Thoughts on Motor Honey?

[SJTD]

Going by his theory that his low pressure is due to the worn pump, if he gets a pressure boost downstream of the pump then there's more oil flowing out of the pump.

The question is whether that boost in pressure overcomes the higher friction in the rest of the engine due to the heavier oil for a net increase in flow to the bearings, etc. Maybe, maybe not.

One way to look at it would be is 20-50 ok for a new 401 with presumably nominal clearances?

If not then he shouldn't use it since even if the pressure is higher than with the oil he started with it won't be as high as it would be with a good pump and the flow isn't enough with that good pump.

[PlasticBoob]

Does anyone have a service manual with 401 tolerances? Are they the same? I am hoping the Steel crank needs slightly higher clearances? I am about soil myself if they are the same or tighter....

Here ya go, from '74:

[Ristow]

Go dump 20w50 in the motor and start it on a 0 degree day and let it idle. You’ll get 60lbs oil pressure yet have little oil flow. You can pull the valve covers and watch oil volume increase thru the pushrods as oil pressure drops and volume increased as it warms up.

Pressure does not necessarily mean flow.

[PlasticBoob]

I see a Bulltear nickel-plated timing cover in your future....

https://youtu.be/9nEF5n9gZGY

Do they even still make them? haha

I have the valley oil line mod and still make insane pressure like this.

I'm at around 12-15psi in gear on a 90* day with 10w-30 synthetic fully warmed up. IMO these 401s in warmer climates need oil coolers, especially since most machine shops bore them .030 over.

[PlasticBoob]

I'm at around 12-15psi in gear on a 90* day with 10w-30 synthetic fully warmed up.

Scratch that - I just looked at the gauge again and I'm around 15-20psi. Ugh, I really need to drive the Jeep more...

[Ristow]

I got a bunch of covers here , sometimes the covers are just wore out. I’ll run a good own cover over a gimmicked up Chinese pos every time.

Your clearances are fine. You really need to verify with a mechanical gauge. Especially if you have replaced the oil sender, the new ones make the gauge even more unreliable.

[babywag]

Idle was 750 at last OP check. This BIN I lowered it to 650 but have not started on this BIN yet.

My Machinist receipt says Mains are .0023 (plus or minus .003) and rods are .0026. 1979 Service manual for 360 says the correct clearance is .0017 to .0020 on No 1-4 mains and .0025 to .003 for the rear main. I do not see a clearance for the rods. This means I am out of tolerance and that may be the source of my low OP.

Does anyone have a service manual with 401 tolerances? Are they the same? I am hoping the Steel crank needs slightly higher clearances? I am about soil myself if they are the same or tighter....

That is why I didn't pay the shop $300 to assemble my LT1.
I used a mic and have my sheet with every clearance. I don't trust anybody these days.
What's with the +/- .003??? that's very ODD is that a typo?
They couldn't even bore the thing right and I had to bring it back for a 2nd round.

[FSJunkie]

I get so tired of machinists building AMC engines to Chevy clearances.

Nearly all of the problems people experience on AMC V8's is not the fault of the lubrication system. It's the fault of improper clearances. People then modify the lubrication system as a stopgap to cover up for improper clearances.

Buick engines are worse. Same problems but much, much worse. One of them built to Chevy clearances makes 0 PSI at idle, 20 PSI going down the road, and will last a few thousand miles at the most before it wipes out every bearing in the bottom end and trashes the crank in the process. Buicks have to be built very tight. Almost modern engine tight. AMC engines are not quite to that point but it's the same idea.

[rang-a-stang]

What's with the +/- .003??? that's very ODD is that a typo?

DANG IT!!! TYPO!!!! should have been +/- .0003! Receipt:


Looking at Plasticboob's post (74 shop manual) it looks like these clearances are spot on for 401? SO I think I let this ride until I get the mechanical oil pressure gauge AND I replace my timing cover.

[babywag]

That's better. .003 is a huge +/-
Still lame stating +/- .0003 though, that's just lazy so it could be tight as .0020 or loose as .0026.
Just outta curiosity what did they charge you for the lack of actual info on clearances? yes I am picky/anal

[rang-a-stang]

I think that mock up line was $49? I'll verify tonight. I took that picture as I was heading out the door this morning. I had them do it because they are 45 minutes away; that money saved me a few back and forths to his shop. By having him do it, I gave him a box or bearings and my engine and he returned a short block ready for assembly.

Another lesson learned I will add to my build thread: make sure to specify the correct clearances if you are paying the shop to set them.

mechanical OP gauge gets here tomorrow. I hope to install it Thursday.

[SC/397]

Here are the bearing clearances for 1969.
Mains .001" - .002"
Rear Main .002" - .003"
Rods .001" - .002"
Both of my machinist usually hit .0015" - .002" on both the rods and mains.
Some of the low oil pressure issue could be due to oil pump end clearance. I lap the timing cover to get near zero clearance with the gasket in place.

The grooves inside the housing don't seem to affect oil pressure as much as the end clearance.

I personally wouldn't buy any after market timing cover nor would I use a mid plate. If you want to send your timing cover, oil pump, and oil pump cover to me I could tune it up for you and at least eliminate that variable.

Which brand bearings did you use? King bearings run to the big side compared to Clevite.

[Ristow]

Yah, I wonder if he has full groove main bearings , that will bring pressure down a bit. ACL are full groove as I recall.

[rang-a-stang]

Sigh...

I used Clevite 77's all the way around.

I am going to pick up another (OEM) timing cover tomorrow morning and re-do the oil pump in the coming week or two. I think I must have done a poor job clearanceing this one. (AND I still need to verify my oil pressure gauge) I may take you up on the offer, Rick. I'll PM you for payment and shipping.

They are half groove mains. I posted up asking for recommendations when I was getting ready to buy them and your (Ristows) advice was to avoid the full groove mains.

So with clearances this wide, am I doomed to run 20W-50 for the life of this motor?

[Ristow]

Cleverest are good. Your clearances are fine. Get a better cover. Also you were crushing filters, you may have other issue too.