25 and 36 horse parts differences

[npbusguy]

I am sorting a bunch of 36 horse parts I just picked up and I think I got some 25 horse parts too. I did a search but could not find a post that covered this topic. What are the major differences?

Here are some of the heads that were in the pile:
36 horse

25 horse?

Are the rods different? How about the lower heater box tin?

Thanks,
Neil

[johnshenry]

Yes the upper one is 36hp, the lower 25. The lower one does not have the 3x3 part number, so it was probably an original one, made during 25hp production.

The rods are the same, I believe, but I am not much of an internal engine guy, perhaps someone else can verify/dispel.

Lower tin is different, 25 has 3 bolt bores on the rear flanges

36 hp have only 2.
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John Henry

'57 Deluxe
'56 Single Cab

[kafer53]

25 horse?

I've seen some 111 part # heads being referred to as 25hp. I thought heads with the 04 025 # were 25 horse ones. Is this true?
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1953 Zwitter 11C (L73)

[johnshenry]

[52HoffmanSplit]

Rods are the same as 36hp... Crank, Cam, Bearings, Camfollowers (pushrods to some) and pushrod tubes are all interchangable with 36hp.

Only thing unique on a 25hp internally is the Pistons and Liners, Rings and the heads (and head bolts, skirted nuts.).
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DB

11/1966 Porsche 912
7/1968 Type 265 Double Cab
4/1955 Type 117 - 3 Fold

[npbusguy]

OK guys, here is another question. Are the head studs on a 25 horse shorter than a 36 horse head stud. See the picture below. The single stud has been pulled from a 36 horse case for comparison. I am trying to figure out what the shorter studs are for. I have 16 that are the same length and do not look like they were modified.

Thanks in advance.

[splitjunkie]

Yes, 25 hp studs are shorter. They are all the same length, top and bottom.
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld

[npbusguy]

One more thing....
John mentioned three holes on the rear flanges on the lower 25 hp tin?
I would assume this is what he was talking about.

Thanks,

[johnshenry]

[npbusguy]

[johnshenry]

Are those yours? One thing I see that indicates they may not be original '51 and earliers but rather a later, functionally correct replacement part, is that that oval flap appears to have a rubber seal.

The original ones were a single thickness with no rubber seal. Later ones, used on the early Porsche 356s which used the 2 flap type box well into the 50s, were two oval pieces of steel with a larger rubber oval piece sandwiched in between to create a seal. I have seen a few of these type VW boxes (none of the 356 ones were interchangeable with the VW ones) recently with the rubber seal oval flap. And they show some pressings in common with the later 36hp boxes which leads me to believe that they were post-'51 replacement parts made by VW to support the early cars....

Here's a pic of one of the boxes I restored and put on my '50 engine:

Some detail on the engine tin detail on these early split engines in this thread...

http://www.thesamba.com/vw/forum/viewtopic.php?t=309726&postdays=0&postorder=asc&start=0
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John Henry

'57 Deluxe
'56 Single Cab

[npbusguy]

Yes, these are my boxes.
Here are some detailed shots of the secondary flap.
The rubber is there as you suggested, though it is very hard.

Thanks again for the information.
Neil

[HeSa]

[johnshenry]

[bwaz]

These are what came with my zwitter... would they look to be correct?

Sorry to add the heater boxes, but rather than two posts...

Thanks for the help!

[nlorntson]

Those are 25hp shoe boxes and the heater boxes will work but I don't think they are correct.

John, your thoughts?...

[johnshenry]

The shoes boxes have the x plate flange and I think that was dropped well before zwitter. I would guess that those are '51 or early '52 latest, but that is just guess. Haven't seen any zwitter era engine pics that show them.

Heater boxes look correct for zwitter. They have the "test tube" external pivot so they are not he very earliest version of those ('51), but also have nut and bolt hardware which I think ended around '54.
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John Henry

'57 Deluxe
'56 Single Cab

[bwaz]

thanks for the replies, as the car had sat since the 70's, and most everything else (within reason) seems to be original to the car, I'd assume the shoe boxes are likely original, and maybe heater boxes likely too. I don't know if they would have replaced J-tubes in the 60's, but as they're so thick, they probably would have lasted. I wouldn't think a repro was made to emulate the old ones back then but could have been replaced from some old stock from somewhere?

[Zwitterkafer]

BWAZ, the showboxes and the heaterboxes look correct to me. IIRC the Zwitter shoeboxes still have the little flanges for the X-plate, but the X-plate was dropped well before the Zwitter, as already mentioned here.

H.
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"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[bwaz]

Thanks Harv, I'm just preparing to clean a bunch of small parts to paint/powder coat various pieces and unless I could say a specific part is a 40hp that I wouldn't spend time on, I'm going to go with what I have. If I have to get a replacement later, will do.