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Drilling out the oil passage to the center main on the 1725 engine

AlsPine

AlsPine

Donation Time
There was some documentation describing opening an oil passage to the center main with a 21/64th drill going through the hole where the oil pressure line is connected. It also increases the oil flow to the rockers.
I am unable to find the documentation describing this.
Anyone know where to find this and perhaps post a link?
Thank You
 
husky drvr

husky drvr

Platinum Level Sponsor
AlsPine said:
There was some documentation describing opening an oil passage to the center main with a 21/64th drill going through the hole where the oil pressure line is connected. It also increases the oil flow to the rockers.
I am unable to find the documentation describing this.
Anyone know where to find this and perhaps post a link?
Thank You
Click to expand...

AlsPine,

I don't recall that particular bit of information. I recall jumpinjan once describing how to drill the oil pump feed line passage on a mill. He might know more about what you're asking and will reply.

There are several engine performance enhancement articles in "The Alpine Marque" PDF's on the home page. If you've got some time, I suggest searching through those articles for possibly more information.

http://sunbeamalpine.org/alpine-marque/

Hope this helps,
 
sunalp

sunalp

Diamond Level Sponsor
You actually have to take the plugs out of the oil gallery. I'm not sure what size drill was used (you may be correct)
as I didn't do it, my machinist did. He used the same size drill as the plug. If I'm not mistaken the oil passages that need
to be opened were on #2 and #4, but don't hold me to that.
Cheers!
Steve
 
spmdr

spmdr

Diamond Level Sponsor
AlsPine, seeing this is in the Stock world, can we assume Just Street use?

I would be surprised if ANY oil galley mods, by them selves, do any good.

I would be more concerned with reducing losses of oil pressure from the front cover oiler and the oil pump housing
cam gear groove.

And this is after getting all of the other oil clearances in order, along with the PRV.

I am running 2 Alpine engines in the Vintage Racing events with NO mods to the engine block oil galleys.

I would HOPE I have run the VR Alpine engines harder than you would on the street....

BUT there are other mods I have done to the oiling world like Bigger oil pans, etc.

DW
 
puff4

puff4

Platinum Level Sponsor
I made this modification to my 1725 engine when I rebuilt it about 10 years ago. I don’t know if it made a lot of difference, but it’s caused no harm. Many miles later I still have great oil pressure and there’s no little men with hammers inside it.
 
alpine_64

alpine_64

Donation Time
puff4 said:
I made this modification to my 1725 engine when I rebuilt it about 10 years ago. I don’t know if it made a lot of difference, but it’s caused no harm. Many miles later I still have great oil pressure and there’s no little men with hammers inside it.
Click to expand...
How 'bout little ladies? :p

Kevin what psi id your motor running at hot idle and are you still running the stock SV oil cooler?
 
husky drvr

husky drvr

Platinum Level Sponsor
AlsPine said:
There was some documentation describing opening an oil passage to the center main with a 21/64th drill going through the hole where the oil pressure line is connected. It also increases the oil flow to the rockers.

Thank You
Click to expand...

AlsPine,

If your primary reason to contemplate this modification is oil flow to rockers, you should be aware the engine is not designed to allow that to happen.

The engine is designed to meter oil to the rockers with the small port in the camshaft center journal. The rocker assembly gets a squirt of oil once every two crank rotations.

This is part of figure 7 in WSM 145's engine section showing the oil flow path and how the cam interrupts the flow.

Hope this helps even if that wasn't your reason.

upload_2021-8-23_1-52-24.png
 
puff4

puff4

Platinum Level Sponsor
alpine_64 said:
How 'bout little ladies? :p

Kevin what psi id your motor running at hot idle and are you still running the stock SV oil cooler?
Click to expand...

It’s been a while since I’ve run the Alpine and I’m at our vacation cottage now so I can’t go start it. But I’m almost certain that it was just to the right of center (straight up) on the pressure gauge when hot and under light throttle. At idle it doesn’t drop much either. But then I also machined the oil pump to give >.001” end-clearance when assembled and I machined the crank for the installed diameters of the main and rod bearings (as opposed to just assuming a standard grind would be ok... the bearings you get are rarely accurately sized!). Further, I built an adjustable relief valve as per Tiger Tom’s design (at least I think it was his design).
 
AlsPine

AlsPine

Donation Time
Hi spmdr,
Yes just a stock street car.
I bought one of SS short block's and it is at the machine shop getting the cosmoline cleaned off and having the low compression pistons swapped out for a set of standard compression pistons. Rick had gotten some in.
The cam is off to Delta for a KB grind, Don said that right now he has a 5 day turnaround. Have a new set of lifters from SS.
Rockers all ready to go. New oil pressure regulator.
The head is all done. Oil pump has been lapped down for a .001 clearance. Aluminum oil pan has had a fitting welded in for the oil temp gauge.
OD trans from England is ready to go with shortened and rebuilt drive shaft.
Should have the short block back in two weeks.
Then the fun part, getting everything put together and installed in the Series 3,

spmdr said:
AlsPine, seeing this is in the Stock world, can we assume Just Street use?

I would be surprised if ANY oil galley mods, by them selves, do any good.

I would be more concerned with reducing losses of oil pressure from the front cover oiler and the oil pump housing
cam gear groove.

And this is after getting all of the other oil clearances in order, along with the PRV.

I am running 2 Alpine engines in the Vintage Racing events with NO mods to the engine block oil galleys.

I would HOPE I have run the VR Alpine engines harder than you would on the street....

BUT there are other mods I have done to the oiling world like Bigger oil pans, etc.

DW
Click to expand...
 
alpine_64

alpine_64

Donation Time
@AlsPine what are you doing with the head? At minimum clean up the ports per the rootes special tunning guide and do a 3 or 5 angle valvr seat cut.
Or..go more and add the vizard chamber mod.
 
AlsPine

AlsPine

Donation Time
Head is stock other than a multi angle valve job.
Decided not to drill out the oil passage.
I'm using a aluminum oil pan and no oil cooler. I added a fitting to the oil pan for the oil temperature sender.
Will monitor the oil temperature, then decide weather to add a cooler.
The unlabeled switch on the dash is for the OD. Will make a tab with OD on it.
 

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alpine_64

alpine_64

Donation Time
Even if you dont want to do much on the head port match your manifolds and head.. Its worth it... And so is cleaning up the runners... But the transition from head to the manifolds wont require and pulling the head apart
 
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