How to Build a B20 VTEC Part 5: Bottom End Assembly

Enough measuring for now, it’s time to do some assembly and get the crank, pistons, and rods installed. Overall assembly of the bottom end isn’t super complicated, but it’s important to be careful while assembling everything.

Installing the Crank

First up is the crank. Before proceeding you’ll want to make sure the crank and block are as clean as possible.

(The numbers on my block are the bolt torque sequence because I kept messing up the order)

Then you can pop the bearing halves in.

If you’re using OEM bearings make sure you match each one to the correct journal. I’m using ACL race bearings and they should all be the same size but out of precaution I put each one back in the same journal I measured bearing clearance for to account for any variances.

Each bearing was given a coating of assembly lube, the crank was carefully lowered into position and the thrust washers were slide into place.

Note: Make sure you don’t install the thrust washers backwards! The slots on them should be facing out towards the crank. An easy way to verify they are correct is if the chamfered edge on each end is facing the crank.

After that, the remaining bearing halves can be installed in the main caps, coated in assembly lube, and the caps can be torqued to spec.

Make sure each main cap is installed in the correct spot as they are numbered and also make sure the crank can spin freely. If you’re not able to rotate the crank by hand you’ll need to take things apart and figure out what went wrong before moving forward.

If the crank does spin freely you can proceed with installing the rear main seal and oil pump.

Installing the Pistons on the Rods

I’m using Supertech pistons and SCAT rods. These use a floating wrist pin which means I’ll be able to install them without needing any special tooling.

Popping the clips that hold the wrist pins in position can be a little difficult but with some patience and a small flat head I was able to install them.

The main thing to be careful about is ensuring the intake valve reliefs on the pistons are properly oriented with the bearing tang grooves on the rods. I set mine up so the bearing tangs were on the exhaust side.

Popping the Piston Rings On

I used a cheap set of piston ring pliers from Summit to install the rings.

Rings are pretty straightforward to install and you just need to ensure the correct one is in each spot and the rings are in the correct orientation.

Rings will have a marker to tell you which side is up.

But you should refer to the manufacturer’s recommendation to be sure. For example the CRV FSM has an example on page 7-18 for OEM style rings.

Installing the Pistons Into Their Cylinders

Before you can put the pistons into their cylinders you need to make sure the piston rings are properly positioned so none of the gaps line up. Piston rings will naturally rotate as the engine is running so this isn’t a super critical step but it’s still good to do as a precaution.

Source: 97-00 Honda CRV FSM page 7-19

Now is also a good time to double check the rings and ensure that each ring is correctly facing upwards because once they’re in the cylinders you won’t be able to check anymore.

Then using a piston ring compressor each piston was slide into place and the rod bolts / caps were installed and torqued to spec.

Make sure you properly orient your rod caps and that the engine can still rotate once everything is torqued down. If the engine won’t spin by hand you need to stop and retrace your steps to figure out what went wrong.

Checking For Rod End Play and Crankshaft End Play

With the pistons, rods, and crankshaft installed the bottom end is just about assembled other than some finishing touches like the oil pick, and what not. Before they can be installed there’s just a few more measurements that we need to double check.

Crankshaft End Play

This is how much the crankshaft can move forward or backwards. Every crankshaft will have some play but it’s important to ensure that your crankshaft is within the allowed range. In order to check it you’ll need a dial indicator with a magnetic base and a pry bar.

I double checked mine and found I had .004" of play which is on the tighter end of the OEM range of .004" - .014" (Source: 97-00 Honda CRV FSM page 2-3)

If your crank has an excessive amount of play you should double check you installed the thrust washers.

Rod End Play

Rod play is how much each connecting rod can move back and forth on it’s crankshaft journal. This is pretty easy to check using a set of feeler gauges.

The OEM range is .006" - .0012". My rods were as follows:

Rod	End Play
1	.011"
2	.012"
3	.012"
4	.012"

This is on the looser end of the specs but is not cause for concern. If you were doing a build and re-using the existing OEM rods you could probably skip this step.