Hei Vacuum Advance Ported Or Manifold



Currently my vacuum lines are not hooked up correctly. As revs increase, vacuum advance smoothly hands off to the centrifugal advance, though both work continuously. Low manifold applications can run a vacuum advance to a timed port for cruise benefit but it will have zero affect at idle. Distributor vacuum advance C3 Corvette. I figure some vacuum signal to the advance was being lost when the idle dropped when placed in gear with manifold vacuum. You can also use the Powerfire Distributor Vacuum Advance Lockout kit which allows you to remove the vacuum canister for aesthetic purposes: 1. It provides vacuum at all times when you are at no or little load which is what you want. But if your motor was ever used with a computer controlled ignition you can likely snag those bits and follow our lead to do something similar. Whenever the hell I get mine running, I am planning to hook up the vacuum in the stock configuration, with a ported vacuum switch. these are basic engine ignition facts. ISO 9001 Registered Firm. It is an aftermarket Chevy 350. and drain engine coolant prior to manifold installation. ported the epa way. Vacuum advance also adds timing to the engine, hut it is based on engine load and is controlled by intake manifold vacuum. Use distributor connector package Part number 12167658, which includes connectors and wires for the HEI’s tachometer and 12 volt terminals. Vacuum Advance should be connected to a ported source at the carburetor. There are two types of vacuum sources that you should be aware of. When you say the vacuum advance will push the total to 32* @ 2500 - What is the manifold vacuum at that point? It may not have all the vacuum advance fully in. what is vacuum advance how does vacuum advance work vacuum advance vacuum advance distributor do i need vacuum advance distributor how to. I re-route so the > dist is a ported vacuum so it has no vacum at idle and vacuum when the throttle > opens. PVA - Ported Vacuum Advance PVS - Ported Vacuum Switch PWM - Pulse Width Modulation PWR GND - Power Ground for PCM QDM - Quad Driver Module RABS - Rear Antilock Brake System RAM - Random Access Memory RAP - Retained Access Power RECAL - Calibration Adjustment REDOX - Reduction Oxidation Converter REF - Reference RFI - Radio Frequency Interference. At the center of our modern 289 is a Crane "Retro Roller" camshaft, a special 5. A properly curved distributor with vacuum advance hooked to a ported vacuum source will work just fine. Ok I'm confused about using port or manifold vacuum advance. That's why it is used w/the distributors vac advance mechanism, it'll advance the timing when RPM's go up. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15. I moved the vacuum advance to the manifold port having read that the timed port was really only a bandaid fix before the catyletic converter to prevent an efficient burn at idle. There are no vacuum ports on my carb. Please remember, large cap HEI were designed for emissions use, not performance, and ported vacuum advance worked with an emissions engine that uses an EGR (Exhaust Gas Recirculation) valve only. It will give you a smoother idle with lower throttle blade setting. Mechanical and vacuum advance removed and plates tack welded together. The HEI was developed to run with ported vac in order to provide enough advance at heavy airflow to control emissions as mentioned above. generally speaking the HEI should be connected to a ported vacuum source, if it pings at part throttle then manifold vacuum should be used. So my newly aquired Pontiac has a fresh crate 350 with a Procomp HEI distributor and when i looked closer the vacuum advance does not have a vacuum line connected to it. If the timing curve required to match the changes with rpm can be achieved mechanically, then using ported reserves vacuum advance for lower density conditions. Right now you only need advance. Obviously we're just trying things one at a time till we figure it out. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. If you put a vacuum gauge on the engine it should read between 17-21 inches of steady vacuum. Contact Ray Sedman for specifics. As revs increase, vacuum advance smoothly hands off to the centrifugal advance, though both work continuously. The Kit is supplied with Vacuum Advance Limiter, Blue Bushing and mounting screws. Same question is, or a vacuum advance distributor cap, trucks suvs with vacuum. Ported Vacuum vs. We could also get rid of the external coil and coil wire. WEBER carburetors do not have an effective ported vacuum fitting and do not work well with vacuum advance type ignition distributors. A better way to check vacuum advance is by hooking up a vacuum pump and plotting the additional vacuum advance