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. In the case of putting the squarebore on the spreadbore intake, the primary bores of a spreadbore, though small, are spread further out than the primaries of a squarebore. The squarebore primaries of the carb would not line up well with the holes in the manifold. Also, most spreadbore primaries are smaller than most squarebore primaries, so even if they did line up, the manifold would present a sudden, constriction. In the case of putting the spreadbore on the squarebore intake, the secondaries of a squarebore intake are smaller than those of a spreadbore carb, so in that case, you’d have significant flow problems.

Vacuum advance fitting?? for Tri-Power

Retired Hey Chester, here’s some input for you on your blower questions. I have a on my T. It’s not my daily driver per se, but I do drive it almost daily during the hot rod season here in KC. I set my blower up myself and have been tuning on my motor for coming up on five years. I’m running the blower 1:

Jul 20,  · FWIW I’ve got an edelbrock performer intake and an edelbrock carb on it. Other than tri-y headers, the engine is stock. I’ve tried both the timed and regular vacuum ports and get pretty much the same thing (not sure if vacuum increases at the .

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.


Originally Posted by TheShanMan Post what does ported do when accelerating if it is 0 at idle. It does exactly what manifold vacuum does. Ported vacuum comes from a small hole directly above the throttle plate. The ONLY time ported vacuum doesn’t match manifold vacuum exactly is at idle when the throttle plates are closed. Since it’s above the throttle plate there’s no vacuum and it reads zero.

Holley carburetor vacuum lines together with watch together with edelbrock carb parts diagram as well as c4 transmission vacuum line diagram together with watch in addition restoreamerican furthermore sucp big block tunnel ram intake moreover stainless steel micron replacement fuel filter also volkswagen carburetor diagram furthermore along with

Dominion October 5th, , I have a brand new Edelbrock sitting atop my on a XR7. The is bored. The stock 2 barrel autolite had hard starting problems, and liked to stall, which caused me to change out the manifold, and purchase the I even stalled a few times. However, if I accelerate moderately, or blip the gas, it gets through the rpm “wall. No difference after a full cleaning, and with or without a cheapo fuel pressure regulator set at 5.

I then purchased the Edelbrock tuning kit, and subsequently richened and leaned out the mixtures per the instructions in the manual.

How to Swap in a Carb-Equipped LS Engine

Introduction – FI Imperials – Technical Advice Here are nearly 3 years of email on the Imperial, primarily on fuel injection issues. This document is copyrighted and cannot be reproduced, except for personal use without written permission. Bob Schmitt, January 15, Subject: Wed, 20 May I suspect the hardest part is to “get your arms around” the topic.

Feb 06,  · For the most part, the vacuum advance is not hooked to “Manifold” vacuum, I.E. a vacuum at idle, It should be hook to a “ported” source. On a normal Holley carb, the port is located on the primary metering block.

Now I see there has apparently been an update, and they now come with a vacuum line ran from the regulator to a full manifold vacuum port on the throttle body. I have people telling me I need to move it too full mainfold vacuum for it to work properly. Should I change mine to where it references from a full manifold vacuum source? I would recommend that you update to this but by no means will your system not work properly the other way.

We just found that pulling fuel pressure down in a low load situation helps the learning feature in the EFI. Allen Porter January 9, at 3: Will not start back for quite awhile. Where do I go from here? Other possibilities are no RPM reading in, low cranking voltage, or throttle closed too much. Shane January 9, at 5:

dual quads

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.

Sep 22,  · I ended up blocking the emission junk in that carb, re jetted it & made it work as a normal carb disguised as an emission carb, minus the extra crap. Rapidrob said: The engine has been played with over the years and several of the vacuum “t” s have been blocked off.

Gift Shop Technical White Papers Allright,,, I don’t mean to be confusing or vague but the little picture machine in my head seems to outrun my mouth and fingers, plus I’m lazy so I suppose Dave gets his wish These are the screws on the sides of the blocks on Holleys and the two screws on the front of the rest. These are the screws on the side by the throttle arm. There are three common methods of doing this- with vacuum guage s , with a tach, or by ear.

Of the three, the most accurate is the vacuum guage method, best to have one for each carb, but it’s not absolutely necessary. Pick one of the 3 below: A Vac guage method- find your full time vacuum fitting on one or both carbs- this is the one lowest on the carb below the throttle plate.

Edelbrock 1400 User Manual

If you dont use vacuum timed advance for Do not hook it up to the positive. Vacuum hose schematic except lockup torque. Were does vacuum advance line hook up on carburetor Where on a motor for a GMC Sierra Pickup does the vacuum lines hook up to a 4barrell quadrajet.

Aug 11,  · Looking at Edelbrock’s site they list both the Performer and AVS cfm carbs when used in single carb applications as having the same jets, metering rods and step up springs. They only list specs for the ABS carbs for a dual quad application.

