Hi,
I have a '68 122 with a motor that says "B20" of unknown origin. I'm trying to put AC in the car and am in need of an idler pulley. I've found one that is mounted on a post that comes straight out the back. It looks like this mounts in a hole on the drivers?!? side of a B20 in a photo on my site. I can't find a corresponding hole on my block and I can't figure out why the idler would be on the driver's side?

I've also found one that has an arm. This mounts on the passenger's side and again I can't find a corresponding hole on my head. I have a hole near there where my alternator attaches(GM alternator on homemade bracket) but I don't think it't the same spot as the mounted idler of that style on my site.

Last I posted a picture of my friend's '68 with a B18 and its stock idler. This is the style that mounts on top of the head through the head bolts. I can;t find one of these anywhere.

I've posted pics at:
http://homepage.mac.com/bearschmidt/122ac/
If anyone has any thoughts on how to mount the two styles I have or knows of one of the others for sale I'm interested.

Thanks!
Bear

I think you might have a B18 head or if not, a VERY early B20.
All my B20 heads have a boss on the front above the alternator belt tensioner
mount on the passenger side. (B30 likewise) But all mine are FI heads.
If you can give me the 49xxxx number on the driver's side of your block
(first 2 or 4 digits will be cast, the rest stamped) I can tell you the
approximate year and hp of your engine.
--
George Downs Bartlesville, Heart of the USA!

Thanks for the info George. As I said I have no idea of the engine's origin(it may even be the stock one.) The numbers are indistinct, but I think they are 49 8285 16956. Is it really possible that it's a b18 head? Thanks. Bear.

According to "Motortypen" from the German Volvo club 498285 is a B20F
with 115 HP, no other info given. But if it has the original head it should
have injector ports on top of it above the area where the manifolds bolt up,
about the size of a nickel over each intake port. If you are using carbs
they will be plugged. If there are no injector ports you definitely have a
different head. Could be a B18 head. To tell you can look into the oil
filler and see the ends of the valve spring retainers. B18 valves have
11/32" stems while B20 valves have 5/16" (slightly smaller) stems.
Also B18s should have black plastic "seals" ABOVE the retainers, while the
B20 seals (which actually work) are fitted over the end of the valve guide
down inside the spring. So if you see something black and not metal on top
of the valve spring retainers, it is a B18 head.

BTW the first B20 engine was 496900. Earlier numbers are B18s.

The correct head for the 498285 engine should have both injector ports and
bosses on both sides for tensioners, idlers or other accessories.
--
George Downs Bartlesville, Heart of the USA!

According to my chart,[which I copied from a parts bulletin] engine no. 498285
is indeed a B20F with 125 BHP[SAE] and originally came in a 140 with a BW35 trans. Oddly it is the last B20 listed on my chart.


Cheers, Jim R.

The set-up on my '72 1800 had the idler pulley on a straight bar, and bolted to the head on the driver's side, in the threaded holes shown in your picture. The AC was above the steering box. I have removed it during a restoration process and not re-installed it yet, so I can't give you a picture.

Thanks for the reply. I believe you mean mounting the "post style idler" here:
http://homepage.mac.com/bearschmidt/122ac/PhotoAlbum401.html
I have a couple of questions if this is really where they mount. The metal "post" doesn't go into the motor at all and it seems hard to believe that the bolt wouldn't eventually break off. It is also pretty far forward. I think it's too far forward(my double crank pulley is not on the car at this time so I cna't tell for sure.) I suppose I could take some metal off the post but ???

The part that really confuses me is that it would place the idler and the compressor on the same(driver's) side of the motor. The compressor brackets I've seem are all fixed and the idlers are usually what you use to tension the second(AC) belt(and all the other style idlers are on the passenger side). How did you adjust the tension on your setup?

Thanks again.
Bear