Marvel Mystery Oil

[psyolent]

vlad - good work - thanks mate.

[OZ38]

That pic was a cut up from their Series II 3800 which is our Ecotec. Their earlier V6 blocks must have has similar issues as the drilling of the oil galleries as a performance mod started with them & Jack Merkel of the Turbo Buicks time. If you look at the Ecotec engine block oil galleries from cam bearing down to mains, you will notice all four have a different size drilling. The one closest to front of engine is about 10mm (3/8"), the next one drops to about 6mm (1/4"), the next another 6mm drilling (1/4"), then finally a small step up to 7mm + almost 5/16". So it is strange drilling sizes considering all use the same size hole through the bearing shell to control oil flow. Why didn't GM just drill all of them at 10mm (3/8") past the cam bearings. Or maybe they didn't think it was a problem for your humble standard V6.

Cheers

[vlad01]

on pre ecotec from front its 10, 9, 7.5? , 8 iirc when I measured them. I will double check and give the numbers tomorrow.

From what I have read on ecotec gallery sizes are a lot smaller than these.

From my experience the pre ecotec never seem to suffer any issues. All engines I have torn down but one shown no sign of oil issues.

By a renown V6 builder who also shared the same pic of the engine core said its not the size so much but the location of the gallery vs the tunnels vary from block to block and can be blocked by the cam bearing as in the pic. Not all engines suffer this, I have seen quite a majority of the later VX/VY block not suffer the misalignment and live happy life with abuse like this 355,000Km that my mate owned and personally thrashed it myself, its had a very hard life. The crank has 0 scores and has polished like finish. The bearing still has the original manufacturing machine marks.

The engine was well looked after though, high quality oil always and serviced regularly, not a trace of solid carbon or sludge anywhere in the engine.

[psyolent]

nice pics vlad.

OZ38

So it is strange drilling sizes considering all use the same size hole through the bearing shell to control oil flow. Why didn't GM just drill all of them at 10mm (3/8") past the cam bearings. Or maybe they didn't think it was a problem for your humble standard V6.

would the galleries be drilled at production time, or, would these be a casting thing? i would have thought due to where the oil galleries are the sizing would have occurred at casting time.

happy to stand corrected though

[immortality]

The oil galleries would have been drilled post casting as part of the block machining process.

[psyolent]

yeah looking at that original picture reckon youre on the money. too 'clean' to be cast.

[vlad01]

ok oil holes are as following on early VP engine.

front to back

11mm, 7mm, 7mm, 8mm.

Looking down them with a torch the cam block about 1/4 for the 11mm hole as it appears to be drill offset away from the cam bearing, the others are exactly half blocked and appear to be all in line of each other.

I think there would be a reason they have been drilled like this, maybe some attempt of restricting oil flow to the middle 2 mains, after all they do have 2 oil holes in the crank journals for the 2 middle ones and outside ones only have one to feed.

The front one being so big might have something to do with oiling the timing set?


John Hamilton of? (forget his business name) the guy in Vic who only builds L67 did state that he drills them out to 8mm, 10mm I recall he said was too big causing pressure drop at idles speeds. Makes some sense as small pipe = lower volume, higher velocity , big pipe= lower velocity and higher volume.

It may be bigger galleries bleed off faster then they can be filled at lower engine speeds and oil pressure. But in high performance engines bigger galleries will help, but the argument of too big still applies imho.

[immortality]

It's my understanding that volume is more critical than pressure. Ideally the oil gallery should be slightly smaller between the cam bearing and main bearing because you want to maintain flow even though you have lost some volume at the cam bearing. I remember something about idle oil pressure recovery been an issue if the holes are drilled to large.

I think John Hamilton also rotates the cam bearings, uses the original oil hole to pin the bearings in place and then drills a new smaller hole to feed the cam bearing.

On the early V6 engines you could possibly get away with only removing the cam bearings and then using a die grinder to sweep out and enlarge the oil gallery around the cam bearing without enlarging the actual gallery.

[vlad01]

Personally I would bother with the earlier engines. they don't seem to have the same chronic issues the ecotec did with oiling.

Only time I have seen failures with pre ecotec is when the engine was full of sludge blocking the pickup or excessive debris physically breaking the oil pump of those that use 2 flats to drive them. Broken oil pump leads to a whole lot of other damage from lack of pressure.

This is why I upgrade my pumps to spline drive ones.

[immortality]

I've not ever seen one with as much crud in it as the picture earlier in this thread, hell, the ones I've pulled off have been fairly clean TBH.

The oil volume would probably be of more concern if the engine spent the majority of it's life at sustained high rpm greater than what the standard engine is capable off.

Nobody really seems to turn these engines to excessive rpm, most tend to just add more boost