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Sat Sep 19, 2020 12:57 am

I've been doing too much reading on Veedub restoration and engine builds and so I thought it's about time I did some practicals and build my first engine. After all, I've been offering invaluable advice to people owing to the theories in my head.
So I had a 1200cc motor that I disassembled some years back at a friends place and went with it home in pieces. When I wanted to start a build the other day, I wanted to take stock of what I have and what I'll need to buy. But somehow, I was missing a crankshaft and a flywheel. So I began a search in my town and eventually found some and in the process, found another 1200cc motor assembled by a roadside mechanic and bought it as well so I can build one for trial and then one will be built after learning all my mistakes with the first.

Now, here I am with two standard cases and pieces for building two motors. The "freshly assembled" one had very tight conrods that were like almost stuck on the crankshaft. I'm still waiting for a caliper I ordered to be delivered but all the bearings are standard. So my question is, how can standard bearings be so tight on a crankshaft? I thought they should actually be loose fitting because the crankshaft is used. Are all crankshaft measurements the same for a 1200cc and the others from 13/15/1600cc motors? I know the stroke is 69 on the others and 64 on the 1200cc so is it possible that both these cranks are from 13/15/1600cc motors? How can I visually tell the difference and measure stroke? Trial fitting the conrods on both crankshafts yield very tight fitting even with finger tightening by the way. Or is it because I'm trial fitting with no lube?[/b]

Sat Sep 19, 2020 1:46 am

With a block that had been assembled and just left sitting, I can see certain types of assembly lubrication could bind up. I bought one such engine that had sat for many years in a hot Arizona garage and it was seized up totally.

Anyway, that does not sound like the issue here.

The connecting rod bearings are the same between 34bhp/1200 and 1300-1600, the base width, overall length and the piston pin bearing were the differences. The at-crank width difference is 1mm, so it should be extremely obvious if you have the wrong one.

Now, sometimes rods can bind up when tightening them, VW mentions this in the service manuals, this excerpt is from a 60s manual about the 34bhp engine:

Sat Sep 19, 2020 5:35 am

Always lube bearings. Even when trial fitting components.

The rod bearings will bind when finger tight. Torque to spec and the rods should fall at the same rate when the crankshaft is in the horizontal orientation.

Most importantly. Measure everything carefully before assembling parts.

Sat Sep 19, 2020 5:58 am

Silver line bearings? Sometimes known to be tight.

Sat Sep 19, 2020 6:17 am

You can check each rod bearing half on the crankshaft journal by laying it onto the journal and observing/feeling that the bearing is fully contacting the journal. Lube the crank journal with engine oil. The bearing should not pinch up in the center (bearing too small) nor just sit on the top and the ends stick out (bearing too large). If each bearing half sits correctly, put the other bearing half onto the journal. Their ends should be a "hair's width" apart, and the bearings should rotate easily per your finger pressure. That tiny gap should come together when the rods are tightened during assembly.

Most rod bearings are stamped on the back surface, usually near an end, with the size. "Std", "0.25" (millimeters), etc.

Did you match up the rod big end caps with the rod shanks per the small ID numbers stamped into the flat pads on each component? The numbers not only have to match on a properly machined rod, but both numbers need to be adjacent. You can put the big end of a matched set the wrong way so that the stamped numbers are on the other side of the big end. That usually causes a very slight misalignment of the big end so that one edge protrudes past the shank. This causes the rod to become wider and might contact the adjacent crankshaft "cheek".

Sat Sep 19, 2020 6:44 am

Are they new rods? Did you fully torque them?

Sat Sep 19, 2020 6:59 am

Thank you so much @Glutamodo for that. The motor sat for about a month or two since the dodgy mechanic assembled it. I even found two cam followers were seized tight and actually damaged the outer edges of one with teeth of a grip pliers when trying to unbind it. Inside the motor, I found 4 re-usable followers (lifters) including the knackered one. I guess I'mma need a new set anyways. Thanks for the images. Quite helpful. Will go take a look once I get home later.

@67Rustavenger, thanks. Will try with lube. Was just checking to know the next cut for the crankshaft. The bearings are actually used and standard yet tight. This dodgy mechanic that sold it is actually and junkyard man and not really a mechanic. He is known for cobbling things up together and assembling stuff with mixed up internals just for a quick buck. But we buy things from him anyways. Parts.

@Baz76 These were used bearings and I've no idea which brand they are. But I'm informed silverline are very good bearings coz they are normally steel-backed.

@Rome, I usually thought that the rod halfs should have the bearing dimples on opposites. If I try matching the stamped numbers on one side, the bearing dimples are on the same side. I will try the other way so the numbers align and report back.

Sat Sep 19, 2020 7:02 am

@Slalombuggy.. Nope. They are not new rods and I only finger-tightened them.

Sat Sep 19, 2020 8:46 am

Now that I'm back home, I actually forgot to state in my reply my real worry. Identifying conrods are relatively easier following the 20mm vs 22mm for the 13/15/1600cc gudgeon pins. I'm not finding it easy to know if the crankshaft is the 64-stroke ones for the 1200cc. Is there any visual tell-tale for confirming which crankshaft it is? Maybe a part number or something?

Sat Sep 19, 2020 10:13 am

Silver line mains are good, rods not so much in that a lot of folk avoid them.

You need to torque the rods correctly before checking fall regardless of bearing manufacturer.

Sat Sep 19, 2020 10:37 am

wokokow wrote: I'm not finding it easy to know if the crankshaft is the 64-stroke ones for the 1200cc. Is there any visual tell-tale for confirming which crankshaft it is? Maybe a part number or something?
The cheeks on the 1600 crank are thicker and less tapered. In the pic below, the 40hp/1200 crank is on the left and the 1600 crank on the right.

Sat Sep 19, 2020 10:49 am

Another clue, from hazetguy:
"On the left is a crankshaft that uses a stepped, 6V flywheel.
On the right is a crankshaft that uses an o-ring type 12V flywheel.
Notice the different depths that are machined on the ends of the crankshaft."

In this photo, the crank on the left is most likely a 1300cc one which was the 69 mm stroke but still had the 6 V flywheel. But this style of flywheel joint was also utilized on the 1200 40 hp (34 hp DIN) engines.

Sat Sep 19, 2020 12:37 pm

Quite helpful @Mukluk. Now I know I have the 64 stroke 1200cc. Many thanks @Rome as well.