K-frame question

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BTYM

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I didn't know whether to put this thread in the /6, or small block forum. My car was originally a /6 car. The previous owner replaced the /6 with a 318. I was wondering what the differences are, if any, between a /6 and small block K-frame. How could I tell whether or not the K-frame was replaced when the /6 was replaced? I'm planning an engine build this upcoming winter, and when I pull the 318, I would like to put a 360 in it. From what I understand (Ex-GM guy here) going from a 318 to a 360 is like going from a 305 to a 350. They have the same bolt patterns, so I shouldn't run into too many issues.
 
They have the same bolt pattern but they are balanced differently or so I've learned on here, never done the swap myself. Others who know LOTS more will chime in I'm sure.
 
318 & 360 are balanced diff. as to the k frame when going from a 6 to a small block you have to change the k frame now if I remember right the later 360s did not have what they call the pancake motor mounts they had the round ones but im thinking that all small blocks are interchangeable when it comes to the early k frames I had a 69 cuda with a 6 cyl. & put a 318 in it & I had to change the k frame, then later I put in a 360 from a 74 truck I used the same motor mounts good luck with yours
 
BTYM said:
I didn't know whether to put this thread in the /6, or small block forum. My car was originally a /6 car. The previous owner replaced the /6 with a 318. I was wondering what the differences are, if any, between a /6 and small block K-frame. How could I tell whether or not the K-frame was replaced when the /6 was replaced? I'm planning an engine build this upcoming winter, and when I pull the 318, I would like to put a 360 in it. From what I understand (Ex-GM guy here) going from a 318 to a 360 is like going from a 305 to a 350. They have the same bolt patterns, so I shouldn't run into too many issues.
Click to expand...


First, it would help if you could take pictures of your engine and k-frame that you have now. there are basically 4 different k-frame styles:

1. Early A-body from 64-66.

2. 67 A-frame had a unique idler arm mount.

3. 68 - 72 had the flat rubber (sandwich) mounts with the center bolt.

4. 73 - 76 with the "biscuit" type mounts.

We have to know what we are dealing with to give you the right answer.


Next:

To remove a 318 and install a 360 will require a different left side (driver's) engine mount. It is about 1/2" different between the cast ears on the block. Some people "shim" the difference with a shim or stack of washers. If you want to do it right, get an engine mount for that period/vintage k-frame for a 340 or 360, depending on what years you are dealing with (340 for sandwich mounts or 360 for biscuit mounts).

The spread between the engine mount ears is different on the left side. The 273/318 are the same, and 340/360 are the same, but the left side between the 273/318 are different widths than the 340/360 ears.

The right side engine mount is completely interchangeable between the 273/318/340/360.


Also, the 273/318 usually have a 904 automatic trans. If you upgrade to the 727 with the 360, you will have to get the drive shaft shortened by about 2" because the 727 is slightly longer than the 904.

also if you upgrade the rear axle to 8 1/4" or 8 3/4" from 7 1/4" will also require you to shorten the drive shaft about another 2" depending on which way that you swap them. If you have to shorten and rebalance the driveshaft, you may as well get it all done at one time and save an extra trip to the drive shaft shop.

I do not recommend using a 7 1/4" axle with a 360. It will eventually break (not IF, but WHEN). I blew up 3 of them with a mild 318 with a 340 cam, 600 cfm vac secondary carb, and dual exhaust. Noting radical. 3 axles in 4 years on a daily driver. Changed to the 8 3/4" and never broke again in over 250,000 more miles on that car.
 
cawley said:
318 & 360 are balanced diff.
Click to expand...

This is a whole different subject.

Internal balancing vs external balancing. This will affect the crank, vibration damper, flex plate, and torque converter combinations. :violent1:

If you already have a complete 360 and trans for it, then keep the original crank, vibration damper, flex plate and torque converter together. Otherwise if you do not match all of them correctly, you will get a drive line vibration. :banghead:

That can be addressed once you figure out what you are going to use. Just make another post for help on matching those components for balancing.

I hope this helps get you started in the right direction. Good luck.
 
Original slant 6 K , torsion bars, etc.. are most likely just because adapter mounts make the engine swap so easy.
 
Yes, if you have an early A (64-66), you can use the stock biscuit v-8 mounts and drop it in on the slant 6 k-frame. No need to get "exotic"...
 
