[zerngl]

I just bought a 71 Challenger and want to swap out the 318 in it. I was going to get a junkyard fully dressed 440 with tranny and a radiator but the guy I bought it from said I would be better off going with the 360- 380 HP crate engine and wouldn't have to swap out the tranny and radiator. Any thoughts on performance the differences between swapping for a 440 junkyard engine that has been rebuilt by the machine shop (usual cleanup, pistons, rods and rings with a valve and porting job, I will put it together and add the cam, intake HEI dist, headers and carb) or dropping in a crate 360/380 horse.

[Roger]

All depends on what you want it to do, how well you want the car to handle and how big your (fuel) budget is? It's most probably fitted with a 2.76:1 ratio rear end and a 904 transmission, the smaller diameter torsion bars and all the other associated small block items (like mine has too), which is fine for a small block, but if you start to swap things over, then you have to consider the additional stresses you'll put on everything, and your costs start at the radiator, engine mounts, torsion bars etc and work their way to the back, including exhaust, transmission, driveshaft and rear springs etc. For what it's worth, I would keep the small block set-up and save yourself a bundle of money trying to make a big block R/T clone out of a 318 sleeper. If money is no object, then drop in a hemi and beef the whole car up, including frame connectors and a Dana sure-grip (my lottery dream......) as they say - there's no replacement for displacement.

[Roger]

The other and most obvious alternative is to keep the 318 (as I have done) and sweetener her up a little. I imagine that its a standard bore, so you should have no problems giving it a freshen up. This way you'll have no worries about changing anything on the car (keeps it original too, which is a consideration for any future re-sale). There's heaps of information about how to do this on this site and many other sites too. You can potentially get 600+ hp out of this little motor if you believe some of the hype and articles, parts are readily available and tend to be cheaper than RB stuff so you won't need a second mortgage or big bank loan to do the upgrade. If you can find a 340 with a virgin bore then this is one step better, but they're getting to be like hens teeth too. Whatever you do, keep all the original parts.

[dave-r]

If I was starting out again I would use neither.

I would either use a stroker 340 or 360 with a 4" crank or I would build a 400 b-block with a 4.15 or 4.25 inch stroke.

[439]

hi dave..

i find it interesting that you would want a 400 bb...i've just purchased a 71 challenger that originally had a 383 in it..the owners had spun a bearing in it so they stuck a 400 with the 383 heads/intake/carb and cam and told me that it would perform as good as the 383..i found a 383 out of a 69 plymouth fury 3 and am getting them to put that motor in for me...what do you think?? is the 400 actually as quick as the 383... the 400 hardly spins a tire off the line but pulls fairly good at around 2800 rpm...i never did get to drive the car with the 383, so i can not compare..

[dave-r]

The 400 is the same as a 383 except it is stronger in the casting and has a bigger bore. The 400 is the best block Chrysler ever made. How much power it makes is up to you.

You have to remember that if you are talking stock engine then yes the 400 was a low output smog motor. Low compression and emissions concerns were the thing when the 400 came out. But with the same compression, cam and heads as your 383 the bigger bore will make more power than your 383 and the block is stronger too.

Fitted with a 440 crank it yealds 451 cubic inches and is both stronger and lighter than the 440. With Edelbrock heads and a stroker crank you are talking about a streetable 600hp 500 incher lighter than a stock small block.

Yeah I would prefer that over a 383 that you can't even get decent compression pistons for these days every time.

[72 Challenger (Hans)]

What Dave said! Besides a Hemi a 400 stroker is the way to make some serious power... and keep the engine together while stepping on it. I would say keep the 318 and save up for a more serious engine if you wanna go real fast.