Ferrari Cam Repair alla Deckel

Doing a little project in the shop that i thought some here might find of interest....
Here is the problem:
Have a Ferrari 250"California Spyder" in the shop....initial problem is that the engine had low oil pressure. These engines rarely exhibit problems with oil pressure so the engine was removed from the chassis. A tear down and inspection revealed that the main and rod bearings ,while being worn, were within clearance specifications...
Looking further, it was discovered that the cam bearings were running well over .010" of clearance on the cam. Big clearance here = pressure loss
Bearings and caps had the appearance of having been worked over by hand, and not a nice job at that.....


So the cams were sent off for hard chrome on the journals and a reconditioning grind on the lobes. Size of the journals was raised from the nominal stock 25 mm to an oversize of: 25.25mm.
Both heads were straightened, then surfaced both top and bottom....Both heads made to the same overall thickness.

To repair the oversized cam bores the first step was to cut the head side of the cam bores.....Now i own a dedicated line boring machine...but the reality is that line boring a 25mm bore
over 610mm long is a total pain...and quite time consuming as the cuts must be by nature very small and light.....I have a different approach for this operation.

To re-pore the head side of the bearings, i used a ball end mill....Resharpened to the same size as the cam.
Photos show the operation. The vertical head of the FP4NC is angled....this is for several reasons....First off by tilting the cutter, i eliminate the dead cutting zone at the center of
the tool, and i get a better finish...
Second, the FP4NC does not have enough travel to cut the full length of the cam bearings in one setting...but by angling the vertical head to the right and cutting half of the head, then it is reversed and
angled to the left allowing the opposite side of the head and bearings to be cut.... The machine repeats well when doing the angle both right or left, so no issue on the setup as to accuracy of the cut.
The depth of the cut is gauged to keep the cam center line at the top surface of the cylinder head,and flat with same.





After milling, the head side on all journals (6) on each head, they are finish scraped to their individual cam.......The scraping gives clearance to the milled trough and corrects any small errors induced
by the milling setup.

So now i need to machine the mating part to finish the cam bearings....
The arrangement for the head is that there are 6 cam rocker carriers and each carry two roller rockers that activate the valves for each cylinder (2 valve setup).....
That carrier also becomes the cam cap....The carrier is secured via 4-8mm studs with two ring dowels located diagonally at two of the studs.....
The second photo of the head being machined shows the stud holes (removed to gain access to the cam bearings) larger dowel holes and the cam bearings..

The cam is laid into the cylinder head, seating on the freshly scraped cam bearings. Carriers for the head are visible in the background of the below photo....



To use my process , there are three pieces of dedicated tooling needed.....
First off there is what i call the "dummy" cap....this is a piece of material that i have machined to replicate the cam carriers with bolt holes and dowel counter bores....
Further, it has the center relieved to allow clearance for the cam lobes, and has been machined for 3 indicators.....


Indicators are placed so that the top one sits vertically to the cam and is positioned over the cam journal.....
The side indicators come in at an angle and point to the journal center line...and like the top indicator, are positioned over the journal of the cam.
Indicators are secured by set screws which allow some adjustment.....

More to follow.
Cheers Ross

Additional pictures of the "Dummy" cap....Bottom side, indicator pointers seen projecting slightly form the body of the tool.....
Clearance for the cam lobes, dowel bores and mounting holes.



The Dummy cap is fitted to a cam cap in place of the real cap, bolts applied to secure....and the dials are zeroed to the cam......



The "Dummy cap" is then removed from the head, being careful to not disturb the indicators.....

Enter the second bit of tooling.....Here is a setup piece that is made to duplicate the cylinder head where the cap bolts up....This fixture is made with the surfaces flat and true to the bolts and dowels
so that setting up is a matter do indicating the top and sides.

Here the fixture is mounted in a vise and the machine set up to run horizontal.....



Finally here is the final bit of "kit" ...here is an accurately turned shaft mounted in a collet holder where the outer end is the same size as the can shaft journal....



Now for the operation......................
More to follow
Cheers Ross

OK so remember we set the "Dummy" indicators to the aat zero on the cam , then removed it from the head......Now i place the gauge, on the fixture that is in the vise...
and carefully move the shaft (cam journal representative) into the mounted gauge.....Then i move the machine until all three indicators are reading the same as when it was mounted on the head....



Once the indicators are at zero...i set the machine position at zero as well (X and Z)...
Then the spindle (shaft) is withdrawn) and the gauge is removed from the fixture.....

Final step is to bore the cap to size by mounting the real cap from the position just gauged on the head...and then bore using a pre-set tool.....


Setting the boring tool was accomplished prior to fitting the fixture by gripping a piece of scrap in the vise and boring to finished size.....



Some information...Boring tool is a Sandvik "Capto" boring tool...Chosen because i have it and because it uses insert tooling, so keeping a good edge does not require any resetting...

Final chore is to finish the fit of the journals by a bit of clearance scraping to correct any setup errors....

