Mopar 360 Performance Shortblock

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Gib Warnick

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Has anyone used the mopar performance 360 short block non magnum assembly(#4876908-9.5 compression)? Is it really available or back ordered? I have seen it advertised for $1250 which when you compare to the cost of having my '72 340 block done locally seems like a good idea. What do you guys think-are they available and are they a good foundation? they are bored .20 over, cast pistons and crank, 509 cam, double roller timing chain-not inc/lifters. thanks
 
I would think you could have your 340 short block done for that price at a local shop if you have a reliable shop in your area. You could then use what ever cam you wanted. If you wanted to upgrade to some forged pistons it would cost you a little more.
 
I own one. Run away, be afraid, very afraid.
Poor machine work, loose bolts and it lasted less than 2 months.
No, I have not over reved it and know how to break in an engine etc.....

Just walk away from it. Unless you don't mind giving your money away to crooks putting one over on Mopar.
 
I too have heard some bad things about them, never had one though. Build your own, you can do it and it is much more fun. Get the best machine work you can. It will make or break the build. Put it together yourself and you will know what you have. You can do it. And you have ALL of us to assist if needed. Good luck, Terry.
 
Thanks for the info guys- I haven't gotten a price yet on redoing the 340 block-Have may J heads to pick up this week though.
 
I sold one that i bought, to a buddy,360-9.5 comp.
and it runs very well.
They are made by Cummins diesel in Canada,or at least mine was.
but if you can get close on the price,Even spending little more....I would follow the advice of building one.
cause the mopar cams are pure crap!!
good luck to you
braveseal
 
AHH CRAP!! I JUST BOUGHT A 360 SHORT BLOCK FROM MOPAR...bein' the 340 didn't work out...
 
Wilnutt, have a good machine shop pull it apart and check everything, then put it back together correctly. Now that you've already invested the cash in the short block, you might as well go a little further to protect that investment and give yourself some peace of mind when you do finally fire it up. Good luck.
 
Good advice 'Oldvart'. If you already have the engine...just go thru it and you will have a good piece and piece of mind. I believe that 'blue printed' engines ALWAYS make more hp than 'assembled' engines do. Check everything. Ring end gap is often overlooked. All bearing clearances, guide clearances, big ends on the rods check them. Deck height on some of these motors not consistant from right bank to left. Check cam CL, While degree wheel is mounted, check '0' on balancer with true TDC. And while heads are off, pull valves and have them back cut 30 degrees...nice low lift flow increase for little money. 30% in some cases below .400. Big help in torque production. Manifold to head alignment check it. Just making sure everything is right. Also this is a good opportunity to make some changes to your combo if you choose to. Good luck and give us a follow up. Terry.
 
Wilnutt said:
AHH CRAP!! I JUST BOUGHT A 360 SHORT BLOCK FROM MOPAR...bein' the 340 didn't work out...
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Not to worry so much. Perhaps the machine work won't have a crap side of it. Mine was zero deck on the passenger side, +.010 on cyl. #1 and graduating to +.13 @ cyl. #7.
They are made by Cummins diesel in Canada,or at least mine was.
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Perhaps they'll do it right. The JackA$$ Redneck comapny from La. did poor work on mine. Biggest waste of cash ever yet!
 
The 360s are the best of Mopar crate enignes. I still wont buy one, but if I had to, I'd feel better installing one of them vs a $13000 hemi. I'd runa torque wrench thru all the lower end, that kind of thing. I'd also degree the cam. I'lll bet it's not even close...
 
I know this doesnt apply to the current crate motors or the topic exactly, but my 360 was the from the early 90's commando series. I took it apart and checked everything. It was entirely spot on, but it was also built by chrysler marine and industrial, and was a totally new assembly - not used.

I've not heard good things about these current short blocks, so if I were to buy one I'd tear it down just like I did with the commando motor, just as a regular course of activity, and check it over completely.
 
They must be hit or miss cause I've read so many guys have bad luck with them but this past Sept. at the Monster Mopar weekend I talked to a fellow that was running one in his 68 Cuda and he said he'd been racing it for 4 yrs. now nearly every weekend and it's still going strong. The amazing part is he runs 11.80's with it. Maybe his was built at Cummins.
 
moper said:
The 360s are the best of Mopar crate enignes. I still wont buy one, but if I had to, I'd feel better installing one of them vs a $13000 hemi. I'd runa torque wrench thru all the lower end, that kind of thing. I'd also degree the cam. I'lll bet it's not even close...
Click to expand...
Thats a create engine. We are talking about create short blocks. They seem ro be built like crap in the earlier days. I did a little research into the arcives of different sites with little to report, but it was all good on the short blocks by cummings.
 
Rumble, I dont differentiate between anyone. No crate engine, or crate shortblock from MP is worth it IMO. I know I can get better quality work without "faith in lowest bidder" builders MP uses. I also know guys who had no issues with the 360s from years ago. I just dont place faith in others' work much anymore. I havent had much from MP that is perfect within the last 6 or so years, and the more complicated the assembly, the more areas for issues. Just my feelings. Guys in other areas who dont have the options I do locally this may be the only option, or the least expensive/easiest option.
 
I hear ya Moper. Sometimes it is just a damn shame.
 
if you just go over it im sure its good, i personally know of one running mid 10's for 3 years.

Steve
 
iam curenlty running one i purchased used from a freind who purchased it new i dissasembed it myself it was a mess one wristpin was smaller than the rest bearing and rings were to tight a lot of scuffing ireplaced the rod bolts with arp had the crank polished the block alined honed honed the cylinders installrd new rings .to get the 9.5 compression they deck the block mine was decked 50 ths this causes problems with intake fit but the sad part is you can get this same bad workmenship at your local machine shop either way you should check the workmenship yourself its a big investment good luck
 
I'm a little late responding since I'm new, so I hope this helps. At the present I have part# P4876908 short block in my 67 Dart. Bracket race vehicle only. I took the 509 cam out and installed a Mopar Performance 557/296 cam and degreed it. I also checked the torque on all the rod and main bolts, They were right on. I installed a Milodon pump, windage tray, and pan. I'm using small chamber W2 heads and a W2 M1 intake. The car runs 11.3's at 116mph and at the present has almost 100 passes on it. I shift at 6k and run through the traps at 6500. So... I'm happy with it and no problems to this point. (knock on wood).
 
Nice toy and times there timmy. Scamp73 also does well.
 
Had one on backorder for 4 months
they couldnt tell me when they were coming in
bought a rebuilt 360 from my friend s auto parts store
for 1100.00
changed the cam and added eddy heads
 
And how did you like it Mikey? Comp. ratio of the rebuilt engine?
 
seems to be about 9:1
havnt fired it yet
have to finish car first
just topped it off with a mopar 6 pack set up
as soon as i figure out how to get the pics out of my new camera ill have to post them
 
My buddy ordered a 360 Magnum short block from them 5 years ago, but we pulled the cam, added our own ported heads. Everything seemed to be in order with it, no complaints, the engine is still working today, untouched. I have to admit, when he got his back then, we heard a lot of horror stories about mopar enfines and lowest bidder doing the work, it almost seem like the old day-of-the week saying, his was probably built on a Wednesday.
 
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