In setting the carburetor idle point with Vacuum gauge, best results are obtained by first jacking up the rear wheels one inch from the floor, starting the engine and putting the transmission into high gear, then adjusting the throttle stop screw until speedometer indicates 7 miles per hour minimum. Adjust hand close to one full turn out from seat until highest reading is indicated. When certain that highest reading has been obtained, check speedometer again. If there is a higher or lower reading than 7 miles per hour, reset the throttle stop screw for the 7 M. On automatic transmissions, the idle stop screw adjustment should be made with an electric Tachometer for specification set up for the individual job. After proper engine idle speed, and approximately correct idle mixture is attained, accelerate engine by quickly lifting throttle arm and releasing it.
A History: ’s Word of the Year
Nearly 22 years ago now. Today, it has 95, miles. A large percentage of that 58, mile difference has been off-road in the Pacific Northwest. The rest has been getting to and from the trail-head to leave the pavement. I traced this rig’s history and spoke to it’s original owner not long after buying it. He had purchased it as a dealer “demo” with 4, miles on the odometer.
Jun 20, · i have a corvette with a quadrajet mdl# when i bought the car none of the vacuum lines on the carb were hooked up so far i’ve got the line to distributor vacuum advance hooked up so it runs but there’s no choke lines hooked up. once warmed up it runs fine but does stumble\hesitate under full throttle. no vacuum lines on it at all and there are open vac ports. vacuum Status: Resolved.
Before you start work, replace any cracked or missing vacuum hoses, and check vacuum hose routing against your service manual diagrams or, in most cars, a color sticker under the hood somewhere. Make sure you get the right grade of vacuum hose; anything carrying gasoline or emissions fumes require a special material. When in doubt, get the pricier but safer gasoline-safe hoses. Vacuum hose, gauges, and Ts are sold by most auto parts stores. Vacuum gauges are usually large dials with a narrow rubber hose or metal hose grip leading out; most come with various plastic tips and fittings.
Warm the car up by driving it around for a bit, then connect the vacuum gauge to intake vacuum; you can put in a T and share vacuum with another function, if you plan to use a vacuum hose inside the cabin, or use a port that supplies vacuum at all times. On cars with two-barrel carburetors, there are two idle mixture screws. On cars with single-barrel carbs, there is a single idle mixture screw.
It often has a spring between it and the carburetor to increase friction and prevent movement. Bob Lincoln pointed out that if the idle mixture screw does little or nothing, the carburetor is probably clogged with deposits of dried gasoline and sludge, and needs cleaning and rebuilding.
Vacuum advance woes
rochester quadrajet 4mc is a 4 bbl carb with electronic Mixture Control and was used many years in the late 80’s and early 90’s until fuel injection became more popular Share to: Answered.
Which port on the carb do I connect the vacuum advance to? And where do the fuel lines hook up? Not sure which design carb you have but here’s a rule that works for all carbs. Attach the vacuum advance hose to any port coming from the carb baseplate bottom. If you don’t have a free one, you can use a “T” in another line or if there’s a fitting on the manifold you could use that as well. Just make sure that the line has full vacuum at idle. Use small rubber plugs to block off any unused ports.
As for the fuel line. You should have a threaded inlet on the fuel bowl. The line attaches there.
Distributor Vacuum Advance Hose
Post by mx5tc on Sept 25, 0: I suspect what is happening on your scoot is that you now have the right mixture for best power at WOT but are too rich for midrange and less than WOT cruise. I’m wondering if a needle with more taper look at the various profiles that Keihin has would still give you the right WOT mixture while providing a leaner and more economical mixture for midrange and cruise. Has anyone figured which Mikuni or Keihin needle series can be swapped into our carbs??
Innovate’s website has some interesting carb articles http:
Apr 15, · ok i got a new quadrajet today and installed it but i dont know where to hook up my vacuum advance. any help would be great, the one i have has no solenoids, electric choke, but i think it has a vacuum choke.
