'72 Barracuda 6 to 8

[44070dart]

Thinking of buying a '72 that was a 6 cylinder car. Changing to small or big block, will the K member need to be changed.

 

[Cuda Hunter]

Yes, K member is different.
Not a difficult change over.
I think there are also some mounts that can be used on the slanty K frame but not sure where they are for sale or why use them when a K frame swap is super simple.
Does the car retain it's original 225?

 

[Spyder]

I'd have a hard time pulling a slant 6 out of an E body. Rare and fun.

 

[44070dart]

He already pulled it because it was trashed.

 

[Spyder]

Big block it is then!

 

[pschlosser]

This is among the more common upgrades made to e-bodies, as the original big block cars get more and more scarce as they're driven, raced, wrecked, and crushed.

The slant-6 e-body cars had weaker components compared to original big block cars, but the majority of the "big block-only" parts are still being made (aftermarket) and with some research, and perhaps this forum, you can get the parts you need.

If you want it to LOOK and be as beefy as the "big block original" was, some key components to look for are the K-frame cross member (with skid plate + front sway bar components) and the correct heavy-duty torsion bars.

There are other details to consider, but if you only change (upward) the K-frame and torsion bars, you'd be in pretty good shape.

 

[Xcudame]

You have a great opportunity as when replacing the K-Frame, you can have the engine and transmission along with all the front suspension parts mounted together and drop the body over it! Much easier than trying to install the engine and transmission from the top or dropping the engine in and trying to install the transmission from below. Everyone who has dropped the body over the drive train will never do it another way unless forced to.

 

[Katfish]

If you plan to drive the car, perfect time for a Gen3 swap.
If just going to local shows, easy enough to go with the old V8s.

 

[Ricks72Chlgr440]

Lots of possibilities for you at this point. Likely much of your direction will be how much money you want to put into this. Let us know what you want to do and the folks here can certainly help you and hopefully prevent undue expenses. The car is a system, and the parts you put on must work together for a good outcome!

 

[44070dart]

I was hoping that there was some sort of motor mount that could be used to mount a small or big block. Changing the K-frame is going to take some garage to do it. I'm at the age where that kind of work is in the past for me. We'll see, thanks

 

[pschlosser]

Most opt to change out the K-frame (to the correct big block one) because its heavier duty than the slant-6 K-frame.

The 440 motor (for example) weighs about 40% more (not counting the tranny) than the slant-6. Furthermore, the slant-6 torsion bars just can't hold up the same car with a 440 motor. It will bottom out turning into driveways, and could even punch a hole in the oil pan. Hitting a pothole at highway speed could cause an accident.

For this reason, there has been little demand for "conversion brackets" from a slant-6 to a big block using the slant-6 K-frame. But, there's nothing stopping you from giving it a try. In my experience, when converting from the slant-6 to a big block, torsion bars and K-frame seem the minimum one must change to get the car drivable.

Another key point with using the "correct" K-frame, is there are fewer surprises. Things will just bolt right into place. Working a combination few have completed in the past, tends to create more issues than it solves. For me, I find the frustration of not knowing how to resolve an issue, or the need to tow the car in to a shop to have something conjured and fabricated, just isn't worth it, compared to how nicely things come together doing things the way "the factory did them."

If you're not sure you got the budget to make the conversion, don't feel bad. Many of us are in the same boat. Original parts are becoming more and more scarce. Some of us have to wait years before we can find the right parts at the right price. Some engine combinations (an original 426 Hemi car, for example) are out of my league, budget-wise.

If you want a cool-ish collector car when you're done, a car you can enjoy, and may be able to resell some day and recover the costs, it's not a horrible idea to try and find a replacement slant-6 motor. While this may not afford the prestige some of the other motors offer, it would likely cost you a great deal less to go this route.

You won't find a shortage of opinions asking for advice around here. It's still your call, and we can all respect whatever choice you make.

 

[44070dart]

Thanks .. big block k frame it is. Next spring.

 

[pschlosser]

Then you got time to shop. Shop for a K-frame and torsion bars. The torsion bars you may have to buy new. You got time to learn, and teach yourself what to seek out. Well done.

 

[Xcudame]

I personally wouldn't run anything less than 1.00" in diameter for a torsion bar. Even on a concours correct hemi car. Let the judges measure them and ding me for points. bigger torsion bars are a key part to handling!

 

[Cuda Hunter]

There are aftermarket K frames that you can purchase that will fit your specific modifications.

 

[Spyder]

Qa1 k frame it is!

 

[Ricks72Chlgr440]

Thinking of buying a '72 that was a 6 cylinder car. Changing to small or big block, will the K member need to be changed.

The QA1 K member was what I used on my 70 Duster (the OE one was damaged at some point and the previous owner had it welded to fix). You will be amazed at how much openness there will be under the car once that QA1 unit is installed. It is pricey, but a very good piece. I got mine from Summit.

 

[cudamark]

Most opt to change out the K-frame (to the correct big block one) because its heavier duty than the slant-6 K-frame.

The 440 motor (for example) weighs about 40% more (not counting the tranny) than the slant-6. Furthermore, the slant-6 torsion bars just can't hold up the same car with a 440 motor. It will bottom out turning into driveways, and could even punch a hole in the oil pan. Hitting a pothole at highway speed could cause an accident.

For this reason, there has been little demand for "conversion brackets" from a slant-6 to a big block using the slant-6 K-frame. But, there's nothing stopping you from giving it a try. In my experience, when converting from the slant-6 to a big block, torsion bars and K-frame seem the minimum one must change to get the car drivable.

Another key point with using the "correct" K-frame, is there are fewer surprises. Things will just bolt right into place. Working a combination few have completed in the past, tends to create more issues than it solves. For me, I find the frustration of not knowing how to resolve an issue, or the need to tow the car in to a shop to have something conjured and fabricated, just isn't worth it, compared to how nicely things come together doing things the way "the factory did them."

If you're not sure you got the budget to make the conversion, don't feel bad. Many of us are in the same boat. Original parts are becoming more and more scarce. Some of us have to wait years before we can find the right parts at the right price. Some engine combinations (an original 426 Hemi car, for example) are out of my league, budget-wise.

If you want a cool-ish collector car when you're done, a car you can enjoy, and may be able to resell some day and recover the costs, it's not a horrible idea to try and find a replacement slant-6 motor. While this may not afford the prestige some of the other motors offer, it would likely cost you a great deal less to go this route.

You won't find a shortage of opinions asking for advice around here. It's still your call, and we can all respect whatever choice you make.

The slant 6 K-member is the same gauge metal as any other K-member. It's just the engine mount perches that are different. Heavier duty torsion bars are definitely a good idea, as are better brakes (if it doesn't already have disc). In this day and age, I'd be tempted to go the Gen 3 route. Plenty of donor drivetrains out there along with all the plug and play conversion parts to go with it.

 

[aussiemark]

Schumacher Creative Services will have conversation mounts for you. I would use the correct torsion bars though.