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Drilling new conrods
#1
A quick tech query for the 7000rpm boys -

I noticed new Pheonix & Hadley rods omit the angled oil relief holes in the top shell, and i wondered if this was because they were a non-useful feature, or was it because of the material property differences between babbit and modern shell bearings in relation to heat & oil flow/pressure, etc.

I'm using Hadley 1.5" rods in a splash-fed engine that will be raced. Is there a benefit to drilling them? Many thanks
Dirk

[Image: IMG_20201016_155125-800.jpg]


[Image: IMG_20201125_114816-800.jpg]
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#2
hi dirk,

i supply and use the hadley. and im sure pheonix will be the same.

rods are supplied without the holes for pressure fed engine.

they are not pre drilled, because if you do so. you end up with people wanting undrilled pressure fed rods, and the only thing you have is drilled splash rods.

same reason for valve chest covers, if you drill 50-50 early and late. you end up with more of one type on the shelf, than the other.

same as petrol tank caps, put the breather hole in, and people want to pressurise the tank.

if you are splash feeding, the rods are hard. but can be drilled. make sure you do the shells seperate, so you dont push the steel shell into the white metal.

thanks tony.
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#3
Not intending to drill mine on a splash fed crank.
It is important that oil can flow through the bearing so check side clearance rod to crank 
I would be looking for 012” - 015” clearance.

On pressure fed engines I believe you drill no 4 only to encourage flow through the crank.

It will be interesting to see other opinions
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#4
Solid copper gasket with no waterways?
What's your plan? Please share.

Paul
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#5
To drill conrods use a 3mm cobalt drill as Tony said drill shells separately I use a small angle vice see photo.  I have never drilled pressure rods, side clearance is more important, and drill the nose feed bolt out larger together with cam restricters and a good oil pump.  Terry.


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#6
Thank you Terry, now I finally know what I want for Christmas.
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#7
Many thanks for all the info, Terry, Tony, Zeto et al.

+1 adding a tilting machine vice and cobalt bits to the ever-expanding Christmas wish list

AMR500 blower to be fitted, hence dry-deck & solid gasket. not a build for the purist but hopefully a strong one (or could all end in tears!)

Bench-testing the engine at the moment with an old updraught carb/manifold, still lots to fabricate.
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#8
sounds a cool build ill follow
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#9
Silly Question possibly, but why would one build a race or hillclimb engine intended for high Rev using splash feed? Surely with availability of front nose castings for pressure feed it’s a no brainer that pressure is better?
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#10
Hi Folks,
If its just a sprint / hillclimb engine splash feed is fine as you are only on the power for short periods in UK events. Continental hills are longer.
The oil pump takes more power to drive it as the pressure rises and it is more complicated to rig up a 60 Psi pump if you want the engine to look original.
Good results can be acheived with extra oil jets and a better angle of oil flow with the splash fed system.
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