Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

Discussion of 4-Cam Type 547 engines (and all the Fuhrmann racing variants) and cars that powered them.
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Harlan Halsey
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#61 Post by Harlan Halsey » Sun Mar 07, 2021 6:07 am

Oliver, Joris,
Jim attributed the wear on the long shaft splines to the Carrera valve train vibration, he never mentioned misalignment to me. Of course, cam drive bearings are honed to size. They came rough finished, Jim had a honing fixture, and knew how to use a Sunnen hone. I made a plating jig to plate up worn bearings so that he could resize them.
The Carrera engine has the problem of too few valves per cam, and the lobes both on one side. The cyclical load gives rise to vibrations which wear the drive splines and destroy cam drive distributers. For this reason, Porsche abandoned the elegant distributer cam drive, at first with the Vee Drive bracketed off he oil pump, then with the 692, the 90 degree case mounted drive.
Align bearings are not going to cure that, and further, the cam drive bearings are also thrust bearings which control the gear mesh.

Olivier AUVRAY
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#62 Post by Olivier AUVRAY » Sun Mar 07, 2021 8:24 am

Harlan Halsey wrote:
Sun Mar 07, 2021 6:07 am
Oliver, Joris,
Jim attributed the wear on the long shaft splines to the Carrera valve train vibration, he never mentioned misalignment to me. Of course, cam drive bearings are honed to size. They came rough finished, Jim had a honing fixture, and knew how to use a Sunnen hone. I made a plating jig to plate up worn bearings so that he could resize them.
The Carrera engine has the problem of too few valves per cam, and the lobes both on one side. The cyclical load gives rise to vibrations which wear the drive splines and destroy cam drive distributers. For this reason, Porsche abandoned the elegant distributer cam drive, at first with the Vee Drive bracketed off he oil pump, then with the 692, the 90 degree case mounted drive.
Align bearings are not going to cure that, and further, the cam drive bearings are also thrust bearings which control the gear mesh.
If you have time to spend: check the misalignment on one engine. Let us know if it's a few hundredth of a mm........ or a few tenth of a mm.
By the same way, use the functionnal dimensionning system to determine the tolerance of each part involved (engine case / cylinders / cylinder heads / shaft & associated parts) and let us know the tolerance of each part to keep the shaft "free" in the bushing. The results is tolerances in thousandth of a mm. then find a company that will be able to make parts.
In my opinion, the Porsche technical team overlooked this point.

On a half case, put cylinders / heads / long shaft & bushings (each part must come within Porsche tolerances). Let us know if the shaft turns freely (it's a lotery: sometime yes, mostime not).

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Ibrahim Kuzu
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#63 Post by Ibrahim Kuzu » Sun Mar 07, 2021 9:43 am

Hi Jacques,
Sorry, It is my fault not mentioning the connection design.
It is just like 911 concept. And basically Porsche design
Got it from Pushrod 356 cylinder head rocker bolts engineering design .
Need it machining the Allen head bolts flange to accommodate our design
We have inside the cam housing 2 more 8 mm stud connection ( can use only one also )
and 2 10 mm bolts on the engine studs on each valve to keep the area super tight
It creates 911 3 stud each valve area connection for a healthy cam loop operation.
Also ,we have a 2nd design on our table to use regular engine stud nuts Com box connection.
Up to the engine owner.
IK
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Ibrahim Kuzu
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#64 Post by Ibrahim Kuzu » Sun Mar 07, 2021 10:02 am

Off to this subject for a second,
I really wish that administration takes a serious look at this and give us a 4 cam Carrera forum as other forums so we do not take space on main talk forum.
I feel kind of bad taking space..... I guess 80 % of the members not interested what we talking in here and no idea of 4 cam engine operation.
My 2Cent.
IK

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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#65 Post by Olivier AUVRAY » Sun Mar 07, 2021 11:32 am

Ibrahim Kuzu wrote:
Sun Mar 07, 2021 10:02 am
Off to this subject for a second,
I really wish that administration takes a serious look at this and give us a 4 cam Carrera forum as other forums so we do not take space on main talk forum.
I feel kind of bad taking space..... I guess 80 % of the members not interested what we talking in here and no idea of 4 cam engine operation.
My 2Cent.
IK
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Jacques Lefriant
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#66 Post by Jacques Lefriant » Sun Mar 07, 2021 11:46 am

+1 but i would put it 95%
 

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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#67 Post by Jacques Lefriant » Sun Mar 07, 2021 11:49 am

Hi Harlan
actually i would use the 3.0/3.2 cylinder head design the 2.0 is for a lower volume individual cylinder and did not have another 10 years of improvements.
j
Last edited by Jacques Lefriant on Sun Mar 07, 2021 2:21 pm, edited 1 time in total.
 

