LA to RB conversion down swap.

[JP8]

Anyone ever heard of going from big block to small block? Or done it? Looking for engine mounts or swap kits.

My Dad's 70 Gran Coupe was originally a small block and now it has a very nice running 440 automatic. It's a pretty hot build. He bought the car with the swap already done. He drove a manual 1970 340 Six Pack in high school for a little while when the owner of the car broke his leg and was in a cast. My dad would drive this kid all over the place for a couple of months. As told, the kid was the rich spoiled type and told my dad to drive it like he stole it! He talks about that car a lot and wants to go with a 360 Six Pack and a TKO 600.

I have an early casting 360 and several parts for it. I have been collecting parts for a 360 build myself but Dad will give me the 440 and 727 in trade. I'll use it in a D100 or one of my Dusters. In my 'cuda is a TKO 600 and I want to trade it out for a T56 so he'll get that TKO as well. Both our cars have a Dana so my driveshaft will even work in his car.

So far I have collected, for the 360 build, a 1972 block and mains, Com Cams double roller timing chain, timing cover, J heads that are at the machine shop for 1.94 intakes right now, original T/A / AAR 6 Pack intake, Eagle forged H-beam rods, and a few other small items.

Needs are stock stroke 360 crank, water pump, oil pump, pistons, cam, gaskets, bearings, distributor, headers, and Fi-Tech's Six Pack EFI. As you see there is still a ways to go on the parts collecting with the biggest item being the Fi-Tech EFI.

Hopefully Dad's k-member is a small block k and someone built the car using a LA-B/RB swap mounts. If not we need to figure this out.

 

[JP8]

Pics

 

[moparleo]

It takes more than motor mounts. throttle linkages, fuel lines, wiring harness, radiator, hoses, exhaust, trans or bell housing, and on and on. Just takes money, that is usually the hard part......different transmissions normally use different length driveshafts so yours might not work.


I know it is just a mount difference, I said it takes More than just mounts. I guess the rest of the info about swapping parts back and forth between your father is what I misunderstood.
My mistake.
You might want to get a Factory Service Manual.
Really only 3 basic types of K members. (1) Slant six, (2) Hemi and (3) LA, B, RB

 

[JP8]

You asked a general question that requires many detailed things to answer.

I didn't ask a general question. Look at the bold print in my opening paragraph. Clearly I was asking if ...

Anyone ever heard of going from big block to small block? Or done it? Looking for engine mounts or swap kits.

But I just discovered the V8 k's are all the same (minus the Hemis and a skid plate for 440's). Problem solved. Wish you could have answered my question instead of trying to make it appear that I'm overlooking a bunch of things, but, no hard feelings. You must not have known the answer either.

Just takes money, that is usually the hard part......different transmissions normally use different length driveshafts so yours might not work.

Anyway, the money isn't a problem. As for listing the parts I was just mentioning the engine parts I have collected for the 360 build that I am giving my Dad. He's getting a huge headstart on the swap because of this.

I don't know why you think my driveshaft won't work on another small block E-body with a TKO and Dana. I am giving my Dad my transmission and everything associated with it (bell, trans, hyd. throwout, clutch, and driveshaft). Both our E-bodies have a Dana. He is swapping to a small block too.

 

[Chryco Psycho]

AS you have figured out the K frame is the same , just need 360 mounts .
If you are going from a big block with a TKO to a small block with a TKO the driveshaft will work assuming you are not switching from a cuda to chall or reverse as the wheelbase is 2" different .

 

[JP8]

AS you have figured out the K frame is the same , just need 360 mounts .
If you are going from a big block with a TKO to a small block with a TKO the driveshaft will work assuming you are not switching from a cuda to chall or reverse as the wheelbase is 2" different .

Nope. Dad's Cuda is a big block now with a 727, going small block. My Cuda IS a small block with a TKO and I'm going T56. I'm giving him my TKO set up (bellhousing to driveshaft) so he can use everything I have in regards to the trans.

We will just be needing to gather the rest of the parts for the swap (4 speed hump, radiator, ...) and the parts to finish the engine build.

 

[heminut]

But I just discovered the V8 k's are all the same (minus the Hemis and a skid plate for 440's). Problem solved.

I haven't been here for a few days, otherwise I would have chimed in earlier on the k member thing. You've already figured this out, and Chryco Psycho has confirmed it, your k member is good to go. Just to confirm, I have a 70 Gran Coupe that came with a 383 and I put a small block in it with no issues with the k member.