IF YOU DON,TY HAVE A FACTORY SHOP MANUAL FOR YOUR CAR YOUR WORKING AT A DISADVANTAGE
when ever you get into unexplained symptoms the answer remains the same....in every case,.... you drop back to the basics and do a few tests, get out a multi meter and verify every fuse is good, and you have 13 volts at the battery and youve got at least a 1/2 tank of fresh fuel, before you start chasing your tail, thinking about more complicated problems
find the cause, you isolate, each function or system or malfunction to its related components then test, each individually, use of the shop manual is almost mandatory
http://www.helminc.com/helm/welcome_sel ... M2S049ETF8
you really need to purchase a multi meter and a SHOP MANUAL and look thru the schematics
without testing theres almost no way to locate the source of your problem,, testing will tell you
http://www.helminc.com/helm
http://www.harborfreight.com/5-in-1-dig ... 98674.html
viewtopic.php?f=50&t=609
viewtopic.php?f=50&t=2847&p=7371#p7371
http://www.autoguide.com/buyers-guide/1 ... g-smoothly
throwing parts at a problem is wasted money, if you don,t ..know whats wrong,
I had two long time friends stop by and ask my opinion as to why franks 1967 chevelle just was not running as well as they thought it should be, now these guys are long time hot rodders, but engine builders and tuners they are NOT!
both these guys have cars that are more SHOW than GO!
I just wish I could get a car to LOOK as good as these guys can!
but tuning and trouble shooting sure escapes their expertise.
anyway I ask whats wrong, and they can,t tell me other than to say the cars missing and not running correctly, they are basically clueless as to the cause and have swapped carbs, distributors,(three times)set the timing,(more times than they can remember)ETC. and can,t seem to nail down the problem.
they ask me to take a look..........now the cars got a crate 502 bbc, replacing the 325hp 396bbc that came in the car, and its got headers and a crower solid lifter cam, 850cfm Holley and a rpm air gap intake, and what they assure me is a stock 1967 distributor.(dual points cast iron, mechanical tach drive, LOOKS to be a 67-68 corvette distributor to me)
when you try to track down any problem with a cars engine you need to start with the basics of
fuel pressure,
and a compression check,
checking for vacuum leaks,
checking the valves are adjusted correctly,
verify the battery has a minimum of 12.5 volts
and the alternator boosts that while running to over 13 volts
verifying that your timing marks are at T.D.C,on the damper
verify that the timing tab indicates true T.D.C.
have a quality timing light and know how its used
and your ignition timing curve is correct, and smoothly advancing as the rpms build.
verify the timing is close to the shop manual suggestions
check all the fuses and engine grounds,
and get out a infrared temp gun and look for marked changes in the exhaust temperatures, indicating non-firing cylinders or fuel distribution issues
verify the oil temperature and pressure
verify the engines got less than 2 psi of exhaust back pressure
learn to read spark plugs as they are a great indicator of conditions in the combustion chamber
learn to use a vacuum gauge
if you have one a fuel/air ratio meters a big help
BUT HAVE A SHOP MANUAL and take the time to READ IT!
first thing I find is that the nicely labeled plug wires are arcing to the headers in two places, and the ohms meter reads over three thousand ohms on two so they need replacing, and that the plug gaps vary from .045-.070
while Im checking that I do a compression check and Im not all that impressed with the numbers but they are semi reasonable so I let that slide for now, I do a valve lash check and they are in need of adjustment.(BADLY) seems they have not set the lash since the solid lifter cams install over 18 months ago :smirk:......... the valves set, I check the timing and its jumping all over, seems they forgot to seat the rotor correctly, and the brass tabs bent sevearly and the screws holding it are loose ., pulling the distributor and checking the slack, I find I need to add a new distributor gear, its worn,(looking at the cam gear it seems far less worn) AND shims as its got almost 3/32" vertical play. while I do that I talk them into getting a pointless electronic conversion kit.
I install that and the new wires/plugs all gapped at a CONSISTANT .045.
next I check the carb,its float levels to high in the rear and too low in the fron,t, that gets adjusted and I test for vacuum leaks......yeah, they had one, gasket gets replaced and intake re-tested, it now passes. next the timming gets set..its now remarkably more consistant :smirk:
anyway, a hours trouble shooting and a few parts replaced resulted in some very happy campers.....especially since they had been screwing with it for two LONG WEEKENDs prior to bringing it by with little success!
the reason I bring this up, is that durring the whole process , they constantly kept insisting it was a flat cam lobe or a jumped timing chain,or a cracked cylinder hear ETC.
NOT ONCE had they dropped back to the basics and set each and EVERY component to its ideal setting and checked that each component was working as designed....no! they were convinced that it needed a new (NAME YOUR FAVORITE PART HERE, THEY WERE SURE IT WAS ON THE LIST)
GUYS I see this stuff frequently,if you cars not running correctly find out WHY, don,t just start installing parts randomly and expect things to get better!
lets start with the basics
whats the COMPRESSION TEST reading for each cylinder?
