i know it's a basic but...

[snakeeater1968]

on my sbc i used to have at least 60 psi and normaly alot more anytime i went above 2,000 rpms no mater how hot the motor got and for a while now the only time the psi goes above 45 psi is when the motor is stone cold..this has been going on for awhile now....should i be worried about the bottom end??? motor is running good no rods knocking no smoke...it doesn't eat any oil...the motor runs smooth and idles good for the cam.....but the psi stays at 45 psi above 2,000 rpms and doesn't climb anymore when the motor is warmed up....when the motor was new it used to pull 70 psi when the motor was reving high...i run royal purple 20/50 ful syn. a fram ph30 oil filter...i've tried all kinds of diferent filters it just seams that the motor doesn't want to maintain the old psi....it's a melling high pressure oil pump...


i know it's a basic question but i'm here to learn....let me know if i need to be realy worried....

[snakeeater1968]

could it be as simple as swaping out the oil pump or could it be the bearings are getting worn out and need replaced....when it's cold i have great pressure like 70 psi but as it heats up it wants to drop to 45 psi..so i'm thinking that the problem may be in the bearings....i'm thinking it could be a cracked bearing maybe and as it heats up the crack widens....but i don't know...just looking for a place to start...and an idea of what to do to fix it...

thanks

snake eater

[Trmnatr]

could it be as simple as swaping out the oil pump or could it be the bearings are getting worn out and need replaced....when it's cold i have great pressure like 70 psi but as it heats up it wants to drop to 45 psi..so i'm thinking that the problem may be in the bearings....i'm thinking it could be a cracked bearing maybe and as it heats up the crack widens....but i don't know...just looking for a place to start...and an idea of what to do to fix it...

thanks

snake eater

It could be the clearances were too tight

Alot of people put engines together and have .003" main clearance and think they are good, What if the crankshaft has any taper? What about the main align honing? Samething goes for the rod pins and rods

Oil pressure is an indication of restriction but you need some pressure.

Usually my engines run 35-40pounds hot at idle @1,200rpm +/- 100rpm

[Trmnatr]

could it be as simple as swaping out the oil pump or could it be the bearings are getting worn out and need replaced....when it's cold i have great pressure like 70 psi but as it heats up it wants to drop to 45 psi..so i'm thinking that the problem may be in the bearings....i'm thinking it could be a cracked bearing maybe and as it heats up the crack widens....but i don't know...just looking for a place to start...and an idea of what to do to fix it...

thanks

snake eater


Forgot to ask the following:
-what crank?
-what rods?
-what bearings?
-what block?
-was the block align honed?
-were the rods checked?
-was the crank turned to true it up or is it true?

I prefer King as the tolerances are much better than Clevite

[snakeeater1968]

Forgot to ask the following:
-what crank?
-what rods?
-what bearings?
-what block?
-was the block align honed?
-were the rods checked?
-was the crank turned to true it up or is it true?

I prefer King as the tolerances are much better than Clevite

- it has a factory forged steel crank spin balanced to 7,000 it's it's had .020 taken off and been polished
- it has pink rods that were balanced and installed w arp rod bolts
- it has fedral mogal bearings
- it was a sprint car motor befor i got it, it is a factory 4 bolt main w/factory forged steel crank i think it is an 81 year factory block
- it was align honed befor it was inspeckted and cleaned and clearences checked again
crank was checked again and polished along with the oiling ports being chamfered as well
-i have speed pro flat tops that have been balanced and polished on the valve releifs child and alberts chrome moly rings


the motor when it was new ran like a champ....it now has alot more miles on it...the motor is now 10 years old w around 70,000 miles on it...and brand new pro 1 heads....i had replaced the heads becasue the valve guides were worn out and decided to go ahead and replace the hole thing all at once....i'm realy looking at trying to fix what i have and maybe freshen it up or go with a stroker motor or even try and build a 400 sbc with a 3.75 stroke....i hate to walk away from a motor that i've put so much time and money in but if in the long run it's the best move to make i'll do it...seams like so many people are going to the 400 sbc set up i hate to give up on the motor but if i need to replace the rotating assembly and i see the new shp blocks are cheap enuff.....i will peace together a better motor....i had tried to keep the car as original looking and to date as possible running double hump heads and everything you would find on a car in that era but i see now that thier are so many great new parts out thier that it only makes sence to get with todays techknowledgey....especialy with gas prices so high and un stable....sorry so long but i think you know what i mean...

thanks for the help

Snake eater

[snakeeater1968]

- it has a factory forged steel crank spin balanced to 7,000 it's it's had .020 taken off and been polished
- it has pink rods that were balanced and installed w arp rod bolts
- it has fedral mogal bearings
- it was a sprint car motor befor i got it, it is a factory 4 bolt main w/factory forged steel crank i think it is an 81 year factory block
- it was align honed befor it was inspeckted and cleaned and clearences checked again
crank was checked again and polished along with the oiling ports being chamfered as well
-i have speed pro flat tops that have been balanced and polished on the valve releifs child and alberts chrome moly rings


the motor when it was new ran like a champ....it now has alot more miles on it...the motor is now 10 years old w around 70,000 miles on it...and brand new pro 1 heads....i had replaced the heads becasue the valve guides were worn out and decided to go ahead and replace the hole thing all at once....i'm realy looking at trying to fix what i have and maybe freshen it up or go with a stroker motor or even try and build a 400 sbc with a 3.75 stroke....i hate to walk away from a motor that i've put so much time and money in but if in the long run it's the best move to make i'll do it...seams like so many people are going to the 400 sbc set up i hate to give up on the motor but if i need to replace the rotating assembly and i see the new shp blocks are cheap enuff.....i will peace together a better motor....i had tried to keep the car as original looking and to date as possible running double hump heads and everything you would find on a car in that era but i see now that thier are so many great new parts out thier that it only makes sence to get with todays techknowledgey....especialy with gas prices so high and un stable....sorry so long but i think you know what i mean...

thanks for the help

Snake eater

i'm afraid to race it like this....w/o 10 psi per 1,000 rpm's :confused:


snake eater

[snakeeater1968]

is it the bearings?? but if so i wouldn't think the oil pressure would be normal till it warms up....unless it's a cracked bearing...and the oil pump would have been my second choice but it runns great pressure til it warms up...this one has me stumped....any addvice??? Don...Jake...Bill???

thanks

Snake eater

[want-a-be]

Well...the short block has been together for 10 years. I can only assume the pump has been along for the ride for the same amount of time. Since your thinking of a new combination I'd say you can inspect it during the tear down.

Don