I purchased a 71 demon a couple months ago. I just got it back from paint and now the fun begins! The car has its original 318 and it runs decent but seems to have a couple of burnt valves. I have a 85 360 I pulled from a wrecked pickup with low miles and runs great. I know the oil pan and pickup are different and it is an externally balanced engine(or so I was told) so I need a diferent flexplate. Will the motor mounts work on this swap? Iam not a big small block guy but times are a little tight so iam using what i have for now. Anyone have an idea what the comp.ratio is? Iam thinking 8 to 1.Yuck! Any cam or head swaps that could make it run a little better without breaking the bank? I have a set of early 90s magnum heads laying around I could use. A bigblock swap is in the future but the 360 will have to do for now. Thanks for your time

actually the difference is in the torque converter,318 would be internally or neutral balance, ie no weights on the torque convertor, a 360 is externally balanced, hence they use a weighted torque convertor.the flex plate on oem stockers is determined by the size of the convertor, there are 2 V8 flex plates, small and large outside bolt pattern.you can use your passenger side motor mount bracket on the 360 as it is the same from the 318, however 360s have a narrow spread on the drivers side mounting lugs, plus 1 is in a different location than on the 318, you can bolt the drivers side 318 bravket to the 360 block and fab up a piece to match the 360 bolt location or buy the68-72 340 a-body specific engine mounting bracket,mopar dealers used to be able to get them a few years ago...so did year 1.

Thanks! I was wondering on the weighted converter. My buddy used an aftermarket flexplate( b and m) that had a flat spot in it. I beleive it made up for the zero balance converter. Also,would it be a major project to modify my 318 driver side bracket to make it work on the 360?

I believe you can use the 318 mounts and just add washers to the drivers side (I don't remember, it's morning still). The comp. ratio is probably around 8 - 8.5. If you do end up using the magnum heads, which I would to raise the comp. and better flow, you are looking at added cost such as pushrods and such. There is a detailed list in the archives about this swap. I think that block is still using a flat tappet cam but I believe you could switch it to a roller by getting the lifters and spider at a Junk yard. Of course you could use the Whiplash cam from Hughes but I would get it soon because the prices will go up on Aug 25.

B&M used to sell a flexplate that accounted for the imbalance of a 360, use that and you are golden. Or use this with the stock flexplate, http://www.kmjent.com/cart/product.php?productid=2077

The 318 motor mounts will work, but on the driver's side you will need a couple of washers to use as a spacer since the 319 ears are wider than the 360 ones.

Make sure you get a center sump 360 oil pan, other than that it's all good.

Tech Archive

You will need to keep the 360 damper for balance. I think they changed the pulley hole alignment in the early '70s, so one of your early style 318 pulley holes may not line up and you may have to elongate it make it fit.

The pulley holes changed with the 70 model year, so his should work right back.

bolt your 318 a body mount to your 360 block and you will see the piece you will need to fab to make it work, 360 blocks have an ear on the block that aint on the 318 driver side mount. washers can be used on the b/c/e body not abody

Thanks for all the help. It dosnt seem like its to complex.