useing a vacuum gauge, and carb tuning

[grumpyvette]

http://www.centuryperformance.com/tunin ... g-148.html

http://www.earlycuda.org/tech/vacuum2.htm

http://www.secondchancegarage.com/public/186.cfm

http://www.visn2.com/UsingVacumeGauge.html

http://www.corvette-101.com/
(info on left border)

heres a couple darn good links you need to read thru, lets have some additional info or comments and questions??

http://www.secondchancegarage.com/public/186.cfm

http://www.nastyz28.com/perftune.html#carb

http://www.chevyhiperformance.com/howto ... index.html

http://www.tuningmadeeasy.com/tuning/va ... nder-tool/

http://www.harborfreight.com/cpi/ctaf/d ... mber=93547

viewtopic.php?f=55&t=264&p=319&hilit=accellerator#p319

The first thing ID do is VERIFY the CAUSE, OF THE PROBLEM FOR THAT, THRU ISOLATING AND TESTING, COMPONENTS AND SYSTEMS
A SHOP MANUAL IS ALMOST MANDATORY,
THESE LINKS should help

viewtopic.php?f=80&t=728

viewtopic.php?f=55&t=1241&p=3037&hilit=+sensor#p3037

always drop back to basics

have you verified TDC on the damper and timing tab?
did you degree in the cam or just DOT-to-dot install it?
whats your fuel pressure?
have you verified the carbs float levels?
does fuel run out the site holes at idle?
are the needle& seat valves working correctly?
whats your ignition timing?
whats your plenum vacuum?
have you verified the engine got no vacuum leaks?
whats the oil pressure?
have you adjusted the valves at idle?
does the distributor timing advance with rpm increases?
have you tried a different carb?
have you done a compression check?
what are the plugs gaped at?
does this happen without an air filter?
have you verified you've have functioning power valves?
what jets are you using?
is there visible fuel flow from the boosters?
whats your battery voltage?
whats your exhaust back pressure?
are you totally sure the fuel free of water and fresh?

vacuum gauges must be connected to manifold vacuum



but a simple vacuum gauge will be a surprisingly accurate tool providing you know how to use it.
you don,t need an expensive tool


http://www.harborfreight.com/cpi/ctaf/d ... mber=93547

BTW remember those cheap crappy fuel filters I told you to never use

well heres where they come in handy, you plug them into the rubber fuel line between the vacuum gauge and the intake plenum where they act like a pulse dampers making the vacuum needle stay a bit more steady and easier to read

HERES SOMETHING THAT MIGHT BE USEFUL

 

[grumpyvette]

Re: vacuum gauge, and carb tuning

vacuum gauge
http://www.centuryperformance.com/tu...e-spg-148.html

http://www.earlycuda.org/tech/vacuum2.htm

checking for vacuum leaks
how can we check for intake vacuum leaks?"

lots more info here in the sub links, of this thread

viewtopic.php?f=44&t=773

BTW
A/F RATIO CHARACTERISTICS
5 RICH BURN LIMIT: Combustion is weak/erratic.
6-9 EXTREMELY RICH: Black smoke and low power.
10-11 VERY RICH: Some supercharged engines run in this range at full power as a means of controlling detonation.
12-13 RICH: Best power A/F: Un-supercharged WOT.
14-15 CHEMICALLY IDEAL: At 14.6 the A/F is at the theoretical ideal ratio with no excess fuel or oxygen after combustion. Good A/F for part
throttle cruise and light to moderate acceleration.
16-17 LEAN: Best economy A/F ratio. Borderline for part throttle drivability (worse than borderline if EGR is used).
18-19 VERY LEAN: Usual lean limit (Driveability).
20-25 LEAN BURN LIMIT: Varies with engine
and system.

yeah the way I find vacuum leaks on carb OR MPFI intake manifolds is clean and easy with no mess. get a propane torch,or you can use your oxy-acetolene welding torch if you have one, (DON,T TURN THE OXY tank/or valve ON)

(Ive used this one for years)

http://www.professionalequipment.com/ex ... ermometer/
Wide temperature range from -58 to 1832°F (-50 to 1000°C)
yes they can be found muck cheaper
http://www.harborfreight.com/non-contac ... -8905.html


