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  1. #1
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    Default New machine (to mer) up and running

    This will be a bit long winded, so bear with me.
    First my apologies, the machine in question is not a Deckel or other Euro make, but in fact made in the USA.
    But thought since its sort of unusual it might be OK to post it here......

    Bought this machine perhaps 10 years back, but never pressed it into service. Have a job pending that screams out for the capabilities of this machine, so i brought it back to life.

    Its a "Tobin-Arp" cam line boring machine. Built to allow boring of overhead cam housing bores in cylinder heads.
    I have a set (2) of cylinder heads that were made new (reproduction) for an overhead cam V-8. Problem is that the cam bores were supplied unfinished, under size and having caps that were never fitted....
    Starting out at just under 1" bore (sort of) and needing to be finished at 32mm. The diameter and length make doing the bores on my full sized Berco line boring machine impossible.


    This is a pretty simple machine. The spindle is fixed with no vertical or side to side movement. Simple belt with different pulleys to give some speed variation.
    Feed is via hydraulic cylinder that is powered by applying air pressure over the oil reservoirs...Direction of the feed is controlled by pneumatic valves while needle valves are used to control the rate.
    There is a drive shaft held in position to the hydraulic cylinder by a collet which allows changing the reach of the drive that couples to the boring bar......

    The only real adjustable part of the machine are the support rails that the work (head) is mounted to....These rails can be moved up and down to accommodate different sized work thicknesses.
    For fine adjustment there are special parallels that set across the rails.
    These parallels can move using adjusting screws both up and down, and in/out....so each end of the part can be trimmed to align the housing bore true to the fixed position boring bar .



    Overall view of the machine.
    Black parts crossing the machine at the lower part of the photo is a parallel. (one of two) Fitted to the parallel is a shop built fixture (more about this later).

    Trick part is the boring bar support and the dovetail way that they fit up to that you can see running along the top of the machine....
    Nice part is that the bearings that carry the bar are in rather narrow over arms that can be positioned anywhere along the upper dovetail...small enough to fit between the bearings so
    that even though the bar is small (15/16") you can get right next to the bore you are machining.....



    Here a view of one of the overarms ...Locates on the upper "V" and against the lower flat.....Overarms made with a cam quick release pull down so moving the arms is quick and easy...
    Note the "U" joint coupling (shop built) between the boring bar and the drive shaft....



    View of the machine control panel and drive shaft extending from the collet that is connected to the hydraulic feed system....



    Note tool setting gauge on top of the operators panel....Setting gauge is stock tooling from my Berco line boring machine...
    More to follow.....
    Cheers Ross

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    So one of the issues here was the cylinder head....In this case the cam bearing housings were made so that the parting line was at right angles to the valve inclination angle....
    (Different by the way from inlet to exhaust)
    Problem is that almost always there exists differ3ences and offsets between the cap and the housing bottom....And boring such you really need to make the
    parting line either flat to the horizon or vertical so that its aligned to the axis of adjustment . Off angle parting lines make for a tedious and unsatisfactory dial up.

    So i needed to provide some method to align the head so that the parting line on the cam caps was flat to the horizon...
    Solution: A fixture that could hold the head at angle and still use the adjustable parallels.....

    Purchased a pair of "cheap" cast iron angle plates. Bought ones that did not have any webs in the angle because i needed to use the inner face of the plate....




    Also machined from large (6"od) steel round bar swivel matching plates that were bolted to the plate....
    Spent way too much time getting the cheap plates flat and square....





    View of the mounting base with alignment key to fit the parallel "T" slot.....



    Round sections are held together via stud in the center...and flanged nut. Radial location is done by a shoulder on one plate socketed into a receiving counter bore in the opposite half...

    Her is the result.....


    Cheers Ross

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    A few more shots.

    View of the fixture with head removed (after using the machine fro the first time)



    Mounting view of the fixture on the parallel...


    Opposite end of the fixture and parallel......



    Cheers Ross

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    Will those fit on a stock 302 ?

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    Some additional detail:
    Here is the setup for indicating the housing bore into the boring bar center line....

    Indicator with body that emulates the boring bar OD...plunger rides in the housing while the instrument is rotated in the boring bar bearing....
    Setup is not reassuring and will need a better setup for future work....



    Note boring bar bearing...is adjustable for fit on bar etc, Also has clearance to allow the tool bit or measuring instrument plunger to pass through....








    Cheers Ross

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    Tobin Arp made a great rod reconditioning machine also

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    A very interesting write up, but is it my browser or something but I see not pictures?

    Neil

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    Quote Originally Posted by AlfaGTA View Post
    Some additional detail:
    Here is the setup for indicating the housing bore into the boring bar center line....

    Indicator with body that emulates the boring bar OD...plunger rides in the housing while the instrument is rotated in the boring bar bearing....
    Setup is not reassuring and will need a better setup for future work....
    ...

    What didn't you like about that setup Ross?

