Small block to big block convert questions..

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07raptorgytr

07raptorgytr

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I've been bouncing around building a monster small block for my streeter. But I'm having questions on the reliability of that build , so I'm kinda kicking around the idea of building a big block for the 73 dart.
Question is what are some of the big issues in making a big block fit in the small area under the hood? I know the drag guys dump the fender wells and etc to make room, but since this is a streeter I need to keep those.
 
I am in the final stages of a big block/a-body build. If I had it to do over again I would go mega small block. Much, much easier build and the $ are about the same. If you must go BB try to go low deck (383/400). BB chassis headers are available. You don't have to hack up fenderwells. "Street is neat, but, track is where it's at,"
 
Just finished up with a 440 install in a 72 dart. Headers are available, but EXPENSIVE. Some allow you to keep power steering, some don't. You'll most likely have to go to manual brakes unless you can figure out some kind of offset system.

Really, It's not he hurculanean task it seems to be. Schumacher makes the mounts and my engine/K member bolted right in from the bottom easily with no issues. I Put Schumacher's Torque strap on there to keep it from rocking and hitting things. I have some modified long tube chassis headers that are very close in many places to hitting the power steering box. THE BIGGEST issue that I'm having is cooling. Space is extremely limited up front with the RB. Without modifying the core support I didn't have room to run a mechanical with a clutch....or even an electric with my current radiator (champion) My current setup is a fixed mechanical with a 1" spacer.....and it's CLOSE, but sucks plenty of air. It's nearly hitting the AC compressor on the top and nearly hitting the RAD on the bottom. It's been a kinda PIA. There doesn't seem to be a consensus on exactly what cooling solution to run in the BB arena. It's seems all our spacing ends up slighting different. In the end, there are solutions to be had after the requisite about of frustration.

Would I change it to a small block? NOPE. The holy **** looks I get when I pop the hood are enough for me.

IMG_3960.JPG
 
383Scampman said:
I am in the final stages of a big block/a-body build. If I had it to do over again I would go mega small block. Much, much easier build and the $ are about the same. If you must go BB try to go low deck (383/400). BB chassis headers are available. You don't have to hack up fenderwells. "Street is neat, but, track is where it's at,"
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That's what I was gonna do, a 400 base built to a 512
 
Yeah, I can dig a 512 low deck. I have a 400 in the wings now. It is possible to put a forged 383 crank and rods in a 400. Makes 406 cu in., for a high winding low deck. I like the 451/470 combo also. Makes good power on pump gas. Traction will be a problem. Good luck
 
I'm put a 383 in my 69 dart. I bought Schumacher headers and mounts. fits perfect no problems no hacking up inner fenders other than that had to change nothing else. But i do have yet to get bigger torsion bars.Was originally a /6 car
 
Putting a big block is a relatively easy swap. There are multiple ways to get the drive train installed and many different header/manifold setups. Decide your goal and go from there.
 
Im also on the fence myself, building a monster small block, or stroked big block. First concern would be block strength for sb, with out going R3 or even finding one for that matter. Headers will be an issue either way. Building a 451/470, plus i think a pump gas, big block (like AndyF built) would be really neat, 93 fuel 700hp on motor... thats tough to do with a small block and making it live. Parts are parts, your going to spend money there which ever route you decide. Weight will be the only downside with a bigblock. Im sure its tight around the spark plugs also with the big block.
 
Lets see, aluminum intake, water pump and housing, and heads. Toss some headers on and now you weigh close to an all iron small block.
 
Before trick flow heads I could kind of get the debate. But a 400/500 with trick flows and a roller cam can't see too many stroker small blocks coming close. And if you care about rod ratios then go 400/471 which is still bigger than any stroker small block.


To me 450-500hp and under go small block and over go big block.
 
Well if any of you have been following my post on the small block side of this forum, you would see that I was looking into doing a 436 stroker capable of 600 hp, but I do not want r3 block simply because I'm not going to drop 2k or more for a bare block. I'm a bit skeptical of the production block holding up long. This is why Iam kicking the idea of a low deck stroker build. My father is building a all out low deck 512 drag motor for his dart as we speak, so i won't be treading into uncharted waters so to speak. Only difference is mine will be a lower compression street motor and still knocking on the door of 600+ hp.
I have heard of guys running the 440 blocks having to ditch the heater blower motor, is this still the case on the low deck motors?
 
273 said:
To me 450-500hp and under go small block and over go big block.
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I respectfully disagree. I've got a stock 340 in my (wife's) GTS convertible and my son has a stock 440 in his Dart convertible (well, had, as it's apart at the moment). Yes, there's a horsepower difference, but the bigger deal is the torque and climbing hills. There simply is no comparison in torque. That's why my Barracuda convertible is getting a stockish 440...
 
Jim Lusk said:
I respectfully disagree. I've got a stock 340 in my (wife's) GTS convertible and my son has a stock 440 in his Dart convertible (well, had, as it's apart at the moment). Yes, there's a horsepower difference, but the bigger deal is the torque and climbing hills. There simply is no comparison in torque. That's why my Barracuda convertible is getting a stockish 440...
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I agree big block all the way, even for low HP, even though the torque difference can be made up by gears but we all know the benefits of going large displacement and drivablity. Wish they fit in early A Bodies easier. But my point was even though a small block can be made to make huge power but when searching for 500 plus hp big block is definitely the way to go.

I know there a bunch of guys running 500 plus hp stokers sb that will disagree but each to his own.
 
I have heard of guys running the 440 blocks having to ditch the heater blower motor, is this still the case on the low deck motors?
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i've done a few 440 abodies and never had to mess with the blower motor. moroso chrome valve covers almost look like they were made to fit a big block abody...

in this one i used the slant 6 k-frame with schumacher conversion mounts.. cleared themaster cul perfectly too...
Demonmotor.jpg


this one i used home made mounts.. engine actually sat a hair high and still cleared the blower motor...

64valiant025.jpg
 
abodyjoe said:
big block swap is cake. the biggest issue is headers.. not cheap and some are very tight.
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--------all of the above ! if you run raised port heads, there is no room for a blower motor at all. you could put a hotrod heater under the dash, w/ the stock set up eliminated.
 
5.7 hemi said:
Lets see, aluminum intake, water pump and housing, and heads. Toss some headers on and now you weigh close to an all iron small block.
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Right, but who wants an all iron small block at this point? Making both light is a cheaper way to go faster, along with the other benefits of making more power, cooling effect. etc etc. Aluminum parts would be on both
Im going monster small block this go around. Made up my mind lastnight after see streetwize build 440" sb. Its on moparts and youtube, pretty slick, pump gas and makes killer power. plus looks correct in my car... kinda :)
 
07raptorgytr said:
I've been bouncing around building a monster small block for my streeter. But I'm having questions on the reliability of that build , so I'm kinda kicking around the idea of building a big block for the 73 dart.
Question is what are some of the big issues in making a big block fit in the small area under the hood? I know the drag guys dump the fender wells and etc to make room, but since this is a streeter I need to keep those.
Click to expand...
Build it the way you want, I always wanted to build a big block A-body, so I did. Very happy with the Schumacher mounts, torque strap and headers. My car run very well with these headers on the street and down the track.
 
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