Ok well some of you may have seen this in regular LT1 tech

here it goes with a twist...

I *THINK* that the pressure itsn't low, its just constant and constantly at idle. the needle sits just above the 20psi mark.

At first I was ready to cry-
thought it was bearing clearances
main bearings were good with plasticguage
rod clearances were a bit high but at that point we just continued building.
This shouldn't be the problem since pressure would still varry from idle to WOT right?

Then I thought pickup fell off-or it was too high...
reasons
1.- Loss of pressure if I stop hard
2. Hear metal clanging on occastion- ESPECAILLY in R on start up- but I was confident its the headers against the chassis.

I thought i'd have ZERO pressure if this was the case
then I added an extra qt to come the same results-
23psi or so...

Then I thought the guage was broke
but it works when I lose pressure from hard stops and when I have more pressure from thicker oil (startup)

Things to keep in mind-

1. no windage tray- used main studs (any way to get that thing in with studs?)
2. Drove many WOT runs and ~14-1500 miles (mostly highway)
3. Engine is throwing codes-
O2 sensor, MAP sensor and knock sensor (broke)
4. Completely new Oil pump, pickup and shaft....
5. Bought the block with 3k miles on it and pre machined
6. Was broken in with a thicker synthetic oil 20-50
7. Using dino 10-40
8. Xe 236/242 cam if that matters (some said they had problems)

Thanks guys and sorry so long
Trey

 

Maybe the bypass valve spring on the oil pump is weak/defective only allowing 20-some psi??


It doesn't vary at all from hot to cold or low/high rpm's?

 

nope
that needle is rock steady

 

Did you ever put a mechanical gauge on it and test it.

 

update-
2 qts have gone in -800 miles
just got low oil light..

 

Thats prolly why the pressure was so low..As long as you had 10psi per 1k rpm you should be fine..keep an eye on your oil level.

Cody

 

the dipstick reads it to be operating range

is it possible the high volume pump is sucking it dry?

 

If you're oil pressure never varies from the 23 psi you stated then you may have a oil galley plug missing in the block. If you remove the rear main c/shaft cap and look up into the block where the main cap sat, you will see a 1/2" hole in the block. Recessed in that hole should be a pipe plug. If the pipe plug is missing your engine cannot build oil pressure. It is a common mistake for some machine shops to accidently leave out that plug after cleaning or machining a motor. Also, by not using a windage tray and depending on the output of the pump you have, your motor will be short-lived.....Extra hi-volume pumps are not always the best choice when building an engine. You need to match the pump volume to the engine application.

 

why will my engine be short lived without a windage tray?

 

The windage tray helps to keep the crankshaft from mixing the oil like a egg beater. The whipping action creates foam/air pockets in the oil. The other reason is that every time you floor it on take-off, most of the oil will go to the rear of the pan and you can have your oil pump suck air momentarily which reduces oil flow throughout the oiling system for a second or two which creates a lack of or low oil volume to critical areas.

 

Trey,

When I originally built my stroker, I used an SPX high-volume pump, a Federal Mogul stock-type pickup, and the stock oil pan with no windage tray and modifications to clear the crank. I didn't have any oiling problems at speeds below 3K or so, but if the motor quickly revved above that mark the oil pressure would start to sag. I believe that the lack of a windage tray caused a significant amount of the oil to be pulled away from the sump, especially considering how close a stroker crank comes to the floor of the shallow area of the pan.

A Canton pan, pickup, and pump (which appears to be nothing more than a re-boxed Melling 55SV high-volume pump) solved all my problems. Might be something to consider if you end up pulling the motor.

Good luck, man!

 

There was NO way I could get my windage tray on w/ my stock oil pan so me and my engine builder left it off...he has done many lt1's and doesnt use the windage tray with them and never has had any problems..my oil pressure is fine..no windage tray,HV mellon pump/pickup(WELDED ON),stock oil pan..

Cody

 

If the oil galley plug is installed as I previously mentioned, then the only other thing that is giving you low oil pressure is excessive bearing clearances.....I'm out of ideas....Have you or have you not installed a mechanical oil pressure gauge to double check your readings???

 

Oooo, good catch! I never even thought to mention that plug. I'm not sure if the motor would still build good oil pressure when cold (maybe it could), but it sure as hell won't build it when hot if that plug is missing.