It may also be the bolts stretching. And congrats, that is amazing power out of an old Y.

That’s a good catch by John on the oil pressure drop during the dyno run.  The oil pressure is expected to increase if the crankcase is experiencing a pressure build up which is what I would expect in a boosted application.  If you can manage to pull a vacuum on the crankcase, then the oil pressure typically drops in that scenario.  Assuming the various engine bearing clearances are not excessive, how much oil is in the oil pan and what kind of oil pickup to bottom of pan clearance are you running?

Lorena, Texas (South of Waco)

The old blower motor I had Ted rebuild for me had machined steel main caps. This was from a drag boat with a 6-71 blower back in the 60's. Maybe they knew something? The steel caps look pretty simple though I'm sure the machine work isn't cheap. I don't know but perhaps they could be made with 4 bolts. Also has a stud girdle that must provide some lower support. Love the numbers though! 

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Ted, have you ever had a thought of building a window to oil pan to see exactly how much oil goes to upper part of engine on a dyno pull? In our case there will be some of oil quantity going to turbos and return hoses too. Too bad, we didn't remember to take our full oil cans with us to dyno. Stupid me! So, that is not crank case pressure issue... We are thinking about adding an oil pressure logging to megasquirt too to see how things go at the strip in the future.

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

I have run an engine on the dyno with a lexan cover in place of the valley cover and with the holes drilled in the lifter valley, there is a large volume of oil coming back up through those drilled holes. when the engine is running at rpm
 
While I haven’t modified an oil pan with any kind of viewing panel so that the level can be observed while running the engine, I do have a couple of ‘low oil in the pan’ experiences I can share.  I recently had a Ford 390 FE on the dyno that was experiencing an oil pressure drop when the engine was being held at 3000 rpms for as little as 20 seconds.  The oil pan was a factory design with a total of five quarts with filter which was the recommended factory fill amount.  The oil pump was a standard volume pump and not a high volume pump.  The oil pump pickup to pan clearance was between ¼” and 3/8” so that was good.  Adding one additional quart of oil solved the oil drop issue which showed how critical it was to have sufficient oil in the pan.  In this particular instance I’d feel more comfortable with seven quarts of oil in that five quart designed system.
 
Another instance I can share is from years ago when running a Ford 427 Hi-Riser in a drag raced ’64 Fairlane.  This engine was carrying a total of seven quarts with an aftermarket deep sump pan and was experiencing a pressure fluxuation at the end of each quarter mile pass.  It eventually spun a rod bearing and it was at that point it was realized that the pan was being sucked dry at the end of each quarter mile pass.  Upon putting the engine back in the car, the oil capacity was upped to 9 quarts (two quarts over the full mark) and this engine ran flawlessly for another eleven years without any further issues.  As a side note, the performance of the engine did not falter or fall off as a result of the additional oil.
 
I had my Y powered roadster up to nine quarts and was still having issues with controlling the oil in the pan either at launch or stopping depending upon where the oil pickup was placed.  I put a dry sump oil system on the engine and now it runs a total of five quarts of oil without issue.

Lorena, Texas (South of Waco)

Thanks Ted! We will chance the bearings anyway now after that dyno visit, Before it we just checked those and as they were all good after one full racing season, we let them be there. Or was it two racing seasons ... hard to remember... We broke two turbos as a result of too low oil level couple of years ago but I guess we will never learn. 

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

I've noticed my pressure drop slightly during a pass.  Maybe I'll add an extra quart.


Lawrenceville, GA

Seppo: re the main caps etc. Micheal Henaults who writes in Y-Block magazine on occassion, has reported that his oval dirt track engine, running in the very hot summer in Calif. appeared to have what he called main cap "walk". He used an idea that apparently came from Verne Schumann, former racer years ago, (Schumann's Sales & Service, [Y-Block parts] Iowa U.S.A) where the caps were "pinned".  However, I don't know any details on the method. Maybe someone else here can comment on that method?    


Paul

I watched my in truck video during the last pass I made, paying attention to the oil gauge.  The pressure drops a lot, not slightly, by the time I'm at the end of the track so that is something I will have to resolve before I race again.
I installed a gate, made out of piano hinge, on the baffle.  Maybe that is not allowing oil to flow as well back to the pickup.  Will get a pan gasket set and check things out.




Lawrenceville, GA

First of today on left...




Hyvinkää, FI