HOW did you adjust the valves?
is there water or crud in the gas or fuel filter?
CAN you post detailed pictures of EACH spark plug?
whats your FUEL PRESSURE?(does it stay steady as the rpms build?)
HAVE you verified the throttle blades in the carb and linkage fully open?
how are the carb FLOATS SET?
yes I KNOW YOUR SURE,
but JUST GO BACK and VERIFY THE FIRING ORDER AND IGNITION WIRE CONNECTIONS
what air filter SIZE and is it clean?
whats the TOTAL IGNITION ADVANCE?
whats the VACUUM READ AT IDLE?
whats the VOLTAGE at the COIL?
AT WHAT rpm does the advance reach MAX advance?
WHAT is the exhaust back pressure reading? (IDLE and 4000rpm under load)
HOW did you determine true TDC or did you just assume the timing tab and damper are correct?
What color is the ignition spark?
what is YOUR OHMS reading on the plug wires?
whats your spark plug gap?
CARB JETS? METERING RODS?
HAVE you REPLACED the cap and ROTOR?
ANY indication of a MISS or BOG?
HAVE you tried a DIFFERANT CARB?
have YOU verified EACH cylinder is firing?
have you VERIFIED the FIRING ORDER IS CORRECT?
HAVE you VERIFIED the LASH/PRELOAD on the rockers RECENTLY, and are you sure the cam is not worn?
are you SURE the trans fluid and rear differential are filled to the correct levels?
whats the engine temp after it warms up?
whats the trans fluid temp?
If your tuning a carb, the first step is verifying the fuel pressure is in the 4-5.5 psi range and the floats are correctly adjusted, a RETURN STYLE fuel pressure regulator with a byepass line back to the tank is almost MANDATORY for maintaining consistent fuel pressure, and having a gauge to check/verify not guessing IS MANDATORY
yes I know your 100% sure the ignition timing and the plug wires are correctly installed..CHECK THEM AGAIN CAREFULLY SEVERAL TIMES
http://www.toolrage.com/prodView.asp?sku=SLI-PV618
http://www.toolrage.com/prodview.asp?sku=SLI-PV300
http://www.classictruckshop.com/clubs/e ... ac/uum.htm
a tool like this, with its 1/4" lens and cable lets you remove the spark plug and lets you closely inspect the piston and valves at least giving you some better info on the condition in the combustion chamber, its also good once the oil pan plugs been removed to inspect what you suspect to be lower end rotating assembly conditions in many cases.
I bought one and while its not used daily its a great help when you really want to inspect things before dis-assembly, as for example if you want to know if a salvage yard engines a two or four bolt block, without pulling the oil pan
when ever you get into unexplained symptoms the answer remains the same....in every case,.... you drop back to the basics and do a few tests, get out a multi meter and verify every fuse is good, and you have 13 volts at the battery and youve got at least a 1/2 tank of fresh fuel, before you start chasing your tail, thinking about more complicated problems
find the cause, you isolate, each function or system or malfunction to its related components then test, each individually, use of the shop manual is almost mandatory
http://www.helminc.com/helm/welcome_sel ... M2S049ETF8
you really need to purchase a multi meter and a SHOP MANUAL and look thru the schematics
without testing theres almost no way to locate the source of your problem,, testing will tell you
http://www.helminc.com/helm
http://www.harborfreight.com/5-in-1-dig ... 98674.html
viewtopic.php?f=50&t=609
viewtopic.php?f=50&t=2847&p=7371#p7371
http://www.autoguide.com/buyers-guide/1 ... g-smoothly
throwing parts at a problem is wasted money, if you don,t ..know whats wrong,
I had two long time friends stop by and ask my opinion as to why franks 1967 chevelle just was not running as well as they thought it should be, now these guys are long time hot rodders, but engine builders and tuners they are NOT!
both these guys have cars that are more SHOW than GO!
I just wish I could get a car to LOOK as good as these guys can!
but tuning and trouble shooting sure escapes their expertise.
anyway I ask whats wrong, and they can,t tell me other than to say the cars missing and not running correctly, they are basically clueless as to the cause and have swapped carbs, distributors,(three times)set the timing,(more times than they can remember)ETC. and can,t seem to nail down the problem.
they ask me to take a look..........now the cars got a crate 502 bbc, replacing the 325hp 396bbc that came in the car, and its got headers and a crower solid lifter cam, 850cfm Holley and a rpm air gap intake, and what they assure me is a stock 1967 distributor.(dual points cast iron, mechanical tach drive, LOOKS to be a 67-68 corvette distributor to me)
when you try to track down any problem with a cars engine you need to start with the basics of
fuel pressure,
and a compression check,
checking for vacuum leaks,
checking the valves are adjusted correctly,
verify the battery has a minimum of 12.5 volts
and the alternator boosts that while running to over 13 volts
verifying that your timing marks are at T.D.C,on the damper
verify that the timing tab indicates true T.D.C.
have a quality timing light and know how its used
and your ignition timing curve is correct, and smoothly advancing as the rpms build.
