JBUGS VIDEO SERIES

JBugs Video Series

VW Super Beetle Crank & Rod Assembly:

Video Overview:

Our 1971 Super Beetles engine case is back from the machine shop and ready to be built. We're going to do a mild performance build and start with a 74mm counterweighted crankshaft at the heart of our engine. To ensure the crank and rotating assembly doesn't contact the case we assemble the crank and rods and test the fit and clearance in the engine case. Follow along with our tech as he starts our 1800cc engine build.


Video Tips:

The tools you will need are:

Torque Wrench
3/8" Ratchet
6" Extension
11mm Socket (12 point)
19mm Socket
17mm Socket
Snap Ring Pliers
Brass Hammer
Small Punch
Pocket Knife
Permanent Marker
Assembly Lube
Hot Plate or Grill
Vegetable Oil
Old Pot
Tongs
Welding Glove
Engine Stand
Parts Cleaner
Lint Free Shop Rags
Grinder
Air Compressor & Blow Nozzle
Blue - Medium Thread Locker

Video Transcript:

Hello there, I'm Sam with JBugs.com In our last few videos, we pulled apart the engine from our 1971 Super Beetle, as it wouldn't turn over. We discovered a dropped valve, a hole in a piston and excessive crank end-play which meant the engine needed to be fully rebuilt.

 

We were hoping that the bottom end was in better shape as we were planning on a set of thick-walled 88mm pistons and cylinders, along with big valve heads and installing some high ratio rockers. This would have increased the factory displacement from 1600cc, which is actually 1585cc, by 94cc to 1679cc. More importantly, none of this would have required splitting the engine case.

 

That opportunity is gone, and while we'll still be using the same bolt on top end parts we originally intended, we're going to build an 1800cc engine by adding a 74mm crank to the mix. The intent of this rebuild will be to keep special machine work to a minimum. While we did have to head to a machine shop to have the case line bored, like anyone who is rebuilding an engine would have to, that was it. Everything else for the rebuild can be done with common tools most of you would have at home in your garage and a few inexpensive specialized tools here and there.

 

This isn't a high-performance race build though, and all the steps of our engine build can be done by the average person. We aren't weighing every part, spin balancing every component, or blueprinting the case. This will be a simple garage build. We start by cleaning the crankshaft and so we don't have to mention it over and over again, every part that we will be working with is cleaned completely with parts cleaner and blown off before it's test fit or assembled.

 

Our engine case is clean and all the passages have been flushed and blown out. Often times, the same part is cleaned three or four times in between test fitting and final assembly. We start at the bench with our crankshaft, which has been eight dowelled with an offset pin, and we're matching it up to a lightened eight dowelled flywheel.

 

The crank is set up right onto it to make assembling the rest of the components easier. We start with the number three bearing and coat it and the crank with assembly lube and slide the bearing onto the crank journal. Make sure the dowel pin hole is offset towards the flywheel so the bearing will align properly in the engine case later. The timing gear keyway is set in place on the crank.

 

Then we'll prep for installing the cam and distributor drive gears which will not fit onto the crank unless they are heated up or pressed on. As we don't have a press here, and most of you don't have one at home either, we'll move outside, for safety, and fire up a propane grill. The cam drive gear and distributor drive gear are set in a pot of vegetable oil and placed on the grill. It takes some time but eventually the oil and most importantly the gears get hot enough. More or less once the oil itself starts smoking steadily, we're ready to install the gears. The timing gear is pulled from the oil, with a set of tongs, grabbed with a welding glove-covered hand, and set onto the crankshaft. Making sure the timing marks are pointing towards the crank pulley side.

 

The gear slides down freely and actually knocks the keyway loose. Some quick hands are needed along with a punch and hammer which are used to straighten the keyway and then tapped the gear down completely. Next, the full circle gear spacer is installed on top of the timing gear and it's followed by the heated up distributor drive gear. The grill is turned off and we'll move back inside to continue our build.

 

B the timing gear snap ring is slid into place, with a pair of snap ring pliers, and tapped into place, into the groove on the crankshaft. Next, are the rods. Seeing as how stock rods won't last longer than 5,000RPM and our new engine build will easily turn past that mark, we'll install a set of stock length chromoly "eye" beam connecting rods.

 

New standard rod bearings are installed and not that our connecting rods don't have a raised nub like our stock rods to indicate the top. We instead look at the stamped numbers on the rod ends [which sit along the top sides] and the bearing tangs, which will sit at the bottom. The bearing and the rod journals on the crank are covered with assembly lube.

