comparison, 496 stroker w 230/2

2021/05/21

For comparison, 496 stroker w 230/236 duration at .050, .541 lift hydraulic roller, at 14 initial and 900 rpm, 12 inHg. This means the engine is producing less power and, therefore, less vacuum. Conversely, a choked or restricted air cleaner would result in a higher than normal reading, depending on how hard the engine works to pull in air. If you are running a PCV, eliminate it. Could you repeat the test with the linkage to the secondary carbs detached? Its so valuable, in fact, that OnAllCylinders contributor Lori Sams put together thisvisual cheat sheet to help youunderstand common gauge readings. Finally after hours of trial & error it started with the carb unplugged It is a Howard's 250021-11 cam that says Ford FE on the card profile. The gauge at left shows an extremely low reading, which holds fairly steady. They are: Correct. So here is what I have: HEI Distributor and vacuum circuit, HELP! Look for the highest reading without going past that. I have the compcam XE274 camshaft in my 383 and am in the process of tuning the engine. Low quality gauges can leak internally and give unreliable readings. He said the Flame Thrower coil has 1.5 ohms built in to it, so I think I am good there. Need help with 440-3 cutting out on heavy acceleration. the bigger cams = less engine vac.= no brakes. It depends on a few things. Now perform the wiggle test. Mike's love of cars began in the early 1970's when his father started taking him to his Chevron service station. Low reading between eight and 14 inches, turned out to be a bad spark plug or plugs in my case. Adjust your carb and distributor. Instead they live as they please and finally are forced to depart this life., The Fora platform includes forum software by XenForo, My detailed instructions for adding ABS to a Fox width rear axle FFR, https://www.youtube.com/channel/UC7cBpeIW286xO3U4l4RtVMQ, http://www.youtube.com/user/joeembery#p/u, http://s207.photobucket.com/user/JoeE13/library/FFR Cobra?sort=6&page=1, http://outintheshop.com/faq/Vac Adv Spec.pdf, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. screw dialed in by itself overnight ! Flooring it should cause vacuum to drop quickly, maybe to zero. As stated, a stock engine should pull 17-21 In/Hg of vacuum at idle. For a better experience, please enable JavaScript in your browser before proceeding. Hallo John. You ought to be pig rich in gear at idle and Everytime you mildly take off. I am working on a 82 Kawasaki kz1000. Sofa hit it on the head. Edelbrock Air Gap manifold The car idles and sounds as if it has a decent cam in. You obviously have a problem. Come join the discussion about performance, production numbers, VIN decoders, modifications, troubleshooting, power adders, DIY tutorials, and more! Your correct,with 224 deg dur @.05 in 350 cubes you should not have 21" idle vaccum . Your email address will not be published. I ran vacuum advance on the old crane electronic distributor. :beers: 40 DEG AT IIDLE WITH VAC ADV HOOKED UP TO FULL VACUUM ALL THE TIME ISNT THAT FAR OFF. Once on the throttle 11 to 12 A/F, I am generally too rich. What cam are you running? Need other technical information or engine specific advice? Scott, we are mostly in agreement here. Your email address will not be published. To me that 'no less than 1 turn out' is simply a guideline. Terms of Service - If that is where you get your highest vac number than it is the best mixture for your engine. How much vacuum you get is mostly dependent on your cam. Once you find it, that can be used to figure out the proper power valve. I'd []. I bought the vette with that Cam" That is the 1st thing I will be pulling out next winter. Not a good cam to start with, especially with only 9-1 compression. Unless the vacuum is really jumping around on the gauge, there is no reason to suspect a valve timing issue. Thanks Tedster! Spray the base of the carburetor and the intake manifold rails with carb cleaner while the engine []. I haven't checked it so i dont know what its at. A steady low reading between eight and 14 inches of mercury is usually indicative of incorrect valve timing. Archive - On a 383 I'm surprised you have that much vacuum Really - I thought where I am currently at is way low. a SBC, but only if all the parts were perfectly matched. - Toyota Nation Forum : Toyota Car and Truck Forums, 85 300 not running right - Page 2 - Ford Bronco Forum, Mailbag: Tracking Down Common Causes of Sluggish Engine Response - OnAllCylinders. There is no oil/coolant mixing that I can see. About Us -