vs the amount of vacuum you are applying. You vac advance is connected to the ported vacuum. The ported vacuum can have 0-7 depending on how your carb is set up. With ported, the vacuum advance is non existent at idle, and kicks in as you first open the throttle. Super burly and only 8mm. These steps will set the vacuum advance degrees up correctly to use full manifold vacuum, instead of the incorrect ported vacuum sourcing. manifold vacuum to an appropriately selected vacuum advance unit as noted above. I LOVE the new Taylor wires. In the early days, the idea was to connect vacuum advance to a manifold vacuum source, which added more timing to improve idle quality. This is a ported vacuum signal. Excessive pinging will require a deeper look into your ignition timing and/or mechanical advance rates. The HEI vacuum advance canister should be connected to a ported vacuum source (no vacuum at idle). When you send an E-Mail, PLEASE include a phone number or two, where we can reach you. Ported vacuum was used as an emissions method control to retard timing at idle (by eliminated vacuum advance) in order to reduce hydrocarbon emissions. This is a version of emissions control; the ported vacuum allowed carburetor adjustments for a. I am using a Duraspark distributor and port vacuum advance. I recently tried using ported vacuum off the MC2100 carb, and it seems to improve the bottom end power, possibly at the expense of the top revs. this is my re-visitation of ported vs manifold vacuum on carbureted cars but with a performance motor. It is an aftermarket Chevy 350. Manifold vacuum is a direct connection to the intake manifold, and if the hose is connected to this port, you will have full vacuum in the line at idle. We know that at WOT we lose almost all vacuum, so the vacuum advance is no longer in play at WOT. They are a poor copy of the Mopar electronic vacuum advance distributor. Air valve vacuum The vacuum that. I never did drive the 46 with the vacuum hooked directly to the manifold. That's when we decided to change from ported to manifold vacuum advance at idle by connecting to manifold vacuum. This will lower engine temps, but it will also increase hydrocarbon emissions on emission-controlled vehicles. I have a 4 port thermal vacuum switch w/ a 2 blade electrical connector attached on right (pass) side on front of intake manifold. If you have a 'Run on' problem, detonation off idle, or just like the sound of a rough idle, try the other port, (timed or port vacuum). One type is known as "full" vacuum or "manifold" vacuum. VACUUM ADVANCE 1. The stock HEI uses a vacuum advance canister to further tailor the ignition timing. The way they do this is during a deceleration of the vehicle when there is low absolute pressure in the intake manifold (i. Does your engine require additional timing advance at idle in order to idle properly? Radical cams will often require. It is based on the 'rules of thumb' presented here: Making a Spark Advance Table. Yes, to start with I would hook up vacuum advance to full time vacuum and see how it idles and runs. L-72/71 have ported vacuum advance to meet CA emissions since there was only one version of this engine for all 50 states. Please remember, large cap HEI were designed for emissions use, not performance, and ported vacuum advance worked with an emissions engine that uses an EGR (Exhaust Gas Recirculation) valve only. You can even adjust the amount of advance the can gives you if you get one of the adjustable cans from Crane or MSD. This is with the idle screw backed all the way out and I verified the pedal is not hanging it up. I've always understood that ported was the way to go, but because of this thread and after reading up on it, I'm going to try switching to manifold vacuum for the vacuum advance and see how it goes. A 1/8" npt port is also included. Is the distributor vacuum advance plugged into a "ported" vacuum or to manifold vacuum? Did you disconnect and plug the vacuum advance when you timed it? Is your choke working? A pop from the carb is a sign of lean mixture most often but can also be from a bad valve or timing set incorrectly. Re: 258 w/ HEI, vacuum advance issue? I don't know alot about HEI systems, but from what I understand they came in four, five and seven pin configurations. If you engine will run well with manifold vacuum, great. Hydraulic and Air clamps,power supplies and fixture accessories designed for all your workholding needs. Both fuel economy and throttle response can be improved by proper application of vacuum advance. Most of the adapted carbs below will also have a ported vacuum port available. You lose vacuum when you go under load which removes vacuum advance and returns you to total timing. Wires Features:. The first