cut approx 1 inch off the end of the sector, and using your tool or machine of choice, make your double D face, and the jamming bolt notch. tighten down the jamming bolt, i used threadlocker red since i have zero intention of ever taking this thing apart, and grond the head down to clear the manifold. now in my case i had to grind the bolt because i used a 1974 vintage 360 valiant drivers side manifold. Contrary to popular belief they WILL work, but ONLY with the coupler i used. the flaming river one is too big in diameter and will eat the manifold worse than the factory coupler did. for the pasenger side manifold i used the drivers side manifold from my old 73 D100 i used to have, that turned out to have a 74 monaco PI 360 in it. worked swell, and had zero clearance issues. most of the exhaust issues (manifold wise) were because of the 360 size ports in the head, otherwise i would have spent the dough to get a set of factory 273 mannies. factory setups would have choked the poor motor out so i figured the time i had invested finding something that would fit was well worth it. the radiator wasnt factory, it turned out to be from a 74-76 A body no a/c slant car. another common belief is the slant radiator cant be used. this is true to a point, with a cast iron water pump, no, aluminum, hell yea! use a factory lower radiator hose with a reducer, and an upper hose from a late 80s dakota with a 4 banger, and viola. works just fine for now. next on my list is a champion radiator CC2374, and itll actually run where i want it to temperature wise. right now she runs around 202-207, not horrible, but a smidge warmer than id like, but for my daily get to work rig, its working for now. Transmission cooling can be done however you want it to, i bent my own lines before i dropped the motor and trans in, and a magnum mini starter will be your best friend to help with clearance. i rigged up a remote cooler thats entirely overkill, but in this respect, you can never have enough transmission cooler-ness, especially in stop and go traffic. now for the brakes, i DO NOT full out race this thing, maybe a little stop light action on the weekends, but nothing too crazy, factory 9 inch drums work just fine. ive read countless posts where people seem like theyre saying "if you run 9 inch brakes your car will explode and eat the ditch doing mach 5" yeeeaaa.....i beg to differ. no problems, stops like a champ, new shocks and torsion bar adjustments, no problems, none at all. NADA!! Ive recently acquired a 73 swinger parts car for a front end disc and power brake swap, but like the radiator, thats going to be a winter project. 9 inch brakes wont kill you, just dont forget what you car is capable of. sorry i wrote a novel, im just trying to heap all my little tricks into one shpeel here, and once again, if it wasnt for FABO and the helpful tips, id probably still have a mopar lawn ornament.
 
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