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hitachi secondaries question
Posted 13 January 2004 - 12:44 PM
Posted 13 January 2004 - 01:06 PM
Posted 13 January 2004 - 02:04 PM
ts supposed to open at 3/4 throttle and allows more fuel to go into the engine right?
Posted 13 January 2004 - 02:17 PM
thats why everybody likes the weber, its not vac operated, its mechanical. so as soon as you mash the throttle its wide open.
but now, i think im running with a single barrel 20mm carb.
Posted 13 January 2004 - 02:38 PM
Posted 13 January 2004 - 02:46 PM
Anyone got any thing on modding it open?
Posted 13 January 2004 - 04:13 PM
Posted 13 January 2004 - 04:57 PM
Torxxx, I could also show you how to get better secondary actuation while keeping the economy of a vacuum secondary on your hitachi when you are over here for the "lift party". I even have all the stuff for it here, and since I've got the weber now I have no need for it.
I would try to explain it here, but without pictures or seeing it in person, it's kinda hard to explain.
Archemitis: I think your actuator is probably bad. Most likely it has a hole or a crack in it. When you apply vacuum to that line while it's running, it should be just like stomping on the gas.
Posted 13 January 2004 - 05:54 PM
if thats it i will be so happy. my car runs reel funny with only one barrel
Posted 17 January 2004 - 12:15 AM
Posted 17 January 2004 - 01:08 AM
1 electrically actuated vacuum valve (i got one from my spare engine. There are two attached to the intake manifold)
1 large pushbutton starter switch or similar device
assorted vacuum tees
a bit of vacuum line
some wire (18 gauge is fine)
small chunk of sheet metal (i cut some out of an old road sign)
two medium-sized hose clamps
How to make the basic system:
Find the vacuum line that taps into manifold vacuum and goes to a vacuum reservoir. Put a tee in this line and run a line from it to the vacuum valve. Put a tee in the little vacuum line that attaches to the secondary actuator, and run a line from it to the other port on the vacuum switch.
Now, use the sheet metal and hose clamps to mount the pushbutton switch on the steering column so that the switch is triggered by the end of the accerator pedal that the cable attaches to. Make sure that the switch is only activated at wide open throttle. Hook up wires so that this switch controls the opening of the vacuum valve.
Improvements to the basic system that make it much more effective:
Improvement 1, which I actually did, is adding an additional vacuum reservoir, teed into the same line that is your vacuum source for this mod. This definitely helped, because the reserve vacuum allowed for better actuation under low-vacuum running conditions, such as near WOT.
Improvement 2, which I was going to do if I didn't convert to a Weber carb, is to put a one-way "check valve" right next to the tee that I put in the vacuum line on the carb. I think this is necessary in order to reach this mod's full potential, as it seems that when running at WOT for prolonged periods of time, the normal carburetor vacuum source produces greater vacuum than the manifold source. This results in actually lowering the amount of available vacuum under prolonged high speed driving. By adding this check valve, the actuator will always be receiving the greatest amount of vacuum possible.
Overall, I was relatively satisfied with this modification. It was pretty easy to do once I got all the conceptual stuff figured out. There was a definite "hit" when this thing did its job under acceleration, and I think the addition of improvement 2 would have perfected this setup. Mine was also plagued by a leaky additional vacuum reservoir, but once that was taken care of, it worked fine. If you are like me and have more time than money to spend on your car, and like tinkering, this mod is probably for you. And it just makes you sound smart and makes your car sound cool when you have something like this on it that nobody has ever heard of.
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