Carb Questions
02-13-2002, 06:48 PM
#1
Racer
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Location: macon, ga
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Carb Questions
first, i have a edelbrock #1910 and im doubting that my secondary's are even opening. while i was adjusting the timing i noticed to that when i reved the engine the butterflies would not open. is there some way to check if the are working right? shouldnt they open some. i reved it to about 3500 rpm. thanks for the help guys
02-13-2002, 09:56 PM
#2
Melting Slicks
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Re: Carb Questions (ykp53)
It depends. On my big block, which sucks a lot of air and fuel through 750 cfm Holley throats, (the Firebird), it will open when I rev it WOT with my hand on the linkage. But most of the time, you need a load on the engine.
Years ago when big blocks were unpopular and the gas crunch was on, I had a Ford (forgive me) with a 460 big block. When I stayed out of the pedal, it returned a pretty amazing 18 mpg, but when I floored it, you could almost see the gas gauge go down.
Because I couldn't physically verify when the secondaries were opening, I had designed an LED pack that would be signalled by the position of a rheostat attached to the secondary linkage, so that I could monitor the degree of secondary opening and better control my driving for fuel economy.
Now that gas is so much more expensive, I don't even care when I go into secondaries. The more the better. Go figure. Shifting priorities I guess.
But the idea is still a pretty good one, except this time for the sake of performance.
NOS sells a microswitch that attaches to the secondaries of your carb for fool proof activation of an armed nitrous system upon nothing less than true full throttle. It would be very easy to wire up a light or LED to come on bright upon full throttle. Might seem gimmicky, but I like the idea. Performance-wise, it would be great to know when your secondaries open and how long it takes.
But the easy way to do it is to tape a piece of tissue on the secondary linkage and see if it rips when you go WOT. Make the tissue just long enough to rip when the secondaries open all the way.
Another way is to remove the hood and watch, I guess, but that's too much work.
Could be that you need to lighten up the spring on the secondary side.
At least that's what you would do in the case of a Holley. An Edelbrock I'm not familiar with.
Write Lars, he should be familiar with that type of carb. Let him know if you find out you're not opening fully.
Years ago when big blocks were unpopular and the gas crunch was on, I had a Ford (forgive me) with a 460 big block. When I stayed out of the pedal, it returned a pretty amazing 18 mpg, but when I floored it, you could almost see the gas gauge go down.
Because I couldn't physically verify when the secondaries were opening, I had designed an LED pack that would be signalled by the position of a rheostat attached to the secondary linkage, so that I could monitor the degree of secondary opening and better control my driving for fuel economy.
Now that gas is so much more expensive, I don't even care when I go into secondaries. The more the better. Go figure. Shifting priorities I guess.
But the idea is still a pretty good one, except this time for the sake of performance.
NOS sells a microswitch that attaches to the secondaries of your carb for fool proof activation of an armed nitrous system upon nothing less than true full throttle. It would be very easy to wire up a light or LED to come on bright upon full throttle. Might seem gimmicky, but I like the idea. Performance-wise, it would be great to know when your secondaries open and how long it takes.
But the easy way to do it is to tape a piece of tissue on the secondary linkage and see if it rips when you go WOT. Make the tissue just long enough to rip when the secondaries open all the way.
Another way is to remove the hood and watch, I guess, but that's too much work.
Could be that you need to lighten up the spring on the secondary side.
At least that's what you would do in the case of a Holley. An Edelbrock I'm not familiar with.
Write Lars, he should be familiar with that type of carb. Let him know if you find out you're not opening fully.
02-13-2002, 10:07 PM
#3
Re: Carb Questions (ykp53)
First get someone to push the gas pedal to the floor for you while the engine is off and see by hand if the cable is pulling the carb all the way open.The cable might be positioned in the wrong hole.That 454 should yank the secondaries open pretty easily not in neutral though nor at 3500 rpm
02-14-2002, 07:47 AM
#4
Le Mans Master
Re: Carb Questions (mountainmotor)
I've never been able to get any vacuum secondaries to open by themselves (no hand assist) by revving the engine. They are not designed to work that way. The engine has to be under load. On Holleys, I have used the paper-clip-on-the-vacuum-diaphram-rod-method, and the micro-switch trick. Slide a paper clip on the rod up at the top, and go for a WOT test drive... if the paper clip slides, then the secondaries are opening. I am assuming the Ed carb is designed similar to the Holleys...?