Amazon: B18 Camshaft spacer ring

[sleek lemur]

Here's a question to test even the most detail- minded member... Assembling the cam shaft in my B18 rebuild, the spacer ring that came with my timing gear set (part # 418363) that goes behind the flange plate seems too small. In the parts catalogue it looks much more like a washer. Hole diameter on the part I have is fine and thickness also, but when I offer up the flange, the spacer will pass through the hole in the flange. pics attached.

Surely the ring needs to have a big enough circumference such that the flange plate can push the ring onto the camshaft thrust face?

I have emailed Brookhouse, who I'm sure will investigate, however when I Google the part number, I see other suppliers have the same too-small ring as I have. On the basis that it's unlikely that Brookhouse and all other suppliers are wrong and I am right, what have I got wrong?
Cam flange 1.jpg

Cam flange 2.jpg

Cam flange 3.jpg

[Burdekin]

I believe it should be smaller but a wee bit thicker.

[Burdekin]

https://youtu.be/D-JVOhefUcQ

[sleek lemur]

Thank you for such a quick reply ! Thanks, but I don't understand. thickness seems fine, but surely the ring needs to have a big enough circumference such that the flange plate can push the ring onto the camshaft thrust face? Otherwise the only thing holding the spacer in is the woodruff key and the thrust plate is not doing anything.

The cutting from the parts catalogue shows what I mean.

[Burdekin]

Originally Posted by sleek lemur

Thank you for such a quick reply ! Thanks, but I don't understand. thickness seems fine, but surely the ring needs to have a big enough circumference such that the flange plate can push the ring onto the camshaft thrust face? Otherwise the only thing holding the spacer in is the woodruff key and the thrust plate is not doing anything.

The cutting from the parts catalogue shows what I mean.

I was thinking it was the crank gear, I need to have a look as can’t remember for sure.

[Burdekin]

The ring is definitely smaller and a bit thicker as it is torqued up together. If the plate pushed it in it wouldn’t spin.

[sleek lemur]

Thanks, Burdekin. "Spacer would not be fee to turn" is what I was missing. Now it's beginning to make sense. A bit.

So, the spacer ring is a loose fit on the camshaft. The woodruff key allows it to move forward 3 or 4 mm. The spacer ring is smaller than the hole in the flange and the large timing gear fits flat against the flange plate. Then, what is the purpose of the flange plate? It doesn't seem to do anything other than act as a spacer between the timing gear and the block.

[Burdekin]

I assume the plate is to limit axial movement of the cam shaft.

[sleek lemur]

Thank you, Burdekin, that explains it. I also just found the following.

https://www.youtube.com/watch?v=JLALHr3lFt8&t=2131s

[142 Guy]

It has been a long time since I reassembled my engine; but, your assembly is looking 'mostly' correct. The hole in the thrust plate does seem larger than I remember. I thought the spacer was a slightly tighter fit in the thrust plate opening; but, that is probably not super critical.

The thrust plate / flange does not push the spacer on to the camshaft. The back of the timing gear hub does that job. The job of the spacer is to keep the timing gear from pulling the camshaft forward and clamping the thrust plate between the front thrust face on the bearing and the back face of the cam gear. That would prevent the camshaft from turning. The spacer should create enough clearance between the camshaft thrust face and the thrust plate to allow the camshaft to rotate freely. For the B20, the Volvo service manual specifies a permissible 'end float' of 0.0008" - 0.0024"). I interpret end float to mean axial play in the camshaft once everything is installed an tightened. Too much end float and the camshaft is going to bang back and forth (axially) and be noisy. Too little or no end float and the camshaft won't turn or be difficult to turn.

If you have micrometer or vernier caliper you can check the thickness of the spacer and the thrust plate. As Burdekin noted, the outside diameter of the spacer should be slightly smaller than the ID of the thrust plate hole and the thickness of the spacer should be slightly thicker than the thrust plate (by 0.0008 - 0.0024 ") to give the required end float.

If you are reusing the original thrust plate check for wear on the back face where the camshaft bears on the thrust plate. If there is significant wear that will mess up your end float measurements.

On the B18 there should have been locking tabs for the two bolts retaining the thrust plate. If you don't have those locking tabs (the B20 did not get them) use a little Loctite blue thread locking compound to keep the bolts secure.