View of head with caps and cam fitted.....



Cheers Ross

I can't argue with the results, which I'm sure will be excellent, but why not line bore the cam bores?

I have line bored these before and at least for me its lots more trouble...Problem is the length to diameter relationship....
You want the largest bar possible ...like 7/8" on that 25mm bore...but at that there is almost no room for chips from the cut...they pack up on the bar and
tend to shove it out of line at the cut...plus in the middle of that span, almost impossible to prevent chatter. No space for a center support...there just is not any room.

Further, by cutting the head side first with the ball , its possible to adjust the overall position to get the best average with the minimum amount cut...With a line bore, you dial up on
each end...if the end journals are poor then there is the strong possibility that the inner journals will not clean....

Do the same process on Miller straight eights....there the bore is 7/8" and just under 30" long...
I do own a Berco cam bearing boring machine that uses small bars with a system of supports for the bar that you move along a rail, rather than try and carry a long bar...but the machine is
just too spotty.....not a very nice system and holding size and getting the bore straight is really hit and miss....

Bores could be line honed...but that offers no control of the final bearing location,,,and the line hone is almost useless when having to make a large size change on just one side of the bore (cap w/oversize journals).....

In reality, since i have the tooling (made years ago ) running this as i did is really pretty fast....almost no setup of the head....and pretty easy to set the fixture in the vise..Boring is all done in a single pass.

Cheers Ross

Nice, it must be ever so slightly terrifying to work with vintage Ferrari parts
Luke

Sent from my XT1072 using Tapatalk

whidbey said:

Nice, it must be ever so slightly terrifying to work with vintage Ferrari parts
Luke

Sent from my XT1072 using Tapatalk

Click to expand...

Not near as 'terrifying' as Miller - or even Gordini or Alfa-Romeo - straight-eights, I am sure.

"Tough job, but somebody has to do it".

And we envy him for it.



Bill

Ross
Always love your post Always edjucational for many of us

One concideration
Someone knowledgeable in tribology once explained to me that a plain bearing consists out of 3 elements
Bearing material, shaft material and lubrication
If from a existing plain bearing you change one of these elements you have to reconsider/recalculate the whole bearing
In this application you changed the material of the shaft (hardcrome)
Did you reconsider/recalculate this plain bearing or do you have good experience with hardcrome on aluminum??I think it is ??

Peter

As an aside, those little Travers Tool "gold plated" dial indicators must work pretty well for you to trust them for something like this !

It looks like the bearing material and lubrication will stay the same*, so the only change is the shaft material. It really only matters that the shaft is much harder than the bearing and a dissimilar material, as long as the surface finish is up to snuff. Thus, there should not be much reason to change other parameters, like clearance. The engine will let you know soon enough if the clearance is wrong, especially too tight!

* Lube should be improved by virtue of better modern lubricants.

rklopp said:

It really only matters that the shaft is much harder than the bearing and a dissimilar material, as long as the surface finish is up to snuff.

* Lube should be improved by virtue of better modern lubricants.

Click to expand...

I was picking the guys brain for a plain bearing on a surface grinder
And he explained to me in detail the material does matter along with finish and hardness
Now of course I all forgot about that

Peter

As something of an aside, did you give the owner an estimate on this work? Nice job, and well presented. Regards, Clark

No hard estimate, but an outline of the job and how i was going to attack it...
Luckily the owner is quite hooked up and understands what it takes to do this sort of work, and he is a stickler for doing a proper
repair, which i enjoy!....He was even present while i did some of this work.
Pretty much here i work time and materials...with progress statements to he customer as work progresses....

Cheers Ross

Ross,
Having been in similar situations with worn journals. My Chrome plater says Aluminum and Chrome is a NO NO.

Even though I wanted to try it anyway I listen to him since he has been chroming longer than I have been alive.

And really did not want to have a running failure due to my own stubbornness and ignorance.

It seems to work on taps OK. Maybe not Ideal but......

I have seen cylinders lined with chrome using aluminum pistons.

I do not think I have used a chromed crank journal on a modern Aluminum bearing shell, chroming cranks has sort of fallen out of favor.

What is your experience with Hard Chrome rotating or reciprocating on Aluminum or vise versa? Of course machined, ground, polished and lubricated properly.

My thinking is they are probably not the best dissimilar running mates but if done right results could be satisfactory.
And the alloy of Aluminum may have a lot to do with it.

yzfr1pwr said:

Ross,
Having been in similar situations with worn journals. My Chrome plater says Aluminum and Chrome is a NO NO.

Even though I wanted to try it anyway I listen to him since he has been chroming longer than I have been alive.

And really did not want to have a running failure due to my own stubbornness and ignorance.

It seems to work on taps OK. Maybe not Ideal but......

I have seen cylinders lined with chrome using aluminum pistons.

I do not think I have used a chromed crank journal on a modern Aluminum bearing shell, chroming cranks has sort of fallen out of favor.