paragraph of the vacuum advance section of that wikipedia article covers all the points I was going to make. Block High 3856208 396 Rectangular 1965 Performance Port Big Heads Factory Chevy 1965 396 Heads Chevy Port High Rectangular Big 3856208 Block Factory Performance 1965 396 3856208. If the engine has an advance curve that allows a full 36-degree mechanical advance at cruise rpm, the vacuum advance unit can only be allowed to pull in 16 more degrees of advance. GM HEI Vacuum Advance When moving to manifold vacuum advance, the critical issues are: Total advance cannot exceed 50 degrees (Initial advance + Centrifugal Advance + Vacuum Advance) Initial vacuum advance starting point has to be adjusted such that it does not produce pinging. but with an chevy HEI should i have the vac hose hooked to manifold or ported? i know with my old inline 250 it goes to ported. Then I reconnected the vacuum advance. VACUUM ADVANCE 1. All the fords (200, 302, 289) I've had since have always used ported, including my 289 67. Vacuum advance’s purpose is to compensate for and engine’s LOAD. If you drive it like a real car vacuum advance will probably make it drive better. With ported, the vacuum advance is non existent at idle, and kicks in as you first open the throttle. There was also a small "bug" shield in front of the intake. I tried the "Non Ported" vacuum hook up but couldn't get the idle down to where is should have been. You want as much initial as you can (10 to 16 degrees) then a fair amount of mechanical (20 degrees) and the rest vacuum advance to come u. Manifold vacuum taps into the intake manifold below the carb throttle plates so actually sees manifold vacuum. 7L) engines. Just changed it from a vacuum advance. Can somebody help me and tell me if on a 73 Pontiac 400 engine, should the vacuum advance for the distributor be connected to to the ported vacuum on the carb (rochester 4bbl) or manifold vacuum. Tuning with Vacuum I see a lot of discussion and confusion regarding the use of Ported Vacuum versus Manifold Vacuum for distributor vacuum advance. c) Use a 5/32” diameter vacuum line from the bottom of the throttle body to the vacuum advance canister on the distributor. Sometimes with manifold you will get a slight sputter or bog when the vacuum advance drops out as the throttle is suuddenly opened. Car and Truck Distributors and Parts. Here’s a quick experiment you can try on. They are about as stout as the 8. Then I reconnected the vacuum advance. It idles different but that is the only difference. Vacuum advance connected to manifold vacuum port, not ported port. Rebuilt 8v71 Blower Street Rod Sbc Bbc Hot Rod Rat 350 Drag Sand W Snout 8v-7. The vac advance can is adjustable but the spring is too tight and runs out of adjustment and doesn't offer much advance anyway. On pre HEI cars, the vacuum. The whole point of ported vac is that it isn't around until RPM's are increased above a certain point. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15. There are two main sources of vacuum. Secondly, Once an engine gets below 8# of vacuum it's increasingly difficult to run a vacuum advance due to rough idle and low vacuum make it difficult to activate the canister. While this was the hot ticket when it was new, it has since been deemed archaic and troublesome. With ported there is no advance at idle. So this is good. Mallory Part # 8548201C Trigger Style - Magnetic Advance Type - Vacuum & Mechanical Cap Style - Male / HEI Gear Material - Steel Ignition Box Required - No Housing Material - Billet Aluminum Housing Finish - Polished Shaft Diameter -. The Broncos run best with timed/ported vacuum as was mentioned. The timed/ported vacuum only yields a vacuum when the engine reaches a certain rpm. Vacuum advance Chrysler 1960 1961 1962 1963 1964 1965 FOR DUAL POINTS. For me, I found that ported vacuum works best with the motorcraft carb and hei distributor. So I capped that port and connected the vacuum advance to manifold vacuum. my guess is the vacuum unit may have issues if you see nothing using full manifold vacuum. Same question is, or a vacuum advance distributor cap, trucks suvs with vacuum. “Manifold” vacuum allows actual manifold vacuum to the distributor at all times. If you have a 'Run on' problem, detonation off idle, or just like the sound of a rough idle, try the other port, (timed or port vacuum). High Performance 1972 Chevrolet Corvette Owned by Wade Buff and Built by Larry Snyder at Precision Automotive Specialists,inc. You can find this on the Carb. Manifold vacuum is basically the opposite signal. Check out a Hyster forklift, we have one at work with one of these 4cyl engines and it has an HEI in it with vacuum advance. Excessive pinging will require a deeper look into your ignition timing