tuning, where to start



tuning, where to start

Postby grumpyvette » November 25th, 2008, 9:00 pm

Id start by checking for vacuum leaks and verifying the timing curve
STEP ONE IS ALWAYS GET A FACTORY SHOP MANUAL, AND DO YOURSELF A BIG FAVOR AND READ THE LINKS BELOW
Verify fuel pressure,. by using a fuel pressure gauge on the shrader valve on the fuel rail, or carb feed. with a pressure gauge,
Verify injector pulse by using a noid light, & spark at the plugs by using a spark tester.
verify timing with a timing light
pull the trouble codes and check all fuses, and for darn sure adjust the valves at idle and check carefully for vacuum leaks

it helps a great deal to know what your working with ,ID suggest starting, by verifying TDC on the engine and the marks on the damper and timing tab reflect reality after carefully checking that, and having the correct timing tape on your damper then,start with 8 degrees btdc and verifying the full ignition advance of 36 degrees total is all in at 3200rpm , and progresses smoothly as the rpms increase, as a base line, once youve got that, as a standard you can tune and run the car and eventually try tweaks to the basic ignition curve if needed, once you have an ignition base line, move on to the carbs tuning.
having the engine temperature remain in a fairly consistent temperature range while operating helps you tune the car and make repeatable power, and insuring better durability.
verify your alternator and battery voltage remains fairly consistent, and having an infrared thermometer to read cylinder exhaust temps, and a multi meter and vacuum gauge, is always a good tool to help diagnose problems.

related link
viewtopic.php?f=57&t=4974&p=29925&hilit=INFRARED#p29925
it is always helps to post your location,when posting questions, at least the city & state your located in because theres a good chance an experienced hobbyist or mechanic on this site may be reading this, located local to you, who is willing to help either for free or at low cost! or at least post advices and places to get parts locally
if youve already built the engine and can,t quite figure out why its not running up to expectations, ..a logical step bye step approach is best, youll need to verify cylinder compression, ignition, spark strength and ignition,timing ignition,advance,and fuel and air delivery, ID also suggest a compression test and a general checking over,each potential engine and drive line sub-system carefully, with a timing light,vacuum gauge, fuel pressure gauge, VOM meter , ETC. and adjusting valves, checking for vacuum leaks, check fuel pressure and post clear pictures of spark plugs as they give a ton of info if you know how to read them, etc.
Id also be pulling and changing the oil filter and inspecting the old one for metallic debris indicating a worn cam lobe
basically an in depth tune-up and system verification is whats needed
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watch this
http://www.youtube.com/watch?v=UYGU7mTwsZc
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http://www.harborfreight.com/5-in-1-dig ... 98674.html
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having a fluke multi meter and an assortment of test leads helps

FLUKE is the brand of choice but they are expensive, shop around, Ive still got the original fluke multi meter I bought in HIGH SCHOOL and it STILL WORKS Ive purchase several imported multi meters from harbor freight , in the last 10 years alone and only one still works

http://www.fluke-direct.com/shop/itemDe ... urer=FLUKE

http://www.fluke-direct.com/shop/catego ... TERS&path=

viewtopic.php?f=70&t=1809

viewtopic.php?f=70&t=875

viewtopic.php?f=57&t=4701&p=12741#p12741

many carb tuning issues are really basic fuel supply issues, if you can,t maintain a consistent flow at a constant pressure to the carbs feed the car will more than likely have tuning issues
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standard vacuum connections
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manifold to power brake booster
manifold to distrib vacuum advance
pvc to carb or air cleaner assembly

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=635

viewtopic.php?f=55&t=264&p=1301#p1301

viewtopic.php?f=44&t=5575&p=16927#p16927

Id start by dropping or raising the fuel pressure to 5.5 lbs and verifying your getting a minimum of a 1/2 gallon a minute unrestricted flow,but in most cases the fuel pressure at the carb inlet port NEEDS to read 4.5-5 psi MAX and you NEED to set the float levels per the carb manufacturers instructions, having the pressure at 6.5 psi will in many cases cause the needle & seat valve to constantly leak excess fuel, into the carb while the engine runs

