got on it in first gear lost oil pressure and developed a rattle sounds deep in motor,any ideas a rebuilt early 70's 350

 

main bearing gone bye bye....now when u rebuild it go for a 383

 

motor was supposed to have been rebuilt recently? when i bought it who knows it ran awsome,

 

just because it was rebuilt doenst mean it was rebuit right. but im just speculating id have to hear it to give a better opinion....

 

i know ,and i appreciate you help
ive dumped so much money into this car in last 2 month lol,heck i got it from paint shop yesterday,another guy localy says it could be a rod bearing? i dont know.the rattle gets louder if i gas it up a little,deffinatly not a lifter type noise

 

yeah thats what i mean id need to hear it, could be rod bearing i just threw the main bearing one out there first. sorry dude.

 

Did it have good pressure prior to this noise? Sounds like a bearing spun.. from your discription im gonna say rod, time for a rebuild or a new engine most likely..

 

on my cheap oil pressure gauge it had bout 30 while cruising around,and around 20 psi at idle

 

wow thats no good, 45-60 psi is good.....yeah u had some bearing issure clearances and now one of them spun

 

so... crank kit make it all better then?

 

have to tear it down and check out the damage to see, and you should probably have it cleaned to make sure there is not metal dust, basically need a rebuild....how much power are u wanting and how much money you have to spend and i can make some sugestions....

 

power? it has tons of it im guessing prob around 350 hp just by comparing to my old l69,305 i just swaped to this one.so i dont necessarilary need any more power

 

just asking about power cause i figured u might want to just swap motors for something like this that you know is built right, i have it and it makes good power.....http://www.sdparts.com/catalog/crate...omyEngine.aspx

 

well pulled motor and tore it apart today and guess what,lol the oil pump fell out when i took off pan,bolt came completly out of pump.but after looking at it all decided to check bearings anyway and they are trashed deep grooves showing copper in most of them,so thats where im at now,on the plus side we ran the block #s online and its actually a 400 small block

 

That was before the spun bearing right? 10 psi for 1k rpm is acceptable. On a newer engine with a stock pump 30 psi or so is right on the money for idle.

 

10psi for every 1k plus its nice to have about a 10psi buffer, and the logic for that is on the top end, cause by that rule 10psi at idle is good, my new crate motore runs 50psi at idle (45 psi when its up to temp) and goes up to about 70k at full throttle....

 

20lbs at idle is fine... my 350 has around 20k kms on it now, and its about 20psi hot at idle (700ish rpm) with a 10-30 oil. I've never had any problems with it running like that.

 

yes it will run and work but doesnt mean its right, too many people on this board think just because it works its right this is one of those times when this is not true, that shows your motor has alot of wear or some other problems, that will show themselves sooner or later...

 

actually thats not true at all, that's pretty normal, 30-35 psi is normal for a new engine. 50psi at idle is quite high, it most likely either due to an inaccurate gauge or a high volume and or high pressure pump.

 

20psi is perfectly fine for a small block built to stock specs with a stock-type oil pump and a 10-30 oil in it. Yes, a new motor should have more pressure - its new.

My engine has nothing wrong with it at all. I actually have it out and on the stand right now, as I'm painting the engine compartment. I took off the pan just to give the bottom end a once over, and everything looked like new inside. The cross-hatch still visible on all the bores, no sludge buildup whatsoever, and the bearings look like new (took a couple main caps off to see), as do the crank journals. I have no reason to think anything is wrong, and the oil pressure is well within GM specs, so I don't see a problem? Oil pressure specs are not one hard number, where more is a problem and less is a problem.. its a range. If your engine reads within the specified range, its fine.

Plus, its not like the pressure level has been dropping since it was built, its always been around 20-25psi hot. Nothing is changing, and nothing is wrong internally, so I'm not worried about it.
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Or an engine built too 'tight' or using an oil with a much heavier viscocity than is necessary. Too much pressure can cause problems, just as too little can - though different problems.