Forum for competition engine enthusiasts. RIP Guy Croft 09/11/2020 - This forum will continue both as a source of information and as a memorial to Guy.
As part of a parts purchase for the buildup of a Fiat 1500cc SOHC engine I acquired a performance camshaft. This camshaft is from a well known local firm that is no longer in the Fiat performance business. When they offered such parts both new and reground camshafts were available. I would like to know if the one I have is from a new blank or reground, and as such should be considered for use. I do not see any identifying marks besides the company's name and cam spec stamped on the end. What should I look for to identify its origin?
The best way to find out is to overlay a regrind map on yours. However if it was a regrind it would probably have a markedly smaller base circle than yours has. That's how regrinds are generated, grind the base circle smaller and you get more lift for the same cam nose height relative to the centreline, because obviously you can't add metal to the nose (though some try). It is certainly an cast-iron cam because you can see the sand casting marks on the flanks of the cam profile regions and shaft and as one could never buy unground (ie: raw) billets from Fiat and it has no codes on it at all (which Fiat cams all had) you can be pretty sure it's an aftermarket billet.
How good the blank is I don't know but someone is making top grade chill-cast cast iron billets for these and also TCs because the cams I have ground at Kent and Piper are such. A good chill casting will be extremely hard - take a file to a redundant region of the shaft and try and file it. If you can barely make an impression it will be properly chill cast. If it's easy to file I would not use it. Non chill-cast billets don't last very long, even with new shims, the right running clearances, cam lube, good startup regime and great oil. Chill casting utilises blocks of steel in the mould to draw off heat and make the metal cool more quickly, hardening it. Something like that anyhow, done plenty of casting but never actually done that...
Looking at your cam map it has 3.2mm nominal lift at TDC, that's at 125 deg on your map (if timed at 110 ATDC deg full lift, ie: 180 - 55) and full lift is nominal approx 10.2mm. Nominal being the lift measured with zero clearance bucket-cam of course. With running clearance 0.4mm inlet the valve lift (actual) would give 2.8mm at TDC and full lift 9.8mm. Not a million miles away from a Piper BP270 fast-road cam and maybe worth a try.
I am pleased you have taken the trouble to write this thread with some care and done your best to map the cam.
Thank you for the informative reply Guy. I took a file to one of the casting seams and did the same with a stock cam for comparison. I would rate the aftermarket cam as a bit harder requiring real effort to remove any material. While I had the stock camshaft out I did a visual comparison between the two. My original intent was to do some measurements of the base circle and relative nose height to completely rule out the possibility that this is a regrind. However just a close look comparing the nose of the stock cam with the aftermarket cam clearly showed that this cam started with a blank. I was surprised and can now see why you won't deal with a regrind at all. It is just not possible to even come close to the same profile. I'll follow up with some photos and graphs because for me it really drove the point home, and hopefully will be illustrative for others like myself who read your site. Thanks again.