(DONT LIGHT IT) just SLIGHTLY open the valve so its allowing gas to flow at a low voluum,start the engine and let it idle at the lowest speed you can then place the tip of the UNLIT torch at any suspected vacuum leak and listen for the rpms to increase and watch the tach, gas flowing into a vacuum leak will increase engine speed.
look for loose or missing vacuum hoses, cracked or broken power brake connections, emmisions system hoses that are loose, vacuum connections to the trans or ignition, loose connectors missing or loose bolts cracked hoses missing assessory connections

 

[grumpyvette]

Re: vacuum gauge, and carb tuning

HEY GRUMPYVETTE? are those A/F metters and IR temp guns really useful?


thats a good question for this forum,
Ok Ive got one and have tested several of them.

http://www.professionalequipment.com/ex ... ermometer/

http://www.modernperformance.com/produc ... ts_id=1149

http://www.3barracing.com/product_3.htm

http://www.rbracing-rsr.com/rsrgauge.htm

http://www.scirocco.org/tech/misc/afgauge/af.html

http://www.innovatemotorsports.com/products/lm1.php

http://www.autospeed.com/cms/A_0217/art ... larArticle

http://thedynoshop.net/prod01.htm

heres my take on them, short answer,
they are a big help,
but a P.I.T.A. to set up and use,
if your not going to semi permenantly install them on your car.


IVE come to use reading spark plug condition,

http://www.digitalcorvettes.com/forums/ ... hp?t=80783
http://www.digitalcorvettes.com/forums/ ... ight=plugs

use of a good timing light and vacuum gauge , fuel pressure gauge and use of a GOOD HIGH TEMP INFARED THERMOMETER (THIS ONE)

http://www.professionalequipment.com/ex ... ermometer/

as a very quick to use and accurate set of tools.

OK WHY???

well your main concern when tuning an engine is to keep the all the cylinders running aproximately the same ratio and at about 12.8:1 for max power up to about 14.7:1 for low emmissions and good mileage, AND WHILE A A/F GAUGE IS A GREAT ASSET, ITS EASY TO DAMAGE, AND ITS BEST INSTALLED IN YOUR CAR , NOT USED AS A SHOP TOOL.

so whats the advantage/disadvantages

a fuel air meter uses a o2 sensor, if you place it in the header collector it gives an AVERAGE of all the cylinders on that cylinder head,If theres an (X) installed close to the dual collectors reversion pulses can occasionally even give data from the other side of the engine, so in theory and in practice you can have two cylinders run lean and two rich and the AVERAGE tends to look RICH to the O2 sensor as it SEES unburnt fuel, if you place it in the individual primary header tubes you either need eight O2 sensors (VERY EXPENSIVE, and keeping the wires from burning or grounding outs a TOTAL P.I.T.A......IF you don,t succeed you destroy the O2 sensor and need to replace it.) or you need to be constantly swapping very hot and fragile O2 sensors and bung plugs constantly, but with the IR thermometer you can almost instantly see which cylinders are running hotter or cooler and adjust the jets or look for vacuum leaks, or other CAUSED for the TEMP DIFFERANCE, ETC, far faster too get all the cylinders running at approximately the same temp, indicating the same fuel air ratio, youll be amazed at how close the temp follows the fuel/air ratio, and you can confirm it with plug condition and the other test equipment. run any cylinder too lean and detonation can break rings or melt pistons, run it too rich and you can wash the oil off the cylinder walls and ruin rings/scuff pistons, you need to know whats going on in EACH CYLINDER not the AVERAGE of all cylinders.

SO, if your going to install a decent wide band fuel air ratio meter on your car thats fine, its going to be an asset to your tunning skills, if you install the indicator/gauge inside the car and weld in a couple extra bungs in the collectors for tunning and wide band O2 sensors which are a big help, but you will quickly find that its a P.I.T.A. to use it for tune ups on all your buddies cars with the welding collector bungs and installing plugs and O2 sensors while the IR thermometer route is fast and very simple and you can confirm with oplug reading the condition of the engine.