Its a 383 with a Holley 770 Street Avenger. I have a baby by comparison 246/256 @ .050 on a 110 centerline with .580 lift I have a 1100 idle with 25 degrees locked in timing and 8-10 inches of vacuum solid flat tappet cam and 1150 carb on a nitrous fed 408W. Next I would have never recommend such a large cam for street use not worth the hassel, I have a 292 cam and that has to be the dummiest thing one can do to a street engine. " Carb Size Street Car - Advantage of QF 780 cfm over 735 cfm? Higher elevations may cause slightly lower readings. Turn the idle adjustment screw(s) out all the way and then turn it/them in until the engine begins to stumble and back off a quarter turn. Scott, FFR #3870 MK II, Spectra Blue/Arctic White, 1974 414W, 10:1, Eagle 4340 crank and rods, KB Pistons, Ported Performer RPM 2.02 heads & intake, QFT SS-650, Comp XR282HR, Quality Roadsters pan, Crane ignition, TKO600, 3.55 gears, 3 link, SA QA1's, Breeze LCA's, Heim joints & VPM F/R bars, Power steering with Hiedts valve, Power brakes, Fortes bump steer kit, 5 bolt axels, SSBC rear brakes, Oil cooler, Pusher fans, Halibrand Cobra III's with Nitto NT555 G2 245/285/17, Thanks Scott,that is a great video,my HR680 is brand new,(1600 mi.). Do the idle mixture screws effect the engine? A forum community dedicated to Ford Mustang owners and enthusiasts. JavaScript is disabled. I have a vacuum gauge and A/F meter in my dash so I see these readings all the time. The question of the vacuum in the runner is not really the same as a multi-carb motorcycle with individual runners - those do have to be synced and can have different vacuum based on each carb opening. The swing on the gauge is usually anywhere from 10 to 22 inches of mercury, depending on the speed of the engine. All graphics from forums.neon.org unless otherwise noted. I put it on the dash above the speedo so I can see the fluctuations as Im driving and link them to the driving conditions under which they occurred. Just shoot for the highest at idle. You can hook a tee-fitting into an existing vacuum source or pull a line, such as one that leads to your transmission. EZ EFI 2.0. Yes, at the base of the carb or right in the plenum is better, but total vacuum should be about the same. Timing is the biggest factor. Begin your engine check-up by making a thorough preliminary inspection. The vacuum gauge pulses from about 6inHg to 14inHg at an idle of 750rpm in gear. I think you may be using idle speeds that are a touch too high and I am using a simplified model appropriate to a MT and not an auto. idles at 950-1050 rpm. ]Donor $2,500 -Kit $18,000 -Extra "needs stuff" $100's -$1,000's. Thanks for that great information Tedster! It is set at 10 deg BTDC right now. Keep in mind, this reading is ideal for stock-cammedengines running at sea level. Kim. If your valve covers don't have baffels in them like the stock one did, it is common for oil to get spashed into the PCV valve. I tried connecting to manifold once and it was terrible. Often, a sticking valve will cause more sporadic drops during this pattern. at idle, all 4 vacuum gauges rapidly flicker from about 4 pounds of pressure to about 15 pounds of vacuum. The needle on my vac gauge moves about an inch or two until you are accelerating then it is smooth, on decal and light acceleration I see about 12". But you can go probably a full turn richer and not notice a change. I need an opinion from all you pros out there! Timing & carb adjustment will help. Here are pics. What could it be. Do Not Sell My Personal Information -, By logging into your account, you agree to our. JavaScript is disabled. Something like a plugged cat or muffler is usually the culprit here. Read our Privacy Policy for more info. Nice work thanks, I recently spent a lot of time with a vacuum gauge while attempting yo sort the idle mixture on my 65 Olds 330 V8 engine.Of over 100 mixture adjustments the median vacuum was between 10 and 11 Hg but I dont think my engine has a valve timing problem as suggested in the article.These small blocks, like other Olds engines are known for low vacuum and my engine also has a aftermarket high lift cam so I am not concerned about these numbers.Besides the engine runs great! Conversely, if the gauges needle swings back and forth as the engine accelerates, your valve springs are probably too week for your engine. hallo mijn vacuum meter meet een snelle trilling boven de 20 inch He has also partnered with mainstream and trade publications on a wide range of editorial projects. How much vacuum are you guys seeing at idle? You can have any bigger cam ground to diffrent lobe center to get more vaccum at idle. Please list your cam, vacuum, and at what idle RPM it is. I run a 302 with B cam and AFR heads. Vacuum should steady. Carb adjustments next. Don't see another board for your problem? If thats 4 degrees late your vacuum wont be as good as you might otherwise expect. I did notice however that I have a film of oil in the intake plenum and runners. The engine has about 350 miles on it. Then I learned how to adjust that on my Mallory