Cool, I am on the right track for that. The original cap is in the trunk has a non nipple chrome cap on the oil filler tube now. Distributor Vacuum Advance should be attached to a Ported Vacuum source, meaning no vacuum at idle, but vacuum just off of idle. Unaware if the Carbon Canister should also be attached to Ported Vacuum. Yep- a ported vacuum source off the carb does go to the vacuum advance, via a T fitting that also goes to the cannister. I found a pic for that part so I should have that correct. Unfamilliar with that too. That makes two of us. I want nothing to do with it either way. Can’t only find descriptions of it anyway, no pictures.
Holley 4150 vacuum advance port
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.
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.
Ported vs manifold vacuum advance March 21st, , This was written by a former GM engineer as a response to a similar question on a Corvette board: As many of you are aware, timing and vacuum advance is one of my favorite subjects, as I was involved in the development of some of those systems in my GM days and I understand it. Many people don’t, as there has been very little written about it anywhere that makes sense, and as a result, a lot of folks are under the misunderstanding that vacuum advance somehow compromises performance.
Nothing could be further from the truth. I finally sat down the other day and wrote up a primer on the subject, with the objective of helping more folks to understand vacuum advance and how it works together with initial timing and centrifugal advance to optimize all-around operation and performance. I have this as a Word document if anyone wants it sent to them – I’ve cut-and-pasted it here; it’s long, but hopefully it’s also informative.
This requires that lean mixtures have “the fire lit” earlier in the compression cycle spark timing advanced , allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature wasted combustion energy. Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have “the fire lit” later in the compression cycle spark timing retarded slightly so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency.
quadrajet vacuum line woes
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?
Dec 02, · Footage taken from Holley Carburetor Installation & Tuning DVD.
Carburetor Technical Information Rochester Quadrajet Quadrajets were used as original equipment on many vehicles from to Over million have been produced. QJets have a maximum airflow of from cfm. Because the secondary side of the Qjet opens according to the airflow requirements of the engine, the same basic carburetor size can be used on a large range of engine sizes. For example, on a mild Chevy the air valve will never open all the way – because the motor can’t use more than cfm or so.
M4MC Quadrajets have an integral choke and a different airhorn design; also, the throttle shafts are longer than in 4MV carbs. Starting in carb numbers were stamped on the driver’s side, near the back. Identification There are three basic types of QJet:
What does vacuum line to Carburetor do?
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: Same principles hold true for scoots and CV carbs; the challenge is going to be finding interchangeable needles that will fit and figuring out how to modify the existing air bleeds.
Dec 11, · Yes! You are on the right track. That distributor vacuum hose should be connected to the port higher on the carb. BUT, your backfiring issue is a timing issue vacuum leaks, incorrect positioning of vacuum hoses are contributing factors incorrect timing is the big contributor.
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 The national debate can arguably be summarized by the question: In the past two years, has there been enough change?
Has there been too much?
Vacuum advance port from distributor
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.
Jul 17, · Quadrajet vacuum ports, distributor advance Q. Discussion in ‘The Garage’ started by fidelity, Jul 11, hook the distributor up to a manifold (vacuum at all times) port, whether on the intake or at the carb, and see how it likes it. Some quadrajet also have timed ports that have reduced vac to them and don’t work well for vac adv.
Car Year, Make, Model: Tuning carb with a vacuum gauge Hook up your vacuum guage to the intake manifold port of the carb sucks at idle. Set you rpm about where you want it to be. Adjust your idle mixture screws to give you the highest manifold vacuum reading which should be the highest idle rpm reading with the throttle butterflies closed. Re-set your idle rpm. Run it a while and read your spark plugs. If they are sooty, or wet, then lean it out a bit with the jets and metering rods strip kit Be super careful to read your instructions with your strip kit because: I usually let my technician tweak the knobs.
She is that good! One small change at a time and you can crispen this carb up real nice. Hope the info helps.
Vacuum lines from carb 84 s-10 hook ups – 1984 Chevrolet S-10
In a squarebore, the bores are closer to the same size, though, in some squarebore carbs, like cfm Holleys, the primaries may be noticeably smaller than the secondaries. However, even then the bores share the same centerline. Many aftermarket intakes, such as mine, and the Edelbrock Performer and RPM, etc, are “dual pattern” intakes the area where the carb bolts on looks like a butterfly.
Either a squarebore OR spreadbore can be physically be mounted on them with no adaptors. Carter Thermoquads, Rochester Quadrajets, and Holley ‘s, ‘s, and ‘s are spreadbores. If the intakes are true squarebore intakes four individual holes or true spreadbore intakes again, four individual holes, though of different size , you cannot really bolt a squarebore carb on a spreadbore intake and vise versa.
Vacuum advance for was connected thru a solenoid and shut off until top gear using the transmission switch to allow or deny vacuum to the advance in the factory setup.
TH Posted 11 October – And keep in mind that rarely are all ports on a carb. Starting with the front: Choke pull-off and what you sayis the dist capI amassuming you mean the vacuum advance under the distributor cap? Looks kinda like a flying saucer. The metal line lookslike a vacuum line to the transmission modulator. You should be able to follow that and see where it goes.
I personnaly have that line going to manifold vacuum and not ported vacuum like you ave but others can chime in on that. The back T coming off has 1 going to your brakes which is correct. This T-has manifold vacuum full time vacuum. Kinda need your brakes all of the time.
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.
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.