don,t just start throwing parts at a problem.



don,t just start throwing parts at a problem.

Postby grumpyvette » November 26th, 2008, 2:55 pm

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

Image
Image
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 :confused:
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. Image 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

Image

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
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: don,t just start throwing parts at a problem.

Postby grumpyvette » March 7th, 2009, 8:41 pm

yes theres a lot of links, you might be amazed at what you can learn reading thru them

http://www.americascarshow.com/Detail.a ... 4&mid=1638

http://www.2carpros.com/kpages/first_things.htm

http://www.troubleshooters.com/tautomot.htm

viewtopic.php?f=44&t=773

viewtopic.php?f=44&t=384

http://www.autozone.com/shopping/repair ... 60B3D7E2C7

viewtopic.php?f=44&t=777

viewtopic.php?f=55&t=1115

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=1030

viewtopic.php?f=50&t=383

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

worth reading thru

obviously if your tracking down a problem,you should verify the basics, make sure your running 13 plus volts with the alternator and battery,check your oil level,if you've got a IR temp gun ,use it to locate any cylinders that are not pulling their weight, ,verify the ignition timing,Id suggest having a shop test the exhaust back pressure, verify the fuel pressure,reset the float levels, look for vacuum leaks,check the intake vacuum levels,check the carb linkage, check the spark plugs as they give you a ton of info on the cylinder burn conditions, re-adjust the valves and take a compression test so you have some basic reference points
first check the engine for vacuum leaks, verify the fuel pressure and float levels,verify the accellerator pumps working and produces a long duration of fuel spray,starting as the throttle opens, verify the carbs secondaries open at some point, check the timing and ID suggest trying to get it to idle by running in the air bleed screws till they touch then backing both out 1 1/2 full turns as a start point,throw a qt of marvel mystery oil into the sump, its solvents and detergents tend to remove crud if the engines been sitting for months, allowing sludge and corrosion to form, if you adjusted the valves they might be too tight, and id check the plug gaps are set at about .045, yes I know your 100% sure its correct,you won,t be the first guy to find out it was wrong, only after checking it the third or fourth time! so verify the firing order and plug wire routing again carefully ANYWAY


Id say Ive seen more than 4-5 times as many problems with fluctuating fuel supplies, badly adjusted valves, vacuum leaks and badly timed ignitions, badly adjusted carbs, clogged catalytic converters, and bad electrical grounds,or clogged filters, blamed on defective carbs, than any bad carbs Ive actually seen, its hardly the carbs fault if its getting fed far higher fuel pressure than its designed to work with,the floats are set wrong, the needle/seat is being held open with 12 psi of fuel pressure,the intake has a vacuum leak or the power valve, accelerator pump or jets are wrong for the application, and you don,t bother to find and fix the problem, yet the first thing you hear from most guys is (CHANGE THE CARB!)


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?
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?
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: don,t just start throwing parts at a problem.

Postby grumpyvette » June 23rd, 2009, 9:49 am

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

one of the tools you really should have in your tool kit!
a great deal of process of correcting problems, lies in your skill at locating and isolating the source of those problems.
stepping back and thinking thru the possible problems and the necessary repairs, and tests that will isolate the problem, before starting the repairs beats the hell out of just randomly swapping components

WHEN tracking down problems you'll need to use a few basic tools,
use of a VACUUM GAUGE, a TIMING LIGHT AND A V.O.M. METER!
and actually reading a SHOP MANUAL and the skill to read spark plugs
will go a long way toward helping you isolate the problem.


viewtopic.php?f=62&t=953&p=1991&hilit=+timing+light#p1991

viewtopic.php?f=50&t=383&hilit=infrared


tools you really need
SHOP MANUAL
timing light
vacuum gauge
IR temp gun
degree wheel
dial indicator and stand
fuel pressure gauge
V.O.M. meter
magnifying spark plug reader
lift or (4) 12 ton jack stands
basic mechanic hand tools
floor jack
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: don,t just start throwing parts at a problem.

Postby grumpyvette » August 18th, 2009, 7:40 pm

ONCE YOUVE FOUND MAJOR ISSUES THAT NEED REPAIR, IF THEY CAN,T EASILY BE FIXED, WORKING FROM THE TOP SIDE WITH THE SHORT BLOCK STILL IN PLACE!

its time to buy a decent cheap engine stand, LIKE THIS ONE I LINKED TO , BELOW
AND A SHOP MANUAL, and THIS CD/BOOK AS A REFERENCE YOULL NEED!


