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Typ "502" Engine discussion
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OMT
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PostPosted: Wed May 07, 2014 1:01 am    Post subject: Typ "502" Engine discussion Reply with quote

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I would like to open an discussion on the Typ 502 engine, I have included photos of what I have.
This is an engine of mystery and not much information is available on the Internet or thru "Word of mouth".
This is what I think I know, developed sometime in 1950-1951. Hurth crankshaft, Fuhrmann camshaft, normal heads; some variations used 32 PBI carburators or 40 PBIC with an adaptor to fit the manifold used at the time.
The base engine I have is serial number 207xx(forgive me, not my engine).
By no means am I saying that 207xx is part of the "502" engine production, the engine came in boxes.......
I would just like to discuss this unusual engine.
Please disregard the "wrong issues" with the engine, it is an "mock up" stage to fit tin.
Best Regards,
Al
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alanhall
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PostPosted: Wed May 07, 2014 8:33 am    Post subject: Reply with quote

Al,
There is a fair amount of discussion on the type 502 engine in the sticky topic relating to vin number charts. I do have a question on the engine you showed the photos of, does it have modified stud spacing as it appears to have late 3-pc case heads? If the spacing has been changed, how was it done?
Alan
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OMT
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PostPosted: Wed May 07, 2014 4:52 pm    Post subject: Typ 502 engine Reply with quote

Hello Alan, Thank You for the quick reply. Yes, I did view the vin number sticky; very informative. I'll study the Conradt book more.
Best Regards,
Al
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alanhall
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PostPosted: Thu May 08, 2014 7:24 am    Post subject: Reply with quote

Al,
This is what I suspect was the chronology of 1500cc 2-pc case Porsche motors, however I cannot prove this is correct.

Engine nos. P-30001 thru P-30066 were type 502, with Hirth roller crank, 7.0/1 compression ratio, 32pbi carbs with 24mm venturies on cast "normal" manifolds, circular intake ports in the heads, and with "mushroom" air cleaners. Camshaft had standard VW timing. Engine rated at 55hp (din).

Engine nos. P-30067 thru P-30250 were type 527, with Hirth roller crank, 7.0/1 compression ratio, 40pbic carbs with 26mm venturies on cast "normal" manifolds with adapter plates, circular intake ports in the heads, and with "mesh cylinder" air cleaners. Camshaft had standard VW timing. Engine rated at 60hp (din).

Engine nos. P-30251 thru P-30750 were type 527, with Hirth roller crank, 7.0/1 compression ratio, 32pbi carbs with 26mm venturies on cast "normal" manifolds, circular intake ports in the heads, and with "mesh cylinder" air cleaners. Camshaft had standard VW timing. Engine rated at 60hp (din).

Engine nos. P-30751 thru P-33899 were type 546, with plain bearing crank, 7.0/1 compression ratio, 32pbi carbs with 24mm venturies on cast "normal" manifolds, circular intake ports in the heads, and with "mesh cylinder" air cleaners. Camshaft had standard VW timing. Engine rated at 55hp (din).

Engine nos. P-40001 thru P-40999 were type 528, with Hirth roller crank, 8.2/1 compression ratio, 40pbic carbs with 26mm venturies on welded steel "super" manifolds, oval intake ports in the heads, and with "mesh cylinder" air cleaners. Camshaft had Porsche super timing. Engine rated at 70hp (din).

One of the reasons I believe this to be correct is that the hp changes appear to be consistent with the engine changes. The only nagging question is if the type 527 engine had the camshaft with the Porsche super timing. The information please spec book says it had the VW timing, but other sources indicate it might have had the super camshaft, Based on the power rating I think it probably had the VW timing.

Alan
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James Davies
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PostPosted: Thu May 08, 2014 7:58 am    Post subject: Reply with quote

I agree with Alan here. One thing I will add is that racing versions of the 502 or 527 (not clear which) engine probably used the Fuhrmann cam, as they are listed in Conradt and other sources as having the higher horsepower rating, but this may have only been for motorsports applications.

As for the motor numbered P-207xx, this would be for a 506 engine, a 1300 from 1951. You can get the casting date from the numbers in the 3 circles on the side of the generator stand. It would have had the short-throw crank (64mm stroke) with 80mm pistons. It could have had the larger Solex 40s fitted with an adaptor plate, but I believe those were first fitted to the early 1500 engines in 1951. But anything is possible, especially if this 1300 was used for motorsports.
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OMT
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PostPosted: Thu May 08, 2014 7:32 pm    Post subject: Typ 502 engine Reply with quote

Thank You for the replies, Alan and James.
This is an very difficult subject to document. I would like to think that the Typ 502 engines preceded the 30000 engine serial numbers, only because of the time frame of development.
I will need to do some research on the Hurth crankshaft, specifically prototype introduction.
Best Regards,
Al
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OMT
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PostPosted: Fri May 09, 2014 1:00 am    Post subject: Conradt's book 356 Reply with quote

Did an study this evening with Conradt's book "Porsche 356".
Chapter "What was that about the 1.5 liter?", an short synopsis of the chapter states the 502 engine was developed in early 1951. This engine powered the Gmünd bodied cars to record runs.
I also referred to the "Porsche" spec book. Alan you're right on target, the numbers all coincide with "527" serial numbers; but do not coincide with an 1951 build date. Do you think there is an prototype anomaly ? Possibly an different numbering system for this engine not listed in the spec book?
Best Regards,
Al
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James Davies
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PostPosted: Mon May 12, 2014 10:51 am    Post subject: Reply with quote

There were definitely 1500 motors numbered 30xxx produced in the fall of 1951. A case that sold on eBay was cast on Sep 27, 1951. It was a 1500 motor numbered 30079. Based on Alan's numbering above, it was a 527 motor. It had a Hirth roller crank.
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PostPosted: Wed May 14, 2014 4:52 am    Post subject: Re: Typ 502 engine Reply with quote

OMT wrote:
I would like to think that the Typ 502 engines preceded the 30000 engine serial numbers, only because of the time frame of development.


