Oil Pump Rant:

[Comanchedude]

So when the HV pump creates more pressure at lower RPM's that means it is putting more resistance on the timing system and using more power to turn the pump to create that added pressure.

That would be an assumption. Its not a given that you would increase pressure, it can but it’s not a given in every engine. ”barring a brand new engine of course even then it would not exceed the bypass of the pump in any case” so your factory pump would run the same pressure most likely as the HiVol given the same tight engine. so no gain and I agree it may not be needed.but add a oil cooler or remote filter kit and then we have a use for it again even on a new engine.
If you would agree that most 4.0 engines in service have over 100k miles then you would also agree they have increased clearances through normal wear and a Hi vol pump replacement would at best regain factory pressures at the lower rpm and throughout the operational range.Most 4.0 run 3k or below most of their lives so the added “flow” would actually benefit the engine. as for power use? well really unless you run some heavy weight oil..in this case you would not use any significant power. kinda like taking off a belt driven fan, did it save a couple ponies sure.. do you really feel the difference...no

 

[Boatwrench]

Jon,
Getting wrapped around the axle measuring oil volumes, viscosities, pressures and flows to the nth degree as here in this thread doesn't make sense. It's a 4.0, it's 5.5 qts, it doesn't push large hulks of steel across oceans, race down the track or produce combustion chamber pressure enough for us to be concerned with canibalistic frictions or two more degrees of heat in the sump. The larger engines that have large volume of oil, it makes sense.

It's been a fun read, pretty worthwhile discussion, but bordered on uncomfortable for me at times in tone which, and thank you for this, terryd pleaded me culpa.

The 4.0 is a long lasting relatively trouble free little torquer. I have used a hi-vol pump in a 258 to compensate for worn cam bearings, but was never concerned about 'walking the cam' more concerned with spinning a main.

3208s aren't they fire truck engines that not only have to be variable speed, but once on scene have to perform as a stationary fixed output engine? Constant speed duty cycle engines usually have the larger sumps. The 6V92s used on buses had a smaller capacity than those we have on the boats.

Tom

 

[5-90]

Jon,
Getting wrapped around the axle measuring oil volumes, viscosities, pressures and flows to the nth degree as here in this thread doesn't make sense. It's a 4.0, it's 5.5 qts, it doesn't push large hulks of steel across oceans, race down the track or produce combustion chamber pressure enough for us to be concerned with canibalistic frictions or two more degrees of heat in the sump. The larger engines that have large volume of oil, it makes sense.

It's been a fun read, pretty worthwhile discussion, but bordered on uncomfortable for me at times in tone which, and thank you for this, terryd pleaded me culpa.

The 4.0 is a long lasting relatively trouble free little torquer. I have used a hi-vol pump in a 258 to compensate for worn cam bearings, but was never concerned about 'walking the cam' more concerned with spinning a main.

3208s aren't they fire truck engines that not only have to be variable speed, but once on scene have to perform as a stationary fixed output engine? Constant speed duty cycle engines usually have the larger sumps. The 6V92s used on buses had a smaller capacity than those we have on the boats.

Tom

I'm not getting "wrapped up" - but you've known me long enough to know that I'm addicted to information... So, I'm just looking for more. I figure it's about the only hobby that California will let me have anymore anyhow.

The 3208s I worked on where in heavy trucks (airport fuelers) and assorted OHVs, but I think they're used in fire trucks as well - just with slightly different control setup. And, 22 quarts is the small sump on those - I think they can be had with 22, 26, and 30 quart sump pans (or somewhere thereabouts. It's been a while.)

 

[terryd]

If you would agree that most 4.0 engines in service have over 100k miles then you would also agree they have increased clearances through normal wear and a Hi vol pump replacement would at best regain factory pressures at the lower rpm and throughout the operational range.

I do believe one of the PDF"s you posted from Melling said a high volume pump was not designed for this purpose. Also, many production vehicles have oil coolers and external filters and do not have higher volume pumps so I'd also have to disagree on that one to. I do not understand the need for it on external filters, you're still running oil through a filter An oil cooler I can understand a little being that alot of them are parallel to the oil flow paths and not in the direct flow path, creating the need for more oil to be flowing. But so many people out there with towing rigs put on oil coolers with stock pumps and have no problem with them. I actually drilled holes in a few places on my blocks to improve oiling to the timing chain and cam thrusts and didn't see hardly any drop in my oil pressures from when the motor was put together the first time.

 

[1bolt]

Sadly, Chrysler decided to reduce the nickel content of the alloy starting in 1991, along with lightening the casting (for NVH reasons. I don't understand that - if you want a quiet ride, get a Caddy or a Lincoln!)

Not trying to question your nearly encyclopedic knowledge of the 4.0, but I'm curious where you found out about the nickel content? I'd love to read it, is it from one of the mopar engine books?

The lightening was to reduce the _amount_ of iron and weight of what is one of the heaviest per cube gasoline engines in production in the last decade. The 4.0 weights more than either ford or chevy late small block V8 (302 or 350, don't know about the 4.6 modular).

Considering the power output and the RPM range there's simply no reason for it. How rare is a cracked 4.0 block of any vintage? Pretty damn rare in my experience. I can't give away 4.0 bare blocks.

Lastly NVH was done by stiffening... primarily with the crank girdle but also with changes to the internal webbing and improvements in casting technology (read; more consistently in tolerance, less core shift, more consistent wall thickness).

