'73 318 to 400 engine swap

[Sheik_Yerbouti]

hi
My first post here.

Pulling small block 318 out and putting in a big block 400 in my '73 satellite.

Is the k frame interchangeable? Or will I need to swap it also ?

To be clear, will the K frame that was in the 318 car work for bb 400?

Thanks gents.

 

[69SportSatellite]

Interesting user name, but nevertheless....go to Schumacher Engineering's website, I believe it's www.engine-swaps.com they will have much of the information you need re changing motor mounts to adapt to your k frame. Quality products - they have a link on the FBBO as they are a sponsor here. There are also several very informative threads on FBBO which someone will likely soon point you to that have the information you need.

Best of luck.

 

['68 Charger]

If you chose to go with an OEM set-up, I have a pair of 400 BB motor mounts from a 1973 B Body which differ from the small block motor mounts.

 

[YY1]

Schumacher says to cut the driver side motor mount bracket (on the K frame) about an inch and re-drill the hole, and the SB K frame can be used.

What I can't find, is a definitive answer (preferably with pics) about whether or not the pass side inner fender needs to be cut (like a factory big block car) if you use headers instead of factory manifolds.

Note that torsion bars and sway bars were also thicker on BB cars.

 

[PurpleBeeper]

What I can't find, is a definitive answer (preferably with pics) about whether or not the pass side inner fender needs to be cut (like a factory big block car) if you use headers instead of factory manifolds.

Interesting quote above... didn't know that.

Hey Sheik...there is obviously a lot more to that swap than just dropping in the engine. "In general" you either need the engine k-member from a big block car or "adapter motor mounts" for the engine to bolt in. The 400 uses a 727B transmission (your 318 probably has an A-904) and you might need to change the rear end too. How many bolts are on the back cover of the rear end? I think you could have either a 8-1/4" (really weak and will never handle a 400) or an 8-3/4" (no bolts on back & plenty strong enough for a 400).

 

[Nacho-RT74]

rear axle swap is not mandatory but just an upgrade. 8 1/4" will plenty hold a 400 for regular use even with a "touched" 400

T bars upgrade is better, just for the weight added on a BB/727 setup. Sway bar too. Even neither of both mandatory.

Both of these statements are TIPICALLY what factory did on BB cars.

Inner fender cut out, is not mandatory, just makes "easier" the spark plug access, but doesn't mean without the cut out is imposible to do it

engine mounts adaptors provided by Creative services is the easier and cheaper way, specially if you don't care about correctness of the upgrade setup.

K member if you have some handy would be better IMHO, just to keep using correct stock engine mounts.

Then, radiator, engine wiring harness ( new one or modify ), etc... rest of stuff of course

 

[Sheik_Yerbouti]

What I can't find, is a definitive answer (preferably with pics) about whether or not the pass side inner fender needs to be cut (like a factory big block car) if you use headers instead of factory manifolds.

Interesting quote above... didn't know that.

Hey Sheik...there is obviously a lot more to that swap than just dropping in the engine. "In general" you either need the engine k-member from a big block car or "adapter motor mounts" for the engine to bolt in. The 400 uses a 727B transmission (your 318 probably has an A-904) and you might need to change the rear end too. How many bolts are on the back cover of the rear end? I think you could have either a 8-1/4" (really weak and will never handle a 400) or an 8-3/4" (no bolts on back & plenty strong enough for a 400).

-----
I've rebuilt the tranny that was with the big block. And changed the torsion bars from the BB donor car. You are correct, it's an 8 1/4 rear end. But that's what the donor car had as well. I've gotten mixed reviews and opinions on whether the 8 1/4 can handle the 400. 8 3/4 rear end that are complete are incredibly difficult to find. I don't intend to race this thing. Just a slight hot rod romp occasionally on highway, but am planning to drive it as a daily a couple days of week during the nice weather. But yes, I'd put in the 8 3/4 if and when I find one.

Before I realized I may have a k frame issue I got motor mounts from classic industries for sb to bb swap. But no one is mentioning that particular brand here.

I do think I have access to the k frame the big block was in, so maybe I'm better off to just swap it?

Thanks to all who have given responses. Much appreciated

 

[Nacho-RT74]

didn't know Classic industries could be offering those... maybe from creative services too???

 

[Sheik_Yerbouti]

didn't know Classic industries could be offering those... maybe from creative services too???