Id start at all four jets #70

If theres any doubt as to component condition like for example your power valve, Id install a NEW power valve and ID buy several, more of slightly higher and lower ratings if your carb uses them, so I could play/exchange/test, you generally start with one rated at 1/2 your idle vacuum reading IE if your pulling 17" at idle youll want a power valve rated at about 8.5" or 7.5# rated power valve, and having a selection of jets sure helps

http://www.summitracing.com/parts/HLY-36-181/
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http://www.summitracing.com/parts/PHP-15001/
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viewtopic.php?f=44&t=1788

viewtopic.php?f=55&t=1820&p=4717&hilit=edelbrock#p4717

http://www.holley.com/TechService/Instr ... ry=&page=4

viewtopic.php?f=50&t=383&p=1637&hilit=+infrared+tuning#p1637

viewtopic.php?f=44&t=579&p=743&hilit=+infrared+tuning#p743


start here, reading thru these links and info, there's no sense in guessing, so do the testing and research then adjust or tune as necessary, but knowing what your looking for helps a great deal.

viewtopic.php?f=44&t=745&p=1054#p1054

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

http://www.themotorbookstore.com/holley ... etors.html

http://www.themotorbookstore.com/motuhocavo2.html

http://www.themotorbookstore.com/holley1.html

http://www.bob2000.com/carb.htm

http://www.mortec.com/carbtip1.htm

viewtopic.php?f=70&t=5428

http://store.summitracing.com/partdetai ... toview=sku

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

http://www.centuryperformance.com/vacuum.asp

http://www.carcraft.com/techarticles/carb_tuning/

heres where
a infared non-contact thermometer helps diagnose mixture problems very quickly, but youll need one that reads into the 1400F range for the headers for quick diagnoses

http://www.professionalequipment.com/xq/ASP/ProductID.3461/id.22/subID.177/qx/default.htm

temperature range from -58 to 1832°F

I use this one :grin: (above) and youll need to learn how to read plugs (this may help)

http://www.chevytalk.org/threads/showfla...rue#Post1448415

heres A/F

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

http://www.mummbrothers.com/SRF_Stuff/Secrets/Driveline/Air_Fuel.htm

http://www.airfuelmeter.com/english/

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

http://thedynoshop.net/prod01.htm

viewtopic.php?f=50&t=1853&p=4848#p4848

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

http://www.dawesdevices.com/airfuelmeter.html

http://fastrides.com/articles/DoItYourself_AirFuelRatio_Gauge.html

http://www.fuelairspark.com/Products/Information/AirFuelMeter.asp

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

http://www.thecarburetorshop.com/Troubleshooting.htm

viewtopic.php?f=56&t=572&p=7457#p7457


a few places to look for plug/ignition info

http://auto.howstuffworks.com/ignition-system.htm

http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp?nav=31000&country=

http://www.gofastzone.com/techtips/sparkplugs/sparkplugs.htm

http://www.acdelco.com/html/pi_plugs_ident.htm

http://www.autolite.com/framer.cgi?page=http://www.autolite.com/products/racing.htm