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Martin Benade
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#68 Post by Martin Benade » Sun Mar 07, 2021 12:24 pm

I’ll never own a four-can but I am sure I’m not alone in finding this discussion extremely interesting. The only downside is all the unrequited drooling.
Cleveland Ohio
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Ibrahim Kuzu
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#69 Post by Ibrahim Kuzu » Sun Mar 07, 2021 2:17 pm

Martin,
I am with you. I started with regular Pushrod engine cars 1981 and never new there was a 4 cam Carrera engine existed...As we go we learned.
Know that some members likes in here what they read, but 4 cam cars have a tremendous history what made Porsche world wide known
In here as we post on main forum ,information going all over, not organized in as a unit scattered all over.
If I need pre A info or interested in pre A cars, I go to Pre A forum and get all the info nice and organized...This is not the case
on 4 cam Carrera cars .And members going other web sites to look info or place their knowledge ....I wish we can get all stay here as a one body
strong and informed.
IK

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Ibrahim Kuzu
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#70 Post by Ibrahim Kuzu » Sun Mar 07, 2021 2:29 pm

On Second note;
Wishing all valuable 4 cam mechanics long life ,but no one has any guaranty for our time ...Bill Doyle RIP in young age left us.
He was putting info on many 4 cam issues in 356Club California registration.
If we can get the 4 Cam Forum here ,We will be doing a great service to next generation care takers in many subjects on these Jewel of an engineering art.
IK

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Mike Smith
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#71 Post by Mike Smith » Sun Mar 07, 2021 5:33 pm

Wishing all valuable 4 cam mechanics long life ,but no one has any guaranty for our time ...Bill Doyle RIP in young age left us.
He was putting info on many 4 cam issues in 356Club California registration.
If we can get the 4 Cam Forum here ,We will be doing a great service to next generation care takers in many subjects on these Jewel of an engineering art.
IK
+1
Mike Smith (Essex - UK)

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Craig Richter
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#72 Post by Craig Richter » Sun Mar 07, 2021 5:50 pm

Martin said it very well. You don't have to own a 4-cam to appreciate it's place in Porsche history.
+ whatever number we're up to...
 

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Ibrahim Kuzu
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#73 Post by Ibrahim Kuzu » Sun Mar 07, 2021 6:05 pm

Hello to every one,
Seems to me Ferry says; " Keep my Jewel alive " :wink:
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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#74 Post by Harlan Halsey » Sun Mar 07, 2021 10:13 pm

Olivier,
I've pulled assembled Carrere heads several times, often to CC the piston crown re relieve for spark plug electrodes, and never noticed any misalignment of the long shaft on reassembly or removal. Nor any particular wear on the splines. So for me, I'm not making a problem where there isn't one. The anecdotal evidence I had when in the 1970s, and the street engines were piling up in garages as owners replaced them with pushrod engines, was that the failures occurred about 40,000 miles and they were mainly cam drive distributer failures leading to burned pistons, valve issues and rings wearing through the chrome cylinder liner into the aluminum. The wear on the driveshafts I had refurbished at the time was the journal bearing, and the solution was to grind about .005" off between centers to true it, hard chrome plate, and regrind to spec. (Hone the bearing to fit.) JIm Wellington's method.
The problem was that the tube sealing ring was of a softer material than the typical Buna-N o-rings readily available, as was the small shaft passage o=ring. They weren't available, and I couldn't enlist Bill Doyle in a bulk order. The hard ones do work, but they are clearly not right. Today things might be different.

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Re: Bob Garretson's idea 3 piece Carrera Cylinder Head work completed.

#75 Post by Harlan Halsey » Mon Mar 08, 2021 5:09 am

Jacques Lefriant wrote:
Sun Mar 07, 2021 11:49 am
actually i would use the 3.0/3.2 cylinder head design the 2.0 is for a lower volume individual cylinder and did not have another 10 years of improvements.
j
I think Bob chose the 2 liter because the cylinder size is close to that of a 1500/1600 Carrera. 2/3 of 3.0 is 2L which matches a Carrera 2, not a 547. In any event, were the project mine, flow bench and dyno testing is how I would go about it. The 911 is just the starting point. I would also do everything possible to lighten the valves, and soften the springs. Smaller titanium valves probably.
It is interesting to see the development going on with the Carrera, although the days of several Spyders showing up at the MHAR and running in two classes seem to be over. I think only one very ratty Spyder, which the owner laughingly thought to be "original" showed up last time.

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