General: Identifying a camshaft

[chirlas]

I have a B20A block reportedly reconditioned by the last owner. It is already assembled, so the only part clearly visible are the pistons, which look like new. In order to make decisions on head and carburettors I would like to know what camshaft is inside. What I can see through the 4 orifices between the valve lifters is, beginning from the timing gear side:
- 41820
- 1
- nothing
- N

I was not able to find a Volvo part no. 41820.

[packers1712]

I think the only identifying marks on the camshafts are on the flywheel end of the engine, certainly when I recently did the camshaft timing gear on my car there were no marks at the front.

Doug.

[packers1712]

Picture taken from another thread.

Doug.

[powen1]

Hi
attached is picture of my old Cam you can see the detail on the side of the Cam mine was a K cam as seen in the pic - you may be able to pick up from your cam more information
Paul

[Rustinmotion]

If you don’t want to remove the cam you could workout the open and close timing by putting a dowel on the cam follower and mark the crank pulley as soon as it starts to lift and mark it again as soon as it stops closing, website Turbobricks has a post with a link to all B engine camshafts
If you measure carefully from pulley mark TDC to pulley mark 10 degree and divide that distance by 10 you have the distance by 1 degree so easy to wrap a tape around pulley circumference and calculate the degrees BTDC for opening of valves

[Derek UK]

If you can't talk to the guy who rebuilt the engine and find out about the cam I would bite the bullet and take this one out to check. He may have put an A cam in or not even changed it. I guess that you don't want an A cam. Measuring the lift by the method posted may give you some numbers but they may not be accurate enough to tell you what cam you have. If the short block is on the bench or on an engine stand you can have the cam out very quickly. Yes you do need a puller to get the cam gear off. Don't try and lever it off with a couple of screwdrivers if it is a fibre gear.

[142 Guy]

Rustinmotion's method is similar to the method described in the Volvo service manual. The service manual procedure is a little different and perhaps a little less fiddly. The service manual for my 1971 140 listed the measurement points for all the cams used in the 1971 model year. Of course, the specific Volvo method is only useful if you have one of the Volvo grind camshafts.

I think the comment about markings on the bell housing end of the camshaft is correct for original or Volvo supplied replacement cams. These days I think most of the OEM spec replacement camshafts are not supplied by Volvo and do not have markings indicating the grind. I don't recall markings on the end of my D cam when I did the replacement 10+ years ago.

[chirlas]

After rotating the flywheel a new code showed up in the "nothing" third orifice:
- 41820
- 1
- K3 (new)
- N

Will it mean it is a K grind cam?

[Derek UK]

Only by coincidence. I'm guessing the K you see is cast onto the cam. New cams start out as blanks and are ground to the required spec. All of the blanks will have basic part numbers cast on them. The same blank could end up as an A,C D or K. There is a tuning technique where you grind the base circle of the cam. This increases the lift but the existing lobes have to be in very good, unworn, condition for that to be considered. The proper Volvo K cam might be a good choice of cam for you. They are also cheaper than aftermarket cams. Use new followers.

[142 Guy]

The traditional location for the camshaft marking was on the very end of the back camshaft journal. I have attached photos showing the mark for an R and F grind. With the cam installed in the engine this marking would only be visible if the expansion plug in the bellhousing area at the back of the engine is removed. If it is a rebuilt engine with a new camshaft chances are that it will not have the traditional marking indicating the cam grind.

There are some sources that indicate that Volvo may have marked the grind on the front of the cam. Whether this was visible on the very snout of the cam or the front surface (requiring removal of the gear) is unclear. I have never seen a cam with a marking on the front.

The numbers you describe may just be casting numbers and have no relevance to the grind because it may be the same casting for all cams. If you absolutely need to know then do the crankshaft angle and lift measurements to confirm the cam grind.