Hi, I am looking to replace the /6 in my valiant with a small block V8, and I really haven't decided to go one way or the other, but I think I want to buy something that is complete and running , then rebuild it. This is going to be more of a budget build but want it to be reliable.
With that said, I want to buy a small block 318/340/360, and I have seen engines out there that come from RV's and trucks that are either 318 w 727 or 360 w 727.
So, what is the difference in these engines when built for an RV or truck vs a car?
Please pardon my ignorance, I'm a GM convert and trying to stay away from putting an LS motor in my mopar.
Excuse me while I get my "AJ" on.
This is generally a common swap. There are a few things (caveats) you'll need to know about.
Generally speaking, exhaust manifolds and oil sump locations, there all the same. Except trucks. A 318 is a 318 is a 318 in no matter what it came in. There are special packages on some engines that have upgraded items that IMO ain't worth it because of age and/or material used.
The slant 6, small block and big block have there own transmission bolt patterns. That means that you need the matching transmission to what ever block your using.
All the cars (for the most part, not every case) use a K frame designed for that engine. So your A body car w/a /6 has just that K frame in it.
In the old days and sometimes still today, a K frame swap was/is done. This is a chit ton of work. An easier way is the
Schumacher Creative Services for a kit. I have used them several times. Easy to follow instructions with minimal tools needed. Perhaps a drill and proper sized bits and a cut off wheel to trim some metal.
Another PIA thing about the Mopar's that may or may not be on other makes in the transmissions mention above, is one more thing. The 904 and 727 have different lengths to them. To keep things on the K.I.S.S level, stay with the same trans you have behind the /6 now, just the small block version.
FWIW, the 904 is lighter and uses less power to operate.
Again as above with rear ends, the mopar camp uses several rear ends sizes that are also wide and varied in width.
The 7-1/4 is most likely behind the /6. It should be considered weak for moderate V8 use.
The 8-1/4 is a very good (& highly underrated unit) that will be very good for most street strip duties.
The 8-3/4 (like the Ford 9) is a good strong rear and also a good bit more expensive. All of these rear ends have a different lengeth as well as there width.
In short, save the driveshaft to be cut down.
Engine wise, since your a ex-GM guy you can be look at the MoPar engines like this;
318, cheap, sometimes free. Very similar to a 327. BxS = 3.91-3.31
340, similar to the 350, expensive due to low numbers and legendary performance. BxS = 4.04 x 3.31
360, also similar to the 350 but with more stroke. The mopar crowd was slow to look at this engine for any other than people move due to low compression and mostly 2bbl. carbs. Known as "A Dig motor" ,the mopar crowd is finally starting to wake up to these much cheaper and plentiful power plants. BxS = 4.00 x 3.58
The 360 is externally balanced.
Magnum series engines offer better heads and are normally found cheap & in excellent condition. Due to the FI package. Edelbrock offers a RPM carb intake. MoPar used to have offered a pair of intakes. 1- an aluminum 340 copy and a single plane race intake.
IMO, go with a 360 Magnum engine, rpm intake, 650 carb & small upgraded cam. You can install the older valve covers. No problem.
(Edit, spelling & grammar)