dist. Is this normal for a cam with an intake duration of 230 degrees and a lift of .48 inches? When you are at the lean best idle, a 1/8th turn leaner makes a very noticeable difference in the engine. IMO, yes, its low. Contact Us - lift .673/.648, @.020 286/286, @.050 250/254 lobe at 107 centerline at 105. wat kan daar de oorzaak van zijn. While its tough to diagnose remotely, in my experience, any rapid vibration will likely mean some sort of valvetrain issue: valve guides, springs, seat, etc. What will happen is that the tip-in of throttle will be less responsive because now you'll need to re-tune the accelerator pump timing / shooter size. The engine seems really cold blooded, and takes its sweet time to warm up. Turn the idle mixture screw and watch the vacuum gauge. tell you if the bearings were not the right size. The most I've seen in a big solid cam is 17". we change to the 750 DP that came on the engine. Terms of Service - Actually, you can lean it to the point where the engine will not idle for long or at all and you won't damage anything. I knew without a doubt my valve timing was right, I changed the plugs just because there was no where left to go and it worked. Very interesting,happy to know Im not running to lean,tried using the vac. No matter where you get your vacuum source, make sure its not ported. I have a 1970 chevy 250 6 cylinder, at idle I get a quickly vibrating needle between 12 and 15 inches, whats wrong? Pull the vacuum hose after the PCV valve and see if it is coated with oil too. The aluminum Trick Flow 2.02 heads needed work and a couple springs that were weak. It should drop almost to zero for an instant when you accelerate quickly. Privacy Statement - hello, sorry for my writing I am French, I have a pontiac firebird 2.8l manual transmission of 1988 and on my vacuum gauge I read 16 hg with the occasion very slight increase to 16.5 hg and after having all check all the ignition it turns out that all works well and with the good advance besides if I try to advance the ignition i have a misfire can someone have an idea? I was looking at a Comp Cams, but I let him run with it. I believe the original owner of the truck had the engine rebuilt at one point, but, I don't know if he switched the original cam out or not. If that is an old design('70's ish) 300/510 sure could have low vacuum. With a big cam you can uncover the transfer slots and start drawing fuel from the main circuit rather than idle circuit. Dont bang or drop it. 4,000 rpm WOW, then nothing. You are using an out of date browser. Engine RPM bouncing around with vacuum ranging between 10 and 20 are symptoms of weak valve guides. If the needle drops quickly and returns to a normal reading, a burnt or sticky valve is indicated. Advertising - Make sure you have the timing set correctly before doing any carb adjusting. Good luck! With 10* static timing, 900 rpm idle, the idle mix screws set at 3/4 (best idle quality) gives me a 13-14 vacuum with an air fuel ratio of 13.5 to 1. Slow it down as far as it will go and run smoothly and see what you have. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Please tell me if thats the proper Can't get more than 13 inch.Hg while adjusting idle mixture,is that normal with this engine. Advertising - Can you kill the engine by adjusting them? A regular swing between high and low readings often means a blown head gasket between two, side-by-side cylinders. The vacuum advance will be pulling off just before the mechanical advance takes over. If the gauge is bunching back a forth the valves may be not seating do to past zero lash. Thinking of adding power with a new combination? The cool thing about using a vacuum gauge to diagnose engine problems is that different engine problems show themselves by vacuum readings in different ranges. Carb tuning is part art and part science. When diagnosing engine performance problems using vacuum, you must use a direct source of vacuum, such as the vacuum tap on most intake manifolds. Test vacuum connections to make sure theyre tight. I have sprayed starter fluid around the manifold and carb base and didn't notice any jump in rpms. 