Clearances and Oil Pressure
 

I know when something is out of my wheelhouse...so I need some advice.

Just received my short block back from the machine shop...after the previous shop completely buggered it up. It required an align hone on the mains and cam tunnel. This time it was balanced properly etc.

Compression is 11.5:1 , lot of work done to the round port E-Heads, Crower 60919 cam with 1.65 rockers., domed pistons

It is a 455, bore's are now 4.182, main bearings clearance .0032"-.0033", Rod bearing clearance .0026"-.0027".

Should I be using an 80lb. oil pump or stick with the 60lb.?

I ran a 455 with looser clearances than that and a 60lb pump for years.
Its personal preference, both will do what you need.
Latest engine I have has a shimmed 60lb pump that is now 80lb.

I assume that since you are running dome pistions that your E heads are not the 72 cc version?

With that Crower Cam and your CID you not going to need to shift above 6000 rpm, so I would shim the pump for 70 psi and call it good.

All 455 cranks are crossdrilled from the factory so they oil the Rods some 30% more then the 3.00" main journal cranks as it is even without the use of half groove Bearings.
The added pressure is needed strictly for the 4.210" mains.

Any unneeded pressure and rod side clearance will only serve to put more oil draped around the rotating crank & Rods and this leads to a power loss and potential oil control issues

"Any unneeded pressure and rod side clearance will only serve to put more oil draped around the rotating crank & Rods and this leads to a power loss and potential oil control issues"

Will also throw more oil at the camshaft , thats not a bad thing

Then why does the factory not build a short block that way?

So you denie that a short block built otherwise can't go well over 60k plus miles like a factory build can with normal oil changes and good oil?

I think your stretching things a bit here!

If your talking to me 25 I never alluded to any life expectations..

the factory did use higher pressure pumps.

And " Then why does the factory not build a short block that way?"

Pretty silly statement because that statement could be used against EVERY modification you have done to any engine your whole life

flat tappet cams will never be worse off with more oil.

does it depend on what weight oil you end up using?

Ok, I’ll play this game you started longer.
So exactly how does one determine how much extra oil wound around a crank due to increased oil pressure is enough to extend cam life?
when the exh starts to smoke at idle from the second compression / scrapper rings starting to be overwhelmed, is that then enough?

Not playing your game.. i didnt start any games i pointed out a true simple fact go play with yourself

Actually they are a very early version of the Performer RPM that is 87cc.
Between the block decked and heads shaved, the Venolia pistons had to be shaved down to lower compression to 11.5:1.

Motor spent most of its life in a 1975 Firebird Pro Street car (2800lbs., 4:11 gears, tube chassis, big tire, CC290B solid cam). So I had to make some changes to use in my 81 TA street car.

I would run a 80 psi pump. Have built many with similar clearance. I use vr1 20 50 also.

X2 here

GT

I see that the difference between the 60lb. and 80lb. pumps on Butler's site is mainly the spring length.

But is adding a shim to a 60lb. pump just as good as using an 80lb. pump?
Otherwise, why wouldn't the 80lb. pump simply be using a stiffer spring instead of the longer spring?

I hope I am not asking too many questions, but I got stiffed by crooked machine shop and had to go to another shop to get the short block redone correctly.
So I want to be sure everything is correct this time.

You can swap a 80 PSI spring and cup onto a 60 psi pump and make it a 80 psi pump. I have shimmed the 60 psi spring around .070 and it nets you around 8 more psi. At some point you will hit coil bind shimming the spring.

Looks like it's better to be safe than sorry and go with a new 80lb. pump.
Costs a lot more to fix than prevent.

60lb pump imo.

2X Slowbird.Tom

Old 455 had .035-.004 on the mains, 60 lb pump. Ran forever.
New engine, 60lb pump, 9/16 ball and .074 shim. Lots of oil pressure. Modified pickup with near .90 inlet dia.
I had so much pressure with 30 WT I had to put some 10-30 in just to get it below 90lbs.

Curious: So if engine being spun to say 7200 rpm, 60 psi pump still or would you go 80 psi?

There are many factors that go into a answer to that.

First and foremost is the crank a 3”” or 4.210” main?