 

The rods are set in place making sure the rods and most importantly the rod numbers are aligned and facing up. In our case, seeing as how we're using a stroker crank, we will be checking clearances so we won't be using thread locker on the threads of our rods yet. The rod bolts are coated with assembly lube and then torqued sequentially to 15, 20, 30, and finally 38- foot-pounds.

 

Those specks are specific to our aftermarket rods. Stock connecting rods will be tightened to 15, 20 and 24-foot-pounds. With the connecting rods tight we check that they rotate freely on the crank and rotate them, to check the alignment and the stamp numbers all face the same side.

 

Starting at the flywheel side the rods are in order number three, number one, number four and number two. Next, the front bearing is coated with assembly lube and slid onto the crank. Again, make sure that the dowel pin hole is offset towards the flywheel. That's followed by the oil slinger, which is disced, and set in place with the dish pointing towards the crank pulley. The crank pulley keyway is tapped into place. We check the fit of a stock crank pulley, making sure it fits over the keyway.

 

Next, we mount the left side of our freshly machined and cleaned engine case to our engine stand. We install the four main bearing dowel pins and set the number two half-circle crank bearing into the case and coat it with assembly lube. We also test fit the rear number one bearing, which was cut down by our machine shop to match our cut down thrust surface on the case, and mark the bearing so that lining it up later will be easier.

 

Since we have a stroker crank we need to check for crank and rod clearance to the engine case. We will only be doing a test fit. If you're using a stock crank, this next process isn't necessary.

 

The crank assembly is pulled off the flywheel and the number one bearing is lubed and slid onto the lubed crank at the rear. Making sure again that the dowel pin is offset towards the flywheel. The crank is lightly set into the case while holding the number one and number two connecting rods up. With the crank in place, the three full circle bearings are rotated until they align with the dowel pins in the case. We start with the number one bearing.

 

Then the front bearing [is] aligned. With the bearings all lined up with the dowel pins, the crank will settle fully into the case. Spin the crank over by hand to verify the bearings are set in place. The bearings should not spin and an additional check would be to set the remaining center half circle bearing onto the case at the number two journal and check for a gap by trying to push the bearing towards either side. If the bearing moves, there's a gap and the other bearings are not lined up properly.

 

With the bearing alignment confirmed, the bearings are marked at the side of the case so lining them up again the next time will be easier. Back at our bench, the right side case half is prepped by inserting the alignment dowel and the remaining center half circle journal bearing is set in place on the case and coated with assembly lube.

 

The right case half is brought over to the stand and set in place onto the left case half while keeping the number one and two rods upright to clear the case. The washers and studs are set onto the main studs and snugged down lightly. Now we can rotate the crank and check to see if the crankshaft or connecting rods hit the case. For the most part the rods clear. But at the outside of the stroke, our rod bolts hit the outside of the engine case. Interference is minimal and only at certain angles but the bolt heads or the case must be clearanced to ensure the two will not hit.

 

At this point, either the case or the rod bolts can be clearanced. The rod bolts are the simplest to clearance and won't require another thorough cleaning of the engine case. We mark all eight of the rod bolt heads to indicate where the material will be ground away. Note that the next torque sequence till most likely line up the bolt heads up a few degrees clockwise past this point that the bolt heads sit at now.

 

So that will be taken into account when we grind the bolt heads down. The nuts and washers are removed from the main studs and the right side case half is pulled off, set aside and covered. The crank assembly is lifted from the left case half, set on our flywheel and the left case half is covered. All the connecting rod bolt assemblies are removed, the crank assembly is bagged, and then the bolt heads are ground down at an angle so they won't fit inside the case.

 

We still leave a bit of material for our 12 point socket. With all the bolts clearanced they are cleaned re-coated with assembly lube at the heads and a drop of blue thread locker is applied to the threads before the bolt is threaded back down in the rod and tightened down in sequence again to 15, 20, 30, and 38-foot-pounds. Stock rod nuts will be tightened to 15, 20, and 24 foot pounds and then either peened over after being torqued, or of the rods do not have a notch for peening, thread lock will be used on the nuts.

 

We test fit the crank assembly into the engine case to make sure the clearanceing is sufficient and with the rod clearance confirmed we pull the crank and bag it for safe keeping until our next video. There we'll get back to the engine case that is sitting on the stand and we'll install all the engine internals, drop the crank back in, set the opposite case engine half in place, and get the short block torqued down.

 

This will obliviously be a multi-part series and while some of the steps are specific to our mild performance build, these same processes will be used on a stock 1600cc build. If you're looking for something to keep you busy until the next video is released head over to JBugs.com for all your vintage Volkswagen parts and accessories.