1971 Pontiac Lemans engine running problem/load problem

Tiny
GTOJOYCE
  • MEMBER
  • 1971 PONTIAC LEMANS
  • 6.6L
  • V8
  • RWD
  • AUTOMATIC
  • 33,000 MILES
I got the car last year from a guy just wanting to sell it. At the time I bought it the carb was done and it needed electric work. I fixed both problems by taking it to a shop for the light issue and installing a new 2 barrel 600 eldelbroke carb in it. After installing the new carb it worked fine at first. This is the problem. For some reason when driving it, it doesn't put out the power a 400hp engine should meaning. When I hit the gas it starts out real slow then picks up speed later. Some times it feels like it never shifts at all between gears but it speeds up. So my first problem is that the engine does not perform well. The second issue is the load. When ever I put it in reverse or drive at times it just wants to shut off. It does that at idle as well. Ive missed with the idle screw on the carb alot and thought I had it right, but never changes just goes back to lowering then shutting off after 15-20min, but any ways. When I back up it shuts off right before I put it and drive. So what do you think is going on? This is really a project/learn about mechanics car for me.
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Monday, December 9th, 2013 AT 7:02 PM

4 Replies

Tiny
CJ MEDEVAC
  • EXPERT
I'M THINKING TIMING.....AND TUNING!

KINDA ON THE SAME LINES, MAYBE THE TIMING IS PERFORMED PERFECTLY....BUT THE HARMONIC BALANCER'S OUTER RING HAS SLIPPED (BEFORE YOU GOT IT).....(JUST A POSSIBILITY) AND YOUR MARK'S NO LONGER CORRESPOND WITH "ACTUAL TDC"

AS FAR AS CARB AND ENGINE....I MIGHT CAN HELP YOU SOME..........AUTO TRANNYS AIN'T MY THING

WE ALSO MAY HAVE "JETTING" ISSUES AND MAYBE "ACCELERATOR PUMP" ISSUES

FLOAT HEIGHT IS ALSO CRITICAL

I'M PRETTY GOOD WITH MAKING A JEEP CJ'S CARTER BBD CARB WORK....AS WELL AS TUNING A HOLLEY DECENTLY

I PRESENTLY HAVE A 390 CFM 4 BARREL HOLLEY INSTALLED ONTO AN OFFENHOUSER INTAKE.....HANGING ON THE SIDE OF MY 258 STRAIGHT 6 CYLINDER.......I LIKE IT!......GREAT MPGs AND POWER WHEN I WANT IT

I, MYSELF, HAVE OWNED NOTHING BUT CARBURETED JEEPS......FOREVER!

I RECOMMEND YOU STICK WITH THE MECHANICAL FUEL PUMP....AS IT WILL PRODUCE MORE THAN ENOUGH FUEL FOR REGULAR STREET USE...IT'S CHEAPER...IT'S NOT COMPLICATED....IT WILL NOT CONTINUE TO PUMP FUEL ON YOU AFTER YOU CRASH AND THE ENGINE DIES

HERE'S WHERE WE NEED TO START

DIS PUPPY GOT POINTS???.....KNOW HOW TO ADJUST 'EM?

ELIMINATE ANY VACUUM LEAKS ANYWHERE

THE CARB MUST BE INTERNALLY ADJUSTED RIGHT (FLOAT HEIGHT-ACCELERATOR PUMP)

THE CHOKE NEEDS TO OPERATE CORRECTLY....I LIKE INSTALLING AND USING MANUAL CHOKES (WE'LL DEAL WITH THAT IF YOU NEED TO....MANUAL OR AUTOMATIC.....LEMME KNOW YOUR PREFERENCE)

TIMING NEED TO BE PERFORMED CORRECTLY

ADJUSTING THE THE MIX SCREWS AND IDLE SPEED.....DO YOU HAVE THE SPECS FOR THAT ENGINE?.......MAYBE SOMEONE HAS NOT OVER TIGHTENED THEM AND RUINED THEIR "SEATS", WHICH WILL MAKE "CORRECT MIXTURE" SOMETIMES IMPOSSIBLE TO ACHIEVE

