hi , i'm filippo , i live in italy, have a questions, i have rebilding a evo ultima 113 ci , i have a ultra 97, i like drive slow and i love a low torque, in this moment have assembly a s&s 546 cam, bat i non happy , whats is the better cam for have the very low torque ? s&s 585? s&s 600 or..... thank filippo

 

the cam in that motor is incorrect for city driving - if you live in the country with no traffic lights and open roads its great

crane cams had made a 600 lift short duration cam and it allows that combo you have to idle smooth and behave slow running for inner city driving and yet it has great low end power for crusing the open roads with good fuel milage not like the cam you have

i will look for the number for the cam i think its a 314 maybe i know we have a few in stock as this is the one we use for NYC / new jersey traffic driving

 

thank, johnjzjz

 

Ultima engines have a different rocker arm ratio that makes a smaller cam big. Do your homework on this one and for referance Ultima specialist John Sachs uses the stock Ultima cams in alot of his engines with good horsepower.
If you change the rocker arms to standard ratio then cam choices are opened up or calculate the current rocker arm ratio but a quick ramp cam becomes a really quick ramp cam with stress on the valve train

 

I suggested Filippo post in here, as you chaps are likely to be able to give him some useful tips. Certainly the 585 cam in my S&S 107 gives a wide and gentle torque curve, with just over 100HP/TQ. It will happily roll along at 1500rpm fully loaded, on a level road, although obviously prefers a couple of gear changes to pull away briskly.

 

yes, I know the difference between the rocker arm, ultima is 1,675. and the stock is 1.62, in this momentn I use oem rocker box with stock rocker arm and hi lift spring, probably if I decide to use cam with raised above 585 I will use the rocker arm with the roller, but right now I do not know which cam choose, for my style touring driving

 

ive seen a few home builders mess up on this. they see those roller rocker on flebay for 100.00 and think they are getting stock ratio. you have to do the research and math before you buy the first part if you don't its going to fail. my favorite brag from a novice home builder ( it has 10:1 compression ) when I ask how they came up with that number the reply is always the same (I put 10:1 pistons in it)

 

ok i can add a bit so some can catch up on what is being talked about

cam shaft lift number is an end product of the cams Lobe lift times the rocker arm ratio

example - cam lobe lift .337 X 1.62 is OEM rocker ratio = 54594 or 546 lift

example # 2 - .337 X 1.675 Ultima rocker ratio is 564475 or .564 lift net gain of .018 thousands not that big a real if you have .575 lift springs but its a engine killer if you only have .550 lift springs as the spring will bottom out with this change of ratio