http://members.uia.net/pkelley2/sparkplugreading.html

http://www.atlanticjetsports.com/_techtalk/00000005.htm

http://www.strappe.com/plugs.html

http://www.babcox.com/editorial/cm/cm59910.htm

http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

http://www.nightrider.com/biketech/spkplghnbook.htm

viewtopic.php?f=44&t=5615&p=17136#p17136

http://www.tsrsoftware.com/sparkplug.htm

http://www.gnttype.org/techarea/engine/plugs.html

http://www.dansmc.com/sparkplugs1.htm

http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp

http://www.pajjakid.com/ubipa/sparkplugs.htm

http://www.edelbrock.com/automotive/sparkplugs.html

http://www.bullittarchive.com/Maintenance/Sparkplugoverview/

http://www.powerarc.com/sparkplug.htm

http://www.carcraft.com/techarticles/64378/

http://www.wakularacing.com/TechnicalInfo.htm

http://www.geocities.com/MotorCity/Flats/3877/spark.html

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

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

http://www.rmlautomotive.com/ignition.html

http://www.bgsoflex.com/auto.html

http://ourworld.compuserve.com/homepages/JET_AV8R/Vision/Ignition/CDI.HTML

http://www.howstuffworks.com/ignition-system.htm

http://auto.howstuffworks.com/ignition-system1.htm

http://www.familycar.com/Classroom/ignition.htm

viewtopic.php?f=44&t=5615&p=17136#p17136

http://www.motocross.com/motoprof/moto/secontent/seign/ignprin/ignprin.htm

http://www.northwestautorepair.com/ignitionsystem.htm

http://www.boyleworks.com/ta400/psp/distcurve.html

http://www.chevytalk.com/tech/index.html


heres other options

http://www.davessmallbodyheis.com/


http://www.msdignition.com/

http://www.proformparts.com/catalog/distributors_GM.html

http://www.atlanticspeed.com/store/MSD%20Chevrolet%20Distributors.asp

http://www.holley.com/HiOctn/ProdLine/Products/IS/ISD/ISD.html

http://www.performancedistributors.com/gmdui.htm


Spark plug /ignition info

http://www.edelbrock.com/automotive/sparkplugs.html

http://www.ngksparkplugs.com/apps/car_truck_suv/default.asp?nav=60000&country=US

http://www.strappe.com/plugs.html

http://www.applink.net/cct/tips/plugwires.html


http://www.acdelco.com/html/pi_plugs_ident.htm

http://www.atlanticjetsports.com/_techtalk/00000005.htm

http://www.ngkspark.com.au/spark_plug_cross_ref_chart_index3.htm


http://www.strappe.com/plugs.html

http://www.babcox.com/editorial/cm/cm59910.htm

http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

http://www.eric-gorr.com/techarticles/sparkplugs.html

viewtopic.php?f=50&t=6174&p=20791#p20791

http://www.gnttype.org/techarea/engine/plugs.html


http://www.tsrsoftware.com/sparkplug.htm

http://www.racinghelp.com/read_spark_plugs.html

http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp

http://www.gofastzone.com/techtips/Spark...20Reference.htm

http://www.geocities.com/zgarage2001/adv...01/advance.html

http://www.hotrod.com/techarticles/43300...harticles/43300

http://www.centuryperformance.com/vacuum....com/vacuum.asp

http://www.custompistols.com/cars/articl...tion_timing.htm

http://chevyhiperformance.com/howto/4567...com/howto/45673

http://www.lmengines.com/Ignition_Timing...tion_Timing.htm






http://www.bgsoflex.com/auto.html

OPTISPARK info

http://www.gmhightechperformance.com/tech/0310htp_optispark/

http://www.charm.net/~mchaney/optisprk/optisprk.htm

http://www.fierolt1.com/lt1_95_up_OptiReplace.htm

http://www.noid.org/~muttvette/opti.html

http://www.gulicks.com/vette/projects/opti/index.html

http://www.houston-f-body.org/tech/optispark/


http://www.dynotech-eng.com/dynaspark.htm

http://www.corvetteclinicinc.com

http://www.corvettefever.com/howto/16758

viewtopic.php?f=55&t=58

viewtopic.php?f=55&t=109

viewtopic.php?f=55&t=211

you may find these links ans sub links rather useful
keep in mind that within reasonable limits carb size is not as critical as the ability of the cars operator to get the combo correctly set up and tuned, you can slap a 650-750 cfm carb on darn near any chevy v8 and a skilled tuner can get it running rather well
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: tuning, where to start

Postby grumpyvette » December 1st, 2008, 2:11 pm

tracking down a MISS/STUMBLE, or other problem?
there can obviously be several issues like ignition timing coming in too rapidly ,tuning an engine is partly ART and EXPERIENCE but mostly its letting the engine tell you what it wants, that takes both experience and understanding what the symptoms and the engines reaction to the changes you make, are telling you, which might require you to change the distributor advance weights or springs or on more modern systems a bit of programing or loss of enough fuel pressure, or fuel volume, entering the carburetor, low float levels, non-responsive, annular carburetor boosters , on holleys,,weak valve springs , a leaking valve to valve seat seal, or a non-return style fuel pressure regulator that can,t maintain consistent fuel .etc.
edelbrock carburetors don,t have nearly the tuning flexibility of the HOLLEY carbs when your using a radical cam simply because they use a totally different transitional fuel flow system, using stepped diam. metering rods that slide thru jets, that don,t react to the changes in vacuum the way a Holley carburetor does.
generally a bit of testing, or carefully changing a few adjustments or jetting and keeping detailed notes and not assuming you know whats wrong but letting the engines response to changes lead you to the answer, to see what tends to make things better or worse with changes can give a good indication of what the problem is
read these links
viewtopic.php?f=55&t=1820&p=4706&hilit=1406+edelbrock#p4706

http://www.popularhotrodding.com/tech/0 ... index.html

viewtopic.php?f=55&t=635

viewtopic.php?f=55&t=211

viewtopic.php?f=70&t=202

but any engine matched to a fairly long duration cam timing, tends to have a a good deal of reversion in the intake runners as the valves don,t fully close before the pistons well up on the compression stroke before the cylinders sealed.