I'M GONNA LINK YOU TO A JEEP POST I ANSWERED.....IT DID NOT COMPLETELY "TRANSLATE OVER" WHEN THEY HAVE REMODELLED THIS SITE SEVERAL TIMES IN THE PAST FEW YEARS

I THINK YOU WILL RECOGNIZE THE MINOR GLITCHES (NOT TYPING ERRORS OF MINE) I THINK YOU WILL BE ABLE TO SIFT THRU IT..........EVEN THOUGH IT'S NOT YOUR ENGINE AND CARB, THE TECHNIQUES REMAIN THE SAME

IF YOU HAVE POINTS THAT ARE NOT SET RIGHT, OR OTHER STUFF I MENTIONED ABOVE AIN'T RIGHT...THINGS MIGHT NOT GO WELL

LEMME KNOW WHAT WE NEED TO ADDRESS

HERE'S THE LINK

http://www.2carpros.com/questions/jeep-cj7-1985-jeep-cj7-stalls-when-hot

(KEEPS ME FROM PECKING ALL OF THIS OUT AGAIN)

I HAVE MORE HELPFUL LINKS TOO!

YOUR TURN....I ALWAYS ANSWER BACK WHEN I GET TIME.....USUALLY WITHIN 24 HRs OR SOONER!

THE MEDIC
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Monday, December 9th, 2013 AT 8:49 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
What size engine is in the vehicle? Very few engines produced 400 HP back then and if they did, for sure they didn't have a 2 BBL carb. As far as the stalling, are you sure the choke is opening properly? Have you checked for vacuum leaks?
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Tuesday, December 10th, 2013 AT 5:51 AM
Tiny
GTOJOYCE
  • MEMBER
CJ MEDEVAC THANKS FOR ANSWERING. NOW FOR WHAT YOU HAVE SAID SO FAR IS THAT I NEED TO LOOK INTO THE HARMONIC BALANCER. COULD YOU TELL ME WHAT EFFECT IT HAS ON MY ISSUE? WHERE WOULD THAT COME IN WHEN IT COMES TO ITS LAK OF POWER AND WANTING TO SHUT OFF IN REVERSE AND SOME TIMES AS SOON AS I PUT IT INTO DRIVE? AS FAR AS THE CARB. I CHECKED FOR LEAKS. NONE ARE AROUND AT ALL. AT LEAST NOT NEAR THE CARB. WHERE ELSE COULD AIR LEAK COME FROM TO EFFECT THE CARB? AS FAR AS FLOAT HEIGHT I SHOULDN'T NEED TO TOUCH DO TO THE FACT ITS A BOLT ON EDLEBROKE CARB. INSTRUCTIONS SAY NOTHING OF TUNING FROM THE INSIDE UNLESS I FEEL I NEED TO. I'VE ONLY ADJUSTED THE MIX SCREWS, IDLE SCREW, AND SPEED IDLE WHICH I DIDNT MEAN TO TOUCH THE SPEED IDLE BUT I DID. MY CHOKE IS ELETRIC AND THE CAR IS AUTOMATIC THATS WHY I HAVE AN ELETRIC CHOCK. I HAVE NO INSTALLED IT BECAUSE I WAS TOLD I DON'T NEED IT IN SUMMER WEATHER AND THAT ITS UP TO ME IF I WANT TO INSTALL IT OR NOT SO I DIDN'T. I HAVE NOT OVER TIGHTEN FOR IM REAL CARFUL AT THAT BECAUSE I DON'T WANT TO BREAK THE DAME THING LOL. I TUNED THE MIX AND IDLE AND IT IDLES GOOD, BUT LIKE I SAID AFTE 15MIN IT BOGS THEN TURNS OFF.

