Electric scavenge pump on rocker cover?

[BLSTIC]

So one thing I've noted with some V8s in a dirt track situation is the tendency for the outside rocker cover to not drain. This probably has to do with the cylinder bank leaning at 45 degrees plus cornering forces = not much gravity drain.

Would an electric scavenge pump between the rocker cover and the (probably left hand side of the) sump be enough to solve this?

[Tom68]

Sure you're not fixing s problem that doesn't exist ?

[BLSTIC]

Well it wasn't my problem, but someone i know was asking me about it, and apparently the speedway guys with Holden 304 engines suffer from it, but the earlier engines don't. So no, I'm not sure if I'm trying to solve the right problem.

Actual problem was smoke at high rpm out the breathers and a stack of oil being sucked through the pcv when backing off. Litres per race kind of amounts. There's no way the car could have done a 40 lap race without either being black flagged or running out of oil.

I later found out that the engine assembly and honing wasn't the greatest which could be a contributing factor. But that it was a noted pattern with a stated problem got me curious about potential solutions.

[Tom68]

Holden V8s have enough drainback, what they don't have is a a lot of breathing area around the pushrods.

You could seal up the rocker convers and put the breathers into the valley through the manifold.

Or of course better still address the blowby.

[BLSTIC]

Yes, once I heard the bore was honed on an engine stand with whatever tool was cheapest at the parts retailer I thought that was at least part of the problem.

Have you heard anything different about the 304 vs 308 engines being different regards to breathing/drainback?

[Tom68]

Same.

20230108_091411.jpg

20230108_091429.jpg

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[BLSTIC]

I'm not sure what I expected to see but it wasn't that. I must be vastly overestimating the amount of oil that has to come down, but even so, it looks like those would only be barely adequate. And they run from the outside of the head to the valley, so probably shallower than the 45 degree angle of the cylinder.

I'll need to look into this further when I get back into the country and get my paws on the heads

[Tom68]

I'm not sure what I expected to see but it wasn't that. I must be vastly overestimating the amount of oil that has to come down, but even so, it looks like those would only be barely adequate. And they run from the outside of the head to the valley, so probably shallower than the 45 degree angle of the cylinder.

I'll need to look into this further when I get back into the country and get my paws on the heads

Same as a Small Block Chev (been a few speedway laps done by them) what you don't see is how crowded the hole is where it feeds the valley, I think Holdens are OK, SBCs can do with a little bit of a relief on the block, Clevelands drain back through a hole in the deck and need matching up.

The oil runs back nearly flat, breathers on a sound engine won't be a problem as long as they're not in the outside rocker cover and even then they often don't cause problems.

[pamotorman]

air has to get in for the cover to drain out and i used this type on my circle track engines.
https://behlingracing.com/images/a94618 ... 7141-1.jpg

[greenhj]

Are these guys using HV oil pumps?

[BLSTIC]

Actually that's a good point. I didn't think about airflow aspect.

Now there's a dumb idea... Assuming I did something like a pan-evac that somehow had excess vacuum (see advanced forum for details of a good one) having a bleed in the outside cover could literally suck the oil out. But I don't even know what "excessive" vacuum numbers are let alone whether I could get enough ring seal and header design to achieve it.

[KnightEngines]

Best fix for speedway holdens is restricted pushrods, ported drainbacks, no breather on the RH cover & dual 1" dia breathers on the LH cover.
Std vol oil pump with a few mods, block the crossover port behind #4 cam bearing & re-feed that lifter bank from #1 cam brg by drilling a hole & grinding a groove behind the cam brg.
That fixes the issue of starving #4 main & by extension #6&7 rod bearings.
Pickup goes to the right side of the sump.

I've spent way too much time sorting the oiling & breathing on speedway holdens, but done right all the issues are fixed.

[BLSTIC]

That sounds like pretty good advice, thanks. I'll keep that in mind.

[KnightEngines]

That sounds like pretty good advice, thanks. I'll keep that in mind.

Call me if you need more info.