Technical Which camshaft did the 500R have?

[smart51]

I've read in different places on the internet that the 500R had the same camshaft as the 500F or the same camshaft as the early 126 which it shared the engine with. Does anyone have a definitive source on the matter?

As said elsewhere, I'm chasing a bit of power loss on my car. Thinking through where the power could be going, I've turned my attention to the valves. When I replaced my fuel pump, I noticed that the push rod stroke isn't as much as it should be, which made me think that perhaps the cam is worn.

I've just looked under the rocker cover. The valve clearances are good. The battery has died in my vernier callipers but measuring the valve lift with a ruler suggests the push rods are moving the rocker arms by 5.5mm. The 500F cam should be 6.1 and the 126 cam should be 6.2. I'll double check tomorrow when I've got a new battery. Either way, it sounds like a lot of wear.

 

[Toshi 975]

I can’t answer your question but I can tell you some of my experiences with cams. Some years ago I got together with a like minded pal to have a number of standard used camshafts reprofiled to a sport spec. Between us we had about 20 camshafts and initial inspection showed 3 had a very worn out lobe and we rejected those. They were all sent to the camshaft specialist and their inspection rejected another 3 so amazingly about a third were too worn mostly just on one lobe but also signs of wear on the fuel pump cam.
I have measured the lift on a number of cams from standard to Abarth and Alquati etc. 5.5mm would be a bit low as the smallest I measured was 5.7mm, a new Polish 126EL cam 6.55mm, a new Polish 35/75 cam 7.0mm and an Alquati 40/80 7.75mm.
I suspect that there are quite a few engines out there that are running worn camshafts on that evidence and I always recommend guys to inspect the cam if possible. The throw for the fuel pump should be 2.5mm I believe.

 

[smart51]

Confirmed with the verniers, 5.7mm. Depending on which cam I have, that's 0.4mm or 0.5mm less than the spec.

That's 8% less valve opening. If that corresponds to 8% less air and 8% less power, that is costing me 1.8 BHP.

 

[fiat500]

I've read in different places on the internet that the 500R had the same camshaft as the 500F or the same camshaft as the early 126 which it shared the engine with. Does anyone have a definitive source on the matter?

As said elsewhere, I'm chasing a bit of power loss on my car. Thinking through where the power could be going, I've turned my attention to the valves. When I replaced my fuel pump, I noticed that the push rod stroke isn't as much as it should be, which made me think that perhaps the cam is worn.

I've just looked under the rocker cover. The valve clearances are good. The battery has died in my vernier callipers but measuring the valve lift with a ruler suggests the push rods are moving the rocker arms by 5.5mm. The 500F cam should be 6.1 and the 126 cam should be 6.2. I'll double check tomorrow when I've got a new battery. Either way, it sounds like a lot of wear.

I've previously put out the question about the number of varieties off the standard camshaft by year or engine-type. It's odd that something that the camshaft, that seems to be considered so important in the aftermarket provision seems to be backed-up by so litte, written detail in original literature.