FOR JACOB SORRY I DIDN'T MEAN TO SAY 400HP I MEAN 400CUBIC LOL THATS THE SIZE OF THE ENGINE LOL.

CJ MEDEVAC. SO FAR IVE TUNED, AND I DON'T HAVE THE EQUIPMENT TO TAKE APART MAJOR PARTS. SO WHAT DO YOU THINK? THE HARMONIC BALANCER I WOULD NEED TO TAKE TO A SHOP BUT I WANT TO FIX EVERYTHING THAT I CAN MYSELF FIRST
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Tuesday, December 10th, 2013 AT 4:10 PM
Tiny
CJ MEDEVAC
  • EXPERT
THE HARMONIC BALANCER IS JUST "ONE POSSIBILITY"

IF IT HAS SLIPPED. AND IT MAY NOT HAVE.A QUICK EXPLANATION OF HOW IT WOULD AFFECT YOU IS

. BEAR WITH ME, I'M MORE OF A "DEMONSTRATION KINDA GUY". COMPUTERING IT ACROSS IS A CHALLENGE. OR AT LEAST TO GET YOU TO COMPREHEND IT!

WE KNOW THIS IS A 4 STROKE, SO WE KNOW THAT #1 PISTON IS UP TWICE DURING THE CYCLE (BEGINNING OF THE INTAKE STROKE AND THE BEGINNING OF POWER STROKE). WHICH MEANS THE TIMING MARKS ROLL BY TWICE. BUT THE TIMING LIGHT ONLY FLASHES WHEN WE GET TO "TDC" OR WHEN THE PLUG FIRES THE "ONE TIME" IN THE CYCLE

OK. ALL IS PERFECT. IF I BRING MY TIMING MARK AROUND TO "ZERO" OR "TDC" (TOP DEAD CENTER)

. SEE PIC 1. MY JEEP'S BALANCER WITH THE WHITE TIMING MARK IS LINED UP WITH "ZERO" ON THE SCALE (I'M SURE YOUR MARKINGS DIFFER. BUT DISPLAY THE SAME SETTING)

WHAT THIS SHOULD MEAN IN A PERFECT WORLD (AS JEEPS ARE!) IS MY #1 PISTON IS AT THE TIP TOP. THE SLIGHTEST MOVEMENT CLOCKWISE OF MY CRANKSHAFT AND IT'S HEADED DOWNWARD. THIS IS WHEN THE SPARK IS SUPPOSED TO FIRE. NO MATTER WHAT. TIMING IS A BIT MORE COMPLICATED AS WE MUST SHOOT THE SPARK EARLIER AND EARLIER AS THE MOTION GETS FASTER AND FASTER. SO THAT IT WILL SPARK AND FIRE THE CYLINDER EXACTLY AT THE MOMENT THAT THE PISTON STARTS DOWN. WE CANNOT SPEED UP ELECTRICITY SO WE THROW THE SWITCH EARLIER!

WHEN I TIME MY JEEP AT 8 DEGREES BEFORE TO DEAD CENTER AT 700 RPM

SEE PIC 2. THIS IS WHAT FLASHES IN MY TIMING LIGHT. THIS IS "MY CALIBRATION" FOR WHEN MY SPARK SHOULD FIRE. IT'S SORTA THE "POINT" WHERE MY DISTRIBUTOR'S "ADVANCE MECHANISMS" ARE CALIBRATED OR ZEROED TOGETHER

I'M ACTUALLY STILL "EXPLODING" AT (LET'S SAY) 1 DEGREE AFTER TOP DEAD CENTER. AS THE ENGINE SPEEDS UP, THE CENTRIFUGAL AND VACUUM ADVANCE GRADUALLY TIME "MR. JEEP" FURTHER AND FURTHER BACK. AS A STUPID EXAMPLE. WHEN I'M TIMED CORRECTLY, AND I'M DOING 2000 RPM, MY "EARLY SWITCH ON OF ELECTRICITY" / OR "CALL FOR A SPARK" MAY NOW BE AT 25 DEGREES. CONSTANTLY, WHEN I DO 2000 RPM