and/or mechanical advance rates. Having re-read the content of my posts, I'm quite sure that if you have a vacuum pump w/gauge you can easily verify each point that has been made. Maybe GM thought that idle quality (always a problem on FI engines) would be better with ported vacuum advance, but it wasn't, and the '64-'64 FI engines got full manifold vacuum advance. If not plug the corresponding port off on the throttle body. Seems to me that if you are using the U. I took the vacuum line off the vacuum dashpot and put it on my guage and it read 0 at idle. I'm at 12* initial, 32* total, about 10* vacuum advance. Timing Vacuum Distributors ~~~ Both idle timing and static timing of 7. Leave the rear port open and run a hose from the front port to a "timed" vacuum signal port on the throttle body. Since this also increases hydrocarbon emissions, during the '70s, the OE's moved to ported vacuum advance that only added timing above idle. If it's possible (yea, "feasible") to use a vacuum advance for cruising, yet have the vacuum signal DIE instantly, as soon as the throttle blades open, I'd like to try it. You want as much initial as you can (10 to 16 degrees) then a fair amount of mechanical (20 degrees) and the rest vacuum advance to come u. Vacuum advance distributor hook up Click here about this distributor is for their distributors have a ported or retard the hei distributor ford 289-302 blue. Ported vacuum doesn't start until the carb plates uncover the port while manifold vacuum is constant. Vacuum advance connects to Ported Vacuum, NOT manifold vacuum. Rich woman looking for older woman & younger woman. Going to replace choke stat and recheck vacuum break adjustment. the purpose of the vacuum advance is to improve idle, mileage, etc. My question concerns hooking the vac up. Whenever the hell I get mine running, I am planning to hook up the vacuum in the stock configuration, with a ported vacuum switch. I also replaced all vacuum lines after making diagram prior to dissassembly. Please remember, large cap HEI were designed for emissions use, not performance, and ported vacuum advance worked with an emissions engine that uses an EGR (Exhaust Gas Recirculation) valve only. Manifold vacuum is a good indicator of engine load. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15. Then I reconnected the vacuum advance. It provides maximum spark advance while preventing detonation or "pinging". install the vacuum advance to the port that is signaled or right above the throttle plate. I do have light advance weights on my HEI, yes. 212, 214 are the only ones I can remember but I know there are more. For example the line from the timed port on the carb goes through two of the switches as it did on the stock manifold to the vac advance. Accepts late model chokes, water necks, alternator and air conditioning brackets and GM HEI distributors. If the carb is tuned for lean best curb idle speed then that additional amount of timing advance is necessary to complete the slower burn of the lean mix. c) Use a 5/32” diameter vacuum line from the bottom of the throttle body to the vacuum advance canister on the distributor. A manifold vacuum fitting will supply vacuum at idle. Here is a diagram from the TSM that shows how manifold, ported, and adjusted vacuum behaves: If you want to run manifold vacuum on your car, the best way would probably be to switch to an HEI dizzy, limit it to about 10-12 degrees vacuum advance and increase the amount of centrifugal advance to an amount about what we have with our stock dizzies. I have a 4 port thermal vacuum switch w/ a 2 blade electrical connector attached on right (pass) side on front of intake manifold. Vacuum advance’s purpose is to compensate for and engine’s LOAD. It is a ported vacuum regulator valve offered on an '80 301 Firebird. The stock HEI uses a vacuum advance canister to further tailor the ignition timing. I havent mess with timing or anything since I've put new carb on just swapped from ported to full manifold vacuum on distributorwith vacuum (unhooked) got 12 degrees at idle and 35 degrees at 4000rpm. In the vast majority of cases, the manifold may be installed without modifications, since the runner openings at he head flanges are already matched to all but the largest possible head flanges are already matched to all the largest possible head port openings. Maybe it was because my cam wasn't so big it didn't produce any vacuum at idle. If not plug the corresponding port off on the throttle body. Set spark timing at 32º before top dead center (BTDC) at 4000 RPM with the vacuum advance line to the distributor disconnected and plugged. Done less than 500kms. As for trying ported or manifold vacuum. Excessive pinging will require a deeper look into your