Always dial in mechanical first. The full mechanical should be in around rpms. The full mechanical is the full action of the weights, the end where there is no more advance. The 20 will or should remain constant. The adjustment for more advance is done with initial. So, if you engine performs best with 34 degrees mechanical advance, you adjustment will be on the initial, that is moving it to 14 degrees.

If you’re cruising at let’s say rpm the amount of mechanical advance will be less than full less than 34 degrees so, your vacuum comes into play and provides a little extra, increasing it to 34, 35, If you were to cruise along at turnpike speeds, where your engine is turning over rpms, the full mechanical is in play plus some amount of vacuum assist.

So, it could be Tailoring vacuum advance can be done with an adjustable unit; before they were readily available, hot rodders limited the vacuum rod travel by brazing in a stop. Both methods are trial and error propositions.


It has been said in our forums that a Ford Mustang Convertible 5. Swap the mounts to opposite sides Left-Right. The convertible engine mounts and hardtop engine mounts are not the same. The Ford Mustang GT uses the same engine mount. Ford Mustang Convertible 5. We’ve been telling people how to do this for years, and you really are probably better off buying the stock Mustang Convertible mounts, but there is a way to make your own.

Will this carburetor hook up directly replacing a cfm Edelbrock. The existing carb is with the “Edelbrock Stumble”. Is the Fuel inlet and throttle linkage hookup the same.

I think what people forget is that some people want different things from a cam. I am willing to trade 50HP total for the ability to slip off the clutch slowly at rpm and take off and not stall. I know cliff is a fan of some other grinds that he has seen make “more power” and the has seen the stock manifold make “more power” than the performer even though Jim hand showed it made a tiny bit of difference for him. The thing is, “more power” to you guys is like 10hp! As a pontiac HOBBYIST on a site about street performance, i can’t be bothered to chase down every last 5 hp at the cost of decent right of idle performance, and vacuum, and fuel economy.

If i wanted that, i’d head over to pontiaczone or something more drag and road race related. I just don’t have the heart to run my pontiac over rpms, why do i want a cam that goes further for street use? FWIW i had the same setup with my headed , you dished the pistons for compression as my ‘s were, but i was still a bit higher. It ran like a raped ape, was great off idle, i got about 17mpg of an ecarb! Sometimes, i feel i would be happy with a stock HP with tons of torque and no issues to work out and dead silent valvetrain.

Technical White Papers

All About Car Restoration How to Use and Interpret a Vacuum Gauge Few tools or test devices are more useful and versatile than a vacuum gauge, yet very few hobbyists own one. A vacuum gauge can tell as much about the internal and external workings of an engine as the combination of a voltmeter, compression gauge, stethoscope and timing light. An engine’s vacuum readings can tell an awful lot about its running parameters, provided you know how to read the gauge in the first place.

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April 28th, , Thank you very much, very interesting! SouthernCatXR-7 April 28th, , If so, are you running the stock distributor? Yes and yes Hawk1 April 29th, , Experiment and see what works best for you. There can also be differences in engine heat generated at idle. Hawk1 xr7g April 29th, , At other than idle ported vacuum and manifold vacuum are the same.

Ported vacuum means that the vacuum port is not revealed until the throttle plates are opened above idle. On a Ford we like to run around 12 degrees initial advance at idle. Some a little more, some a little less. This means that we have 12 degrees of advance before the vacuum or mechanical advance kicks in.

Quick question, Manifold or Timed Vacuum port for distributor on Edel 1406?

It has the auto feature for the lights, and the switch function is good and tight. Is there something I am missing? Thanks, Hello Jon, Some of these ” Autolamp ” systems can be difficult to diagnose without the Factory Shop manual and wiring diagram as they use relays and amplifiers that can fail. Have you tried turning off the Autodim and the Autolight tabs at the main headlamp switch on the dash to find out if the headlamps operate properly in the manual position? When you tested the foot switch did you do a continuity test in all positions?

Rochester Quadrajet Vacuum Advance Port Holley Carburetor Vacuum Hook UPS. Vacuum Advance Port On Holley Carb. Related Images. Rochester Quadrajet Carburetor Vacuum Diagram. Hi folks, I fitted a reconditioned Rochester Quadrajet to my Log onto Where does the vacuum advance hose hook up to a holley ? Any place.

Remove the distributor cap, right valve cover and the 4 cyl rocker arms and pedestal. Set up a dial gauge on the 4 intake push rod. Rotate the engine to TDC 1 cylinder. If the dial reads thousands, your valve timing is right. If the dial reads thousands, your valve timing is retarded or your chain is streched. If the dial reads thousands, your valve timing is to far advanced. These s are for stock engines and wouldn’t work for engines with aftermarket cams.

By inducing high voltage in the tube, the gas is ionized and thereby lights up. In the case of plug wires glowing, the Corona effect can happen when atmospheric conditions are right.

1971 Chevy vacuum lines