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Help! LT1 Hotcam Install , Valve clatter

G Winter

Well-known member
Joined
Aug 21, 2004
Messages
2,177
Location
NW Iowa
Corvette
1990 red convert 6 sp
I just looked up the oiling diagram. The oil passes through the filter then has two choices, crank or upper engine. I think if the engine oiling wasn't primed then the oil might take the path of least resistance first , which would be upper engine with no oil to create a back pressure. Combined with oil passages draining during the tear down you could get bearing starving. I would almost bet that it is the front rod bearing that go , I think they are the last in line to get oil.
I always prime and engine if any oil passages have been opened.

I was looking at the zr1 engine. After more research I found an oil passage diagram the seem to indicate that the oil comes to the main bearings from the cam bearings. After seeing this I remember when installing cam bearings they must be oriented correctly to get the proper oil flow. Someone jump in and correct me if my memory is wrong on this.



Glenn
:w
 

Cruzen

Well-known member
Joined
Nov 7, 2008
Messages
97
Location
Scottsdale, Arizona
Corvette
White 1994 Roadster, Purple Pearl 1998 Roadster
Oil in the engine takes the path of LEAST resistance so if you were spurting oil near that # 8 lifter than maybe oil was not getting to the bearings. It doesn't take much to affect oil pressure. Depending on how long it was driven in that manner it could have done damage to one or more bearings. If you found that amount of particles in the filter and oil it would lead me to believe that more than one bearing has been affected. A friend had that problem on a rebuilt engine. Did you monitor oil pressure during this time period??

By the way, while synthetic oils are great when a engine is tight, under the conditions you have indicated they are unforgiving. They will leak through worn gaskets when conventional oil will not.

My personal maintenance schedule is such that I do not use synthetic oil in any engine that has gone over 80k and never when breaking in a new engine. Call me old fashioned but I still prefer to break in a new cam and rings using conventional oil. Old habits are hard to break.

Denny
 

ddahlgren

Well-known member
Joined
Nov 22, 2008
Messages
65
Location
Mystic CT
Corvette
91 Dark Green Coupe
I think if you follow the oiling diagram it migh show that the oil enters the rear of the block and if number 8 is leaking badly nothing else gets any oil. Even worse the oil pressure is measured there as well and before all the other leaks in the engine. I don't know if all engines have a tapping in the front of the block but remember many 350's did have one there. It was a 1/8 pipe plug just above the timing cover. That is the place to measure the pressure as it is after all the other leaks from suppling everything with oil.. Just be ready for a lower number than usual. It is real handy as well if you notice unusually high oil pressure you have probably started to spin some bearings and a good time to shut it off or at least open the hood and see if things seem unusual sound wise.
 

tuff96lt1

Member
Joined
Feb 15, 2008
Messages
15
Location
SC
Corvette
1996 Red Coupe
Oil was primed with drill during build. But seems I had a multitude of bad luck on this one. Started with a defective lifter ( or was oil problem what made it go ?) I did use 5w30 Mobil 1 and all the time, even now, the oil pressure is normal. I think that I had a weak link that finally decided to go. Read somewhere that was the primary weakness in the LT1 , spun rod bearings. Damn, and the thing ran great and sounded awesome for a 100 miles or so.

Well I will be calling Chad GOLEN next - looks like a 396 maybe.
 

JAKE

Well-known member
Joined
Nov 10, 2006
Messages
313
Location
KEMPNER, TX
Corvette
1996 388 LT1
So, you're saying you DID prime the oiling system when you did the cam install, right? If so that pretty much kills my suspicion that not priming was the cause.

I do believe that the rod bearing clearances on the LTx are tight. Much tighter than on high-performance built engines built by racing shops. My thinking is that those tight clearances allow the use of 5w30 and still maintain acceptable hot oil pressure at idle.

Years back I, too, had an oil filter problem that caused ZERO oil pressure when I fired the engine. I had the BIG RED-EYE oil pressure light on the dash and after putting the old filter bad on, pressure returned to normal. I never found out why the Fram filter caused that problem.

Of course, after seeing no oil pressure for 30 seconds or so, I was concerned about damage to the bearings, so I dropped the pan to have a look-see. Since I had the pan off, I changed all of them (rods and mains) as a precaution after seeing the #1/2 showing signs of no oil stress. The #1 main was hurt too.

Jake

Jake
 

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