Yup, you are sort of mixing issues.

K frames. You MIGHT have any K frame in the "Kar" from 67 to 76 because any will fit. That is, "they" might have removed a /6 K and put in a 67 V8 K because they got one cheap. Jus sayin.

So go here and find out.........

http://www.engine-swaps.com/

Tech info, engine ID and K member guide

http://www.engine-swaps.com/Pages/TechInfo.html

and destructions if you have their swap mounts for the /6 to V8 swap mounts:

http://www.engine-swaps.com/Pages/Instructions.html

So general about K members:

67--76 K members all bolt under the bodies

67 have unique idler arms you don't want them

Slant 6 have different mounts, so if you install a V8 in a /6 K, you need "conversion" swap mounts as from the people above, or else get a V8 K

V8 K's from 67 to 72 have the older inferior "biscuit" engine mounts

73 and later K members have the superior "spool" mounts which are not only better but cheaper to get engine mounts.

===================================

Engine balance

First, split into LA and Magnum. Magnum and LA engines are balanced differently. That is, 360 LAs are externally balanced, but they are also weighted differently than 5.9 Magnums.

So in LA series, FACTORY was originally weighted by balancers and by flywheels and converters.

SOME LA engines are internally neutral balanced, IE forged crank 273, 318, 340. Some cast crank 318, 340 are slight external balance, all 360 are external balance. All these mentioned are different FROM EACH OTHER

when swapping, you need to keep a proper balancer, or buy a proper aftermarket balancer

AND either keep a proper factory converter or aftermarket weighted converter OR buy a weighted aftermarket flex plate from places like B&M

or if a stick, buy a proper balanced or weighted flywheel if a stick

This gets sticky if you are buying some built engine, crate, custom stroker, etc...... make SURE you get proper documentation on the engine you buy, so you know what you are getting!!!!
 
Here are some pics of the mount to show you guys what I have.
 

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The rubber "sandwich" looks a little thick to me. I think that's a truck rubber. The ones for the cars are thinner.
 
As I mentioned in your other thread, this K frame has obviously been replaced, as it is the biscuit style and your 73 car should have the spool mount! I believe it to be a small block K Frame from a 68-72, and quite possibly from the car where the motor came from! Check the VIN on the motor, it may have the entire ViN stamped on it, which would tell you that's its post 69, and would tell which body style of car it came from! Just a little sleuthing on your part should turn up some info!! Geof
 
krazykuda said:
The rubber "sandwich" looks a little thick to me. I think that's a truck rubber. The ones for the cars are thinner.
Click to expand...

Some people use those for a little extra header clearance.....doubt these pros knew that, but he OP does have headers!!
 
cosgig said:
As I mentioned in your other thread, this K frame has obviously been replaced, as it is the biscuit style and your 73 car should have the spool mount! I believe it to be a small block K Frame from a 68-72, and quite possibly from the car where the motor came from! Check the VIN on the motor, it may have the entire ViN stamped on it, which would tell you that's its post 69, and would tell which body style of car it came from! Just a little sleuthing on your part should turn up some info!! Geof
Click to expand...

That's the thing.............since these are biscuit, or pillow........this could just as easily be a 67 K Look at the idler arm. If the idler arm bracket...........the part on the K frame, only has ONE bracket on the bottom, it's a 67 K. If it has TWO brackets, one above, and one below the idler, it's a 68-72.

Now this is "OK" except for the fact that you have the inferior "biscuit mounts"

The next part of the equation is the steering linkage

The steering linkage could be late or early. Don't assume that just because you have pillow / biscuit engine mounts, that you have "early" center line / steering linkage. When / if you go to replace steering linkage / or ball joints, you need to ask again!!!

It's a whole new ball game!!!!
 
Here's what the car 360 engine brackets and rubber mounts look like. they are the Schumacher conversion mounts that we bought from Mancini Racing. These are what you will need to drop a 360 in that k-frame. The "thinner" rubber will allow for more hood clearance and keep the engine center of gravity lower than the thicker "truck" mounts:

View attachment 360 Eng Mts A01 B.jpg

View attachment 360 Eng Mts A02 B.jpg

View attachment 360 Eng Mts A03 B.jpg

View attachment 360 Eng Mts A04 B.jpg

View attachment 360 Eng Mts A05 B.jpg
 
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