I get it and totally agree with you.

 

Well, sorry guys, but as a Physics Teacher I am going to have to call this one "Myth Busted" That would be correct about a HP one, but not a HV one, depending on some other details. You've heard of "urban legends" and the "story that goes around the room"? Well, unfortunately a lot of that goes on in racing, and it is sometimes very difficult to separate the wheat from the chaffe.

This HV pump was installed for a very specific reason for a very specific problem that needed a solution. And it is not a HP pump.

Here is a link to some myths and information about oil pumps: https://www.melling.com/aftermarket-...u-k/technical/

Engine Oil Pumps explained:

The key point is fluid dynamics says there are only two items that control oil flow through an engine:

1. Engine clearances
2. Oil Pressure

Note that pump output volume has nothing to do with it! Obviously if the clearances are loose the openings are larger and more oil flows. If the pressure is increased by any means, more oil flows. However oil pumps are positive displacement pumps and their output increases linearly with with RPM. So what gives? Duh? At low rpm a gear rotor oil pump is barely moving enough volume of oil (gpm) to keep an engine happy. The clearances are a bit large for the output flow so the psi can't build very high. It just kind of oozes out under 10 psi pressure. Thank heavens the rods aren't pushing on the crank very hard. Somewhere around 4000 rpm or so the oil pump is pushing out all the volume of oil that the clearances can get rid of, and the increasing pressure finally pops off the internal oil pressure relief valve inside the pump. After this, with extra rpm, the pump tries to pump more oil, but the engine can't take it, so it is "bypassed" from the output of the pump back to the inlet, by the PRV, inside the pump. Aren't BBCs set at 70 psi or so? At double that rpm, the pump is bypassing 50% of its output back to the inlet. Why go thru all this? Because at peak power levels 4000-7000 rpm the bearings need 70 psi of oil pressure, not 10, to keep from scuffing. You could run that psi at idle, but the oil would heat up excessively. You could run a electric pump, but think of how un-reliable that would be.

So increasing the PSI with a HP pump will definately pump more oil upstairs at high rpm. More pressure on the clearances and more oil flows. Don't some Fords run 130psi? Ouch! If you run the engine clearances "loose" for racing, then even more oil flows. And the whole motor, oil pan, drain back and every thing else had better be designed for it. That is not a speed where you want the oil pump to suck dry. It's really too bad we do not have "Oil flow" meters on our engines, the "Oil Pressure" ones are just an easier band-aid fix, although somewhat confusing.

But at low rpms, before the psi peaks and the PRV begins to bypass, the oil pump is really not putting out much volume, maybe 10% of what the pump is rated at, because it is positive displacement gear pump and totally dependent on rpm. The factory oil level at this rpm is enough for a factory built clearanced engine. This is why worn-out engines or race-clearance engines have such low oil pressure at idle!

But this is a solid roller lifter engine. Their well known weakness is not enough oil flow at idle. That is what kills the rollers, the Idling. So solid rollers have had bad reliability when driven on the street. So in this engine several precautions were taken for the solid lifter rollers to live on a street engine.1) High Quality Morrel Lifters.2) Pressure fed oiling to the rollers. 3) Carefully inspected/measured lifter bores. 4) Then we increased the oil flow at low rpms by putting in a HV High Volume pump, but a standard pressure one. Jeff may have taken a HP/HV pump and put the std pressure spring back in, I am not sure there. Or he just bought a HV one that was not HP. But the HV pump will put out 15% more volume at every rpm vs the std one, until the two pumps hit their pressure setting. So after somewhere in the mid 4000 rpm range both pumps would be reading exactly 70 psi or so and pumping exactly the same volume of oil. The HV one will be bypassing a little bit more than the other one. So cruising oil temps need to be watched a little. Well isn't hot oil the case on every BBC anyway? The volume of oil pumped thru this engine at 6000 rpm should be exactly the same as a stock one because the PSI is the same, and the clearances are tighter than a race engine, they are closer to factory settings.

As an added precaution to ensure that the solid roller lifters survive street use and traffic jams, I will monitor their valve lash settings and the oil change chemistry a couple times a year. If one lifter starts increasing clearance, and or the oil test starts showing roller material in it, then it's time to pull them for a check. I am hoping, and trust my builder, that this will not be too frequent. It's just a safety net so I don't kill the engine.

Sorry if this is long, but I tend to get very analytical with this stuff. I enjoy it, I just hope some of you do and I am not boring you with it.

 

Ok ready for Dyno Test next Saturday!
In the meantime I thought I would detail my engine build costs for you here if anyone is interested.
I probably could have had a 454 rebuilt for about $3500 or so, if I handed him a complete engine to start.
But I did not, I had to buy everything from the air cleaner down to the oil pan, as I started with nothing.
And I wanted an authentic 4 bolt main, steel crank, aluminum snowflake head, forged crank/pistons,4803 Holley LS6, or as close as I could get, and all blueprinted..
So I had to buy a LOT of parts.

Here's the results
$2,100 in machine shop work
$9,600 in parts
$11,700 Total

Detail is attached in case you are building or rebuilding a BB and want to do some estimating.

 

Damn!! That’s pricey... but good stuff is expensive these days. Hell I spent $5600 refreshening my 496 and that was keeping the same rotating assembly and heads...even the same pistons when back in it. Majority of it was valvetrain and head work...but the little stuff will nickle and dime you to death.



Good luck on the dyno!! Playing on the dyno is fun and nerve racking. Gotta get that power out of it though!

