340 Lampredi repairs via FP4NC (lots of photos)

Its a bit slow here and thought some might enjoy seeing a project i just finished, involving lots of FP4NC setups involving the "Toolmakers Table (2038).
To begin, i will fill in some blanks. Lampredi was an engineer/designer working for Ferrari in the 50's. He designed a family of engines intended to be used in competition...Sports,F2,and Grand Prix .
The factory built 4, 6 and 12 cylinder engines to Lampredi's design,all with the signature feature of having the cylinder liners screwed directly into the cylinder head/block.

This job required marrying a set of cylinder blocks with oversize liners (OD) to an original crankcase (std housing bore). Now the initial issue, other than the bores which receive the liners in the case were too small,
is that the liners and blocks were re-manfactured after marker parts. These blocks had never been assembled to the original crankcase , and there was no way of telling how well any of it would fit together.

The liners/blocks were made with a total center to center of 540mm for the 6 cylinders on each bank. A distance just within range of my FP4NC at 550...Ok, good!
The position of the liner/receiving bores is relatively critical....clearance between the liner spigots and the bores they nest into runs about .004" on the diameter.
The liners being screwed into the block are quite rigid and any accumulated errors of position would make assembly impossible.

I decided that the best chance for a good job would be to make an accurate "map" of the blocks with their liners and transfer those locations to the crankcase when the over boring was done.
To do this i needed some transferable reference points..The blocks are located on the crankcase using dowels, one at each end and aligned with the center line of the cylinders.
The block is fitted with male ring dowels while the case has receiving bores.
I decided that the natural choice for a constant reference between block and case was ,of course, the dowels. Trouble being that the center to center distance on the dowels was 657mm.
Too far apart to use directly, i needed a way to compress the dowel positions in order to create a new set of datum's that could transfer between block and case....

Below is my solution......Piece of 1.250" MIC6 plate i had in the shop....drawn up and machined as a matched pair.


They are bored and a dowel inserted so that it projects from one side leaving a hole on the opposite side....






The fixtures are also made with a true and straight edge on the top.



There is a reference bore (.500) that is bored at the exact same position relative to the top edge and dowel hole on each of the fixtures...This bore will become my repeatable
reference. In effect i moved the position of the dowels closer together through teh use of the fixtures.
Once i had a way to reach a good reference that i could transfer between the block and case , i needed to setup the blocks on the machine and map the true cylinder positions for both banks (V12)

Here is a holding fixture i made some time back to allow surfacing Ferrari heads ...turns out that the two families of engines (Colombo and Lampredi) both use the same spacing for the
studs that carry the cam carriers on the head...




More to follow....
Cheers Ross

Here is the first part of the "big Picture". Now you can see the cylinder block (one bank) on the hold down fixture (no clamp bolts yet) and the cylinder liners...You can see the reference fixture on the right of the block
bolted to the block base. Projection of the liners is what enters the bores in the crankcase and seals the cooling water using "O-rings"



The block was aligned using the reference flat surface on the edge of both reference fixtures. Theory being that when the two fixtures were set flat and straight to each other because of ther relationship to the factory
Dowels, all would be in line.



Once the block was aligned Flat parallel to the "X" and "Y"..(use table tilt to align for flat in the "Y", use the rotate to align true to the "X")
The reference fixture bore was dialed up using the right hand fixture, then all control axis values were set to zero....

From there a map was created by making a drawing in SurfCam of each cylinder liner position by indicating the OD of each, making all relative to the reference datum of the fixture.



The above process was repeated for the second block and a new "map" made on a different layer within the same drawing.

With the data collected on both cylinder blocks it was time to move to the crankcase.
Needed a way to hold the case down to the machine, and i really wanted to set things so that i could access the case bores using the horizontal spindle.
IMO the horizontal gives better stability and allows setups with greater reach, a factor that will be important in being able to reach the bores and completer the work.

Had a pair of fixtures i made for another project some time back which would work for this, but i needed some additional parts to make the fixtures functional....
Here is the basic setup: The base angle will give the setup i need, but there is no way to clamp the block to these base pieces.
Made two rectangular plates that can be bolted to the base fixture using the hold down stud shown. The rectangular plate is drilled at teh corners to use the stud location on the crankcase that bolts the block to the case.
Rectangular plate is also slotted to clear both the hole down stud and the dowel (shown in photo)
Additionally there is an adjustment screw tapped through the rectangular plate that intersects the dowel slot.This will be used fro adjusting the block position when setup.