YEAH! theres meters that you can stick in a tail pipe, but they read THE AVERAGE, not the individual cylinders ,
think about AVERAGEs
AS my old physics proffesor once said,
IF, I pour molten lead in your front slacks pockets and pack your butt in solid with DRY ICE,.... ON AVERAGE your comfortable


BTW
http://www.digitalcorvettes.com/forums/ ... hp?t=79676


bits of useful info on these

http://www.thirdgen.org/o2tuning


http://www.thirdgen.org/fuelgauge

http://www.thirdgen.org/tpimod2

http://www.thirdgen.org/injectorswap

http://www.thirdgen.org/coolantbypass


http://www.mummbrothers.com/SRF_Stuff/S ... r_Fuel.htm

http://www.ws6.com/mycar.htm

 

[grumpyvette]

Re: vacuum gauge, and carb tuning

if your getting PINGING/DETONATION
ask yourself these questions, because without info your working blind

WHATS YOUR TOTAL TIMING SET AT ?
and at WHAT rpm does the ignition advance reach full advance?
whats the normal engine temp?
what octane fuel are you useing?
whats the engines compression ratio?
have you changed cams?
whats the fuel/air ratio?
have you verified TDC?
which spark plugs and gap are you useing?
what carb jets and power valve are you useing?
whats your fuel pressure?
have you tried retarding the ignition timing?
is the disributor set with a known advance curve?
yes I know your 100% sure the ignition timing and the plug wires are correctly installed..CHECK THEM AGAIN CAREFULLY SEVERAL TIMES



http://www.tuningmadeeasy.com/troublesh ... hooting-2/

There is one tool that can tell so many things about an engine it’s simply amazing. Yes, it’s a vacuum gauge. And it must be the best kept secret to tuning in the world. We’ve walked around performance cars and visited the pits at professional drag races for years, seldom have we seen a vacuum gauge in use. A few cars have them like most BMWs at one time, but they were disguised as a fuel economy gauge. Besides, the vacuum gauge shouldn’t be in the dashboard it should be in the engine room. Every car and boat we’ve raced on an ongoing basis has had a vacuum gauge permanently installed on the engine. Not to be viewed while driving but to be viewed while dealing with the engine.



The engine is in fact an airpump. The better it pumps air, the better it runs. A vacuum gauge measures the difference in pressure between inside the intake manifold and the surrounding air, and therefore measure the effectiveness of this airpump. That means that the vacuum gauge can be used extensively both for diagnosing/troubleshooting and for tuning. A vacuum gauge will be mentioned many times in the tuning section on these pages.



So, if you don’t have a vacuum gauge, get one! You can do like us, have a beautiful AutoMeter vacuum gauge complete with mounting cup permanently fixed to your engine, or you can buy a cheap vacuum gauge as a testing tool and you on all your engines. Absolute accuracy is not critical, it’s more the relative movement that is important. And remember to plug it to manifold vacuum, not the ported vacuum port on the carburettor.



Diagnosing/trouble shooting

Fortunately a lot of different faults can be found with a vacuum gauge, because the behavior of the needle is different to most situations. Here are the 7 most common scenarios (engine idling and warm):



Steady needle, at 15-22: Engine in good condition. (An engine with long duration camshaft will have a lower vacuum and a less steady needle, maybe 10-15 with 1-2 “jerks”. That’s still an engine in good condition)
Steady needle, lower than normal: Ignition timing too late or vacuum leakage
Steady needle like in 1. but occasionally fluctuates at idle: Ignition miss or sticking valve
Steady needle like in 1. but drops regularly: Valves need adjustment or burnt valve
Floating needle, maybe in the area 10-20: Carb out of adjustment or vacuum leakage
Shaking needle, becomes worse as rpm increases: Ignition miss, blown head gasket
Shaking needle, becomes steady as rpm increases: Worn valve guides



If we’re driving and suddenly the engine behaves differently, then we first check the vacuum gauge, then we know where to start…



Tuning

Most of the tuning actions that we talk about in that section involves a vacuum gauge. While a vacuum gauge seldom can tell you the absolutely best ignition timing, it can get you close and save you a few test trips on the track. In the example in the Section Testing we test all the way from -12 to 3 degrees. Without a doubt a vacuum gauge could have narrowed that down, probably vacuum would drop noticeably below -10 and above 0, would have saved a few test runs. Mostly we adjust carburettor idle mixture and ignition timing simply by turning the screws until maximum vacuum is achieved. That’s a real good starting point.