Swapping a small block to big block...who's done it?

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fastback68cuda

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ok, i know it can be done and most people say it's not a big deal...but i'd like to know from people who have first hand experience or knowledge about what all it takes to install a big block in a small block a body.

my 318 runs fine but like most i'd like a little more punch...i've seen stoker kits for 318's and there are also some 340 blocks out there that can he had at a "decent" price...i'm really leaning towards a 340 but a buddy of mine has a 440 he's let go really cheap. problem is i don't know what all i would end up having to modify to make this happen...

this is a street car and i'd like it to run hard and handle well so i'm not sure if i'm better off just starting with a big block if i'm going to go through the expense of building a more powerful small block.
here's what's in my car now that i think would be relevant:

68 barracuda
318 w/727 trans - trans needs to change to big block?
3.55 sure grip rear end
large bolt axles in rear with 74 dart disks up front

i'm going to be installing new front and rear leafs & shocks soon...any suggestions for a big block?

what kind of issues would i run into...i know schumaker sells the mounts but do i need anything else...are there any clearace issues?

thanks
robert
 
I did a 318/904/8-14 swap to a 400/727/9-1/4 from a Cordoba into a Magnum.
The schmaucher kit provideds very good pictures, instuctions and phone service when I did my swap.
The K-frame needed small work. The oil pump died and required a engine tiliting to get out.

The 727 hooked to the small block will NOT work with the big block.
Since this is a B body car, theres no clearance issue.
For suspention, you'll need to crank up the T bars a turn or 2 max. The shocks should be fine, though an upgrade would be nice. The springs are probably 5 on each side right? Well, you will be short on drag strip or street launchs. Regular driving should be fine.
If you have the 8 - 1/4 rear, do not beat on it. It'll die. Look for a 8 - 3/4 or bigger. The 9 - 1/4 is strong, but not a bolt in. The DANA can be ordered new from strange as a bolt in for your car.
The P/B set up should be fine for sane driving. 10+ inch brakes and drums. It'll do fine.
 
The first one was done in 1975,and have done 20-25 over the past 30 years.If you are good with the tools,and have some good techincal skills,it will be great experience for you,Mrmopartech
 
I agree, it was fun. The result is nice.
 
Getting late so I'll do this quick and add more later.
Parts you will need.
BB Tranny, coverter, flexplate
Motor mounts Schumakers are around $150
Headers around $400
Driveshaft
Radiator, hoses.

Clearance issues.
Tranny mount needs the holes elongated slightly.
My pro parts headers needed a little tweaking for plug wire clearance.
Also Needed to shim the left mount for header clearance at steering column .
And cut out holes in inner fenders for headers.

If you want it to handle, you are going to have to step up to bigger torsion bars.

I'll add more later.
These are a fun ride when you get them together.
 
They're not cheap, but the schumacher headers are a dream to install and you have a lot of ground clearance. You have to give up a little top end HP but unless you're running over 500 HP you wont notice the difference( until you have to put them in)
 
I did it and it is a lot of work and money, but the wow factor is great. Also frame connectors are a must if you want your doors to continue to close properly.
 
You mention that you would like your car to handle?

Well, I have installed a few 440's into A bodies for a number of years and found that these cars are front heavy.

Sure, you can lighten up the front end by using fiberglass fenders, hood, bumpers....etc. Even going to aluminum heads and radiator. Lots of money$$$

Bottom line, if you want your A body to handle, I would go with a small block.

If you want the big cubes, have your car handle and keep the front of your car light, go with a stroker small block!

It's a great way to catch people with their shorts down.

Yeah, tell them its a stock 340, but lurking under that 340 magnum pie tin could be a 416 cubic inch small block monster.

Stoker kits aren't too expensive, but worth it. You can leave them behind you awestruck!

"this is a street car and i'd like it to run hard and handle well so i'm not sure if i'm better off just starting with a big block if i'm going to go through the
expense of building a more powerful small block."
 
my friend is doing this in his 72 Scamp, tommorrow were getting 2 440s from the junkyard, one for the Scamp the other for a 67 Coronet. One thing to remember is that its easier to use a B engine (383 or 400) than an RB 440, it clears things better and you do have power brakes with a big booster in the way so thats something to think about. The 400 can be stroked to a 500 i think but all that costs $$. From what everyone says, this cars are amazing and I want to start getting the stuff to do one of these after my Dart is finished. I dont think you can run AC either but I dont know if you planned to. Where in So Cal are you, I stay down here too
 
If you decide to go small block, you might as well go to a 360 rather than a 340. The 360's are a LOT cheaper, easier to find, and you start out with an extra 20 cubes before you even get started looking for more horsepower.
 