Hi Al,

The thing to keep in mind is that Porsche concurrently produced engines that were numbered

2xxxx 1300
3xxxx 1500
4xxxx 1500 Super

So 2xxxx numbers did not necessarily come before 3xxxx numbers, nor 3xxxx numbers before 4xxxx numbers.

In addition to the casting dates on each half of the block, the 4-digit internal engine number on the front bolt boss on the generator half *is* a sequential number through all types of pushrod motors. So I expect that might tell you something if you get information about where it lies in the sequence.
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Steve Heinrichs
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PostPosted: Wed May 14, 2014 11:24 am    Post subject: Reply with quote

Guys,

Sorry to be late to this party. I agree with James here.

Not sure exactly what problem we are trying to solve.

The stuff I have says 207xx would be 12-51 production. If I knew the full number, I likely can determine the car number.

Steve Heinrichs
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OMT
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PostPosted: Wed May 14, 2014 9:58 pm    Post subject: Typ 502 engine Reply with quote

Thank you for the replies, I would like to go back further in history to the "502" prototype engines. I am looking for records from the Porsche archives or any other evidence; pictures would be most appreciated.
I would like to drop the subject of engine 207xx, it was mentioned as reference. Please disregard this engine number.
Best Regards,
Al
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PostPosted: Mon May 19, 2014 6:57 pm    Post subject: Reply with quote

James Davies wrote:
There were definitely 1500 motors numbered 30xxx produced in the fall of 1951. A case that sold on eBay was cast on Sep 27, 1951. It was a 1500 motor numbered 30079. Based on Alan's numbering above, it was a 527 motor. It had a Hirth roller crank.


My '51 Split Cabrio. chassis #10105 / eng. #P-30023 has a 527 engine. The car has a production date of: Aug. 20th, 1951.
Its sequential engine number is barely visable: 1045. This engine uses a Hirth roller brng. crankshaft.

Noticing AlanHalls numbers: Engine nos. P-30001 thru P-30066 were type 502, with Hirth roller crank, 7.0/1 compression ratio,
32pbi carbs with 24mm venturies on cast "normal" manifolds, circular intake ports in the heads, and with "mushroom" air cleaners.
Camshaft had standard VW timing. Engine rated at 55hp (din).


My engine is #P-30023 is between these numbers BUT its a 527 and not 502. It came with mushroom air cleaners, cast intake manifold
adapters for SOLEX 40's, and normal camshaft similar to engines P-30067 thru P-30250?

BTW: The 502 model designation are the first 3 numbers of the plain bearing, 74mm crankshaft serial number. I believe this was Porsche's
first attempt at converting their VW 64mm stroke crankshaft into their 1st design 74mm plain bearing crankshaft. They stroked a VW 64mm crankshaft,
narrowed its rod journals and added 8 dowels. If I remember correctly, this "new" crankshaft was now being made/forged by ALFING and no longer VW.
This 502 crankshaft has all the characteristic's of the VW 64mm crankshaft as its "cheeks" are thinner and maybe this was a weak point and didn't last
very long and was discontinued until their 2nd plain bearing attempt with their 546 crankshaft which was much stronger.

My .02 cents worth........

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alanhall
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PostPosted: Tue May 20, 2014 2:44 pm    Post subject: Reply with quote

Hi Joe, If you can figure out the variations in 2-pc case 1500 cranks, you are a better man than I!! In roller cranks the original pre-a parts book lists 502-02-101 as the part # (without flywheel) for all 1500 engines and then the March, '53 supplement lists 502-02-018 and 502-02-015, both are listed for 527 and 528 motors and both are supplied with flywheel. For plain bearing cranks the original pre-a parts book shows, on an added page, 502-02-122 for the 546 motor. Then a later 2-pc case parts list issued in, I think, the late 50's shows 502-02-019 for the 546 and 616-02-015 for 546, 527 and 528! They also show the roller crank as discontinued. I haven't checked what the PET lists.
Alan
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James Davies
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PostPosted: Thu May 22, 2014 6:16 am    Post subject: Reply with quote

To add to the confusion, the Porsche rods and one-piece Alfing crank developed in mid-'52 have a 502.xxx.xx part number. In fact, a fun exercise is to run through the parts books doing a search for 502.xxx.xx part numbers. We have from the late-'52 parts book:

502.04.021 Cylinder heads for 1300 and 1500 motors, 80mm bore
502.01.101 Hirth crankshaft w/rods
502.02.116 Flywheel
502.08.307 Intake manifold adaptor for mounting 40PBIC carbs on 32PBI manifold

And modifications for 1953 model year:

502.02.122 Alfing one-piece 74mm throw crankshaft, type 546
502.03.015 Porsche 74mm connecting rods, type 546

Plus a number of small gaskets and bolts for mounting the above items.

Alan, what does the March '53 parts supplement cover? I've never seen that, and would be very interested!

James
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PostPosted: Thu May 22, 2014 6:19 am    Post subject: Reply with quote

Perhaps the Hirth crank + Flywheel part numbers

502.02.015

and

502.02.018

are for different versions of the Hirth 5097 crank assembly? There were upgrades, a believe the last being the 5097c. I don't know the details though. Would love to find out more.
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