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add a radical cam to get that racy sounding idle and the valves don,t seat until the pistons about 40-60 plus degrees past bdc on the compression stroke, that frequently results in low rpm reversion that causes the air flow to go both directions thru the carburetors venturies at lower rpms resulting in the same air occasionally getting an extra enrichment of fuel until the reversion is significantly reduces as rpms increase this is a major factor in that rum-pity- rump race engine idle that hot rodders seem to like.
that same process makes reading plugs a bit difficult because they tend to indicate a rich mix , which is in fact the case at low rpms
while the transition phase might be significantly leaner, thus a change to leaner primary jeting and compensating with a lower number power valve to add fuel as the vacuum drops is the common cure , on holley carburetors even thou it tends to seem counter productive as you plugs already look like your running rich, on edlbrock carbs you need to use a metering rod and jet combo that tends to run a bit lean on idle but gets richer fast as the throttle opens.
also look for mechanical reasons like badly adjusted valves, especially if you adjusted the valves cold on a non running engine

related info you should read thru

http://members.tccoa.com/392bird/tuning.htm

viewtopic.php?f=55&t=109

viewtopic.php?f=55&t=5229

viewtopic.php?f=55&t=1639

viewtopic.php?f=52&t=196

viewtopic.php?f=50&t=1853&p=4848&hilit=+air+fuel+meter#p4848

viewtopic.php?f=50&t=2891&p=9279&hilit=plugs+ratio#p9279

viewtopic.php?f=55&t=109

viewtopic.php?f=44&t=773

viewtopic.php?f=50&t=383&p=2301&hilit=+power+valve+vacuum#p2301

viewtopic.php?f=44&t=777&p=4546&hilit=+power+valve+vacuum#p4546

viewtopic.php?f=55&t=1790&p=4544&hilit=+holley+cam+pump#p4544

viewtopic.php?f=55&t=1639&p=4545&hilit=+power+valve+vacuum#p4545

THESE THREADS SHOULD HELP


viewtopic.php?f=50&t=874&p=1687#p1687

viewtopic.php?f=70&t=270&p=1289#p1289

viewtopic.php?f=50&t=609&p=1298#p1298

viewtopic.php?f=50&t=821

viewtopic.php?f=50&t=817

viewtopic.php?f=50&t=383

viewtopic.php?f=50&t=268

viewtopic.php?f=50&t=477

viewtopic.php?f=50&t=46

http://www.clarks-garage.com/shop-manua ... tm#oil-low

http://www.procarcare.com/includes/cont ... fPbs1.html


http://www.stockcarracing.com/techartic ... index.html

http://www.bob2000.com/carb.htm

http://www.camaros.net/techref/articles/holley_2.htm

http://www.chevyhiperformance.com/howto ... index.html
HERES A GOOD DEAL MORE INFO IN THE LINKS ABOVE, YES IT TAKES TIME BUT READING THRU THE SUB LINKS WILL HELP A GREAT DEAL, DON,T GUESS AT PROBLEMS, IDENTIFY AND ISOLATE THEN FIX PROBLEMS

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its amazing what you can learn about engine combustion chamber conditions, air/fuel distribution and temps, from reading spark plugs
ignition timing thats a bit to retarded will tend to make the plugs run cold and foul, setting your float levels and making 100% sure the linkage functions correctly is mandatory, before you start chasing problems

http://www.barrygrant.com/bgfuel/default.aspx?page=83

http://www.stockcarracing.com/techartic ... index.html

http://www.holley.com/data/TechService/ ... uretor.pdf

unscrew the site plugs and adjust the floats until the fuel level just prevents fuel flow from the site holes at idle, youll need a flat blade screw driver and a 5/8" wrench

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50cc PUMP
QUESTION How do I adjust the fuel level on my carburetor?
ANSWER Setting the fuel level should be the first thing you do before attempting to make any further adjustments.The float level should put the fuel level just below the bottom of sight plug hole. You will make the adjustment with the vehicle on a level surface and the engine idling. You will first remove the sight plug, then to make your adjustment you will need to loosen the lock screw on the needle and seat. This will allow you to turn the adjusting nut to raise or lower the float level. Each hex flat on the nut will change the float level approximately 1/32". When you have the fuel level just below sight plug hole you will then tighten the lock screw and reinstall the sight hole plug. Make sure you have a shop towel handy in case you have any fuel leaks from the Sight plug or needle and seat adjusting nut.