    BR,
    Thanos

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    Thanos:

    The indicators have a fairly heavy spring action. Likely required because of the mechanical action that converts the plunger movement (At right angles to the instrument axis)
    to a push pull move that is parallel to the insturment axis...which then works the indicator ....
    The conversion of direction is accomplished using a ramp and wedge setup . Plunger being pushed down acts on a wedge running parallel to the tool body....Action when plunger is compressed
    is pretty direct, but when moving opposite it all depends on springs to keep the wedge following the ramp on the plunger..

    Further, the tool is too long for the supported diameter.....can't use it with a single overarm....wiggles too much at any distance from the support no matter how tight i adjust the bushing..I have two indicators which should allow indicating both ends of the part at the same time...in reality you have to use two supports on one indicator to make it stable and repeatable.....

    Better solution would be to have an instrument body that stretched between both ends of the part...like the boring bar, and have an indicator at each end.....
    Full length bar would give better results, a more true picture of the actual axis of the boring bar. Would rather have real test indicators making the readings....more sensitive and responsive.
    Have some ideas how to make this work, but it will take some more thinking....

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    Thanos:

    The indicators have a fairly heavy spring action. Likely required because of the mechanical action that converts the plunger movement (At right angles to the instrument axis)
    to a push pull move that is parallel to the insturment axis...which then works the indicator ....
    The conversion of direction is accomplished using a ramp and wedge setup . Plunger being pushed down acts on a wedge running parallel to the tool body....Action when plunger is compressed
    is pretty direct, but when moving opposite it all depends on springs to keep the wedge following the ramp on the plunger..

    Further, the tool is too long for the supported diameter.....can't use it with a single overarm....wiggles too much at any distance from the support no matter how tight i adjust the bushing..I have two indicators which should allow indicating both ends of the part at the same time...in reality you have to use two supports on one indicator to make it stable and repeatable.....

    Better solution would be to have an instrument body that stretched between both ends of the part...like the boring bar, and have an indicator at each end.....
    Full length bar would give better results, a more true picture of the actual axis of the boring bar. Would rather have real test indicators making the readings....more sensitive and responsive.
    Have some ideas how to make this work, but it will take some more thinking....

    Cheers Ross
    Hi Ross,

    thanks for the elaboration, points taken.

    (Now that you mentioned it, I would have assumed this tool was like a dial bore gauge, and now I realized that I am not sure how those work exactly, will look into it)

    BR,
    Thanos

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    How critical is cam bore position in relation to cyl head surface/cyl block deck along with position of cam lobe to valves?

    Are there followers/tappets that allow lash adjustment.

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    The issue of cam position is not generally one of valve lash adjustment. Almost all overhead cam setups have some provision to adjust the lash given the valve and cam are within
    range using shims or threaded valve stems...(unless its an Offy...There the lash is created by filing the tops of the valves to achieve the lash)
    The problem of position is one of maintaining correct geometry.

    Cam to follower is semi critical....Can change the acceleration and deceleration rates of the valve if things are not in the correct position.
    Also for a head using "buckets" the lobe needs to be pretty flat to the face of the bucket else accelerated wear will exist.
    There is also the not so small issue of the dam drive. Most of the engines i see have fixed gear drives to the cams, where cam location becomes a important....

    My point on the indicator not being very reliable is that its important to get the boring bar centered pretty accurately in the existing bore. (assuming that the original bore
    was once good and in the correct position)

    Remember how a "re-bore" works for an existing hole that was on or close to size....
    If the bore is made with a removable cap, the drill is to remove the cap, and remove (cut) material from the parting face of the capo.
    This will of course shrink the original bore parallel to the parting face. However the original bore will not appreciably change in size across the parting line unless considerable material is removed (not usually how one would do this)
    So it becomes essential if one is to get an almost round re-bore to get an accurate centering on the original bore at the parting line....An error of a few tenths in centering will create an oversize hole at the parting line as the tool will favor one side and cut material while missing on the side opposite.....


    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    The issue of cam position is not generally one of valve lash adjustment. Almost all overhead cam setups have some provision to adjust the lash given the valve and cam are within
    range using shims or threaded valve stems...(unless its an Offy...There the lash is created by filing the tops of the valves to achieve the lash)
    The problem of position is one of maintaining correct geometry.

    Cam to follower is semi critical....Can change the acceleration and deceleration rates of the valve if things are not in the correct position.
    Also for a head using "buckets" the lobe needs to be pretty flat to the face of the bucket else accelerated wear will exist.
    There is also the not so small issue of the dam drive. Most of the engines i see have fixed gear drives to the cams, where cam location becomes a important....

    My point on the indicator not being very reliable is that its important to get the boring bar centered pretty accurately in the existing bore. (assuming that the original bore
    was once good and in the correct position)

    Remember how a "re-bore" works for an existing hole that was on or close to size....
    If the bore is made with a removable cap, the drill is to remove the cap, and remove (cut) material from the parting face of the capo.
    This will of course shrink the original bore parallel to the parting face. However the original bore will not appreciably change in size across the parting line unless considerable material is removed (not usually how one would do this)
    So it becomes essential if one is to get an almost round re-bore to get an accurate centering on the original bore at the parting line....An error of a few tenths in centering will create an oversize hole at the parting line as the tool will favor one side and cut material while missing on the side opposite.....


