Question about using a 'lumpy' cam on the street.

[Phoenyx]

I have a quick question for anyone running a 'lumpy' cam on the street.

The cam in my engine has some good 'lump' to it. All the way up to about 1600 RPM. When I'm out driving at the speed limit (50KM/h, 33ish mp/h) my engine is just at 1600. So when I'm going any slower than that, it feels kind of like it's surging. Is that normal for a bigger cam? As soon as it hits 1600 it runs smooth.

I still haven't had a chance to go over the ignition system yet (been raining for days), so it might just be that. What do you think?

 

[LS1GN]

Sounds normal. It has to do with valve events and duration of the cam more than lift. Those "lopey" cams almost always make more power higher in the RPM range.

A steep set of rear end gears will bring you into the power quicker.

 

[GuysMonteSS]

Mine doesent smooth out until around 2000 RPM,and below that it surges just like you are describing,so it sounds normal to me to.
Guy

 

[Peter]

I think that a higher transmission stall would smooth out your lower rpms as well

 

[pfcvdv]

yeah i have that to, i have a performer rpm with adv duration of 296 deg. still a daily driver and good for slow cruisin.
its only the sound that can get annoying in low rpm's, most people think its broken if i drive by lol

 

[rustyroger]

This is something that variable valve timing on modern engine addresses.

A lumpy cam normally gives a rough idle and poor low engine speed running, traded against more power at higher revs, a full race cam is usually horrible to drive on the street.

Nothing you can do about it short of putting a milder cam back in.

Roger.