Hi there,

I reread Doug Dutra's splendid article about blocks and what can be done to improve them. Then I went down and checked the different points on my block.
First, my block is a 170 with 3 freeze plugs.

I've got a few questions for Doug or anyone who can answer me.

#1 : what is the interest of drilling oil return holes between the lifters? I can understand the oil return part but what about cam lobes lubrification? It just points between the cam lobes, am I wrong? Except for the fuel pump lobe of course...

#2 : Do stand-off pipes make a difference? If so, how?

#3 : My oil pump cavities are far smaller on my block than from what I could see in the article, should I enlarge them to gasket size?

#4 : I have a CHC screw at the end of my oil gallery just next to the timing chain hole? Is it normal to be blocked off?

#5 : Do you know how much meat is there around the sand shakeoff holes. I might tap them but, being in Europe it will be metric so I might as well redrill them to a correct diameter...

#6 : When you say drill-out lifter oil feed holes, do you mean drilling them to a larger diameter? Sorry, that's bad english comprehension I guess...

#7 : On this picture :
The hollow bolt is on the oil return cavity or am I completely wrong? I reckon the oil "sending" is the big cavity with two holes at the top, right?

Thanks everyone for your help and special thanks to Doug and its, always brilliant, articles.

Marc

Up!

All interesting questions. I have no answers for you, though for questions #3 and #4 I am sure that pictures of what you are talking about would help whom ever does have the answers.


TopHat

The stand-offs allow oil to pool around the lifters and drain directly onto the cam lobes, especially if you add a groove to the lifter bores.
When you add stand-offs, it reduces the diameter of the exsisting holes, so extra holes ensures that there will be good crankcase ventilation. If you do not add stand-offs, extra holes are not needed.
No, all you need to do is chamfer the main gallery holes were they enter into the cavities.

Yes, the front and rear of the main oil gallery needs to be plugged or you will not have oil pressure.
Just tap the holes with the closes metric size you have and then use epoxy to install the plugs and to fill any gaps.
I drill-out the oil feed holes to the main bearings. (Make them larger)
There are no oil feed holes to the lifters.
The hollow bolt is installed into an unused cavity and is used for a special cam gear oiler... do a search for more info on how the oiler is installed.
The large opening on top is the entry to the engine block's the main oil gallery, all the other oil passageways come-off of the main gallery.
DD