84RX_Se7en

So when I give it gas two barrels of the carb open and work how there are supposed to. The other two don't. I was wondering when they are supposed to open or if they're supposed to open at the same time as the others?
My friend opened the two closed ones while the gas pedal was in reving and the car started shaking because it was reving a lot louder and harder. It seems as though it gained more power with all four barrels open. When do they open up?

trochoid

iTrader: (6)

They are vacuum operated, and the engine needs to be under load to open, i.e., driving it. They won't open when free reving.

Rx-7Doctor

iTrader: (13)

They are vacuum operated and should open probably from mid to full throttle depending. One thing that is common on these carbs is the secondary linkage for these pops out of place.

blwfly

iTrader: (4)

if you want to see them work by hand go mech secondarys
look in the faq page its pretty easey

84RX_Se7en

We're gonna work on our own form of mechanical secondaries and make them all open at once to see what it will do to initial power.

Kentetsu

Bad idea....

fcdrifter13

It will fall on its face.

rxtory

let him try, I love when other people try so when something does in fact goes wrong we no not to do that and if it works and there is a power gain then hell we all could try it

peejay

Mechanical secondaries are a bad idea, for *anything*, IMO. They just invite problems.

90% of the tuning problems we get at work are people who put a mechanical secondary carb on their car and then wonder why they can't give it full throttle from just off idle anymore. Screw around with the accelerator pump enough to make that kind of abuse acceptable, and then the engine stumbles after a shift because now the accelerator pump is too much shot and too much duration for going zero to WOT at 3500rpm...

If the carb is small enough that mechanical secondaries are acceptable for performance, then the carb's probably too small to begin with. Even a stock carb is large enough that you don't want all four barrels open at low RPM.

vipernicus42

iTrader: (4)

I dunno, I like the mech secs that Sterling does. I've had two Sterling carbs and I find they balance out the opening of the secondaries and the AP shot just perfectly. I think the main difference between how they do it and how other people do it is the length of the AP arm changes.

And as for the "I can't stomp the pedal off idle anymore", anybody who drives like that should learn a little more about their car and how to drive before they go racing off down the road.

But one thing that I'm amazed that nobody mentioned is the secondary throttle return spring. It has that little perch that it has to sit on or your secondaries won't open. I'll try to find a pic. That could easily be why the vac secondaries wouldn't open even under load.

Jon

t_g_farrell

iTrader: (1)

I have two barrels only and they seem to work fine. Oh, yeah I have a Dell, oops.

drunkclever

I say cut the spring so that they open earlyer and under half throttle.. or somehting to that effect. Its the easyest way and quickest mod. Theres a spring behind the square thing on the front passenger side of the carb. Its just 4 screws and a pin. Go easy.. you don't want to cut it half way, just do one ring. If thats not enough do another one, be happy with what you got and don't go all out.

Or instead of cuting them you can try to find a spring with less pressure. If you really want something nice consider getting a Stearling modded nikki.

g/l