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if the fuel level won,t adjust, it
sounds like a needle valve needs replacement, or a carb floats defective

SIMILAR TO THIS

http://www.summitracing.com/parts/HLY-6-513/
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http://www.summitracing.com/parts/HLY-6-519-2/

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http://www.summitracing.com/parts/HLY-116-10/
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thoughts guys?
when you suspect a cylinders not working correctly,you always drop back to the basics first
(1)locate the problem
is it low compression?,
lack of ignition?
not enought or too much fuel or air?
valve timing?
do you have access to an IR temp gun?
dial indicator with stand
TIMING LIGHT?
a VOM meter and VACUUM GAUGE?
have you adjusted the valves correctly?
leak down test?
can you read plugs?
have you verified battery voltage?
plug gap? ignition wire resistance?
carb function or injector function?
fuel pressure?
ETC.


http://forum.grumpysperformance.com/viewtopic.php?f=44&t=579&p=743&hilit=+infrared+tuning#p743

http://forum.grumpysperformance.com/viewtopic.php?f=44&t=773&p=1123&hilit=+infrared+tuning#p1123

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=196

http://forum.grumpysperformance.com/viewtopic.php?f=50&t=609&p=5672&hilit=+leak+down#p5672
thoughts guys?
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: tuning, where to start

Postby grumpyvette » January 29th, 2009, 11:10 am

http://www.stockcarracing.com/techartic ... index.html

http://www.stockcarracing.com/techartic ... /fuel.html

http://www.holley.com/data/TechService/ ... uretor.pdf

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

http://www.youtube.com/watch?v=eiRIfcrc2yA

http://www.thecarburetorshop.com/Troubl ... rdstarthot

http://www.holley.com/types/Accelerator ... 0Parts.asp

http://www.stockcarracing.com/techartic ... index.html

http://www.valvoline.com/carcare/articl ... 20000718hm

http://www.shockley.net/holley-jets.asp

http://www.mortec.com/carbtip1.htm

http://www.bgsoflex.com/holley.html

http://www.summitracing.com/streetandst ... 3B3CEE8%7D

http://store.summitracing.com/partdetai ... toview=sku

http://store.summitracing.com/partdetai ... toview=sku

http://store.summitracing.com/egnsearch ... &x=49&y=13

http://www.bob2000.com/carb.htm

read thru these, and check out the links to parts and info, I really can,t do much better in explaining this process

http://www.summitracing.com/parts/PHP-15001/

http://www.summitracing.com/search/Bran ... toview=SKU

http://www.percyshp.com/adjustajet.html

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heres a neat little option for the HOLLEY carbs, its not really In expensive but it does allow you to effectively change the fuel flow rates far faster than you could changing JETS, its basically a needle & seat valve that adjusts like the float levels do on a Holley carb, it comes with detailed instructions , and if you use a fuel ratio meter or an IR temp gun and read spark plugs it will allow you to adjust the fuel air ratio far faster and easier than jet changes will
viewtopic.php?f=57&t=4974&p=29925&hilit=INFRARED#p29925


viewtopic.php?f=44&t=773

viewtopic.php?f=50&t=1853&p=4848&hilit=ratio+meter#p4848

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don,t forget to set the ignition timing , verify the TDC on the damper and timing tab, and adjust the valves, and verify the fuel pressure and float levels before assuming its a carb issue, O a performance engine that your trying to maximize the power potential on, youll generally want the fuel air ratio to be a bit lean at idle speeds (in the 13.5:1-14:1 range to keep the spark plugs burning cleaner) and slowly and consistently transition to (a slightly richer fuel air ratio of about 12.5-13.0) by the time the rpms reach 3500-to-4000rpm or so to maximize the engine power.

1/4 turn in from the point the lifter just stops clicking at idle has worked the best over the years for me
Ive always found the final adjusting of HYDRAULIC LIFTERS is best done at idle, with the engine up to operating temps., as it allows for all the variables like heat expansion and lifter seat movement as the oil pressure lifts the push rod seat) of course a tall valve cover roughly similar to this mod helps reduce the potential for a mess
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If you have a c4 corvette, and If your willing to read a few links and sub links you can isolate and repair your car with the info here

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=3096&p=18612&hilit=scanners#p18612

http://forum.grumpysperformance.com/viewtopic.php?f=2&t=3074&p=8144#p8144

http://forum.grumpysperformance.com/viewtopic.php?f=80&t=728

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=596

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1401
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: tuning, where to start