What is your experience with Hard Chrome rotating or reciprocating on Aluminum or vise versa? Of course machined, ground, polished and lubricated properly.

My thinking is they are probably not the best dissimilar running mates but if done right results could be satisfactory.
And the alloy of Aluminum may have a lot to do with it.

Click to expand...

I have run hard chrome on aluminum with good results.

Have done the hard Chrome in aluminum bearing with lots of cams...Never an issue as far as i know....Never had anyone caution about using a chrome shaft in an aluminum bearing.
Have seen hard chrome on crank shafts (repair) run in aluminum bearings as well and seems that worked fine....my cam grinder (Jim Dour, MegaCycle Cams) is a mechanical engineer with lots of experience, and
does cams for Joe Gibbs Racing among others....was the source of suggesting the Hard Chrome for the journals.....Further, Mike Read at Hard Chrome & Grind tells me "that its done all the time with excellent results"....
Aluminum does not work as a bearing with any sort of shaft material if you don't keep the oil on it.....Hard to believe that Chrome would cause any trouble...Its so slick and hard
can't see it sticking unless it is run dry...then you have quite another problem....

Cheers Ross

AlfaGTA said:

Have done the hard Chrome in aluminum bearing with lots of cams...Never an issue as far as i know....Never had anyone caution about using a chrome shaft in an aluminum bearing.
Have seen hard chrome on crank shafts (repair) run in aluminum bearings as well and seems that worked fine....my cam grinder (Jim Dour, MegaCycle Cams) is a mechanical engineer with lots of experience, and
does cams for Joe Gibbs Racing among others....was the source of suggesting the Hard Chrome for the journals.....Further, Mike Read at Hard Chrome & Grind tells me "that its done all the time with excellent results"....
Aluminum does not work as a bearing with any sort of shaft material if you don't keep the oil on it.....Hard to believe that Chrome would cause any trouble...Its so slick and hard
can't see it sticking unless it is run dry...then you have quite another problem....

Cheers Ross

Click to expand...

Hard chrome works great on valve stems as well. When I rebuild the head on an old pushrod Triumph Trident motorcycle engine I always chrome the valve stems and run them in aluminum bronze guides with Fiat 128 valve seals. This engine has horrible rocker geometry, it puts big side loads on the valve stems and guides as the rocker wipes across the end of the valve stem. The chrome stem / aluminum bronze guide is a good crutch for a piss poor design and lasts 4 x as long as the standard stuff.

Milacron said:

As an aside, those little Travers Tool "gold plated" dial indicators must work pretty well for you to trust them for something like this !

Click to expand...

No complaint with the way the indicators seem to function., i like the through plunger allowing you to pull the tip off the part slightly and release it to verify the reading is sound...just not a fan of the "Garish Gold" trim....

Cheers Ross

If the cam is forged, it can be hard welded just like a forged crank. The process is the same. Weld, straighten, grind, done. But, the chrome is probably fine. I have shafts with grooves from lip seals chromed and ground back to size. It works.

AlfaGTA said:

Have done the hard Chrome in aluminum bearing with lots of cams...Never an issue as far as i know....Never had anyone caution about using a chrome shaft in an aluminum bearing.
Have seen hard chrome on crank shafts (repair) run in aluminum bearings as well and seems that worked fine....my cam grinder (Jim Dour, MegaCycle Cams) is a mechanical engineer with lots of experience, and
does cams for Joe Gibbs Racing among others....was the source of suggesting the Hard Chrome for the journals.....Further, Mike Read at Hard Chrome & Grind tells me "that its done all the time with excellent results"....
Aluminum does not work as a bearing with any sort of shaft material if you don't keep the oil on it.....Hard to believe that Chrome would cause any trouble...Its so slick and hard
can't see it sticking unless it is run dry...then you have quite another problem....

Cheers Ross

Click to expand...

Thinking more about it I have had chromed and ground wrist pins running in aluminum for a Rolls Royce and chromed and spray welded plenty of other shafts and such but can not recall specifically chroming a "rotating" shaft running in aluminum.Have used diamond ground ceramic coating for this instead due to the fear mongering.

There are 2 main hard chromers in my area.Had a falling out with the one I used to use when he did not want to pay me for my time line boring a casting, he had a tantrum but realized he was not getting the casting back in one piece( had the casting in my horizontal band saw with the blade running 1/4" above) unless he paid the piper.

The guy I currently use is more of an old timer but references some ancient chroming scroll when quoting odd jobs and materials.
It is from that text I believe it said" thou shalt not run chrome on aluminum!"

I asked him several times about this but got the same answer every time.

I did not want to argue with the last viable chromer close to me, have enough shit to do aside from chrome plating

Some books are worthless.

My take is someone ground something in the wrong direction too rough, ran with less than optimum lube on a close to pure aluminum bearing and balled it up. Then wrote a book about it.

Since they were a piss poor mechanic they figured they could make ends meet writing books instead teaching others how to be good mechanics.