Ok bear with me because Im not sure exactly what this is but I was speaking to someone about how our LT1 engines have a ball that is underneath the rear main cap where as a normal Gen I 350 engine has a flat plug? If a flat plug is used your oil filter is bypassed and oil distribution can be disrupted. Its a mistake sometimes done by machine shops who are not familiar with LT1's .

Im asking this due to a spun bearing issue I keep having. Engine has been rebuilt 3 times and Im thinking that the place that hot tanked the engine hammered out the ball and all the freeze plugs etc and when the machine shop got the engine back they did not know to use a ball instead of the flat plug. Could this have effected my engine and spun my bearings?

 

upfront im sare for the spelling i have deslexia so spelling and gramer is bad. mabe he forgot to put eather in.i dont think the cap wood help it woud still bypas the filter .etlest this is wat the book sed and cas low presher .wat pumps did you use on the 2 diferent bilds and wat was the presher on both hot and cold .i am using the 10% ocer pump and start uop presher is 70 then drops to like 65 or 60 after very warm but i am still on brake in so like a 45 minit drive may drop more after. mabe some one has had this hapen to them .my machin shop forgot to put it in but i cat it just befor it went in .wich you lock
pat.

 

I use the plug in my engines, (not the steel ball). Works fine that way.
Something else must be going on.
Dirt, aerated oil from windage, detonation?

Karl Ellwein

 

Either the soft plug or ball will work fine.

 

wat about ifthey dident put in this his 3 time spinning all the rode barings but nomber 7 was the warst and a mechin shop did the last 2 i think one had 500 mils and i think the other was 1000 some thing ron ther in supply i think

 

I too, wonder about that. Seems to me that if the ball or plug was not put in that simply the oil filter would be bypassed and if anything, oil pressure would be higher than normal at the gauge. But the oil would not be filtered. A friend of mine thinks that he may have forgotten to put that plug in on a motor he build, (and sold). The motor has been running for 3 years now and very strong, (but it has high oil pressure all the time).

The bearing failures? Probably not caused by a bypassed oil filter if the oil is changed frequently.

Karl

 

i red in 3 diferent books if plug or ball is missing it wood bypas filter and be lower then normil causing damig locks like it will serkilate in haf the block and not start war its suposto and bypas or be low just befor returing i think he sed he was using a stock pump with a wite spring and had like 70 psi cold and 30 wen hot it shoud be hi gher with new barings right my ne bild has 70 with 10 % over stock and wen hot its 60

 

heres word for word out of the chevrolet power, the official factory performance guide. i got this from a friend that raced on the cade race team. this book is made by gm they call it the bible by GM, I was told I must get it. Because I was doing a 2 piece seal in my LT 1 block and it gives very good detail and blueprints. Here's a quote from Chevrolet Power if you forget the plug or ball.

"When preparing a block, make sure that a plug (PN 3701638) is installed in the oil passage above the rear main cap as shown. If this plug is missing, oil will not be routed to the filter and the engine will not have satisfactory oil pressure." This is found on page 20 under the bottom picture.

Thank you

 

please post your pump ypu are using and the presher cold and hot .please and if its a new bild with all barings and cam barings

 

is it the same bearing every time? might be time for a new shop

 

Yeah, what was your pressure cold and hot? Was is the same all 3 times your motor went? Is it the same bearing(s) that is spun each time? Also are you running the oil coolant line on it and which oil filter are you running?

Maybe someone with the "how to rebuild an lt1/4" book can research and post here....3 times rebuilding can cause a lot of frustration!

 

Yeah its frustrating... I could have bought a nice vette by now but I really like my car..
The #7 rod bearing seems to get it the worst each time but others spin also. Im not running an oil cooler line. I use Purelator filters.

Im thinking about just buying a complete other engine and selling my rods/pistons....

Oil pump has always been a stock GM pump (brand new each time). Pick up was welded with the spring out as to not damage it. Pick up sits right above the oil pan as low as it'll go. I've used 2 high pressure springs and 1 regular spring. With the 2 high pressure springs start up was 70 psi.. Driving was around 40-50. Warm up after driving for half an hour the pressure at idle will be 22ish at Idle. 2 engine rebuilds had the high pressure springs and both times were consistent. The low pressure spring was about 60psi at start up, 30-45 driving around, and 20 at idle. When the bearing spins the idle drops to about 17psi and thats how i know.

 

What is the clearance between the bottom of the pick-up tube and your oil pan???

 

maybe a couple centimeters.. I let the pick hit the oil pan and unadjust it up until it didnt hit the oil pain anymore.

 

I am kinda paranoid about my oiling ball for my fresh short block also. I think I am going to have a look under the cap and see if I can see it. Does anybody have the torque spec off hand? Also is it ok just to take off one cap and re torque it?