how do you know if you have a spun bearing?  if just one rod bearing gets loose, will the oil pressure drop considerably?  i have a big block with a standard volume oil pump.  cold pressure is about 60-65 lbs and hot idle pressure is about 28-32 lbs.  it has never gone below 25 lbs at idle.  when hot, the max pressure goes to about 65 lbs when i give it some gas.  i use 20w50 regular oil.  i hear a small knocking or tapping noise.  i dont hear it at idle or when i give it a lot of gas.  i checked the hot lash, and its fine.  i have a solid roller cam and roller rockers.  i hear the cam, but its much quiter than the mystery noise.  could it be an exhaust leak?  thanks for any help.  

Have you allways used a thick oil. Does it get worse if you use 10w30. Have you drained alittle oil to see if there is anything in it or cut open your oil filter to see if there is any bearing in it. You could try useing one of those stethascopes (think I spelt that wrong) with the long probe on the end and see if you can tell were its coming from. A buddy of mine has on, works pretty good. Think he got it at an auto parts store.  

i usually use heavier oil.  after doing some research on oils and filters, i think my mind was changed.  i pulled the motor rather than risking it.  the bearings look ok, i think.  i am going to replace them anyway.  no grooves, burns, or junk in the oil.  maybe one just got a little looser???  not sure, but i will check clearances before putting it all back together.  i would also like an opinion from anyone on filters and oil, synthetic and regular.  i read a lot of bad stuff about fram filter and a lot of good about ac delco and k&n filters.  also, my rings are broken-in, can i use synthetic oil on new bearings?  they dont need conventional to "break-in" do they?  thanks for any help.  

You have it right, stay away from Fram filters and definitely go with that synthetic. If you have good, tight clearances to keep the pressure up it will be undoubtedly better for your engine.  

If you have an engine that is older DO NOT run full synthetic.CarCraft just had an article about the contents of petroleum oil that are detromental to older engines.The specifics I cant recall,but I read the article in the last week or so on the website.If I recall it was headlined Petroleum or Syntheticr sumthing of the likeness.  

Hey CM,

You didn't mention what generation big block you had or whether the crank was stock or reground.  There's a big difference between vintage (90 & older) iron and the new stuff.  Machining and finishing processes and clearances are tighter for newer engines.  If you notice most new engines require the use of 5w-30 because of this, and the new factory roller cams.  65psi running and 30psi at idle is great for a stock pump.  Depending on the area of the country you live in a straight 30 or 40w is always the way to go on older iron, especially if the crank was reground and not re-nitrided.  Unless you live in the great white north,  than a 10w-30 would be better.

As for filters, Most $5 and below filters...well, nuff said.  Comparing a Fram to a K&N is like comparing apples to oranges.  The cardboard media and cheap bypass in a Fram doesn't even compare.  If you don't want to break the bank with that $12 K&N though,  you might look at Wix, Baldwin, or Fleetguard.  A NAPA gold also a good choice (made by Wix).  Decent filtering media and a much better bypass design for about $7-$8.

I've been building engines for about 23 years now and have never used synthetic oils or any additives other than GM EOS at assembly.  I don't have anything against them, most do just what they claim.  Just too expensive for me.  I can't justify $5 a quart for oil.  I've never had a failure of any engine related to oil failure.  I usually stick with an ash base oil (Valvoline, Castrol, Havoline Etc.). Not too fond of the paraffin based stuff (Pennzoil, Quaker state) unless your trying to stop a tired engine from leaking till you can overhaul.  I know all the Penn state oil guys are gonna jump on this but I can tell you after doing many tear downs, the sludge build-up in any engine running those oils is considerably greater than with ash base oils.

You also mentioned that you had a mechanical roller cam.  If this wasn't a total overhaul did you check the cam bearing condition prior to installing the new cam?  Remeber Chevy's oil the top end first.  Bad cam bearings will reduce oil pressure.  Your cam could also be the cause of your tapping noise.  If you've never owned a solid lifter cam before, they make some racket.  Completely normal for this type of cam.  

One last thing about bearings.  Make sure you're not using full groove main bearings.  This was an oldschool racer trick when I was cutting my teeth but it was a bad habit carry over.  Most companys still produce these bearings for the old crowd but they recommend you increase the viscosity of the oil you run.  Should tell you something.  The only groove you want is on the upper main bearing half. Those pistons are trying to push that crank right out of the bottom of the block and the only thing supporting the crank is about .002" of oil film.  That full groove reduces the weight carrying capability of the oil by the width of the groove. If your local supplier can't get you half groove bearings, go somewhere else. Hope this helps.  

