I have seen that there are lot of camshafts around. If i upgrade to 540cc which i am thinking to do as this is the cheapest option for me now, i want to know what kind of cam to use along with the 28 carb. What kind of camshaft does the 500 has and is it the same with the 650?
Is the 35/75-75/35 - 110°/290° camshaft hotter than the 650?
Thomas

Hi Thomas,

I have just had the camshaft re-ground on the 500F engine I am having to rebuild. Camshaft grinding is a bit of a black art and it often comes down to the knowledge of the guy doing it what results you get.

The local guy I use here in Christchurch, NZ has had years of experience and seems to be the go to guy for the race guys in the area.... good enough for me.

His comment on the 500 was that the standard camshaft was setup to produce power at higher revs than what the engine is comfortably capable of. He also said that the cam wasn't the limiting factor in the performance. He felt that a hot cam alone would not improve performance much without visiting the carb, head and exhaust as well.

Long story short, as my engine is otherwise standard we went with a grind that would produce more mid range torque rather than top end horsepower. The profile we used is a Datsun one I believe. I am putting it together today as soon as I have finished my coffee so I'll let you know how it went.

Chris

Chris interesting notes from your cam expert, do you know the new timing numbers?
Waiting for the results.

Another thing I came to while searching also mentioned before by the member cdeorio is that there is a 35/75 cam special designed for the 540cc cylinders. I wonder What might be the difference of this special 540cc and a standard 35/75 cam that goes for example to a 126 engine?

Thomas

Had to check my cupboard but I still have one spare 35/75 unused sport camshaft made and tuftrided by Newman Cams a few years ago. £115 + shipping if anyone is interested.

The more you search the more you confuse. Nanni has a 30/70 cam special for the 540cc!!!

gordinir8 said:

there is a 35/75 cam special designed for the 540cc cylinders. I wonder What might be the difference of this special 540cc and a standard 35/75 cam

Click to expand...

I think mystery solved, the special 540cc cam is not 35/75 but 30/70 (possibly a typo mistake), something between the 20/50 standard 500 and the 35/75 tuned 650 i ques.

Hi Thomas,

I haven't had a chance to talk to Peter and get the figures yet but I'll call him this week for you.

I thought you might like an update anyway. The new cam seems to have improved the mid range performance noticeably. I can't put any figures on it and it is a month or so since I drove it last so I can't compare directly, but it certainly feels as if it accelerates a bit faster. Hopefully as the rings and bearings break in, it will improve even further.

I see from your profile that you are an Aircraft Engineer too. On big planes or small ones?

Chris

Chris Hi,
Well it will be interesting to know your cam and compare with what looks common from tunning "experts" in Italy. As i mention above they suggest 30/70 for the 540cc, looks like a mid range solution as you also said.
Have you also change your carburator with a 28? This will help thinks a little.

I am working on Q-400 and 320 family mostly, mid size i guess.
Thomas