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

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=67015


read thru THESE LINKS

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=699

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=1018

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=26

then pull and inspect the engine........once you know what you can salvage you know where the project starts from, it should take less than one weekend to pull and disassemble and inspect the engine
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

some basics

Postby grumpyvette » August 22nd, 2009, 1:05 pm

most guys install the gauge adapter in the spark plug thread port and hit the starter letting it run thru a couple revolutions
what your looking for is no so much the psi value as the difference between the cylinders readings
lets say you get 155 psi (about average on current street cars) and several cylinders read 155 -160 but several read 90 psi, its an OBVIOUS PROBLEM

read the LINKED INFO

http://www.harborfreight.com/cpi/ctaf/d ... mber=95187
Image

http://freespace.virgin.net/tommy.sandh ... ession.htm

http://www.geocities.com/dsmgrrrl/FAQs/compression.htm

http://autos.yahoo.com/maintain/repairq ... 056_1.html

http://www.aa1car.com/library/compression.htm

read the LINKED INFO IN THESE OTHER THREADS ALSO

viewtopic.php?f=70&t=1411

viewtopic.php?f=62&t=882&hilit=+propane

viewtopic.php?f=4&t=1337&p=2923&hilit=propane#p2923

viewtopic.php?f=70&t=967

viewtopic.php?f=52&t=196
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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Site Admin
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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: don,t just start throwing parts at a problem.

Postby grumpyvette » January 5th, 2011, 1:30 pm

Tom stopped by today to show me his new project car, (recent purchase) and ask me to diagnose, its rather frustrating problem, its a really clean 1970 Pontiac lemans with a nice 402 big block Chevy, installed in front of a muncie 4 speed, now the cars geared badly , as its got a 3.08:1 rear gears , and a cam installed that was a bit longer in duration than the cars gearing liked,and the previous owner obviously had no clue on how to tune a car with a q-jet carb, and said he was selling the car because he needed the money and it had recently had the mileage get noticeably worse, so he was tired of tinkering with the car,and wanted to unload the car and get a 4 cylinder truck as transportation.
TOM got the car for a price that made it a deal even if the engine needed replacement.(he won,t tell me how much, but admitted it was UNDER $1500.)
We had a short inspection, and test drive, after driving the car around the block it was obvious that the cars power band ran fairly decent up to about 3500rpm then nosed over as rpms increased.
now any time you've got issues with how a car runs you need to do a few tests and get the car basically tuned, and inspected so you know where your starting point is, set the ignition timing, verify fuel,oil, check the filters etc.
I checked the ignition timing, verified the fuel pressure ,oil level, and oil pressure, we then checked for vacuum leaks and adjusted the valves, and I used the INFRARED temp gun to check exhaust temps,it was obvious the drivers side of the engine was running a bit cooler, which can be caused by many problems, I checked the plugs just so we knew that was not an issue. it was then I notice the difference in the exhaust sound differed remarkably from side to side,and so did the amount of slight light smoke from the tail pipes when the cars engine was reved.
I put the car on the lift, it had a dual 2.5" exhaust with an (H) pipe just behind the cross member, but what caught my attention was the drivers side past the (H) pipe looked a bit wet compared to the pass side exhaust, putting my hand on the drivers side muffler proved it to be barely warmer than room temp, the pass side muffler was much warmer, placing a piece of white paper behind each tail pipe showed a huge difference in the exhaust flow rate.
I got out a vacuum pressure gauge, and drilled a a test 1/8" hole in the dual exhaust pipes ,just behind the collectors, a quick check showed the drivers side gauge read higher (about 5 psi but the gauge needle vibrated badly) while the pass side read about 1.2-2 psi
it looked like the drivers side muffler was mostly plugged,so to test I disconnected the header from the collector extension on both sides one at a time, luckily, it was clamped, not welded on so I then temporarily removed both mufflers and had him rev the car on the lift, it became obvious both exhaust pipes without the mufflers flowed rather well , so I got a hose out and tried flowing water into both mufflers, the pass side flowed fine, almost no restriction,the drivers side flowed much slower and slowly filled up and overflowed water,obviously plugged, I got out a high pressure air blow gun wand
Image

I forced water and high pressure air into the muffler and got a ton of rust and mud flow with the water,this eventually turned to chunks of rust, and it was clear the muffler needed replacement.
I gave tom the muffler , to examine and we drove down to the local muffler shop, and bought two mufflers, (flow-master 40 series was what they had to fit his car) I suggested installing an (X) and new exhaust while we were under there,but that had to wait until pay day,
(like most of us TOMS on a fairly tight budget, after buying a project car) in about 3 hours his car sounded much better and easily picked up the 50-70hp the restricted muffler was costing his car until it was replaced

Image

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useful related info
viewtopic.php?f=56&t=495&p=613#p613

viewtopic.php?f=56&t=1166

viewtopic.php?f=56&t=2916

http://redlinedetection.com/pages/video/

viewtopic.php?f=55&t=109

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

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


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