Mopar Performance short blocks, any good??

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Lars

Lars

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Part #P4876908

Are these any good? I've heard of a couple folks having problems with the Mopar crate motors. But $1250 doesn't seem too steep. Anybody had a good experience with them?
 
Lars said:
Part #P4876908

Are these any good? I've heard of a couple folks having problems with the Mopar crate motors. But $1250 doesn't seem too steep. Anybody had a good experience with them?
Click to expand...

Wow..... I don't know where to start on this one. :angry1:

I bought a MP short block last spring. Disassembled it, checked everything, cleaned everything, assembled it, and drove the car 20-25 miles before the cam disintergrated. Was it MP's fault? Maybe... My fault? Possibly..... Is a $1,200 short block costing me $4,000 after machining and parts replacement? Yup. Have a decent running engine re-built. If it costs $2,000-2,500 at least you know what you have.

Search the archives for anything posted by me within the last year regarding my engine nightmare......:sad3:
 
Johns is certainly a scary story. GuitarJones has had better luck with his. He runs 10s with one. Also Abody joe has on in the 12s.
 
AdamR said:
Johns is certainly a scary story. GuitarJones has had better luck with his. He runs 10s with one. Also Abody joe has on in the 12s.
Click to expand...

Granted mine might be the exception, but still be careful.....
 
I can tell you what I did to mine though before it ever ran.

I bolted one of my heads on it with my cam and determined the amount of non existent piston to valve clearance. I pulled all the pistons, obtained a spare and cut it up to see how deep I could cut valve reliefs. Ended up with about .030" between the top ring groove and the intake valve relief. On the exhaust side the top of the piston is about .090" thick at its thinnest point. This allows me very minimal valve to piston clearance though. Like .058" intake and .080" exhaust, with the lash set, and I had to move the cam timing around to get that.

I never pulled the crank out but I did install main studs, head studs and weight matched the big end of the rods. I cleaned the cylinder bores with lacquer thinner three times and installed ARP rod bolts. I never touched the rings or even checked their clearance.

I used the cam that came in the shortblock in my sons Scamp.

I don't know what happened to John's motor but I do know proper camshaft break in is important. 2500 rpm's for 20 minutes. If you have double or triple springs take the inner springs out and just use the outers to break the cam in with, then reinstall the inners.

Too much valve spring pressure will also wipe a cam lobe so know what you got or use the cam manufacturers suggested spring.
 
If you decide to do it, use the GM additive...EOS, I think....it will help with the break-in. This engine combined with Eddy heads is one of the best/cheapest bangs for the buck!!

Dave
 
You can also use ARP assembly lube on the cam lobes and lifter face. It's a moly based lubricant that can handle extreme pressure. I'd use this instead of the EOS stuff if I had a choice.
 
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