Yes, Nacho makes me wonder if it the same product. I've noticed that classic seems to sell products thT other companies manufacture a lot.

I'm going to rebuild the front end. So I'm not sure if it makes more sense to try to just get the original k frame swapped, or use the swap mounts I've already purchased.

 

[Nacho-RT74]

Front end upgrades will be the same ( use same parts ) on a BB than a SB K member. They are different JUST on engine mount locations. If you decide upgrade T bars and Sway bar for bigger ones, these will fit exactly the same on both K members. Dunno if that helps to take your choice.

As I told, if you have handy a BB K member ( and cheap ), I would go for it just for... Somehow correctness., nothing else really.

You can go with these upgrades with your actual K member too and if you find some BB K member later, the swap won't affect the parts you get now, since will fit too, with just engine mounts diffeence, getting later the stock ones

 

[YY1]

An E body 8 3/4 is MUCH easier to find, cheaper, and is actually about 1/2" narrower.

 

[Sheik_Yerbouti]

An E body 8 3/4 is MUCH easier to find, cheaper, and is actually about 1/2" narrower.

I've been searching craigslist in like a 300 mile radius of me, (near Wichita,ks) and can't seem to hardly find complete 8 3/4 at all.

Found some for trucks, or bare housings, etc. but finding a complete one has proven difficult.

 

[Sheik_Yerbouti]

Front end upgrades will be the same ( use same parts ) on a BB than a SB K member. They are different JUST on engine mount locations. If you decide upgrade T bars and Sway bar for bigger ones, these will fit exactly the same on both K members. Dunno if that helps to take your choice.

As I told, if you have handy a BB K member ( and cheap ), I would go for it just for... Somehow correctness., nothing else really.

You can go with these upgrades with your actual K member too and if you find some BB K member later, the swap won't affect the parts you get now, since will fit too, with just engine mounts diffeence, getting later the stock ones

So looking at the motor mounts that I had already purchased, they are the Schumacher swaps. Although I got them from classic industries. For a slightly Cheaper price becaus of shipping

At this point, I think it's easiest to just keep my sb k frame. Mainly because I already have the correct motor mounts.

Thanks for your knowledge and time. And help

 

[Sheik_Yerbouti]

rear axle swap is not mandatory but just an upgrade. 8 1/4" will plenty hold a 400 for regular use even with a "touched" 400

T bars upgrade is better, just for the weight added on a BB/727 setup. Sway bar too. Even neither of both mandatory.

Both of these statements are TIPICALLY what factory did on BB cars.

Inner fender cut out, is not mandatory, just makes "easier" the spark plug access, but doesn't mean without the cut out is imposible to do it

engine mounts adaptors provided by Creative services is the easier and cheaper way, specially if you don't care about correctness of the upgrade setup.

K member if you have some handy would be better IMHO, just to keep using correct stock engine mounts.

Then, radiator, engine wiring harness ( new one or modify ), etc... rest of stuff of course

Nacho, so the wiring harness won't swap either ? This is also news to me, as I was lead to believe that it would.

 

[kiwigtx]

hi
My first post here.

Pulling small block 318 out and putting in a big block 400 in my '73 satellite.

Is the k frame interchangeable? Or will I need to swap it also ?

To be clear, will the K frame that was in the 318 car work for bb 400?

Thanks gents.

Hi there Sheik,
It might be an opportune time to visit the Welcome Wagon and introduce yourself. Something tells me that you get around Kansas wearing a Caftan.

 

[Sheik_Yerbouti]

Hi there Sheik,
It might be an opportune time to visit the Welcome Wagon and introduce yourself. Something tells me that you get around Kansas wearing a Caftan.

I shall do so Kiwi.

The handle is actually a frank Zappa reference. One of his best albums. ... Though that's just a hard statement to make.

 

[Sheik_Yerbouti]

I shall do so Kiwi.

The handle is actually a frank Zappa reference. One of his best albums. ... Though that's just a hard statement to make.

 

[super-bee_ski]

 

[69Bee]

Interesting user name...

Frank Zappa album

 

[Nacho-RT74]

I've been searching craigslist in like a 300 mile radius of me, (near Wichita,ks) and can't seem to hardly find complete 8 3/4 at all.

Found some for trucks, or bare housings, etc. but finding a complete one has proven difficult.

E body axles won't be a straight install. Pedestals a quite diff due the isolation system used on 73 and laters B bodies.