bushing lifter bores on 340

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gregcon said:
View attachment 1715583723 IMO, the big issue you face with a pushrod-oiled top end and restricted lifter bores is the need to get oil up the pushrod. You need an oil path to do that...so if you drill a small hole, you should consider the placement of the hole as important as the size.

This is compounded by a hydraulic lifter's need for oil, if you are running hydraulic lifters (which is never a good idea unless you are a 68 year old woman named Agnes).

What I'm saying is....a small hole (like .046") is a good thing, but not if you keep it covered by the lifter body at all times. It needs to align with the lifter's oil hole at some point in time.

The factory 'hole' in the lifter galley is huge - not just in terms of oil flow but also in meaning that it helps ensure the oil hole in the lifter will be fed oil. It's also pretty forgiving when different lifters are used...various lifters usually have their oil holes in different locations along the lifter body.

So....you should drill the hole small but you should also have the lifters you plan to use 'in hand'....with the cam installed, drop them in the bore and measure where the hole sits then use that to position your lifter bushing hole.

I drilled mine at/around .046" but I first dropped the hole (using a 1/8" end mill) 1/8" down. This gives the .046" drill bit a flat surface to start against, and it also gives a much bigger 'landing zone' for the oil holes to align. In other words, the holes is flowing .046" but the lifter 'sees' a .125" hole which makes the alignment more forgiving.

See pic:

View attachment 1715583720View attachment 1715583720

View attachment 1715583721
Click to expand...
I like it
I am not a machinist how in holy hell do you get the end mill and the drill bit to punch a hole half way down the lifter bore? What am I missing
 
512Stroker said:
I like it
I am not a machinist how in holy hell do you get the end mill and the drill bit to punch a hole half way down the lifter bore? What am I missing
Click to expand...

Lifter bores are at an angle. Hole is drilled straight down - or close to it.
 
Phreakish said:
Lifter bores are at an angle. Hole is drilled straight down - or close to it.
Click to expand...
That is what I thought took place
You did such a nice job it just did not look like the hole is at an angle to the bore in your pic's.
 
Yes, the hole is perpendicular to the Earth...it's at an angle relative to the bore. Similar to the Mopar instructions, it is as far towards the centerline of the engine as you can go. That's because even at that position, it places the hole a little higher in the bore than you'd like. I thought of drilling through the other wall of the lifter bore to allow drill access so I could place the hole lower but felt that would be a lot of screwing around for little gain.

Before someone catches it....the drill bit shown is larger than the .046" I actually used.

Lifter bore drill.jpg
 
gregcon said:
View attachment 1715583723 IMO, the big issue you face with a pushrod-oiled top end and restricted lifter bores is the need to get oil up the pushrod. You need an oil path to do that...so if you drill a small hole, you should consider the placement of the hole as important as the size.

This is compounded by a hydraulic lifter's need for oil, if you are running hydraulic lifters (which is never a good idea unless you are a 68 year old woman named Agnes).

What I'm saying is....a small hole (like .046") is a good thing, but not if you keep it covered by the lifter body at all times. It needs to align with the lifter's oil hole at some point in time.

The factory 'hole' in the lifter galley is huge - not just in terms of oil flow but also in meaning that it helps ensure the oil hole in the lifter will be fed oil. It's also pretty forgiving when different lifters are used...various lifters usually have their oil holes in different locations along the lifter body.

So....you should drill the hole small but you should also have the lifters you plan to use 'in hand'....with the cam installed, drop them in the bore and measure where the hole sits then use that to position your lifter bushing hole.

I drilled mine at/around .046" but I first dropped the hole (using a 1/8" end mill) 1/8" down. This gives the .046" drill bit a flat surface to start against, and it also gives a much bigger 'landing zone' for the oil holes to align. In other words, the holes is flowing .046" but the lifter 'sees' a .125" hole which makes the alignment more forgiving.

See pic:

View attachment 1715583720View attachment 1715583720

View attachment 1715583721
Click to expand...
gregcon said:
Yes, the hole is perpendicular to the Earth...it's at an angle relative to the bore. Similar to the Mopar instructions, it is as far towards the centerline of the engine as you can go. That's because even at that position, it places the hole a little higher in the bore than you'd like. I thought of drilling through the other wall of the lifter bore to allow drill access so I could place the hole lower but felt that would be a lot of screwing around for little gain.

Before someone catches it....the drill bit shown is larger than the .046" I actually used.

View attachment 1715583771
Click to expand...
 
It is an R3 block but the procedure would be the same for any block that had its lifter bores bushed.

If your machine shop were agreeable, they could even drill the holes before they pressed in the bushings....that's a lot easier. But it does require them the press them in with the hole at 6 o'clock and at the desired depth.

With a bronze bushing, you wouldn't be able to drill an 1/8" recess, though, because the wall thickness is too small. You'd just drill the small .046" (or whatever) hole.
 
so for the dumb question then why not drill a big hole at least the same height as the factory hole if your 68 year old aunt Agnes whats to run hydraulic roller lifters. just to be safe on oil hole placement
 
The factory hole is 'massive compared to a .046 hole .... it basically has no problem matching up with the lifter oil hole. But when you use a small hole, placement becomes more critical.
 
EddieSketti said:
so for the dumb question then why not drill a big hole at least the same height as the factory hole if your 68 year old aunt Agnes whats to run hydraulic roller lifters. just to be safe on oil hole placement
Click to expand...
Hey come on now I think I dated your Aunt Agnes, she was a good time. LOL
 
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