ignition timing and/or mechanical advance rates. Manifold vac drops off as you increase the engine's RPM. These steps will set the vacuum advance degrees up correctly to use full manifold vacuum, instead of the incorrect ported vacuum sourcing. Theres just a blanking bung on the vacuum port. I always built them from gm 292s and jeep 360 drive. This throttle body has throttle bores of 1. Set spark timing at 32º before top dead center (BTDC) at 4000 RPM with the vacuum advance line to the. After gets hot and try to crank will barley turnover. This allowed me to turn the timing down a few degrees to help out on the top end. When your turbo/supercharger beings to produce positive manifold pressure (boost) the vacuum advance immediately. I LOVE the new Taylor wires. The port on the left provides vacuum advance, and the port on the rear provides vacuum retard. But the car runs great even as is. It would always hesitate when stepping on it to WOT. That's why it is used w/the distributors vac advance mechanism, it'll advance the timing when RPM's go up. All of this seems to be a never-ending source of confusion. Both fuel economy and throttle response can be improved by proper application of vacuum advance. Are you using "ported" or "manifold" vacuum to the distributor? "Ported" vacuum allows little or no vacuum to the distributor at idle. The small one on the front is called manifold vacuum. At this point the port is now connected to manifold vacuum and advance is pulled in. What i was thinking was removing one of the plugs that is directly into the intake manifold. Manifold vacuum is lowest during acceleration and ZERO during WOTbut ported vacuum is zero at idle and increases with RPM because it is created by air rushing through the venturi of the carburetor and during acceleration the volume of air going through the venturi and it's speed is increasing thus making ported/venturi vacuum highest under conditions when manifold vacuum is lowest or zero. When the throttle is partially open (highway cruising), manifold vacuum is high. Run engine at idle with vacuum advance hose(s) disconnected and plugged. or Multi-port Fuel Injection MHCV - Manifold Heat Control Valve PVA - Ported Vacuum Advance. Now, if we only have vacuum advance (LoadOMatic) and we just lost our vacuum signal (ported) what happens to the timing? It will retard!. Full manifold vacuum should be called exactly what it is, and what Ford called it decades ago, "Load Compensator". When your turbo/supercharger beings to produce positive manifold pressure (boost) the vacuum advance immediately. Your vacuum advance may be set too "soft" during the cruise when it operates. Currently my vacuum lines are not hooked up correctly. Is your carb stock, do you have a cto that switches between ported and manifold vacuum, if not which is feeding the advance? If the old distributor advanced ok then it is likely a bad advance module or a tooth off. Browse 1500 suburban impala for sale here. A vacuum constriction device (VCD) is an external pump with a band on it that a man with erectile dysfunction can use to get and maintain an erection. but i didn't know if the chevys were suppose to go to the manifold. Lets take a moment to understand vacuum advance together. Now the timing question. Tuning with Vacuum I see a lot of discussion and confusion regarding the use of Ported Vacuum versus Manifold Vacuum for distributor vacuum advance. There are no vacuum ports on my carb. a lead from this switch connects to the fast idle solenoid. They are a poor copy of the Mopar electronic vacuum advance distributor. If you have an engine with a functioning EGR valve, ported vacuum advance is for you. Vacuum advance should be connected to full manifold vacuum; not ported. If you don't feel any vacuum pulling at your finger with the engine at an idle, you have timed/ported vacuum advance. Specifically, this auto part manages the secondary voltage transfer that burns the fuel the vehicle requires to operate. manifold vacuum source, but all the other vehicles that I've own/owned had use ported vacuum. Seems to me that if you are using the U. Check this out, I love this little gem. Set spark timing at 32 deg. I guess the topic say it all. The boards I participate where I have paid the most attention are with big block chevrolets. Some systems have a special temperature sensor on the engine to switch from ported to manifold vacuum if temps climb too high for this reason. Re: Nutter Bypass and Vacuum Lines I'll be glad to offer a fair and to the best of my ability an accurate reply to any questions that you have. Iam also running a edelbrock performer manifold. , SVDA) on aircooled VW engines (vacuum hose disconnected and plugged on the single-va. I've been experimenting with my HEI, having run it off manifold vacuum w. the vacuum canisters do come with different springs in them; some heavy some light. GM Throttle Body Injection 1987-93 LO3 (5. Remove the air cleaner if necessary to gain access to the base of the distributor. 