Hi. As usual, my excuses for my spanglish.

Friday last my Rojo (a 121 Amazon) lost half of the power (from 80 kph to 42 kph without change on accelerator pressure, in middle of the highway)... @#$#^%! (please, replace the symbols with your favorite irate expression).

Monday I open my B18 engine on the mechanic's workshop. Oh!, the rings on the third and fourth cylinder has a little playing and freely rotate, aligning the space on all rings... as a result a lot of pressure going off to the lower side of the cylinder (compression test: 135, 135, 105, 100 ; 135 was the usual due the headgasket was 2 mm gross - originally intended for use with 84RON leaded gasoline).

Ok, with the help and guide of my mechanic technitian, we are exchanging a lot of parts with rebuilted ones (taken originally from the engine of a 1962 donor car with less of 20K Kms before crashed with the original late owner inside): pistons at 0.30, bearings at 0.10 (original was at 0.20, we transplant the full tree), new metals (german made), new rings (also german, now without the play), a new headgasket (1 mm gross - now I'm using 97RON unleaded gasoline with 2% of 2-stroke engine oil added for valve seats protection) and a new fiber gear (the original lacks two tooths).

Today, in middle of the rebuilt, I check my camshaft (I figure it would be a "A" or "C" type), surprise: my camshaft is a "S 758", I've no idea about this type!.

Please, some of us know anything about this type of camshaft?.

Usually I've some difficult times to have a good idle at 650 rpm (the ideal speed for a B18A engine) and at the same time, remain under the local limits of pollution (600 for CO and 450 for HC, the only two limits ruled on my country - my best result are 550 for CO and 350 for HC at 800 rpm idle and 450 for CO and 300 for HC at 2500-3000 rpm). Probably the camshaft type are one of the sources of it.

"S" is a letter far away of "A" and "C" (and also "K") and due it i assume this camshaft work in a lot different rpm range and a higer idle speed than the more usual camshafts. As my car was originally intended as a police chase car, it would be some sense.

Thanks in advance for your kindly help.

Joaquin Novara
121 Rojo Amazon
Lima - Peru

Hi,

My S cam does not have that writing on it

ozzi '67 220

Thanks Ozzi, now i am sure mine are not a S.
J.

I doubt it's a real S... that one is a very "big" cam made for racing. It makes very little power under 3000 rpm or so, and definitely wouldn't go well with a single carburetor.

I have the same feeling, I use a ZS175-CD2S carb (good after the rebuilt but not a miracle). Somebody see a similar camshaft?

Is the 'S 758' cast into the cam's shaft? If so it isn't really the cam spec - I think they all used similar cast blanks and had the various cam profiles ground on. Usually the cam designation will be stamped onto the far end of the camshaft (opposite the gear).

The S 758 is just stamped onto the far end of the camshaft (opposite the gear):-)

More precisely, the S are stamped on the end end face of the camshaft, another cam (damaged) i own has a "A" just in the same place (and, I concurr, it is a A camshaft).

A,C,D, etc is stamped into the rear end of the cam, A cam grinder would stamp it there too or at the very front where the nut goes. What is written on the sides (between the lobes) are just casting numbers & mean nothing.

Thanks Paul. At the front (where the nut goes) I find a "K". Indeed, it may be a K camshaft. Ok, I have a good mislabeled camshaft (at last, the lobes has different sizes in comparision with a A camshaft) :-)

Joaquin
Rojo 121 Amazon (now on the maintenance shop)
Lima - Peru

hello,

it is a C-cam, S733=A-cam; S760=D-cam;S764=f-cam;S772=K-cam;S759=R-cam;S761=S-cam

B.R

Stefan

Thanks a lot Stefan. Just the data I need.

Joaquin
Rojo 121
Peru