Postby bob » November 5th, 2010, 3:46 pm

It took me several days to read thru the linked info and threads, on carburetor tuning.
but it was NOT a waste of time by any means!
Its absolutely amazing what you can learn by doing so!
Reading thru the links in these threads is like a course in advance trouble shooting and car maintenance ,
all rolled into a self paced flow chart, based school ,where you learn what to look for.
I keep coming back and reading the sub-linked info, ITS amazing what Ive over looked the first time!
, that I caught reading thru the links a second and third time!
bob

 

Re: tuning, where to start

Postby grumpyvette » May 7th, 2011, 7:19 pm

now Ive posted much of this info before, but I recently helped tune a guys 13.7:1 compression big block chevy where the guy could not get the car to run correctly at first because he had failed to check a few clearances and on several cylinders the piston domes were barely contacting the spark plug ground electrodes and closing the gaps down to less than .010-.020 thousands.
when he failed to index the plugs (something he had never encountered before and was totally un-aware of as a potential problem)
just by chance most of the plugs indexed so the ground electrodes didn,t contact the piston domes but a few did, and it seemed to be a random deal to him because sometimes the plugs worked sometimes they failed, he never figured out the cause. well the only reason I spotted it almost instantly was EXPERIENCE, having been that route about 38 years ago with my first real high compression 489 BBC where the pop-up piston domes made indexing the plugs mandatory



read the links below, if you want to take the time to index the spark plugs in your heads you'll need to carefully mark where the electrode ground is on the plugs insulator where you can easily see it with a permanent marker and use spacer washers to insure that the open area of the plug faces the area between the valves but slightly favoring the exhaust valve location, WITH THE GROUND ELECTRODE INDEXED UPWARD TOWARD THE COMBUSTION CHAMBER ROOF , because in some high compression applications, its fairly common for the pop-up piston dome to contact the ground electrode and bend it, closing the gap if the plugs ground electrode is placed in the lower 270 degrees on the plug when its installed , especially ,if you failed to correctly check clearances, between the piston and combustion chamber
in this example the plugs GROUND electrode is ALMOST EXACTLY OPPOSITE, OF THE IDEAL INDEXED location

Image
example , similar too...
Image
if your using high compression pistons like these youll soon see the reason for indexing plug ground electrodes
Image

Image
OBVIOUSLY A PLUG SOCKET DESIGNED TO HELP INDEX PLUGS IS HELPFUL AT TIMES
http://www.jegs.com/i/JEGS-Performance- ... 0/10002/-1
,this can in some cases smooth the idle slightly and add a few hp, in other applications its basically wasted effort, but in some cases the engine clearances make it mandatory, a good deal depends on the compression, intake runner and combustion chamber design, and it should be obvious that if your not running up close to the limits on your ignition advance curve and octane limits on your fuel you probably won,t notice the slight improvements in ignition,only careful testing in your engine will tell you if its worth the effort in your combination.....now I have guys that tell me its always wasted effort, and if you use the 2-4 electrode ground strap plugs is not going to change, well thats true, if you have several ground straps on the plugs you shroud the spark enough that youve effectively reduced its efficiency too ignite a clean flame front, so yeah if you use those its wasted effort
[/color]


http://www.jegs.com/i/Moroso/710/71910/10002/-1
Image
Image
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: tuning, where to start

Postby grumpyvette » June 15th, 2011, 1:53 pm

I was recently working on a 1988 corvette that had an upper rpm miss or general sluggish engine response, a multi meter showed that his factory alternator (now 24 years old) was barely producing 56 amps, and that was not sufficient, he decided to upgrade to a 200 amp aftermarket alternator and install an additional 2ga wire from the alternator feed , per the insulation instructions,to the battery pos. terminal

the difference in how the car idles runs and performs is AMAZING! and the plugs look far cleaner after it ran for awhile, this was a HUGE IMPROVEMENT!, this was $200 very well spent


http://www.db-starter-alternator.com/c- ... 0-amp.aspx


Image



related info
viewtopic.php?f=36&t=3222

viewtopic.php?f=36&t=1169

viewtopic.php?f=36&t=160
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: tuning, where to start

