Slight RPM Fluctuation (Normal ?)
 

OK this is not related to the new msd module I installed.
It has done this with both the stock module and this msd.

I dont think its a big deal or anything, but just wanted to see what you guys have to say.

When at idle my rpm (on AutoMeter tach) will slightly fluctuate up and down. The lines on the tach represent 100rpm. It will move about 50 rpm. It doesnt move alot and it doesnt move fast. Just a little "floating" type of movement. Im just curious is this normal, if not what could casue this? If it is normal, when is the fluctuation not normal, how much fluctuation is normal?

Thanks!

not sure if its normal but mine does it as well

Pretty sure its normal. My 350 does it also, anywhere between 50-100rpm. I used to get pissed, but dont worry about it anymore.

Yeah its done it forever and I though maybe its just the stock module, but then I installed this msd module and its pretty much the same as far as the fluctuation goes.

The msd module is much smoother at high rpm's then the stock module. Engine feels like it runs smoother above 3k.

It has done it ever since I had the tach hooked up. I've checked for vacuum leaks with a gauge and steady reading even with RPM "bouncy".

OK I thought it was normal, just freaks me out sometimes, because I have had the stock module leave me stranded a few times.
But Im hoping this msd
will leave me trouble free
Cause you know me
I dont want to pay that tow truck fee
:)

Mine does it too. I think all engines do this to some degree. I've never seen a tach sit still totally.

i noticed today mine stays pretty constant in park, but in drive it fluctuates a bit..

does the lopiness of the engine have anything to do with it ?

I thought about that, but it shouldnt, the engine should still be rotating at a consistant speed.
Either way mine is stock w/ manual trans. and does it. Runs smooth at idle too.