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Thanks, that's why I was askingthe smaller the engine, the 'bigger' a given cam will behave. I got a tooth 2000 Saturn LS1 its a 4-cylinder a four-door car Im having an issue of when I cut off it dont want to take his gas let you floor it the Lacs power and Im trying to figure it out but the codes I know you dont have no engine codes on it Ill check the fuel pressure and its good and Im just wondering maybe Ill vow timing or maybe the timing chain is loose and that really give me the power I need on the vacuum I need to run a motor out of a Slave candy ideas get back with me thank you, Your email address will not be published. Gonna see if I can't get the vacuum up some. 700R V auto built for up to 650 HP If you have oil in you intake I will bet you you have a leak in you intake manifold, if tha leak is a major one that will also cause your vaccum readings to be all over the place. Also check your pcv. Thats the number of crankshaft degrees past TDC that the intake reaches max lift. Anyway, I will play around with it and report back if I can get it closer to 18-20. To What vacuum reading is okay with a lumpy cam? Thanks Tedster! advance,didnt work for me,lots, Found my problem,long story short,took a long drive That mix. When I drop it in to drive with the engine running at idle, she goes to 13/14 on the vacuum. There is no real number to shoot for. Once youre engine is up to operating temperature, you can begin reading your vacuum gauge. In loving memory of lost CorvetteForum Brothers and Sisters. You should never scrimp on your vacuum gauge. Mike also has experience in the amateur ranks of many of racing's sanctioning bodies. with NO vacumn hooked to carb and the carb port was plugged. Years ago, my fathers main mechanic at the Chevron station, Billy Jeff BJ gave me a vacuum gauge as a birthday present. Remember though, a solid cam seems milder at idle than a hydrolic of the same duration @ .050 due to the lash. A full-blooded Native American Indian, hed often climb up after me into an engine bay (he was only five feet tall) to do stuff and explain what he was doing and why he was doing it. The key is understanding what your gauge is trying to tell you. 318 mopar, BJ was probably the best mechanic Ive ever known. I said that I did a compression test and that all is at the right. With exhaust restriction, the vacuum gauge will often start in the normal range but will soon drop drastically as rpm is increased. Obviously this isnt true for huge lopy cams that can barely idle. Copyright 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Check your spark plug gap as this condition often indicates too narrow of a gap. As mentioned the 17-22 degree reading is normal for stock cammed engines. Using a vacuum gauge to help you tune a carburetor can get you within 1/16th of a turn of perfect carburetor tuning. Engine vacuum will respond much more quickly than waiting for the engine to stumble. ). Run with a breather to atmosphere on one side and hose to the air cleaner on the other. All new parts, car, distribution, wires spark plugs alternator, wire harness. If your vacuum readings aren't steady when cold or hot I would suggest checking for vacuum leaks.starting with the carb's base, throttle plates, look for any brittle or missing rubber plugs on the carb, vacuum tree and brake booster line and swivel. 408 ci Gordon Levy motor with his T5 trans and independent 3.55 rear. The improvements over using feel when tuning in throttle response, power and efficiency wont be huge, but they will be noticeable. The timing comment 66Satellite47 made was about installed cam timing, not ignition timing. Which brings another question, how much have you needed to turn the idle speed adjustment up? Hot Plugs Extra-Long for aluminum heads Thanks

I have a rapid fuctuattion between 14 and 15. Is your car making a strange sound or won't start? out if kilter. Keep it clean. 324/318 intake exhaust, Wow that is big, I guess I should have said "aftermarket" instead of large lol thanks though. I agree to receive emails from the site. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. !It was less than, There are small seals behind the idle air mixture screws. You must log in or register to reply here. About Us - Manage Preferences - Advertising - Stamped rocker arms vs. adjustable, hydraulic cam. Bouncing could be indicative of another problem. Post it here! Mother thumper cam Its high idleling and it has a code p0300 which is random misfire where should i start. Cookie Policy - Has mild rv cam. 327 small journal rebuilt 2000 miles ago. This site uses Akismet to reduce spam. The following errors occurred with your submission. FFR 5353K, 408W, TKO 500, 2015 IRS w/ 315 gear, Breeze QA1 DA coilovers front and rear, APE hardtop, Forte front swaybar. At a faster idle speed the vacuum will increase. you probally know it already ,if you have power brakes . Dad and BJ, more so BJ, taught me early on that a vacuum gauge can tell you almost everything you need to know about your engines health as long as you know how to interpret what youre seeing on the gauge, hearing and feeling. with 18-20 " vac at 800-900 idle thats not a 224 deg int dur @ .05 in only 350 cubes,no way ,thats stock type idle vacuum reading you would get with a 350 250-300hp cam & not a 270 deg/224 deg @.05 int dur cam in a 350,end of story. One thing I would add to that is to make sure how much extra timing you get w/ your vac advance.