Also of note is the cross bar that helps align both holding fixture pieces . Bar is hardened linear bearing guide rod....straight and round (relatively)




Detail of the plate showing adjusting screw and dowel.....




More to Follow
Cheers Ross

Here is the second part of the big picture...the crankcase mounted....
Shown before the reference fixtures are installed....
To get this right requires some patience and aligning the individual parts to make everything point true..

First off the two bade holding fixtures must be set straight and aligned with each other...
Done by indicating along the long side of each base. Also must indicate them to be at the same position (front to back) I indicated the round bar for this.

Next with case installed, i set the case flat as to the original dowels....using a height gauge and indicator i set each end of the block to the same indicated height off the table.
To adjust this i used the adjusting screws in the rectangular plates....This moves each plate up or down the angle of the fixture changing the height of each end...

Once all was level, is used the table rotation to make the block mounting face flat to the "X" travel. Then i adjusted the flat of the block mounting face (Z travel) by tilting the table....
In all this would be a much more difficult setup without the help of the 2038 table....This has got to be the best accessory ,ever!





The next step was to fit the reference fixtures. To aide in setting the fixtures flat to each other , i used a straight edge along the top reference edge then snugged the holding bolts.
Since i had already set the dowels flat, indicating the straight edge would verify that my reference fixture was working as predicted , true to the original dowels.






Now its time to begin the boring process...but first one additional check.
With the case aligned I indicated in the right side reference fixture datum bore (.500) and set all machine registers to zero....
Then just to be sure , i indicated the location of all original liner housing bores on the bank i was about to bore....
Using SurfCam i made a drawing of the crankcase housing bore locations and then overlaid the liner drawing to see the actual error between the two. This was done to be sure that the alignment was
close enough to allow full clean up of the smaller crankcase bores....
With some corrections made to get things to clean up i mounted the boring tooling:
Capto boring head with extension sleeve...this stuff is magic and a real joy to use.




More to follow................
Cheers Ross

Boring in progress. Finally!
I program the boring cycle (RPM, Feed, Speed, Depth and clearance plane) using a sub routine. I run all bores with a single program....Bore hole 1, retract, rapid to hole 2 and repeat....and on.
Begin with a light cut so that i can see that things are going as it should and cutting in a balanced way.....The center to center of all holes was done exactly as the map of the liners dictated,but
some adjustment to get the best average position relative to the case original bores was done to get the optimum clean up....
The finish of the bores here is important and it becomes the seal surface for the "O" rings on the base of the liners....






View from the crank side of the case....



Fixture clamp visible through liner bore of the opposite bank.



Final step: Boring complete...test assemble the block to be sure everything worked out correctly....
Then turn the case around, repeat all alignments,and position checks...bore the second bank using the information from that block/liner data.






Cheers Ross

Really enjoy seeing your thought process and set ups, plus the peeks at the rest of your shop.
Do you bore all 12 with the same boring insert/setting? What kind of diameter tolerance is typical to hold from bore #1-#12 ?

Wonderful work... always love to see the green machines in action Ross.

Nice work, it's probably better than when it was new. i really enjoy your posts having done a fair bit of engine machine work myself.

I can't imagine there are many people world-wide who could have done this job to this level of precision. Amazing development of process and really good setups.

Thanks for sharing this kind of tasks Ross, it's been a while...

BR,
Thanos

Steve:
Think this job took 3 corners (insert edges) For this work i use a Sandvik CCGX high positive aluminum graded insert. The old original bores tend to be rather abrasive having an oxide layer.

Start with one corner and do the roughing on the 6 bores on one bank. Then change the corner for the last .010" or so.

Use that "finish corner to start the next bank. Can pretty easily hold .0003" on the diameter across all the bores in a bank (6) ..Then it starts over.
When the size stops mirroring the tool outfeed its time for a new corner...
I change tools lots more than a production go...Just need to remove the variables and the tools are the cheapest part of doing all this...
"No room here for Maybe"

Cheers Ross

Thanks all for the kind comments.
I have been blessed. Found a "job" that i love that is different every day. Rarely work with budget constraints or some boss breathing down my neck....Makes it easier to do a good job.

Cheers Ross