My pile o' parts shows evidence of oil starvation in multiple places. The kind of thing you would see with an oil pump failure, but that was not what occurred'

Rich

 

Dwayne, I'm going to list 2 examples below where at least I think the stock pump was proven inadequate.

Here is ONE example of the stock pump (a stockish pump at least) being insufficient.
Back when I was first learning and started working on my 1st 383LT1 I ran a Melling SV oil pump in that thing with the big pickup tube. Once per year it would get a tear down inspection and that was also after about 200 1/4 mile runs and a mild amount of street time. The yearly inspection always showed signs of oil starvation. Never concerned me all too much since I knew the bearings would be new each year. A high pressure spring should have been my fix but at that time (and even now) I figure it was working well enough and "don't change the combo". That's a general rule of thumb and I make wrong decisions all the time and learn from them. I never broke that motor from having less than adequate oil supply. But my educated guess would be that the bearings would have only last 3 years with that SV oil pump.
So I have proof in my own engine that a SV pump just won't cut it on a big clearance 383LT1.

When talking stock LT1 with stock bearing clearances then heck yea keep that stock pump in there. The LT1 is so tight it's like .0008" clearance for the #1 main! But we are not talking stock bottom LT1 engines. Some are but most of us are talking about the slightly looser bearing clearanced stroker LT1 engines with more reciprocating mass and mostly more rpm.

Now to the LT1-383 that's in my race car right now with the HV Titan gerotor. The 1 year inspection had me scratching my head in amazement. Is this thing a lucky motor? How can it take umpteen fuel starved test runs and then more than a few low 10 second nitrous runs and still have bearings that look better than new? Only one bearing that had a shiny spot in the middle and that's from a not so perfectly machined Ohio Crank Crankshaft. It's not due to my building ability. These bearings are all at the normal performance build clearance, (looser than stock). It's due to a good strong steady oil supply. Good oil supply covers up a lot of assembly imperfection and yea thankfully it's hard to mess up a small block chevy.

The 2nd example is when I accidentally let my stock bottom LT1 350 be run on the chassis dyno in OD gear up to 200mph and then soon after that found my bearings stuck to the crank. That was a long long time in 4th gear and at 5000 rpm----massive LUG----. (I watch the video tape of that every now and then). I'm certain that a good high pressure GM SV pump would have saved the motor. The standard pressure SV stock pump didn't save it. In my mind those are 2 instances where the stock sized and stock pressure GM oil pump is less than adequate.

Certainly a stock pump is most excellent and the correct choice for a stock bottom. Most engine failure is from rattle/detonation or lean tune piston melt/crack anyway so it's hard to find any examples of inadequate oiling. Bearing inspection is the only way I can think of to find evidence.

Karl

 

You can tell by the way the bearings look. If the pump was sucking air from pumping the pan dry, there would be signs of cavitation. If the oil pump failed, the bearings would look much different.


Rich, if your bearings look anything like this,I would start to believe in your theory. Untill then you still have showed me no proof.

Was there any fretting on the main caps?

Whenever we have an engine failure like yours where I work, we look at every part, and inspect it for as long as it takes to determine the cause. Sometimes the factory reps will come out too. Gotta be sure when the thing may be covered under warranty.

You cant just tell me you have a very expensive pile of broken parts and blame it on the HV pump/stock pan combo. Prove it

 

Those pictures could be from hard detonation and kept on running. Have seen it look very similar before,knowing the motor was detonated and NO loss of OP. It was shut down at the end of the meat and torn down and the bearings looked similar to those pictures.
When ya have a failure it is very hard to tell what happened first as has been well documented by the experts. A lot of it is guess,opinions,and educated guesses. Not to say that educated guesses are all bad as they sometimes hit the nail on the head through having looked at a bunch of disasters. I try not to have those disasters to start with but it will happen and ya learn(hopefully) from it as to what works and what doesn't

Caps "walk" on ANY high HP build with stock caps and block with good bolts.

 

I dont think Rich was running stock caps. I would hope his didnt "walk" at all, because at any high power level that would lead to disaster. Mine better not either with my splayed 4 bolt caps.