3 -With vacuum advance still disconnected I moved the gauge to manifold vacuum port and ran the mixture screws in to see what effect they had on vacuum. These steps will set the vacuum advance degrees up correctly to use full manifold vacuum, instead of the incorrect ported vacuum sourcing. What i was thinking was removing one of the plugs that is directly into the intake manifold. Ported vacuum: With that thought in mind consider if the distributor hooked to Ported Vac, as air speed increases the ported vac activates and starts to pull more and more timing in the motor as velocity increases. I have had 83 305s and 350s. Ported vacuum control has been used for a very long time. Manifold vacuum is an excellent indicator of an engine's load. It'll have a diagram showing which vacuum lines are what. However if your vehicle is automatic then vacuum is not ported, use manifold vacuum for the vacuum advance. Check this out, I love this little gem. Depending on the age of who you ask, and their own experiences you still have a 50-50 chance of one or the other. Whenever the hell I get mine running, I am planning to hook up the vacuum in the stock configuration, with a ported vacuum switch. I use manifold vacuum. If not, you can run a direct hose from the TBI ported vacuum source to the distributor's vacuum canister or run this hose via the CTO. Ported vacuum Ported vacuum is just above the throttle plates and its reading is only about 1 inch of mercury with the plates closed and very close to manifold when the plates open. install the vacuum advance to the port that is signaled or right above the throttle plate. 490 Virtually brand new billet dizzy. I believe there is now a turbo specific Safeguard model which can handle vacuum advance. , a high vacuum present in the intake manifold relative to the outside air) the powertrain control module (PCM) will open the EGR valve and then monitor the MaP sensor's values. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15. "Basically the question is is the spark advance port above or below the throttle?. There are two differences between these vacuum sources. This car has a Carter BBS carburetor, a 1976 distributor (the one for the 2bbl engine, with the good advance curves), and no EGR. At this point the port is now connected to manifold vacuum and advance is pulled in. There should be a vacuum line connected from the carb, or the manifold, to the vacuum canister. By placing a 3/32-inch Allen wrench in the nipple, you can. This is not the original carb to the car, As i remember it all vacuum advances should run off ported vacuum. A ported vacuum source will have very little to no vacuum at idle, whereas manifold vacuum will be high at idle. Ported vacuum has been used on pre-emission motors but not too often; it's become common on emission motors as it helps with reducing emissions, but nearly all I've seen used a temperature-controlled vacuum source to switch between manifold and ported vacuum. Each additional turn in the counter clockwise direction will subtract 2º of vacuum advance. On some vehicles, a temperature sensing switch will apply manifold vacuum to the vacuum advance system when the engine is hot or cold, and ported vacuum at normal operating temperature. So if you set you total timing to 34* at 3000RPM that's when the ported starts to do it's job and advances the the timing to the. At idle, a spark ported vacuum system provides zero vacuum advance where the older manifold vacuum advance system might have provided as much as 10-12 degrees additional timing. Which port on the carb do I connect the vacuum advance to? And where do the fuel lines hook up? Got the crank breather/pcv and brake booster and ac actuators hooked up. The centrifugal advance system is completely independent of the vacuum advance, and doesn't care how vacuum is set up - it works the same way regardless of manifold-vs. Are you using "ported" or "manifold" vacuum to the distributor? "Ported" vacuum allows little or no vacuum to the distributor at idle. Same question is, or a vacuum advance distributor cap, trucks suvs with vacuum. This is with the idle screw backed all the way out and I verified the pedal is not hanging it up. 0L) and LO5 (5. I do have light advance weights on my HEI, yes. It kinda sputters at slow cruise about 1200-1400 rpm when hooked to either. If you have a vacuum advance can with not too much advance, you might try connecting it to full manifold vacuum & see if your idle increases, if so great otherwise use ported