Postby 2Loose » June 21st, 2013, 1:57 pm

grumpyvette wrote:Image

I've gotten the blown '67 Olds 425 motor tuned now so when cruising on the street, pulling 15 inches vacuum (it varies from 20 to 10 inches), my A/F is running around 15, +/- a little, and with the 8:1 pistons there seems to be no problems.
The power valves are set at 4 inches (primary sides only) on a pair of Holley 4150 HP 600's (no choke tower, blower manifold vacuum referenced) and as I head toward boost the A/F moves into the 13's and as boost builds A/F is into the 12's. The motor is running strong and the plugs look good. I need more test & tune runs at the track to try different timing settings. 7 lbs boost max. Tried the boost retard timing module from MSD, but the motor did not seem to like being retarded under boost. Running 36 deg max advance (16 deg at idle, all in by 3000, plus 10 deg idle vacuum advance) and keeping it all in under boost, with 92 octane pump gas, So far so good, but I think there is more to be had and need more tuning time at the track, but that is of very limited availability at our track. Once a month for barely 2 hours and there are always a lot of cars lining up for T&T, can usually only get about 4 to 5 runs in, not enough for some good tuning comparisons. There is no chassis dyno on this island either. My best runs so far, in a 4,050 lb running weight, are 11.7 seconds at 117 mph with a 4.11 rear gear and 31" tall tires, shifting at 5500 and going through the lites at 5200 in fifth (Doug Nash 4+1). I'm running a fairly mild hyd roller street cam with 113 deg lobe separation. The carbs have 4 corner idle adjustment screws, but I got the best results by closing off the secondary idle screws completely, and tuning my idle with only the primary screws. With no choke tower it's a little cold blooded, so a little hard to get running smoothly in the early am when I first start it up. I found I can get it to idle better when first starting it up by opening one secondary idle screw on each carb a half turn, and when it warms up a little, closing those off. It idles smoothly at 1000, no surging, once it warms up. Normal temp is 170 to 180. Fans kick in at 180, mech. thermostat is a 160 unit, works well to warm up the radiator first before the fans are needed, mostly the fans stay off.

It's fun to drive on the street, spins the street tires at will in any gear. Mostly I just cruise it and use it to run errands, it's a daily driver for me. Recently drove it mildly for 200 miles of town driving and used 10 gallons of gas. 20 mpg in mostly 3rd and 4th, stop signs, stop lights, heavy traffic, just kept it easy and eased it into gear each time. But when it's in boost, I can almost see the gas gage move!!!
Aloha,
Willy
Last edited by 2Loose on June 22nd, 2013, 11:22 am, edited 1 time in total.
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Re: tuning, where to start

Postby Indycars » June 21st, 2013, 2:47 pm

2Loose wrote:Tried the boost retard timing module from MSD, but the motor did not seem to like being retarded under boost.


That's a good thing ..... right ? It's only purpose is to keep the motor out of detonation ?

Rick
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Re: tuning, where to start

Postby 87vette81big » June 21st, 2013, 3:24 pm

I am not sure if your blown Olds 425 can stand a more agressive timinng curve or not on pump gas 2Loose.
Oldsmobile V8 engines are different from all out there in my experience.
Super off idle torque & midrange power.
The 6 degree valve inclination to engine cylinder deck is s big factor I believe.
OLDS 403 Engines run best with static initial timing set at 24 degrees BTDC. SUPER FAST ADVANCE CURVE.
ALL IN BY 1100 RPM'S. TOTAL TIMING 39-44 DEGREES BTDC.
DITCH THE VACUUM ADVANCE CAN.

Would try & richen up secondary mixture up a few jet sizes.
Maybe remap entire secondary mixture by changing air bleeds.
Not unheard of AFR IN A ROOTS SUPERCHARGED ENGINE IN RANGE OF 11.0-10.0 :1.
Have to keep. experimenting.
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Re: tuning, where to start

Postby 87vette81big » June 22nd, 2013, 10:55 am

I also want to add a notation about Oldsmobile 1949 Rocket 303ci to 1990 307ci V8 engines.
All early Olds engines use a 45 degree lifter bank angle in reference to the opposite lifter bank. Would be 1949-1965.
Just like all Sbc , BBC, Pontiac, Ford, C.hrysler.
Starting in 1966 Oldsmibile changed the lifter bank angle to 39 degrees.
Legend has it that the 1965 Olds Starfire 370 Hp has the 1st 39 degree lifter angle block used.
What the change did was alter camshaft timing events from a basic classic 45 Degree camshaft.
Hidden secret few know about or understand..

It actually makes a smaller pattern cam run harder.
MORE USABLE TORQUE & HP.