It would be very interesting to see pics of your engine Rich

 

When I say stock I mean factory 4 bolt either SBC or LT1.
If ya make enough HP or turn it enough revs they WILL walk around and leave chatter marks.
Run um with the little marks year after year as long as the register isn't loose. Don't hurt a thing IMO cause they will do it.

 

I dont agree with that. It does cause damage. We have replaced many engines because of minor fretting. Thats entire block kits (block, crank, main caps, bearings). If it didnt hurt anything why have the cummins engineers decided to replace so many engines completely under warranty? Once fretting starts, that block is done. It will wear bearings very quickly.

I guess on a race engine that gets freshened up regularly it may not be a big deal. Or maybe its the size, or average load of the engine that is the difference. But I know for a fact on larger engines fretting is a BIG deal.

 

Why ya think us old timers like plenty of bearing clearance. 'cause we learned years ago if ya turn one 8000 with 2.0 main bearing clearance ya beat up the bearings. Todays factory blocks are not as strong as the old 327/350 blocks from the late '60's IMO.
Like I said I have/am running the same block in one of my customers sprint car engine for the last 3 years and the fret/discoloration in the bottom of the main cap receivers is still there and no worse or better than it was the first year I tore it down. The caps may not move but the block will wiggle under the caps either/or.
The only block I have not seen do it was an older Dart block that had been together for 4 seasons and dry sumped and "loose clearances" with a girdle and turned less than 8000 so it was in good shape.
I have worked on a lot of Cummings as I worked for Manitowoc Cranes for 35 yrs and don't know too much past the "N" series as I have retired and went back to racing.

 

Some of you seem to be saying,
"Hey, I've written this out on a piece of paper with a pencil and used a calculator and what you say about HV pumps can't happen".

I've built my own motors for years so I'm not a newbie or clueless like I'm sure some will immediately accuse. I had my '96 LT1 rebuilt to a 355. On the recommendation of a friend with an LT1 specialty shop, I put in a brand new Melling HV. Upon start up, it had great pressure (40 at idle, 75 psi at 3K). After the motor was broken in, I changed the oil to Mobil 1 10w40 and took it out for a test drive. I took off and wound the motor out to 6,500K and watch the tach. It ran great! THen I looked at the Oil Pressure. DAYEM!!! Shut down!!. THe oil pressure was zero! I clutched and let off the gas. The oil pressure returned. I pulled over and checked the dipstick for bearing glitter. Hmm.. Nope! So I got back in the car, started the engine, looked at oil pressure. Steady at 40 psi at idle. This time, I watched the Oil pressure as I floored it. Damn it! Zero PSI once the RPM's elevated above 4K. However, If I 'crept' up on the RPM's and attained 6K plus, It would retain pressure at 75psi. Puzzled, I drove home and the next day, I ordered a Moroso anti-cavitation model. I installed it and took her out for a test drive. Damn it! It was zeroing even more quickly than the Melling! Next day, I ordered a Stock Z28 pump and it was much better. Holding high PSI in all but the rarest scenarios. But, when I went to the Canton pan/pump and pickup, all the low pressure issues were history.

 

Thanks for posting this. Maybe it will save someone a motor. Bottom line is do not use a HV and a stock 4th gen. pan. I will ask Fred to sticky this thread. People can read what was posted and decide for themselves if they feel lucky.

Rich

 

Can you shoot me part numbers for your pan, pump & pickup?

 

BTW: I just read this post. That motor had Callies steel caps on all 5 positions. ALL of the parts were top quality. EVERYTHING was checked, rechecked, and checked again. No doubt in my mind what went wrong - OIL STARVATION was my conclusion along with two engine pros who also helped with the teardown/autopsy.

Rich

 

Soooo did I get this right?

Its not a problem;

Stock Pump with Stock Pan

and

HV Pump with aftermarket Pan (Canton,Milodon...)

True?

 

That is the conclusion I have come to.

Rich

 

Just a note, I've been running my HV Melling with my Milodon pan at 5.5 quarts for a hard 1k miles now, and all is well. Another oil change coming soon.