I havnt drove the pick up yet, waiting for the registration to come through. Check the simple (inexpensive) things first like your pcv and breather to ensure they're not pulling oil before you suspect a port leak in the lifter valley. Try timing it higher. 17" isn't too bad, but there are some things to check. The following errors occurred with your submission, 1967 - 1972 F-100 & Larger F-Series Trucks, Lightning, Harley-Davidson F-150, Roush F-150 & Saleen F-150, Conventional (Bumper Pull) Towing; Travel Trailers & Pop-ups, Toy Hauler Towing; Fifth Wheel & Bumper Pull, Flatbed, Car, Boat, Utility, Horse & Misc. Most engines will run 17-21 In/Hg while idling at normal operating temperature. It has horrible acceleration until 2nd gear @ [], [] still should have a very steady vacuum reading. Solid roller lunati 51019 with a 1.7 shaft mount rocker setup, put cam at about 256/264 @.050, .650" lift. Time it with the Vacuum Gauge. You can lean the idle fuel mixture to the point of engine stumble without causing any damage. I would try and give it at least 20 degrees at idle and learn how to properly adjust the transfer slot on the carb. I've only played with EFI engines, but that has a huge effect on how much vacuum you can draw. What vacuum reading is okay with a lumpy cam? When the needle drops to a low reading, returns to normal, and then repeats the pattern at regularintervals, youre likely looking at a burnt, sticking, or leaking valve. ", I just went through the same hell. General Engine, How-To and Tech Tips, News, Tech Very informative. Its one of those tools for which you should pay more so you get the best quality you can afford. Mine is quickly vibrating between 5 & 10 at idle. No, you're reading from that port or a manifold vacumm port on the carb will be the same. I thought that stock motors got 21-22 inches at idle and anything with a bigger cam would have less vacuum. Just a good torque cam. How fast the needle vibrates is telling of how many valve guides may be worn. Weve put together this quick-guide to reading your vacuum gauge to help you identify potential mechanical or tuning issues more quickly. While my cam is no race cam, I do wonder whether the slightly higher lift/duration in an "RV" cam can lower the vacuum reading a bit. Hello, Slightly lower could idle a little better. Nothing left to check? Cookie Policy - Archive - Anyway good luck with your set-up. The Fora platform includes forum software by XenForo, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. a few years back and put an "RV" cam in, so nothing radical. You are idling WAY too high to compare vacuum levels. "What vacuum reading is okay with a lumpy cam? 800-900 RPM and I still have 18-20 lbs of vacuum. Yours may be missing or old. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. 2500-2700 stall converter. For example, if youre seeing vacuums readings at idle of: Fluctuations in vacuum with the engine idling at operating temperature are indicative of either an engine misfire or a problem with a valve. God bless you, Sir. Discussion in 'Traditional Hot Rods' started by Devin, May 24, 2014. He's done pretty much everything in the automotive aftermarket from gas station island attendant, parts counter, mechanic, and new and used sales. It is definitely not a stock cam. A forum community dedicated to Factory Five owners and enthusiasts. I always read about how a big cam will give you lower vacuum numbers at idle. A restriction in either the intake or exhaust is indicated if the gauge shows vacuum decreasing slowly instead of quickly. adjustment carburetor