V8 swap info

If this belongs in the mangum swap thread, I apologize. I thought since it's specific to early A bodies, I'd put it here.

After going several rounds with the 170 /6 in my sons 65 Valiant, we might just pull the band-aid off and drop a V8 in. With all of the transmission options, I'm trying to decide on the easiest short term solution to get it going and maybe change it for something better later on.

Engine will be a 5.2 or 5.9 Magnum, most likely from a 2000ish truck

I have on hand ...

The 3 speed out of this valiant
An A-body A833 that needs a rebuild
A 3 speed to small block bell housing from an e-body
A 3 speed from the same e-body

Reading up on this it looks like the path of least resistance is to change from manual to automatic and most likely a 904. I've read if we put a 904 behind a magnum, we can keep the same drive shaft that's behind the /6+3spd that's in the car now.

I believe the a manual will require the drilled crank, however if I get one with a drilled crank, I can use it with manual or auto. os thats what I'll try to find.

My biggest question is about fitment. i don't have my shop up yet so i don't have my compressor, welder etc operational so I need to know what i can get away with that requires the least amount of fabrication.

Obviously long term plans would then include various upgrades to suspension, brakes etc.

At this point everything points to the 904 but if there are other options, I'm all ears.

Any input is appreciated

Thoughts.........The original 3 speed is the smaller lighter version, I would not consider it. Bellhousings must be drilled to match the trans "generally" but some are dual pattern and will take either 3 or 4 speed

Four speed: Do you want, or make sure that it is / is not an OD unit. Quickets way to tell if it has the shifter properly installed is to look at the front shift lever. If it points down, it's an OD. Alternately, you can wrench that shaft CW which puts the box into 3rd gear if straight through 4 speed, or OD if an OD box. Then turn the input shaft 1 exact turn and watch the main shaft. If it turns LESS than 1 turn, it's a "straight through" 4 speed. If it turns MORE than 1 turn, it's an OD

I have a magnum 5.9 in a truck that WAS NEVER DRILLED at all for a bushing. If you use the later, larger "Jeep" style bushing that fits the converter register, you can drill the crank hole "sloppy" as it is not used to support the bushing, but measure for depth

I see nothing wrong with a 904. You can either hog out the one hole for the converter, as the 904 converter has a non symmetrical bolt pattern, or use the older flex plate, if you are not using EFI. The magnum converters are symmetrically drilled. The difference is, that the weights for balancing the assy are on the converter for the 904, and on the later Mag flex plate for Mag engines.

I AM NOT SURE about balance on a 5.2. May / may not be neutral balance

You are aware? I hope? that you need a small block V8 bell bolt pattern, you cannot use a slant 904

I'm assuming the 65 Valiant was originally a three speed? Are all of the pedals and linkage still present?

67Dart273 said:

I see nothing wrong with a 904. You can either hog out the one hole for the converter, as the 904 converter has a non symmetrical bolt pattern, or use the older flex plate, if you are not using EFI. The magnum converters are symmetrically drilled. The difference is, that the weights for balancing the assy are on the converter for the 904, and on the later Mag flex plate for Mag engines.

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If we go this route, I do not plan on using the EFI, but in either case, I think the point you are making is don't mix and match. Use the older LA style flex plate with the older style TC, or a newer style Mag flex plate with a newer TC, ya?

67Dart273 said:

You are aware? I hope? that you need a small block V8 bell bolt pattern, you cannot use a slant 904

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Yup, i am aware of this one.

grimreaper said:

I'm assuming the 65 Valiant was originally a three speed? Are all of the pedals and linkage still present?

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Yes, it's a three on the tree so converting to a 4 speed would also require a shifter and linkage. But the pedals are at least already there.

67Dart273 said:

Four speed: Do you want, or make sure that it is / is not an OD unit. Quickets way to tell if it has the shifter properly installed is to look at the front shift lever. If it points down, it's an OD. Alternately, you can wrench that shaft CW which puts the box into 3rd gear if straight through 4 speed, or OD if an OD box. Then turn the input shaft 1 exact turn and watch the main shaft. If it turns LESS than 1 turn, it's a "straight through" 4 speed. If it turns MORE than 1 turn, it's an OD

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Oh, I am "pretty sure" it's not an OD unit, but I'd need to check to be 100% sure. As I recall the OD are aluminum bodies which leads the bushing wear problem they experience. If that's true, then this one is definitely not an OD unit. it would need a rebuild regardless.

First step, then is to examine the crank and see if it's drilled, and measure it to see if deep enough

67Dart273 said:

First step, then is to examine the crank and see if it's drilled, and measure it to see if deep enough

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Fair enough, that will certainly dictate the options at this point.

You'll need different engine brackets and mounts,and
they say putting the exhaust on the engine,is the biggest PITA.
Then comes the carb hook-up, and KD linkage if going automatic.

I did that swap when I was a kid, 1973ish. I used a JY 340 with a 318 top-end and cam. And bought a complete 273/904 to steal parts off. I used the 904 and engine brackets off it. And Hooker fenderwell race headers were the only game in town. I converted the floor-mount gas-pedal/mechanical carb hook-up, to the later cable system. The slanty rad was just barely adequate. That was a pretty hot combo I thought,and remember it fondly. Traction was a serious issue,there was none
One of the Magnums should be pretty hot as well.
Happy HotRodding

AJ/FormS said:

You'll need different engine brackets and mounts,and
they say putting the exhaust on the engine,is the biggest PITA.
Then comes the carb hook-up, and KD linkage if going automatic.

I did that swap when I was a kid, 1973ish. I used a JY 340 with a 318 top-end and cam. And bought a complete 273/904 to steal parts off. I used the 904 and engine brackets off it. And Hooker fenderwell race headers were the only game in town. I converted the floor-mount gas-pedal/mechanical carb hook-up, to the later cable system. The slanty rad was just barely adequate. That was a pretty hot combo I thought,and remember it fondly. Traction was a serious issue,there was none
One of the Magnums should be pretty hot as well.
Happy HotRodding

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Thanks AJ, as much as i am trying to stick with this slant for now, it's becoming exceedingly silly trying to justify keeping it. We've had the car for a few months now and I was really hoping to have it driving by now. it's my sons first car so the idea of keeping the slant has its appeal. i don't fault the engine, the design is for the most part good, but it sat for a long time before we got it and quite honestly we didn't check it out well enough and now were are "paying" for it in time, money and frustration. We have some big decisions to make so with this thread, I'm just trying to understand the options that face us.

We got a hold of some early abody, V8 exhaust manifolds and though they don't flow the best, they should make it easier to get exhaust on the car than headers. We also for the cable style throttle assy, but I forgot to get the center link .

I don't recall having to change my center link, going from 225 to 340.
But I have heard the scuttle-but on having to do that.

AJ/FormS said:

I don't recall having to change my center link, going from 225 to 340.
But I have heard the scuttle-but on having to do that.

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I've read both, some folks get lucky and might need a shim on the drivers side, some have needed the center link for clearance. If I can find one for a reasonable price, I'd like to go that route. Depends on how the motor fits.