AlfaGTA
Diamond
- Joined
- Dec 13, 2002
- Location
- Benicia California USA
I have a job that i run for another shop. Do perhaps 2 to 3 line bore jobs per year for a gentleman in So Calif that does almost
exclusively 4 cam Porsche engine work.
My part of the work is to make the case parting faces flat, make the cylinder barrel seating faces flat and parallel and bore the main housings to a
size to give the correct crush on the roller bearings for the crank.
Since the case half's get shortened some , the oil pump housing as well as the front and rear oil seal bores must also be trued to size.....
and finally the "jack shaft" that drives the cam drives needs to be bored true and to size.
For years i have struggled with this last part of the work....the cam drive shaft has an internal bore of 1.181" (+.0000 -.0003")
The housing carries two bushings , one at the outside rear of the case (easy) and one that is almost 7" inside at its far end.....That is a pretty good reach.
Further the case material (Aluminum/mag alloy) is somewhat abrasive and tends to kill tools.
For sometime i have used a shop built bar and a brazed carbide tool in a square hole at the end of that bar....making size adjustments by touching the
indicator to a fixed indicator and advancing the tool in its hole...securing via a clamping screw.....
Small adjustments were at best tedious.
Last week i splurged and bought the shop a present....Been watching e-bay for some time and when this came up, i jumped....
Its something called "Silent Tools" and its made by Sandvik.....Its a long boring bar which is over 7 1/2" long.
On the end it has a small slide that carries a small triangular insert.
The slide is moved by a dial and screw that has graduations in .0004" increments on the diameter....Move increments are further sup divided by a vernier .
The one i bought covers a range from about 20 mm up through 32mm if one employs the optional spacer shim on the tool insert holder....
Here you can see the basic setup....Entire length of the bar is extended by the use of an adapter that steps the bar base coupling (Capto C3) up to my
Cat 40 Capto adapter. (Capto C5 to Cat 40)
Could have made the package shorter by purchasing a direct C-3 to Cat 40 coupling piece , but i was already tooled to go as shown , so i gave it a try....
Here you can see the bar running at its full length, just completing the cut.
This shot gives some idea of the size of the bar and the bore.....
Here is a shot looking down through one of the cylinder bores into the case...the bar and inner bearing cap can be seen....
More to follow............................
exclusively 4 cam Porsche engine work.
My part of the work is to make the case parting faces flat, make the cylinder barrel seating faces flat and parallel and bore the main housings to a
size to give the correct crush on the roller bearings for the crank.
Since the case half's get shortened some , the oil pump housing as well as the front and rear oil seal bores must also be trued to size.....
and finally the "jack shaft" that drives the cam drives needs to be bored true and to size.
For years i have struggled with this last part of the work....the cam drive shaft has an internal bore of 1.181" (+.0000 -.0003")
The housing carries two bushings , one at the outside rear of the case (easy) and one that is almost 7" inside at its far end.....That is a pretty good reach.
Further the case material (Aluminum/mag alloy) is somewhat abrasive and tends to kill tools.
For sometime i have used a shop built bar and a brazed carbide tool in a square hole at the end of that bar....making size adjustments by touching the
indicator to a fixed indicator and advancing the tool in its hole...securing via a clamping screw.....
Small adjustments were at best tedious.
Last week i splurged and bought the shop a present....Been watching e-bay for some time and when this came up, i jumped....
Its something called "Silent Tools" and its made by Sandvik.....Its a long boring bar which is over 7 1/2" long.
On the end it has a small slide that carries a small triangular insert.
The slide is moved by a dial and screw that has graduations in .0004" increments on the diameter....Move increments are further sup divided by a vernier .
The one i bought covers a range from about 20 mm up through 32mm if one employs the optional spacer shim on the tool insert holder....
Here you can see the basic setup....Entire length of the bar is extended by the use of an adapter that steps the bar base coupling (Capto C3) up to my
Cat 40 Capto adapter. (Capto C5 to Cat 40)
Could have made the package shorter by purchasing a direct C-3 to Cat 40 coupling piece , but i was already tooled to go as shown , so i gave it a try....
Here you can see the bar running at its full length, just completing the cut.
This shot gives some idea of the size of the bar and the bore.....
Here is a shot looking down through one of the cylinder bores into the case...the bar and inner bearing cap can be seen....
More to follow............................