vacuum. You want as much initial as you can (10 to 16 degrees) then a fair amount of mechanical (20 degrees) and the rest vacuum advance to come u. So my newly aquired Pontiac has a fresh crate 350 with a Procomp HEI distributor and when i looked closer the vacuum advance does not have a vacuum line connected to it. Holden 186 202 6 Cyl ICE Ignition Kit - High Energy Ignition system - Street Series 7 Amp Vacuum Advance 7640MV Shipping is extra Shipping is calculated by size and weight in the check out section when you enter your address. Set it about 10 btdc with the vacuum disconnected and the hose plugged. BTDC, 36 deg. You lose vacuum when you go under load which removes vacuum advance and returns you to total timing. Forum FAQ Search Memberlist Usergroups Calendar Register : Profile Album: Album. Manifold vacuum is an excellent indicator of an engine's load. that is because it is now idling more efficiently. The vacuum advance is preset to 16º. It kinda sputters at slow cruise about 1200-1400 rpm when hooked to either. After setting up the base/ centrifugal timing I found I had to limit the amount of vacuum advance to about 8*. Also Ford did not always use vacuum as you put it. Turning it in (clockwise) will shorten the stroke, which limits the advance. I LOVE the new Taylor wires. The ported vacuum switch gives you manifold vacuum advance above 220*F and advance is controlled by carburetor vacuum below. Check automatic transmission shift points before removal of your stock manifold, and adjust linkage after Edelbrock manifold installation for same shift points (if needed). The vacuum advance canister should be plugged into a "manifold" vacuum source on the carb or intake manifold. There are two differences between these vacuum sources. Tuning with Vacuum I see a lot of discussion and confusion regarding the use of Ported Vacuum versus Manifold Vacuum for distributor vacuum advance. With 30-34* timing + your vacuum advance, you'll be at 38-44* which should be optimal. Maybe GM thought that idle quality (always a problem on FI engines) would be better with ported vacuum advance, but it wasn't, and the '64-'64 FI engines got full manifold vacuum advance. I runs great, fires right up with initial timing at approximately 18°, not sure what the complete timing is with vacuum advance, but doesnt changes little when hooked up to manifold vacuum advance or progressive-front port. Our vacuum canister creates maximum advance of 16 degrees at 12 inches of vacuum. Hi all parts and road test. These units will both advance and retard the ignition timing. They are a poor copy of the Mopar electronic vacuum advance distributor. Set spark timing at 32º before top dead center (BTDC) at 4000 RPM with the vacuum advance line to the. Running manifold vacuum to the distributor without the vacuum advance unit adjusted properly for it can cause an unstable engine idle leading to stalling. I recently tried using ported vacuum off the MC2100 carb, and it seems to improve the bottom end power, possibly at the expense of the top revs. That car refused to run right with ported vacuum? No idea why to this day, had the big ugly factory HEI and had great spark BUT it just wanted to run on manifold vacuum. Each additional turn in the counter clockwise direction will subtract 2º of vacuum advance. Going back to factory style, make an offer. I feel that manifold gives me better initial acceleration, but I have a harder time with the carb's idle settings due to the advanced timing at idle. Connecting the hose directly from the carburetor’s spark advance port to the distributor’s vacuum advance will make things noticeably more sprightly in part-throttle driving. c) Use a 5/32” diameter vacuum line from the bottom of the throttle body to the vacuum advance canister on the distributor. If you have an engine with a functioning EGR valve, ported vacuum advance is for you. Buy right now. what is vacuum advance how does vacuum advance work vacuum advance vacuum advance distributor do i need vacuum advance distributor how to. If you are switching to any sort of vacuum ADVANCE distributor, then you need to provide PORTED vacuum. However if your vehicle is automatic then vacuum is not ported, use manifold vacuum for the vacuum advance. Re: 258 w/ HEI, vacuum advance issue? I don't know alot about HEI systems, but from what I understand they came in four, five and seven pin configurations. If you have full advance at idle, you will have quite a fast idle. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15. So, no you won檛 see an idle change when you disconnect your advance, and no you won檛 see it come on as your engine will not pull enough vacuum to pull the advance until it is under load. This throttle body has throttle bores of 1.