There are a large number of modified vehicles that no longer use an ECM engine control module to oversee the emissions and performance parameters of their vehicles. Because of this, the pre computer-controlled type HEI distributor is often used; it is a relatively cheap, stand-alone unit with good to very good performance potential, and has a good track record for durability and reliability. A computer controlled HEI distributor work basically the same as a non-computer controlled HEI except for the lack of a mechanical or vacuum advance mechanism some early versions did use a vacuum advance ; the ECM determines the advance curve electronically.
The only other change you can make in the advance curve is to manually advance the base timing usually worth a little HP by itself. This is not a bad thing, it leaves funds available for parts that WILL make the car faster! If you have disconnected the 4-wire ECM connector going in the side of the distributor or the wiring between the ECM and the distributor is damaged there will, again, be no advance and the check engine light will come on.
Distributor/carb vacuum hose location for Weber
The rebuild never seems to last and some of the areas like leaking around linkage and dry gaskets are often not fixable. They are too complicated, too hard to adjust, and in a difficult place to work on. I have a new engine, is the old carb still correct for the heavy breather? With a closed loop control, this should be adjusted automatically. I think basically, I hate carburetors.
These are the parts to be added.
Apr 18, · oh yes there is an extra port on the back of the qaudrajet,you are correct. on a edelbrock there is just the brake booster port on the back and the extra ports are on the front which is where i used to hook up my vacuum advance. you should try it! just block off that port on the carb and go straight into the manifold somewhere.
So here’s the poop: First, take a look at your Vacuum can. On the flat side of the can is a hose fitting – for the larger 4. Second, on the cone or rounded side of the can is the smaller hose fitting. This uses a 3. On the rear RIR of the carb should be a fitting up towards, but not on the carburetor top. This push-on fitting is just slightly larger than then one on the side.
Connect appropriately with the 4. The fitting for this jewel is an angled one right at the rear base of the carburetor. Connect the small vacuum hose to it to the Throttle Positioner Diaphragm Fitting. If your Throttle Positioner has two fittings as original on 71 Buses, Beetles , connect another length of 3.
Vacuum Lines Connection
It is an opportunity for us to reflect on the language and ideas that represented each year. So, take a stroll down memory lane to remember all of our past Word of the Year selections. Change It wasn’t trendy , funny, nor was it coined on Twitter , but we thought change told a real story about how our users defined Unlike in , change was no longer a campaign slogan.
But, the term still held a lot of weight. Here’s an excerpt from our Word of the Year announcement in
Apr 03, · There is another small vacuum port at a 45 degree angle that I hooked up the vacuum advance on the distributor to. The pcv valve went to the lower one on the front. Lastly I have one that is hooked up to my th trans that I put somewhere, can’t remember off the top of my head.
Back to Top Post by hippy on Jun 16, 3: Jan 23, Can a Suzuki Gti engine fit into a Gl manual Justy? Jan 24, 8: I think it’s searchable on the forum for more details Jan 30, Thats what Im planning to do. However, if the engine and the transmission won’t fit then Im just gonna upgrade the stock engine and get a tubo kit for it. Jan 31, 4: Anybody bought aftermarket center caps for their wheels?
Feb 16, 1:
How to Adjust Vacuum Advance Timing by Michelle Schaefer The correct adjustment of a vacuum advance unit is critical to ensure that an automobile engine runs at its peak performance. The vacuum advance mechanism allows the distributor to vary the spark timing to compensate for the load and speed requirements of the engine. During light loads on the engine, the cylinders burn leaner and require the spark to be initiated earlier in order to obtain optimum power.
In certain instances, there can be a slight vacuum between the carb and the top of the blower and the last thing you want is for the distributor to get a false vacuum signal and advance timing.
Be sure to save the illustrations separately. The opinions expressed here are my experiences, and your experiences may vary. I don’t put myself forward as the world’s leading expert on Holleys, but I do have some helpful ideas. In some cases, I may not be able to answer specific questions, but I’ll do my best. I know very little about other brands of carburetors and have no information about them, only general operating principles. I have NO experience with any type of supercharger or turbocharger, so please don’t ask me anything about your blower or turbo applications.
The following few paragraphs is a set of rules I had to create because people were emailing me without enough information or asking really stupid questions that I had no way to answer. The rules didn’t just happen overnight, nor were they something I wanted to do.