verify the timing is close to the shop manual suggestions
check all the fuses and engine grounds,
and get out a infrared temp gun and look for marked changes in the exhaust temperatures, indicating non-firing cylinders or fuel distribution issues
verify the oil temperature and pressure
verify the engines got less than 2 psi of exhaust back pressure
learn to read spark plugs as they are a great indicator of conditions in the combustion chamber
learn to use a vacuum gauge
if you have one a fuel/air ratio meters a big help
BUT HAVE A SHOP MANUAL and take the time to READ IT!
first thing I find is that the nicely labeled plug wires are arcing to the headers in two places, and the ohms meter reads over three thousand ohms on two so they need replacing, and that the plug gaps vary from .045-.070
while Im checking that I do a compression check and Im not all that impressed with the numbers but they are semi reasonable so I let that slide for now, I do a valve lash check and they are in need of adjustment.(BADLY) seems they have not set the lash since the solid lifter cams install over 18 months ago :smirk:......... the valves set, I check the timing and its jumping all over, seems they forgot to seat the rotor correctly, and the brass tabs bent sevearly and the screws holding it are loose ., pulling the distributor and checking the slack, I find I need to add a new distributor gear, its worn,(looking at the cam gear it seems far less worn) AND shims as its got almost 3/32" vertical play. while I do that I talk them into getting a pointless electronic conversion kit.
next I check the carb,its float levels to high in the rear and too low in the fron,t, that gets adjusted and I test for vacuum leaks......yeah, they had one, gasket gets replaced and intake re-tested, it now passes. next the timming gets set..its now remarkably more consistant :smirk:
anyway, a hours trouble shooting and a few parts replaced resulted in some very happy campers.....especially since they had been screwing with it for two LONG WEEKENDs prior to bringing it by with little success!
the reason I bring this up, is that durring the whole process , they constantly kept insisting it was a flat cam lobe or a jumped timing chain,or a cracked cylinder hear ETC.
NOT ONCE had they dropped back to the basics and set each and EVERY component to its ideal setting and checked that each component was working as designed....no! they were convinced that it needed a new (NAME YOUR FAVORITE PART HERE, THEY WERE SURE IT WAS ON THE LIST)
GUYS I see this stuff frequently,if you cars not running correctly find out WHY, don,t just start installing parts randomly and expect things to get better!
lets start with the basics
whats the COMPRESSION TEST reading for each cylinder?
HOW did you adjust the valves?
is there water or crud in the gas or fuel filter?
CAN you post detailed pictures of EACH spark plug?
whats your FUEL PRESSURE?(does it stay steady as the rpms build?)
HAVE you verified the throttle blades in the carb and linkage fully open?
how are the carb FLOATS SET?
yes I KNOW YOUR SURE,
but JUST GO BACK and VERIFY THE FIRING ORDER AND IGNITION WIRE CONNECTIONS
what air filter SIZE and is it clean?
whats the TOTAL IGNITION ADVANCE?
whats the VACUUM READ AT IDLE?
whats the VOLTAGE at the COIL?
AT WHAT rpm does the advance reach MAX advance?
WHAT is the exhaust back pressure reading? (IDLE and 4000rpm under load)
HOW did you determine true TDC or did you just assume the timing tab and damper are correct?
What color is the ignition spark?
what is YOUR OHMS reading on the plug wires?
whats your spark plug gap?
CARB JETS? METERING RODS?
HAVE you REPLACED the cap and ROTOR?
ANY indication of a MISS or BOG?
HAVE you tried a DIFFERANT CARB?
have YOU verified EACH cylinder is firing?
have you VERIFIED the FIRING ORDER IS CORRECT?
HAVE you VERIFIED the LASH/PRELOAD on the rockers RECENTLY, and are you sure the cam is not worn?
are you SURE the trans fluid and rear differential are filled to the correct levels?
whats the engine temp after it warms up?
whats the trans fluid temp?
If your tuning a carb, the first step is verifying the fuel pressure is in the 4-5.5 psi range and the floats are correctly adjusted, a RETURN STYLE fuel pressure regulator with a byepass line back to the tank is almost MANDATORY for maintaining consistent fuel pressure, and having a gauge to check/verify not guessing IS MANDATORY
yes I know your 100% sure the ignition timing and the plug wires are correctly installed..CHECK THEM AGAIN CAREFULLY SEVERAL TIMES
http://www.toolrage.com/prodView.asp?sku=SLI-PV618
http://www.toolrage.com/prodview.asp?sku=SLI-PV300
http://www.classictruckshop.com/clubs/e ... ac/uum.htm
a tool like this, with its 1/4" lens and cable lets you remove the spark plug and lets you closely inspect the piston and valves at least giving you some better info on the condition in the combustion chamber, its also good once the oil pan plugs been removed to inspect what you suspect to be lower end rotating assembly conditions in many cases.
I bought one and while its not used daily its a great help when you really want to inspect things before dis-assembly, as for example if you want to know if a salvage yard engines a two or four bolt block, without pulling the oil pan