You can't reduce NVH by weakening an engine block or lightening it... Quite the opposite, to reduce vibrations requires stiffening the block; In key areas that are most likely to reverberate noise, or become the source of noise... Not coincidentally those key areas are also likely to be the weakest surfaces of the engine block, longer planes and angles that can vibrate most readily. A nice side effect of reducing NVH is that those same area's are made less weak with more material or better engineered structure (webbing).

The implication I draw is that the newer blocks should be both lighter AND stiffer, if they flex less, that ALSO means they will last longer, and they will stay straighter, their cam shafts (and bearings) will last longer. If they have poorer iron then the sacrifice will be more wear in the cylinder bore..

 

[5-90]

Not trying to question your nearly encyclopedic knowledge of the 4.0, but I'm curious where you found out about the nickel content? I'd love to read it, is it from one of the mopar engine books?

The lightening was to reduce the _amount_ of iron and weight of what is one of the heaviest per cube gasoline engines in production in the last decade. The 4.0 weights more than either ford or chevy late small block V8 (302 or 350, don't know about the 4.6 modular).

Considering the power output and the RPM range there's simply no reason for it. How rare is a cracked 4.0 block of any vintage? Pretty damn rare in my experience. I can't give away 4.0 bare blocks.

Lastly NVH was done by stiffening... primarily with the crank girdle but also with changes to the internal webbing and improvements in casting technology (read; more consistently in tolerance, less core shift, more consistent wall thickness).

You can't reduce NVH by weakening an engine block or lightening it... Quite the opposite, to reduce vibrations requires stiffening the block; In key areas that are most likely to reverberate noise, or become the source of noise... Not coincidentally those key areas are also likely to be the weakest surfaces of the engine block, longer planes and angles that can vibrate most readily. A nice side effect of reducing NVH is that those same area's are made less weak with more material or better engineered structure (webbing).

The implication I draw is that the newer blocks should be both lighter AND stiffer, if they flex less, that ALSO means they will last longer, and they will stay straighter, their cam shafts (and bearings) will last longer. If they have poorer iron then the sacrifice will be more wear in the cylinder bore..

I'll have to dig through my notes - but I note that AMC was fond of high-nickel iron alloys, while the only real high-nickel "Big 3" castings were for the second-generation 426 Hemi.

While the later 242 blocks may be stiffer (and lighter - the first NVH revision dropped about 50 pounds, with another 20 or so at the second,) the reduction of the nickel content of the alloy actually makes them less tough, not more. Toughness in an alloy has more to do with the chemical composition of the alloy - and a high-nickel iron is both "tough" and resistant to abrasive wear (like with piston rings.) However, increasing the nickel content usually costs more - which is why Big 3 beancounters don't like it.

As far as where I got the information, I think it was from a combination of research into AMC vice Chrysler production - as I said, I'd have to check my notes (and I'm working on something else at the moment, so it may take a while.) I doubt it's apocryphal - I've been wrong before, but this seems too "fixed" for it to be a mistake on my part (and I do know that at least the early blocks had a relatively high nickel content - I haven't had an assay done, but I've seen how they wear, and I'm much impressed.)

And yes, the 242 is a relatively "heavy" engine - both in pounds/cubic inch and pounds/horsepower (a fully-dressed AMC242 weighs in around 550#, so you're looking at about 2.27#/ci and, for RENIX, about 2.97#/fhp, assuming RENIX at 185fhp peak output. Engine pounds/foot-pound of output would be slightly lower.) However, even the traditional small block engines (Chevvy 305/350, Ford 302/351C/351W, Chrysler 318/360) were revised to accept aluminum cylinder heads and aluminum heads have been available in the aftermarket for years - while the AMC six has just caught up as of about six years ago (they came around shortly after I tried to talk to Russ Flagle about the idea, as a "Strokers" emissary, around FEB2002. I was heading to Indy anyhow...)

Those figures are also for a "fully-dressed" AMC six - meaning with all accessories, but "dry" (no fluids.)

There's no particular reason that the AMC six legacy could not have continued tho - BMW has been using inline sixes for just about their whole run, I think MBZ still uses them, Chevvy has brought them back in Vortec trim, and I'm wondering how long it will be before the Chrysler LG/RG series (Slant Six) gets resurrected... That was also a veridam good engine, and I've often wondered why it's not still around (especially as the Hemi Six that was used by Holden in Australia. I think it was Holden, anyhow...)

 

[terryd]

I can't give away 4.0 bare blocks.

If they have the crank and main caps, I'll take every spare one you've got!

 

[MudDawg]

One thing brought up was the issue of SBC engines pumping oil into the valve covers and starving the engine for oil....this was a very common problem (and may still be...I havent seen the inside of a Gen XXX SBC) because the oil returns were smallish and with large diameter pushrods in hipo applications took up much of the space where oil could drain thru the pushrod holes.

Toss in the inherent over lubrication of the valvetrain, and the problem is/was real...we ran a 350 in C Mod Camaro....the oil return was an issue...we cleaned up the oil returns (deburred and opened up) and used the old trick of painting the exposed surfaces with Rustoleum...and restricted the oil flow up the pushrods (we ran roller rockers)...added an 8 quart oil pan...extended the breathers and tied them into a ventilated puke tank...this was well before crankcase vacuum pumps and other such wizardry....this took care of the problem well enough for a 1/4 mile pass....