I agree with Vart. Even after stroking it, the diff in cubes is small. The 340 has the edge due to bore size, but the price of the 340 block just dosen't cut it for me weather it's stoke stroke or 4 inch.
 
thanks for all the input fellas...i forgot to mention the car already has an 8 3/4 inch rear end...i don't have air conditioning or power brakes but do have power steering and would like to keep it.

seems like for the most part most of the new parts required i would have to buy either way if i was to stroke a small block or go with a big block. i would probably have to buy new headers, shocks, springs, etc...but the bigger radiator and subframe connectors were two things i didn't figure on...


maybe i overstated the handling portion...i would like it to handle comfortably, but I am not looking for it to ride like a vette! right now i don't have the sway bar on the front so the car handles like a cow on roller skates, since i've never had the sway bar in place i'm not sure how much of a difference that makes and the thought of things getting looser makes me nervous...would replacing the sway bar make a noticeable difference?

I’m already planning on replacing all shocks, rear leafs and even the torshion bars if need be...headers are also on the long list but i definitely would not want to cut the car at all.


sounds like i might be better off looking for an engine/trans combo if i go wiht a big block to get both...i was leaning towards the 440 (bigger is better right!?) but the 383 might be nice as well...for some reason i thought they were about the same size?



I have also considered a small block stroker...but am not sure if these are reliable enough to drive around on the street? http://speedomotive.com in my hometown has a really good reputation and sells some nice kits. The have a 400 to 450 kit for under $1k...that’s cheaper than the 318-360 kits.

chrysl1.gif


not too bad eh?

I agree with the 360 vs 340...just getting the 340 will drive up the cost of the project...what would be some good years to look for in 360’s? those are pretty much “drop in” right?

BadAss...i'm in Anaheim...cool website by the way

 
Any stroker is fine on the street. They last as well as anything else, to a point. Too much arm can lead to side loading and premature wear, but that's not the case in any 4.15 big block, or 4" small blocks. (BTW, the 340's larger bore cuts this down further) Any year 360 is good, but the best ones are '71-'72, as they share the 340s casting cores, but only use the 4" bore, so the walls are thicker. the 450" Speedomotive is selling is a 3.75 440 crank in that 400 block. A very good budget engine, but a .060 over 440 comes to the same size. The 400 makes it narrower, and lighter, and headers in an A body (underchassis especially) will fit better, unless you use certain heads(edelbrocks, and Indy SRs are 2) because they have slightly raised exh ports. If you are going to stroke a 340 or 360, you want to limit the overbore to .040 or less. You will notice the BB up front, unless you build for it. There is no way around it, but it is quite the conversation peice. Around here, there are a bunch now. Only a few A engine strokers, and I'll take a small block stroker A over a BB A for the street any day.
 
Heres what i did ....got a solid calf. car (1970 swinger custom) it was a 6cyl a/t with air....when out and bought a RUNNING 1970 New yorker 440 4bbl (factory holley).Then got a big block(?) k-frame with spool mounts. Pulled 6 added 440 4bbl with air.. schumaker headers >>>>DON'T waste time looking for anything else..just check the big block manifolds that were just on here sold for over 600!! And i thought we were all friends here<<<.everything bolted right up !! This car still has the org. paint and color key steels with org.dog dish hub caps ..sitting you would NEVER know ..running draws plenty of lookers....WHAT What ...
 
Mrmopartech said:
The first one was done in 1975,and have done 20-25 over the past 30 years.If you are good with the tools,and have some good techincal skills,it will be great experience for you,Mrmopartech
Click to expand...
wec
 
In terms of building the engine, the money is very similar, say, within $500-1000. In terms of support items, the small block stroker wins hands down. You can use all existing stuff..headers, transmission, torsion bars, radiator, etc. Even if it isnt "the best" for the stroker, the fact remains that it will bolt up, and can be run. The secret to any small block stroker is the crank..the bore size is very little bonus, until you begin to approach power levels where things like valve shrouding really come into play. I'm plannig a 318 based 4" crank eninge for my plow/tow truck. It's not any more $$ than others, and I have one nobody else wants. The Speedomotive 400 to 450 kit is for a big block B engine, using a 440 crank core. The B enignes are an easier fit in terms of exhaust and steering clearance, and weight if it's all iron.
 
moper said:
In terms of building the engine, the money is very similar, say, within $500-1000. In terms of support items, the small block stroker wins hands down. You can use all existing stuff..headers, transmission, torsion bars, radiator, etc. Even if it isnt "the best" for the stroker, the fact remains that it will bolt up, and can be run. The secret to any small block stroker is the crank..the bore size is very little bonus, until you begin to approach power levels where things like valve shrouding really come into play. I'm plannig a 318 based 4" crank eninge for my plow/tow truck. It's not any more $$ than others, and I have one nobody else wants..
Click to expand...

I agree 100% in fact I may be building selling them for sell in the near future...

moper said:
The Speedomotive 400 to 450 kit is for a big block B engine, using a 440 crank core. The B enignes are an easier fit in terms of exhaust and steering clearance, and weight if it's all iron.
Click to expand...

One point here fastback68cuda you should remember a B ( 361 383 400 ) is lighter than a 440 I think ~50 Lbs they are heaver than a LA motor. If you are still concidering a B I would sugest a 400 stroked to 451 ( 450 ) I have built them and they have a lot less rotating mass than a 440, A 440 in a a body is tight it can be done but the RB is wider and taller it is harder to work with..