Mr. Scott, I saw your post was fairly recent and felt compelled to reply.  I've built and run many big blocks.  In your configuration, I would suggest scrutinizing the roller lifters.  Solid rollers in street big block chevy's have a lot of failures of link bars, roller axles and roller wheels.  These can occur at very low mileage; sometimes 20 or 30 miles.  These can create clicks, taps or knocks ranging from the very mild to something that hammers badly.  That's my 2 cents worth.  If you find nothing there, you could look for a cracked or broken piston skirt.  Or you can get some odd knocks if aftermarket rockers are contacting valve covers.  One last parting shot:  Many cam manufacturers say solid rollers will live just fine on the street, but you need to buzz the engine every 30 seconds or so to keep them splash oiled.  To me, those 2 statements are at odds.  If a person has to do that, then those particular roller lifters are not street worthy.  I've yet to find solid roller lifters that will live in extended street usage.  Please let me know if you've found some that will live.    Best wishes,  Larry S.  

thanks so much for everybodys help and responses.  i am a bit of a rookie on a budget.  i pulled the motor and checked all the bearings, they looked ok, but i replaced them anyway.  i checked all the clearances with plastigage and they checked great.  i looked at the lifters and the cam and bearings, they all look good.  i dont have a huge cam, so my spring pressure is only around 140 lbs seat pressure, so maybe they will live longer (?).  i thought lifters were fed with pressurized oil?  am i wrong?  i guess roller cams and flat tappet cams have so many advantages and disadvantages.  i always hear that roller cams are the way to go because flat tappet lifters wipe out easier taking the cam with it.  i really like hearing all kinds of opinions, i try to learn something new everyday.  thanks.  

Hey CM,

I wasn't sure of your experience level when I responded the other day so I assumed you had been doing this for a while.  You've got the right attitude.  Most everything I learned when I started was from listening to "the old guys".  Some advice was great, some not so good.  Remember the old saying though "opinions are like ***holes, everybody has one and they all stink".

ASE master gave you a good bit of advice though.  If you put a mechanical roller in a flat tappet engine, there no provisions for oiling the rollers.  Comp makes a tool for grooving the lifter bore or you can groove the lifter body itself from the roller to the oil port to provide an oil feed.  Just remember this is almost creating a controlled oil leak which can also effect oil pressure.  

Another thing to look at is the timing chain cover.  Did you install a cam button or thrust roller on the snout of the camshaft and reinforce the timing cover?  A roller is completely different from flat tappet in that the lifters do not rotate in the bores.  This will make the cam try to "unscrew" itself from the block toward the timing chain cover.  This can create all kinds of problems depending on engine rpm from chipped cam lobes from the roller riding on the edge, chain damage, spark scatter from poor distributor gear engagement.Iskendarian has a very informative section on this in their catalog which you can download from their website.

The real advantage of a mechanical roller cam is the ability to run much more radical spring pressures and higher lift ( up to .700").  Really not necessary or desireable for a mild street build.  The added cost and aggravation of constant valve lash adjustment checks for a very meager if any increase in performance from friction loss isn't worth it.  You can gain much more horse power in the street rpm range from a decent flat tappet hydraulic cam and variable duration lifters like Rhoads or Comps and not have to set lash.  Plus the variable duration lifters will allow you to get away with overcamming just a bit and still maintain a decent vacuum for accessory operation.  Plus you don't have to worry about cam walk.

I've built engines from grocery getters to mud racing, marine and all out 1/4 mile and for the street a good flat tappet hydraulic, or hydraulic roller in a late model block with roller provisions is the way to go.  Set the lifter preload on initial build, do your 20 minute break-in @ 2000 rpm, do one more hot check of preload and don't mess with it again.  I'd rather be cruising than checking valve lash.  

the motor didnt have too many miles on it, maybe 1500 or so.  pretty much everything i have learned is from the "old guys", books, magazines, and just not being afraid to ask and research when i have a question!  i do have a cam button, its one of the fancy ones that have a bearing and spins.  i also have an older block (mark iv), so i guess my lifters arent getting the oil they need.  i only have a .622 lift (238/246 @.050) with .018 lash, so the cam isnt too radical.  actually with the positive locking nuts, the lash doesnt move.  but youre correct, i have checked it to be sure several times, i wouldnt have done that with a hydraulic.  owell, i guess if i dont wrench on it i wont learn anything new!!  thanks to all.