IVO IVC EVO EVC.
Changes the ballgame.

Always wondered if Desktop Dyno 2000 accounts for rhis unique difference un many Olds V8 engines.
Have & use Desktop 2000 Dyno too.

Brian
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Re: tuning, where to start

Postby 2Loose » June 22nd, 2013, 11:12 am

Initially I had the vacuum advance locked out, started at 12, with a 20 deg curve, so 32, and it liked it when we kept adding more. Had the total up to 40, but that scared us, so we "played it safe" and backed it off to 36 total for the track, have kept that for the street with the 92 pump gas. It did not idle well at all with 16, so hooked up the additional ten from the vacuum can, it seemed to really like more advance at idle.

Following your suggestion, I can shorten up the advance curve, have it come in earlier, lock out the vacuum advance, still head for 36 total for the pump gas, but start with more advance, get it in quicker, with a short curve and see how that feels.

The heads are Edelbrock and have been worked over by a noted porting guy, a street and strip porting job. Exhaust ports raised and the headers reworked accordingly. The intake is an Offy dual 4bbl converted to a blower intake by Don Hampton. I have port matched it to the ported heads. Cam is only .507/.516 with 230/236 (@ 50). Bore and stroke are 4.155/3.975 with 7" rods. I have two '67 motors, this 425 and a 400 out of a wrecked 442. Both have the same forged 3.975" crank and 7" rods. I have several spare 455 blocks, which with the 400 crank gives me another 425 if I need it. I'm aware of the change from 45 deg to 39 deg on the lifter bank, always wondered why they did that. I could certainly run a more aggressive cam, but I like what it does on the street now, easy to drive. Just need to find the best tune for this setup. Sure wish we had a chassis dyno available!

Many thanks for the suggestions, much appreciated!
Willy
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Re: tuning, where to start

Postby 87vette81big » June 22nd, 2013, 11:45 am

On the street running pump gas you need a mechanical centrifical advance.
Please forget about the vacuum advance can.
Its for fuel economy needs only .
You want 10's 1/4 mile @ 1/2 mpg.
Who cares about 20 mpg ? Just tree huggers. None of us really care.
Want Maximum Torque & Hp .

You want 10-12 mechanical advance in distributor.
Makes for 20 to 24 added degrees @crank BTDC when all in.
Tuned & played hard with a 1977 Olds 403 in my 1963 Pontiac Grand Prix.
Easy swap.
Blew away many LS CAMAROS & 5.0 Mustangs on street.
Street racing of course.
Open the hood & all said WTF????
I love Olds V8 engines
Can't wait to install my 1965 Olds 425 360 Hp. Rebuilt & Iskendarian cammed.
Custom ground by Ron Iskenderian himself last summer.
He stopped all production & made me the camshaft.
Last edited by 87vette81big on June 22nd, 2013, 11:48 am, edited 1 time in total.
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Re: tuning, where to start

Postby 87vette81big » June 22nd, 2013, 11:46 am

Have a 1966 Vintage Vertex Oldsmobile V8 Magneto.
I rebuilt myself.
No MSD buzz boxes for me.
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Re: tuning, where to start

Postby grumpyvette » June 22nd, 2013, 1:04 pm

I,ve always had very good results from vertex magnetos, if given a choice Id select a good vertex over most other ignitions.
most guys connect the kill switch to a dual circuit , one lead to an oil pressure sensor that grounds it if oil pressure falls below 5 psi and a manual over ride to positively kill voltage to the ignition, when you choose to kill the engine running


READ THRU LINK
viewtopic.php?f=70&t=1320&p=25378&hilit=vertex#p25378
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: tuning, where to start

Postby 87vette81big » June 22nd, 2013, 1:39 pm

I love Vertex Magnetos too Grumpy.
So much I went out & purchased all special service tools & SUN Distubutor machines.
Was single & lots of extra spending $$$.
Married now with kids.
Kept all.
2 Pontiac V8 Vertex Magnetos.
2 CHEVROLET Vertex Mags. One is Daul mechanical Tach drive base.
1 Oldsmobile 1964-1990 Vertex Magneto.
My personal collection.
People don't understand how good a Vertex
Mag is till they try & use 1.
30-40 CRANK DEGREE SPARK DURATION @ EVERY IGNITION SPARK.
MSD BUZZ BOX ONLY 20 DEGREES LONG.
TUNING IS MUCH EASIER WITH A VERTEX MAGNETO IN PLACE TOO.

Brian
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