Getting Enough Oil

[milnersXcoupe]

Crossdrilling a AMC V8 crankshaft should NEVER be done without other heavy mods already in place.

Which other mods specifically ?

We open up the last 3 mains to .339 which is .020 larger than the stock .319.

since AMC rods are fed AFTER the AMC mains -
and one reason people do not cross drill the mains is
because the rods are fed through the mains
and if you cant get oil to the rods you spin a bearing......
but you've rods 2,4,6&8 conceptually "somewhat starved
for oil during the power stroke, which probably is not desirable"........

how does one solve this AMC dilemma ?

Increasing the amount of oil delivered by the main galleries -
which could necessitate rifle drilling them out by how much safely ?

- and -

running a supplement oil line to the back of the block ?


might just add a can of STP and call it even =D>

[AMX69PHATTY]

I'm no expert, but I thought by cross drilling the mains

it allowed more continuous oiling to the rods

since one of the now 2 main journal oil holes would then always be

exsposed to the one main bearing half that contains an oil groove

which main journal in turn then continuously feeds adjoining rod bearings ?

[82Waggy]

Crossdrilling is BS - it requires that the oil flow through the main journals reverse direction twice per revolution - pulses flow to the rod journals and slows flow. All engines rod bearings are fed after the main journal bearings -duh.

Screw all that nonsense. Make sure your pump is in good working order and your bearing tolerances are good - get over 20 PSI at idle and you are fine.

Just say no to valley bypass line leaks - what a crock of moronic engineering.

AMC's have a better oiling system than most - including Fords and SBC's. Tell them all to bite you and go on down the road.

[tarior]

AMC's have a better oiling system than most - including Fords and SBC's. Tell them all to bite you and go on down the road.

As much as I love AMC, the stock oiling system is really only adequate for street passenger car use. Even today, guys have trouble in road race applications, unless they use a dry sump.
Modify it for long life.

[Kevin Johnson]

AMC's have a better oiling system than most - including Fords and SBC's. Tell them all to bite you and go on down the road.

As much as I love AMC, the stock oiling system is really only adequate for street passenger car use. Even today, guys have trouble in road race applications, unless they use a dry sump.
Modify it for long life.

A classic problem in crank oiling is air entrainment. The more air that is entrained the further the oil departs from the behavior of an ideal fluid. Apart from the pickup being possibly exposed in high G maneuvers, the oil conditioning that a dry sump offers (deaeration) is testimony to this.

The scraper helps keep down air entrainment. Another thing to think about is running a vacuum pump on the crankcase. This makes it more difficult to entrain air in the first place. It also allows you to safely run lighter tension rings which in turn reduces parasitic drag.

[Goose]

Another thing to think about is running a vacuum pump on the crankcase. This makes it more difficult to entrain air in the first place. It also allows you to safely run lighter tension rings which in turn reduces parasitic drag.

This brings a question to mind.. Old school drag racing, we used to run a breather line from one of the valve covers to the exhaust behind the header.. This actually imparted a bit of vacum to the crankcase and helped.. But I dont see it much anymore..(I have seen a mechanical fuel pump hooked up to a valve cover?? I cant imagine that helps much but hey what do I know??)

[Kevin Johnson]

Another thing to think about is running a vacuum pump on the crankcase. This makes it more difficult to entrain air in the first place. It also allows you to safely run lighter tension rings which in turn reduces parasitic drag.

This brings a question to mind.. Old school drag racing, we used to run a breather line from one of the valve covers to the exhaust behind the header.. This actually imparted a bit of vacum to the crankcase and helped.. But I dont see it much anymore..(I have seen a mechanical fuel pump hooked up to a valve cover?? I cant imagine that helps much but hey what do I know??)

It is the same idea and it works for an engine under full throttle. It is not a consistent enough vacuum level, however, for the lighter tension rings. The speed and mass of the exhaust flow under partial throttle is not enough to induce a good Bernoulli effect. David Vizard talks about this in one of his books.

EDIT: fuel pump mod -- lots of times this is hidden. It increases the flow rate of the pump. Well -- I should say you "can" hook it up to a vacuum source to increase flow rate. When I first read your post it sounded like they were doing the extractor and fuel pump at the same time.

If they are using a fuel pump to evacuate the block -- might work. Talked to a few builders using the aux pumps from diesel engines and from the GMC SUVs (also BMWs). They will apparently draw down an LS6 10". Longevity is an issue because they are not intended for an oil vapor rich environment.

I was told there is a diesel engined Toyota in Europe with a vacuum pump built into the alternator -- there's your trick setup. ;)

[Goose]

We used the header hookup on a A/econo-rail 402 chevy bb in an old retired slingshot dragster chassis, (wow what a handfull!) Great big tall slicks on both sides of your head and the narrowed 9" rear differential was part of the Seat pan..(I swear really !) with a 2 speed powerglide.. put in drive point it at the far end and pull the trigger, 8 seconds later you found out how it all turnd out..If you opened your helmet and heard harp music or smelled sulphur burning, things had not gone well.