Race Engine Forum UK

I recently bought a 8 valve inlet cam (for a Fiat twin cam) that is stamped "OSE 008" on the big end of the cam. The cam also has an Abarth style series of vernier dowel pin holes at the front end of the cam. It appears to be made from a steel billet. I have not degreed it yet but it appears to have around 10mm of lift and a very big integral.
Anyone recognize it? Have specs?
Tom McGaffigan

Sorry Tom,

that designation does not bring to mind any cam manufacturer I know of, all the Abarth cams I have ever seen were cast iron and stamped Abarth, with 3 digit type code.

GC

This is strange!!! I have a pair of 008 cams and are cast iron. This profile is slightly asymetrical ( valve closing is steeper).

The 008 profile is the cam used in the works 1608 BS1 spiders that won the Rallye Championship in 1972. The cam was designed for the 1608 engine to be used with Weber 44IDFs. These cars produced around 165bhp.

The data for this cam are in Abarth Servizio Informazioni N.4/72, and are:

43-65/71-38, TDC lifts 4.2in/3.1ex, and shimming at in0.40mm/ex0.50ex, cam lift 11.0mm

This cam is a piece of history and very rare indeed. The fact that it's assymetrical and it's timed at 4.2/3.1 at TDC is pretty unique. It has a medium indegral but a big lift.

The cam works in 1.8Lt engines as well and it was used in works cars up until 1974. However I do not recomend shimming at 0.40/0.50mm. Carefull examination of it's lobe ramps shows that the cam is ideally shimmed at 0.25mm both in and ex.

Enjoy!!!

Well done Vassilis, an interesting and useful post.

GC

Thanks Guy,

By the way, why in the world would Abarth time this cam 4.2 in 3.1 ex at TDC, i.e. 100 and 106 degrees lobe centers respectively, instead for 3.6 in and 3.5 ex (lobe centers around 104 degrees)?

Is there a theory behind advancing both inlet and exhaust cams? Is there a torque secret behind as I suspect?

Thanks,

Vassilis, hi

yes narrow lobe centre timing (or lobe centreline angle, LCA) which is the sum of the full lift positions, 104 + 104 = 208 LCA, can help the engine hold peak power better at top end rpm and give more area under the torque/rpm curve, ie: better driveability. When I say driveability I mean the engine will be measurably faster under acceleration than the same one tuned with wider LCA.

In saying this - much depends how compatible the exhaust and inlet are with the rest of the motor.

GC

Vassilis,
Thanks for the information on the cam, I only have one cam not a pair. Thanks again,
Tom McGaffigan