If you really want a 440 them use al heads ( do not use any with raised exaust ports ) and a stroker kit.

With any b or RB in a b I would recomend headers as the manafolds used by the factory in 383 GTS fit but cost HP. Stoker B or RB really need headers I tried to use 440 mag manafolds on the last 451 I built, after a few years I instaled small tube full lengh headers and it made a world of difference.

This is my 2c
 
go with a standard bore 400 depending on your speed requirements, Ive built non stroked 400s using a hyd cam and slightly ported floor 906 heads using a lunati voodoo 305 hyd cam, I like the motor plate best as it allows the engine to sit higher in the frame than the mounts ,fenderwell headers,mill waterpump 1/4 inch for plate so all pulleys will align.easy, no vibration .and overall is a stronger set up, if ya have any questions just ask, also the motor plate can be scrolled making it a work of art.k frames are a waste of money as a 6 k frame is strong as a 440 k frame,dont forget if your going from 6 to 8 you need dropped center link, plate also allows you to use your current steering with maybe a notched pan being required, 440 source has it all for 1800 bux to build a bad 400 that will outrun any 440 withsame components as the 400 has a smaller stroke, meaning lightr pistons 7 lbs to be exact from a 440 440 deck height is around .750 higher than the 400 and its a simple cheap hp engine to build
 
with the plate you can also use the 6 centerlink and have a good 1/4 inch clearance, ask away,ive done many.
 
I think you got most everything covered Robert but I might add a front stabilizer bar is a must and I'd go with the .890 torsion bars. I went with the 383 cuss I like the torque and with big pistons and short stroke she likes to wind out fast and also a little cuss it ticks off the traditionalists in the club I belong to. When you add headers, aluminum intake and fiberglass hood you shed enough weight off the front end that it steers and stops just fine even with manual brakes as long as you got discs out front. A friend did a 440 swap and she is a lot tighter fit and ya almost got to have a hood scoop since with any decent intake manifold you'll be to close to the underside. Unless you're doing a lot of highway driving I'd go with 3.91 gears but you really got to pay attention to the back end cuss with street tires she'll break loose real easy. Oh ya definitely go with Schmacher headers and 2 1/2" exhaust is just fine.

Terry:burnout:

P9100004 (Custom).JPG
 
I would go with a 440. there isn't that much of a difference in size. I think the width difference is 3/4 of an inch than a 383. I could be wrong. personally I don't like fenderwells, and it doesn't sound like you are wanting to cut up your car. a cheaper header would be out of an E body. I am pretty sure that is what I have in my car. ( headers came with car, and I couldn't find a part #) I did put it together, and the headers need just some slight mods to fit. E body headers start at $150, and I think underchassi BB headers start at $600, so there is a big difference in price.

The Automatic tail shaft is longer, so you will need to get your drive shaft cut and shortend and balanced. Should cost about $100

I agree, don't change the K fram. it is just fine.

I would recomend an aluminum Rad. should be able to get one for $300 or so.

and I also recomend frame conectors. lots of people say you don't need them, but I would rather have the extra streigth, than to find that my doors don't close properly, and put them in later.

Its expensive, but have you considered 4 spd. I love it.

The reason I say BB, istead of SB, is cause you get noticed more. Lots of 340's and built small blocks at car shows, but they don't get looked at like a BB A body!!!!!

Phil
 
Hi Phil,

Great advice here. I've got a '76 Duster which is currently 318 - 727, Air Con and Power Steer car so has big radiator, powered discs etc.. I've just purchased a 440 and 727 rebuilder for the Duster. Ive wanted a big block Mopar for years.

Should I just purchase the Schumacher Package Kit (which includes mounts and headers) or is there a cheaper alternative. I dont want fenderwells though and want to make the installation as easy as possible.

Only issue I have is I'm quite sure the Duster is 8 1/4 diff which will have to do for now as 8 3/4 are a rare commodity in Sydney, Australia. The Duster will never see the track or be given a real hard time anyways.

Also, where's the best place to get sub-frame connectors from? Any recommendations?

mrtires24 said:
I would go with a 440. there isn't that much of a difference in size. I think the width difference is 3/4 of an inch than a 383. I could be wrong. personally I don't like fenderwells, and it doesn't sound like you are wanting to cut up your car. a cheaper header would be out of an E body. I am pretty sure that is what I have in my car. ( headers came with car, and I couldn't find a part #) I did put it together, and the headers need just some slight mods to fit. E body headers start at $150, and I think underchassi BB headers start at $600, so there is a big difference in price.

The Automatic tail shaft is longer, so you will need to get your drive shaft cut and shortend and balanced. Should cost about $100

I agree, don't change the K fram. it is just fine.

I would recomend an aluminum Rad. should be able to get one for $300 or so.

and I also recomend frame conectors. lots of people say you don't need them, but I would rather have the extra streigth, than to find that my doors don't close properly, and put them in later.

Its expensive, but have you considered 4 spd. I love it.

The reason I say BB, istead of SB, is cause you get noticed more. Lots of 340's and built small blocks at car shows, but they don't get looked at like a BB A body!!!!!

Phil
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