Originally Posted by twmattox
I am getting my 360 rebuilt. I stripped it and dropped off at a machine shop.
They indicated it needs bored (40 over) and the cam ground (10 under).
I think you mean cylinder bore of 0.040" overbore,
THE CRANK (not cam!) turned 0.010" under size.
This is pretty common...
AMC used a little more Nickle in the cast iron than they should have, so the blocks were softer.
0.040" on the block is usually to take the 'Funnel' shape out of the bore.
Rings wore the top of the cylinder more (less lubricant/more heat at the top) and the cylinder gets to looking like a FUNNEL! Wide at the top and narrower at the bottom!
I've not had the opportunity to receive a 360 AMC engine yet that didn't need at LEAST 0.030" to make it straight/round again, and 0.040" is more common than you think!
Although I try not to turn the cranks under if I can keep from it since the 360 had a cast iron crank, and any material you remove weakens it.
Also, The 'MAIN JOURNALS' where the main caps hold the crank in the block,
And the 'ROD JOURNALS' the connecting rods hook to the crank at can be turned differently if one or the other doesn't need turned...
It's only a few bucks extra for the odd sized bearings, and it's worth keeping the 0.010" of material on the crank if you can...
Although most of the cast iron Rod Journals will be "Egg Shaped" since pressure is only put on 1/4 of the journal during 'Compression Stroke' and then pressure put on the following 1/4 during 'Power Stroke',
1/2 of the journal will have virtually NO WEAR, and that makes for a 'Big Side' and a 'Small Side'.
When seen in cross section, it is 'Egg Shaped' so it all has to be turned round and true with crank centerline again...
I like to have the bearings in the block and/or rods and 'Torqued' before I turn the crankshaft, I can get an EXACT inside diameter measurement from the bearings...
When I know the EXACT inside diameter of the bearings,
I can turn the crank SPECIFICALLY to fit each bearing...
This keeps oil loss to a minimum, and you need ALL the help you can get in an AMC engine!
I want to make sure it lasts a long time and have been told of a few oil modifications to make to the rig (though it is hard to understand why these things would not have been done from the factory if they are such improvements). Problem is I can't seem to find any real instructions on what to do or how to do it.
1) I found a fairly detailed hand drawn picture called AMC V-8 oil system mod #1. It indicates using a rotary file or drill bit to enlarge a hole in the oil pump housing (though it appears to be on the timing chain cover portion). Is this recommended or not?
By all means open that port in the pump body up!
Delivery VOLUME will be increased to the rest of the engine.
Won't matter when the engine is new and fresh and tight,
But later, when the bearings are drooling oil every direction, it will help you keep pressure later!
2) I have found pictures regarding a valley oil mod (sometimes referred to as a rear main bearing oil mod). It appears to be a copper line running from the front of the engine to a hole drilled in the rear (all in the valley). Does this affect oil pressures (my neighbor is afraid this will prevent the engine from building pressure)? What diameter line is recommended? Is this a recommended mod?
Your neighbor doesn't understand hydraulics or fluidics.
What you have to watch is,
You don't want to drill too deep, just into the oil passages both front and rear,
You don't want to use too long of a fitting that will block the passage that is already there.
Personally, I remove the rear gallery plug and drill out the stock passage just to make sure I didn't impinge on the factory passage with the fitting...
You will need a THOROUGH block cleaning after the machining!
You MUST use brushes and clean out all the metal from the galleries or it will wind up in your bearings somewhere!
I don't use copper line, copper will vibrate and fatigue fairly quickly (work hardens where it bends during vibration).
I prefer a flexable line with SOFT jacket!
DO NOT USE STEEL BRAIDED OUTER JACKET LINE!
The stainless steel outer will SAW THROUGH anything it comes into contact with! And those are metal shavings you DON'T WANT in your engine!
As for your neighbor,
Have him put a garden hose to his LEFT ear, then turn the spigot on and see if the water gets to his RIGHT ear...
Then, put a 'Y' in a garden hose, have him stick one in each.... Ear...
And turn the hose spigot on...
Ask him if he's getting water to both sides of his head!
Same difference with a single oil feed front to rear,
By the time the cam bearings, lifters, and front 3 mains leak off all the oil volume/pressure/supply, there isn't any for the REAR of the engine,
In particular the rear two mains and 7/8 rod journal...
By supplying pressure DIRECTLY to the rear of the engine,
The pressure/supply evens out from one end to the other in the engine, and the pressure doesn't drop to ZERO in the back of the block when things get some wear on them!
3) I have heard about a mod that pumps oil from the oil pressure sending unit to the dizzy gears. Again, recommended???
I've done them on race cars, and I've done them on Jeeps.
Never had a problem with race cars, but I've managed to pull the lines loose TWICE in jeeps...
Most of the time, If you make VERY SURE the front thrust washer oil passage hole (if one is used) and the top timing chain sprocket passage is clear,
Like wise with the rest of the passages,
You will be fine without this modification.
What happens most of the time,
You get replacement parts with the oil passages full of Casing flash, chips from machining, or they drilled in the wrong place, or in some cases, just plain missing/not there!
4) One site strongly recommends using special cam bearings, rockers, and push rods (all with smaller diameter holes) to increase oil pressure. Recommended?
Clevite 77 Bearings are the top of the heap, and very competitively priced!
I use them in ALL racing engine and 'heavy service' engines for years with absolutely NO problems!
As for push rods or rockers...
Good quality is the name of the game!
You don't have to pay a fortune, and you don't have to get some special kind...
Remember, there are engines with 200K on them using nothing more than stock,
And unless you are going racing and want ultra light for higher RPM operation, There is no SENSE in getting too bent out of shape on that stuff!
5) I do have one of the late model oil pumps (manufactured by Chrysler that has eliminated the oil filter bypass). I was told this was a good thing...true?
They don't crack as easily/ better casting than the AMC versions.
Pressure bypass wasn't an issue in most cases unless it stuck open from broken spring or crud snagged in it.
Modern canister filters all have filter bypasses built into them, so a dirty filter won't starve the engine for oil...
I'd say use what you have, it should be fine as long as the base for the pump isn't scarred/scratched up.
Though not an oil mod...I do have a question about cam/dizzy gears. I will be putting in a new cam (Clevite 77 RV cam) and a new double roller timing set (I believe Cloyes). Do I need to do something special with this (someone told me I needed to have them "matched")???
Nope, you can use your old gears if they are still in good shape,
OR, you can buy new from a reputable source.
Chrysler still has them available,
NAPA sill offers them, although you will probably have to root through paper books to find what you need,
MSD still offers both in high quality product.
Just stay away from the E-bay and '$20' gears...