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Fri Apr 22, 2011 12:02 pm

I've done a lot of reading on TheSamba about differences between 25HP and 30HP (36HP) engines, but it seems that there is no concensus about all the parts.

The cylinder heads with large holes and allen key nuts, but with number 111 101 371A, are they true 25HP heads or early 30HP (36HP) heads?

I'm also a little confused about the inlet manifolds. I read about K-manifolds and I assume that those are the ones with the heater pipes bending off from the inlet pipe near the centre and both symetrically. I have some manifolds that bend off asymetrically, one quit near the centre, the other a couple of inches further to the side.

The engine tin that covers the top of the cylinders is in two pieces per side on a 25HP engine compared to a one piece per side on 30HP (36HP) engines right? Although it looks like to pieces on my 30HP (36HP) engine, the pieces are welded together and therefore concidered as one piece, am I right? Are the two pieces on the 25HP engine bolted together with regular engine tin screws?

Last thing; I have an engine case which is either a 25HP or a 30HP (36HP) case, but it has no engine number stamped in. How do I recognize if it's a 25HP case or not?

Fri Apr 22, 2011 12:39 pm

Your pictures didn't show up.

Fri Apr 22, 2011 1:17 pm

Enginetin is one piece even on 25 hp from early -52, a pic would help to see what it is.

Fri Apr 22, 2011 2:18 pm

What would you like to see on a picture? I don't know where the differences are on the bare casing (if any) ...

Fri Apr 22, 2011 2:54 pm

Have a look at these:
http://www.thesamba.com/vw/forum/viewtopic.php?t=394807&highlight=case+differences

http://www.thesamba.com/vw/forum/viewtopic.php?t=284171&highlight=differences

Fri Apr 22, 2011 8:00 pm

rainierdeklark wrote: The cylinder heads with large holes and allen key nuts, but with number 111 101 371A, are they true 25HP heads or early 30HP (36HP) heads?

I believe all the heads that have the large holes for the special cone shaped hex head nuts are all 25hp. Measure the size of the cylinder openings to know for sure.

rainierdeklark wrote: I assume that those are the ones with the heater pipes bending off from the inlet pipe near the center and both symetrically.

Yes, this is accurate. The opening that connects to the head is smaller as well.

rainierdeklark wrote: The engine tin that covers the top of the cylinders is in two pieces per side on a 25HP engine compared to a one piece per side on 30HP (36HP) engines right?

In very early 25hp it is. In later 25hp it is not. Each 36hp tin has a pair of distinctive cone shaped protrusions on it to accommodate the head nuts of a 36hp head.

rainierdeklark wrote: How do I recognize if it's a 25HP case or not? measure the cylinder openings is a good start. The casting number could help although replacement cases and heads were cast well into the 36hp years.

Pictures will get you more help too.

Sat Apr 23, 2011 1:48 am

After searching a few more hours on TheSamba, I compiled a list. Please correct if any mistakes appear in the list.

Sat Apr 23, 2011 6:31 am

Fuel pump info is reversed 25hp = 8mm, 36hp = 6mm

Oil filler is true for late 36hp but there were two different versions for early vs late 25hp and the late 25hp version flowed into 36hp until the screw type.

36hp did not use the 383 distributor AFAIK.

Sat Apr 23, 2011 9:02 am

As you see on my
http://www.thesamba.com/vw/forum/viewtopic.php?t=460386
25 Hp is 83 mm piston dia. 75mm
23,5 HP 78 mm piston dia. 70mm

cees

Sat Apr 23, 2011 3:06 pm

nlorntson wrote: rainierdeklark wrote: The cylinder heads with large holes and allen key nuts, but with number 111 101 371A, are they true 25HP heads or early 30HP (36HP) heads?

I believe all the heads that have the large holes for the special cone shaped hex head nuts are all 25hp. Measure the size of the cylinder openings to know for sure.
The allen-head nuts are on several of my 1955 engines so they were used at least through mid-1955.

Sat Apr 23, 2011 3:08 pm

In reference to the chart above:
53 25hp engines have 6mm fuel lines
54-55 engines still have the carburetor with the 28 PCI markings.
The 53 carb. is unique though because it has no vacuum line connection.

Sat Apr 23, 2011 4:29 pm

EverettB wrote: The allen-head nuts are on several of my 1955 engines so they were used at least through mid-1955.

Allen head, yes into 1955. The ones with the cones (in the top row) that fit the larger holes in the head, are 25hp only.

Sat Apr 23, 2011 7:57 pm

nlorntson wrote:
rainierdeklark wrote: How do I recognize if it's a 25HP case or not? measure the cylinder openings is a good start. The casting number could help although replacement cases and heads were cast well into the 36hp years.

Pictures will get you more help too.

Look just under where the oil filler goes. 25 hp have "nub" there but it is not drilled an tapped. 36hp blocks have that nub drilled and tapped. I'll try to get a pic later...

Sun Apr 24, 2011 12:18 am

Be careful :) , early 36-ers had this nub untouched, only the later ones were drilled for oilfiller.
Also in the chart, 6.1 compression ones had dished pistons...
Maybe you can split-up the coloms to be more specific.

Sun Apr 24, 2011 2:02 am

After examining the engine more closely, I discovered it is a 30HP (36HP) engine. :cry: On the right side of the generator pedestal it states 7 1 38 (jan 1958). That engine has 30HP (36HP) heads, but with allen key nuts. It also has a 28PCI without those numbers casted.

On the other hand, I have a 30HP (36HP) engine from sept 1958 that has regular head nuts and a 28PCI with that number casted into the carb.

Now I have too search again for a 25HP engine :?

But I'll continue to research the differences, hopefully with your help :)

Sun Apr 24, 2011 6:31 am

rainierdeklark wrote: On the right side of the generator pedestal it states 7 1 38 (jan 1958).

The casting date just means when it was casted not what model it is for. Obviously a casting number that falls in the years of the 25hp engine is a 25hp engine, but it is possible that cases for 25hp were still cast well after the 36hp engine was in production in order to meet the demand of 25hp replacement parts. In another thread I showed a 25hp case for a KDS replacement engine that was cast in late 1956.

Measurements of the cylinder openings is sitll your best bet for knowing what year it is for.

Sun Apr 24, 2011 11:31 am

But in my case, the 30HP (36HP) cylinder heads and the tapped notch on the pedestal for the oil breather make it almost certain that it's a 30HP (36HP) engine. To be absoluuuutely sure, I'll have to take the engine apart to measure the cylinder opening.

Wed Sep 21, 2011 1:18 am

Is there any difference between a 25HP and a 30HP crankshaft?

Wed Sep 21, 2011 2:14 am

rainierdeklark wrote: Is there any difference between a 25HP and a 30HP crankshaft?

Yes, there is at least a difference for flywheel fitting. You can see on factory manual, page 74: http://www.vw-classicparts.de/repleitfaden_typ11_52_57/repleitfaden_52_57_kapitel_M.pdf

Wed Sep 21, 2011 11:58 am

So if I understand it correctly, the 25HP crankshaft has a chamfered edge in the flywheel bolt hole, followed directly by the inner thread.
The 30HP crankshaft on the contrary has a 5mm bit without thread, between the chamfered edge and the inner thread.
Right?