. BECAUSE I INITIALLY CALIBRATED THE PUPPY AT 8 DEGREES AT 700 RPM. EVERYBODY ELSE IN THE SYSTEM FOLLOWS ALONG AT THE RIGHT SPEED/ PACE/ TIME WHEN I GO FASTER OR EVEN GO SLOWER

. WHAT IF I HAD CALIBRATED AT.4 DEGREES. AT 2000 RPM I MIGHT BE CALLING FOR SPARK AT 21 DEGREES

THAT'S WHY WE HAVE SPECs. MR. JEEP'S SPECS ARE 8 DEGREE AT 800 RPM

.
.
NOW LET'S SAY. MR. BALANCER "SLIPPED" WHEN I DRAG MY MARKS AROUND TO "ZERO" AS IN PIC 1. INSIDE THE ENGINE, THE #1 PISTON IS NOT EXACTLY AT THE TOP. DEPENDS ON HOW MUCH IT SLIPPED!

OK. YOU ARE IGNORANT TO THE FACT IT SLIPPED, SO YOU TIME IT TO SPECs, YOUR MARKS LINE UP IN THE TIMING LIGHT AND YOU THINK YOU ARE GOOD TO GO

. NOT!

YOU MIGHT BE 3-5-10-15-ETC DEGREES OFF!

WHY AIN'T IT RUNNIN' RIGHT?

EVEN THOUGHT YOU "THOUGHT" YOU TIMED IT YOU ACTUALLY "UN-TIMED IT".

. THINK ABOUT IT,

THE HARMONIC BALANCER WAS FINE 2 YEARS AGO. TIMING WAS PERFECT. NOW IT SLIPPED (UNKNOWINGLY) THE TIMING WAS/ STILL IS PERFECT (#1 PISTON WISE) BUT YOUR TIMING LIGHT SAYS THE MARKS DON'T LINE UP RIGHT. SO YOU CHANGE IT SO THE MARKS WORK OUT. THE CORRECT TIMING FOR THE ENGINE TO FUNCTION RIGHT HAS MOVED

ON MY JEEPS, I CAN INSERT A ROD, ETC IN THE SPARK PLUG HOLE AND ATTACH A DIAL INDICATOR TO IT (CAREFULLY) I CAN ROTATE MY ENGINE SLOWLY WITH A WRENCH

SEE PIC 3

THE PISTON WILL RISE TO THE TOP AND I WATCH FOR THE GAUGE TO "MAX OUT", BEFORE IT STARTS DOWNWARD----MY MARKS SHOULD BE ON ZERO AT THAT TIME. SOMETIMES ON OTHER CARS, THE HEAD MUST BE REMOVE TO ACCESS THE PISTON TO CHECK THIS

. JUST REMEMBER. THIS MAY BE JUST FINE ON YOURS!
.
.
STILL NO WORD ON "POINTS".A MIS-ADJUSTMENT COULD HAVE US CHASING GHOSTS FOREVER. DID YOU TIME IT WITH THE VACUUM ADVANCE LOOSE AND PLUGGED OFF? DID YOU HOOK IT BACK UP?

WAS MY "TUNING LINK" (LAST ANSWER) UNDERSTANDABLE?

WE STILL HAVEN'T TOUGHED ON THE ADVANCES IN THE DISTRIBUTOR WORKING RIGHT OR NOT. SO MANY THINGS MUST WORK IN UNISON, ONE THING OUTTA SYNC, AND SYMPTOMS POINT ALL OVER THE PLACE.

. THIS IS WHY IT' SO IMPORTANT TO DO TESTS AND PROCEDURES CORRECTLY AND REPORT BACK YOUR FINDINGS. THIS SORTA TELLS US WHICH WAY TO GO AT A CROSSROADS TO GET 'ER DONE FASTER

THE MEDIC
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Tuesday, December 10th, 2013 AT 8:24 PM

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