Drilled Tappet Blocks

In the bore, about 1/2" down in the groove, is a #31 drill hole at 30 degrees exiting in a oval just below the underside of the flange, that if extended would lead into the flywheel side of the crankcase.
Is this peculiar to any specific model or just a racers mod? Looks Professional!
Or is this to aid in low RPM lubing of the valve train, ie, servicars? The three I have are screwdown type, both intake, and front exhaust.
None of the 12 U camsides I've seen are drilled to match.
Don

[This message has been edited by don (edited 31 January 2000).]

Oh come on! Opinions ARE acceptable B/S too!

Hey Don,
I checked a tappet block and seen the groove, but no hole. I then looked at the 40-47 Big twin Shop Manual and as I thought it shows a diagram of the lubercation system of the Big twin and it shows oil being forced by crankcase preasure and splashed from the cam gears up to lube the valve stem's and guides.

My thought is that these could be WR guides do they have the lifters with them and if they are the flat tappets that could be a clue.The tappet blocks for flat tapets have a wider opening to allow the tappet to travel further up inside the tappet block.

So compare the opening to a stock WL Lifter block and see if theres a differance. Either way someone was thinking about getting more lubrication to the valve guides I beleive.

Tom Roop (00)



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Tom,
Now you got me rechecking all my guide blocks, the roller opening on most of my sets are square at the top .820" deep, this set is cut differently at the top like an -M- .820" at outside, .780" deep at the tang[middle].
beside these 4 screwdown, I have one clip type guide w/ the tang.[checked 12 sets]
The oiling holes, all identical, must have been some fancy jig to index and drill them.
Don

Hi Don,

A long time ago i got a hold of some WR cams and the Flat tappet Lifters that look like a shoe from the side and they would not fit in a WL-G lifter block so I had to hand mill the opening wider so the lifter would travel un-obstructed inside the lifter block.




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I'm not for certain, but somewhere it seems that I've heard that very late servi-car had a tappet block modification. Maybe that is what you have.

I lean towards the late servi-car theory, it is a shame, a technical note or service bulletin probably came with the part, long ago trashed.
Don

Jerry's right - it's a late Servi-Car (1958-*?) mod, includes an angled hole through the right case wall allowing case pressure/vacuum to communicate with the interior of the block. Purpose? Additional oil drain back to the case? If it were intended to transfer oil to the guides, why is it down-hill? Anyone?

Could it be that galling of the valve&lifter/guides was becoming a problem with 'City's parking enforcement fleet?
The hole from the flywheel side has greater pressure during the power stroke creating a suction up the groove from the camchest like an eductor thus more oil, Excess has time to drain during compression/exhaust.?
Seems it might work better with a lopeing idle.
Don

I think you hit on it Don when you mentioned
protecting the valves and guides and lifters from galling and the hole is for more lubrication of such at idle when hot. It seems they figured out an additional souce for this lubrication, because it does have to go up hill under pressure to get to the valve guides.

The crankcase preasure builds as the rpms increase and the scavanger pump does its job by returning the oil to the oil tank and leaving an oil mist in the cam chest that lubricates the gears and lifters and guides.

Another componet of the crankcase breathing is the Flutter Valve, and does its job in the breathing of the crankcase by acting as a sort of PCV valve or else oil would be leaking from everywhere under the crankcase pressure.

Tom (00)



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I asked this question on the Victory 45 Tech Board and learned more about the reality of this mod. Thanks to Rene at jwboon!
In a word oil, lots more oil to your valves and guides, so improve your cover seals, and install guide to stem seals.
I can picture the engines life blood oozing from every crevice!

how far below the flange does the hole come out?

A gasket thickness below the flange on the outside is a 1/4 oval[due to angle] #30 or 1/8" drill width.
On inside bore 1/2" from top threads in the oil groove is the start of the angled down hole.

Long buried back to the top.
don

Several years ago, I viewed K model Cases Drilled for these tappet blocks.
don

i have a wl engine case a later one ,that has the holes for the oilways to the tappet blocks , i used them to drill a set of blocks and then used tose blocks to drill aset of 44 wlc cases , i havent had that engine running yet so dont know how much oil it will throw into the blocks , but i think Dr dick , had this set up on a big twin flattie and said that he had blanked off or was going to blank off the rear ones as was over oiling the valves