 

My Dad has an original 67’ 427/435hp engine at the machine shop right now getting rebuilt. We’ll be dynoing it as well in a month or so. We even used the OEM 11.0:1 pistons and everything. Gonna be a 100% factory stock 435hp. I’ll be super curious to see what it really makes.

 

Thanks! Yeah it was a bit more than I expected, 'cause I had no way to estimate all the little extras. And last time I rebuilt an engine was like 1980 and it cost me less than $2000. But that was a SBC and I did drop off a complete LT-1. Different story these days!

I saw a couple of those original 435s dyno around 450-460. My dyno shop has an all original early '65 L78 vette that dyno' at 485. And he swears it is 100% original. But he does also own a cylinder head porting shop, just sayin' , so I wonder....

 

Subscribed.

 

I have every part and component to complete my 496 sitting on a shelf in my garage except for seals, gaskets and the timing chain.
I read this and thought, I wonder what I have sitting there in parts and added up the receipts.
I think you got off pretty cheap so far.
Looking forward to your dyno results.

 

My 496 new from VortecPro was $7800 shipped when I bought it 10 years ago which I thought was a great value. So 9 years and 27k miles later to refreshen it, was $5600... using 90% of the same parts. I was like “damn, I should just buy another new one for $2200 more”....lol

Once he sent me the parts/labor break down pricing, it all jived...and nothing excessive. We just spent a lot of money on the solid roller valve train this time... I spent $3k in parts, $2500 in labor..... good parts aren’t cheap, especially valve train stuff. We gained an honest 25hp on the rebuild and gained a lot of rev ceiling. Plus the sound....🤤



You mention the 65’ L78, we built one of those as well about 4-5 years ago. It was a “date code correct” type build, but we wanted a good driver so we lowered the compression to about 9.8-1, put a Straub hyd roller valve train in it etc. Stock heads, stock intake, stock exhaust manifolds. It made 441hp through stock exhaust manifolds and a 650 carb...(this was by mistake). I was hoping for more but... I figure with headers and a 750 carb it would have made 475hp or so.

Thats what I really want to compare this new 427 we are building too.

My dad also has another 67’ 435hp car that is built to 100% oem spec’s, and that thing sounds completely different from the 65’. It has a LOT more pop/crisp.. the 11.0-1 compression is very noticeable in it... I haven’t driven that one yet to see how it feels compared to the 65’ L78 but....just by the sound/throttle response, I’d say it’s gonna be considerably stronger.


The 65’ L78 ^^^

 

Leigh1322....great job on oil pump discussion. I've typed that exact explanation more times than I can count. The only thing a HV pump does different is it "outruns the leaks" at a lower RPM and will increase low speed pressure and typically reach max pressure at a lower RPM. I can make 100 psi easily with a stock pump....but I can do it at a lower RPM with a HV. I've used HV pumps forever with no issues...and I actually kick up the oil pressure on the top end because I like it. And my bearings have always looked perfect after numerous 8000+ RPM blasts. Never wore out an oil pump gear yet either! LOL.

I do like the Schuman pumps...he changes the bypass so it dumps to pan instead of pickup and seems to help aeration and reduce drag at same pressure.

JIM

 

Great to hear from those with experience with these HV pumps! I know some of my buddy's drag race customers have had "oil in the valve cover" issues, and "drained the pan" or had "low oil psi at rpm" but virtually all of them are running very loose clearances. They do it because they think it makes them faster.............. Well it ain't fast if it won't last! .....Or at least not for long.

 

Many years ago...somewhat looser clearances helped if everything was not 100% right in the assembly. I doubt it was any "faster". Oil drain back and windage was the downside.

Tight clearance and thin oil is great but it must be 100% perfect if it is to survive.

 

Mark 4 big blocks oil the cam first........then the mains. When equipped with an HV pump and tight clearances for street.....they pump a LOT of oil upstairs under sustained high RPM. It is the only series of Big Block that does this as well.
Leigh, your post is a wealth of info.....but the issue I speak of has been well known since the late 60's and the very reason why oil restrictors were created.
I hope you have no issue........but what I said in the earlier post is a fact.
Just FYI....I like to run clearances in the .001 per inch of journal diameter.

Jebby

 

What did your engine make on the dyno? I thought the session was this past Saturday... did I miss it in the thread?

 

Thanks for that Jebby. And I hope you are right. I really can't envision putting this on the race track for any sustained running so any rpm I get should be short bursts. Very short if on the street.


Thanks for asking. This Saturday is Dyno Day!
Five days away!
Not like I am counting or excited or anything......
I promise I'll get VIDEO.... with SOUND

 

So my guess is 550 horsepower at 6300 rpm

Jebby

 

I hope you're right!!

I have never driven anything stronger than an old-school LT-1 on a regular basis (except for test drives).

This is gonna be fun!

 

Waiting sucks, good luck, hopefully you'll post the graphs. I spent about the same as you on my 460 build ( I don't think my builder did all the stuff yours did, but I'm happy with my end result). Also excellent post for the HV Pump fitment issues, I trimmed the pan baffles on mine, wish I would thought of grinding the casting.

I haven't seen any oil pressure drops (I do glance at the factory gauge in second gear) during my 1/4 runs, I will be adding Oil Press. to the data logger next spring so we'll see if there's an issue (I don't think my builder put in restrictors, I will be asking him).

I'm betting over 550hp.

 

Looking forward to see what kind of power that stock LS6 can handle, Im going to use it on my roller 454 as Well.

 

WELLLLLLL?????

Drum roll please...……….