Blower surge

[Flatblack 57]

Hey guys,
Don't know if blower surge is the correct term, but I have tried to research this subject and have not found any good answers. At shows and events I have seen blown cars idling around with a roll in the idle, maybe between 700 and 1000 rpm. It actually in some cases caused the car to jump along the road, as if he was stabbing at the gas. What exactly is causing the motor to surge like that. Has it to do with wild cams and short LSA or rich mixture at idle or too much boost at low RPM. I really want this impractical idle in my new 540. Any idea how to archive.

[pat mccarthy]

my 548 idles fine but i can get it to do it very easy if i play with it. i work on a truck that the guy wanted it to do just that they played with the carbs if you have a wide lsa will do it

[blwn31]

The engine builder that did all my machine work has a Blown Hot Rod on Alcohol. His lopes like you are talking about. I asked him what caused it and he said it was the injector. Motors with an injector or hat like a Hilborn can be made to lope like you are referring to with the blip of the throttle pedal. My guess is that the fuel pump/system is a manual bypass style. Blip the throttle more pressure RPM rises then back to low pressure RPM lowers and then it catches itself, pressure jumps up and the whole thing just continues. Hi, low, hi, low thus lopes with that grunt we all love. Pat should be able to elaborate on it more.

Keith...

[pat mccarthy]

well like you said it is hi low lean rich or with carbs hi low vacuum ? with the power set up springs ? or you could get it with vacuum pull on the dist?

[500caddy]

flatblack, if your running power valves in the carbs i'm about 95% sure the valves are opening and closing causing you problem. seen it many many times..

[pat mccarthy]

i think he wants that surge?? yes holley power valves or AFB set up springs

[nitrowarrior]

so, if the power valves are fluctuating, that means his throttle plates aren't sealing off at an appropriate setting and the mid transition and cruise part of the circuits are flowing fuel.....wouldn't it be slobbering? Not lean surging?

[pat mccarthy]

so, if the power valves are fluctuating, that means his throttle plates aren't sealing off at an appropriate setting and the mid transition and cruise part of the circuits are flowing fuel.....wouldn't it be slobbering? Not lean surging?

ok they would have to be past the idle trans slot ? but you still get inrich ment i did block up my set ups springs on my afb s i think they did run rich?? if not then the idle air bleeds

[nitrowarrior]

I can see idle air bleeds or some call emulsion passages....I would like to hear more from him on his set up or what his tinkering is accomplishing

[pat mccarthy]

well i think he want some to tell him how to get the THE SURGE..... the idle air bleed s did it on the truck i work on i was told i tune it and they retune it to get THE SURGE they told me the air bleeds?? is what they swap out

[500caddy]

mis read i though he was trying to stop it... looks like he wants it go figure!!!

[pat mccarthy]

mis read i though he was trying to stop it... looks like he wants it go figure!!!

yes he wants it to run ILL

[nitrowarrior]

hhmmm....the sound will get your attention but not condusive to good performance....than again, everybody likes a twist

[pat mccarthy]

hhmmm....the sound will get your attention but not condusive to good performance....than again, everybody likes a twist

i would get on and off the pedale before i pull in to some car show to get the sound

[500caddy]

just pull some spark plug wires LOL.