Mopar 340 Engine feedback...

[Risko1]

I have an opportunity to buy this motor from a neighbor for around $1500. What do you guys think??? Good price? What sort of HP do you think this puts out? I currently have a rebuilt 318.

The following is the details he emailed me:

1. New dealer standard bore 340 block (no overheating problems or stress cracks)
   2. Steel externally balanced crankshaft all standard as well
   3. 10.5 to 1 compression TRW Forged pistons (new as well)
   4. Solid lifter Comp Cams camshaft adv. duration is 272/276 @ .050 lift duration is 242/247 int.lift is .540 ext. lift is .549 centerline is 108 degrees.
   5. Forged steel adjustable rocker arms by Mopar Performance ( I had thought this was a roller rocker set up but I was mistaken...my bad)
   6. 340 "X" cylinder heads (very rare) they have had a nice port and polish job done on them. High quality stainless steel valves as well
   7. Choice of intake manifolds ( Edelbrock Victor Jr., Edelbrock Performer RPM Air Gap amongst others available.) personally I recommend the air gap as its the newest technology and its better all around suited.

[bb71challenger]

It sounds like a pretty good deal to me but make sure to check everything over really close before taking the plunge. I bought just about the same setup a long time ago. 68 340 block that was freshly machined, pistons and everything for 1k. My brother in law checked it over and missed 2 things. One was the crank was cast(external balance) not forged which was not a big deal. The second thing was the block had been dropped and was cracked where the tranny bolted up. Not a big crack but it did require welding. I still have the engine but will probably never do anything with that block just because I know it has a repaired crack. Look it over close and if possible take a mopar buddy with you to catch anything you might overlook. Good luck.

[dodge freak 2]

For the money is sounds like a great buy.

X heads -in good shape-sell for $400+ on E-bay, engine blocks go for about that much too, crank is a good $150 or more, those rocker arms not sure but $$$. Plus since its right by you no shipping charges.

I go for it.


But if it turns out too good to be true, don't write off your 318 motor.
I just swap some MP casting # 4772576-like the 308 heads but no smog air holes in the exhaust ports and 2.02 valves.
Man, that little motor woke up! I have 3.91 gears plus a low 2.74 first gear in my auto trans 904-with only a 1800 stall conv. Using a holley street dominator intake and a 750 dp carb. It takes right off and zips right up to 6200 rpms. Sounds better and feels better. I did have the heads milled .030 or to 63cc but still, my compression can't be more than 9-1 and I am burning 87 gas. A msd 7 al box and hvc is firing the spark plugs--I am sure its helping to burn all the fuel thoses heads and carb is ramming in.

So grap the 340 if its true or find some good heads for your 318, IMO.

[bb71challenger]

I am pretty sure that the Mopar Performance adjustable rockers are the ductile iron ones made by Crane. They are supposed to be good for a LONG time. I hope it turns out to be a good deal for you.

[74 340 4speed]

Sounds good to me.  My 340 has a forged shortblock, the 248/248 .508/.508 on a 108 LSA mopar peformance purple cam, J heads with the big valves in them and it is an absolute screamer.  It doesn't like to lug around below 2500 rpm, but from 3000-7000 it pulls like a freight train.   If you plan on turning it in the higher RPMs, I would get a victor style intake.  My car has an LD4B edelbrock on it now and I know it is killing the flow in the upper rpms.  Good luck with your combination.

[matt63]

I would try and match the intake rpm range to that of the cam. (and make sure it's what you want and matches your converter and gears).  You'll have to found out the make and grind no for the cam.  The cam is easy to change if it doesn't meet your needs.  I'm not sure I follow the specs you list but it sounds like it should be a nasty cam for a 340.  It may not be good for power brakes.

[Chryco Psycho]

 
 the RPM air gap is a good intake but with a smaller cam
you need to match cam & intake better , are you sure you want or need a cam that big , 1 of the most common mistakes is choosing a cam that is bigger than needed & moves the powerband up very high & beats up your parts.
while the X heads are decent with a 7000+ rpm engine I would use a better head , even the 88-92 408 truck casting will out flow the X head , an indy or Brodix  head would be even better choice if you want power at 7000 rpm