Blower surge

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.:confused:

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

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...

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?

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..

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

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?

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Originally Posted by 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?

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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

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

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

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

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Originally Posted by 500caddy

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

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yes he wants it to run ILL:whacked:

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

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Originally Posted by nitrowarrior

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

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

just pull some spark plug wires LOL.

just run some chokes hook them to a up a push pull solenoid:rolleyes:

Hey Pat, haven't you ever built a fairgrounds cruiser or a full blown alcohol injected motor. They are bada$$ sounding, but it's gotta become a pain in the a$$ after a while. The guy that did my machine work, said he drove his car on the freeway about 10 miles took a full load of fuel (alcohol). It's wierd how he can just start to drive the car normal and the injector will act normal, but blip it and here comes the lope. He grabs a crowd everytime.

Keith...

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Originally Posted by blwn31

Hey Pat, haven't you ever built a fairgrounds cruiser or a full blown alcohol injected motor.

Keith...

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well did you see my 731 donovan i am building? i posting it on here . think i will run it on alcohol the 632 donovan in the gto and the 548in the 50 chevy are both just built for short runs .as for the fairgrounds they know the circus is in town when they here a my big blocks running down there road with the 4 inch EX shaking there windows:whacked: what the hell is that sound ?:confused: that McCarthy clown is in town:whacked:

I haven't seen the 731 Donovan, Would like to see it! I've got a 406 Aluminum Rodeck! Nice piece.

Keith...

:D :D yes i like them alum blocks

Hey guys, Was just wanting to know what caused it. Can not learn if I don't ask. So you are saying its related to carb sett up and not so much cam? I dont know about loss of power with this set up, Some blown cars down here are making big power but still lurching around our shows. If I cant get that big cam idle with a blower, I want the surging.

You can tune in some surge by playing with the idle mix....I just never liked watching the tach bounce around from 1000 to 400 and back, makes the car a little harder to drive on the street also...