    Cheers Ross
    Thanks for the response! Your machine setups are quite impressive. One last question when you get a chance...what RPM range does this particular head setup run at--and weight of vehicle?

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    The head is one of 2 (V8)
    Car is a Z102 Pegaso.
    Spanish car from the 50's...somewhat rare.
    They were a relatively heavy car ...Believe this setup is the 3.2 liter version. They also built a 2.8L version
    Redline at 6200 RPM
    overall weight at about 3100# or so...To tell the truth in this case i just have the engine, i have never seen this specific chassis ,so don't know if its a coupe or roadster.

    Pegaso Z-102 - Wikipedia

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    Car is a Z102 Pegaso.
    That guy is crazy. I was hoping it was something like the Foyt Ford, that would have a real market for heads.

    Some people have too much money

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    sometimes the whole idea is to spend on something that only they appreciate, as to show how little regard they have for the money they have and are willing to spend, and potential profitability actually lowers the "value" of such an endeavor for them

    I know a guy who likes fiddling with early generation rally cars, they, restored to as new condition are just horrible to drive, but for some reason he gets a kick out of it... I can't appreciate the end result, because I care more about how it drives rather than the historical significance, but diversity is good in this case, history gets preserved is something more than fading memory or poorly scanned photos from 1970ties or 80ties

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    Quote Originally Posted by AlfaGTA View Post
    The head is one of 2 (V8)
    Car is a Z102 Pegaso.
    Spanish car from the 50's...somewhat rare.
    They were a relatively heavy car ...Believe this setup is the 3.2 liter version. They also built a 2.8L version
    Redline at 6200 RPM
    overall weight at about 3100# or so...To tell the truth in this case i just have the engine, i have never seen this specific chassis ,so don't know if its a coupe or roadster.

    Pegaso Z-102 - Wikipedia

    Cheers Ross
    Damn You!---Down the Pegaso rabbit hole. LOL

    Rare cars and pricey depending on coachwork. Interesting engine--is it typical of the period?

    This verson caught my eye.... 1954 Pegaso Z-102 3.2 Berlinetta by Touring | New York - Driven By Disruption 2015 | RM Sotheby's

    Problem my budget is small block chevy...guess I won't be on Southebys mailing list...

    Impressive engines you bring to life!

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    The entire Pegaso story is interesting.
    In the 50's the Franco regime wanted to demonstrate to the world that Spain was a serious industrial world player....
    Government put money into developing the Pegaso.
    The parent company ,Enasa a builder of heavy trucks is still around.

    The project recruited engineering students form the technical schools.
    To head the project they hired a Spanish born engineer who had been a head designer at Alfa Romeo...Wifredo Ricart.
    Wifredo Ricart - Wikipedia

    Cars are filled with complex solutions to poor design concepts...sort of having to work themselves out of a corner IMO....

    I can give a single example:
    The engine is built with wet cylinder liners. Steel with a nitrided bore. Liners are sandwiched between the bottom of the block and the cylinder heads....

    The heads have a perimeter gasket to contain the coolant...but the cylinders are fitted up into counter bores in the head (One for each cylinder)
    Makes each cylinder an individual fit to its combustion chamber...There is no head gasket as such, just a solid copper or aluminum ring at the top[ of each liner...
    This makes for an almost non-compressable joint at each cylinder... And since they are fit as individual liners and not surfaced as a unit getting all the liners to the exact
    height to seal on each cylinder is a real task.....
    This is further complicated by the need to maintain the gear lash of the cam drive gearing which is controlled by the head gasket thickness, which affects the liner projection into the
    head counter bores.......
    The underlying question becomes ....WHY would one make it so difficult....Surely it does not help with the head sealing, rather quite the opposite...In reality it makes it unreliable....

    At any rate its one reason i have the engine....They are trouble, and i have done more than one and have solutions for the design problems....

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    The heads have a perimeter gasket to contain the coolant...but the cylinders are fitted up into counter bores in the head (One for each cylinder)
    Makes each cylinder an individual fit to its combustion chamber...There is no head gasket as such, just a solid copper or aluminum ring at the top[ of each liner...
    This makes for an almost non-compressable joint at each cylinder... And since they are fit as individual liners and not surfaced as a unit getting all the liners to the exact
    height to seal on each cylinder is a real task.....
    92 series Detroits are a little bit similar ... the liners extend out of the block a few thousandths, the bottom of the head is flat tho, and they use o-rings to seal the coolant. Seems like Pegaso took an okay idea and screwed it up

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    I always wanted to do work that needed machines like this

    Now I am too old to have the time to even figure out how they work

    [sigh]


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