I got this motor from a reliable source. It's been sitting in a garage for 8+ years. Thought I saw a chunk of metal laying on the piston but turns out it was only my cheapo borescope and pulled a head. Piston and bores look fine except for a slight ridge, just enough to catch your fingernail. Not sure if this is normal for a 100k mile motor or is it worn out, Before tearing it fully apart I checked compression on the bank with the head and see only 300psi,.

The motor in my truck now has 380ish psi, no smoke, no leaks, and is perfect IMO. A rowdy bitch with PHP tunes 180/0 and a kc300x G2/S1

I saw a lot of carbon when using the borescope so douched it using carbon cleaner and berrymans and all that crap flaked off inside the bore. My first compression test was 80psi and I could hear blowby coming out the crankcase. Also pressurized the cylinder with a compressor and heard a lot of blowby, nothing out the valves

Then filled the cylinder with 30 wt oil and turned the balancer with a breaker bar till it hydro locked and carefully waited fir the oil and carbon to bleed by the rings before applying more pressure, No, I didn't bend a rod. Then it tested @ 300psi shown in the video. I don't know the cranking RPM but it was lower than the normal 400 RPM but the rocket arms were off so it's 2x, building pressure on both intake and exhaust stroke so I'm sure that's equivalent to 400 RPM if not more.

Not sure if this represents a true compression test or is it "off" because of my ghetto setup. This motor is for a future build, targeting 500hp and I'm want to start with a good base platform and don't want to rebuild it and do machine work for nothing.

Just looking for opinions. Thanks

 

your getto setup gave you a higher yet wrong reading, adding oil tells us the rings are worn, if the compression didn't go up that tells us there's a burned or bent valve .

 

Thanks Charlie. I was afraid of that. Now all I need is a good local machine shop, not having any luck

 

that doesnt sound like its cranking fast enough to me

 

I'll have to measure it. From the video, iooks like the piston is 2 per second which is 120 RPM..so yea, you might be right
Wonder if it makes that big of a difference?

 

i think the good ones are up in north jersey near me, LRB performance hardyston ,tester performance oakridge,ARC race engines rockaway

 

Phil, call Chris at Ryan industrial on rt79 in matawan..
(732) 566-9538
I am pretty sure he is still equipped to do the largr diesels.

 

Perform a leakdown if you still have it mostly assembled. Find out where the air is going.

300psi is okay if all are about that and would come up with a head job

 

It's a miracle you get any compression readings with the rocker arms off.

 

If your planning for 500 hp eventually out of a 7.3l go ahead and pull the heads... Look for any smiles at the upper part of any cylinder walls and for decent hash still there... No smiles and decent hash and you can stick to standard pistons. Also if you want to hit 500 rotating assembly needs balanced... Last one I did had 2 smiles and hash was gone. Ended up having to go 30 over to make it right.. Have fun..

 

Would stock rods even hold 500rw in a reliable manner? Bolts aside.

I swear one member here fractured one recently. @fordman67 maybe?

 

I did brake mine and stainlesstroler95 broke a rod on 238/80.
Imo just a ticking time bomb. I have 160/80 now and my junk tuned back in general. I don't need to brake mine again. People may make 500 for a while but eventually it's going to brake.
It's an unpopular opinion but honestly the 160s with my s467.7 are great. In general bigger sticks are a waste of a big injector that is tuned back so who cares.

 

I guess that depends on how you drive it. Truck will be for daily driven with only occasional beatings when someone pisses me off.
Just a nice to have option for me

 

Just an update:
Everything is the motor is like new, just the rings/bores worn to crap. Probably dusted running around the farm with a torn intake boot or no filter.
Gonna get the block done by Chuck Exton in Canadensis Pa and throw a OEM rebuild kit in it.

General block prep, bore/hone, light decking maybe .003"-.005" for $600 sounds like a deal

 

Even with 160/0 I managed to take out my last rebuild engine, wrist pin snap ring came out due to fractured pistons, I'll admit I wasn't easy on the truck, WOT take off with 15k+ trailer with load, WOT just for ****s and giggles, did make it to or close to 100k on that rebuild.

now with my new rebuild engine I'm not driving like that no more, to much dinero on the rebuilds to do it a third time., I even took my tuner off and went with factory tuning.