Distributor problem

[57larry]

my buddy,Fred and I drove his 40 pickup down to the Nats in Louisville. Almost there, he hit a hole in the road and the truck stopped running. After an inspection, it seemed the distributor cap came half off. Put it back on , ran but not great. Made it to the hotel and pulled the cap. The rotor button tang was twisted. Went to Auto Zone and bought a new cap & rotor. Ran great. 2 days later leaving Louisville, we went about 40 miles and the truck just died. Had weak spark, gas flow ok, dist (rotor) turning but no start.

The engine is a SBC with a Pertonix dist and coil. (no room for an HEI)

What can we look for and at? Thanks, Larry

[kb426]

How old is the Pertronix?

[wayne petty]

a few tests...   check for spark from the COIL wire disconnected from the cap.  got a  bright blue snappy spark or a dim orange spark..

if you get a bright blue snappy spark.. do the same test at the spark plug wires.. there will be less snappyness there but it should still be nice and blue.. not dim and orange..  

if you got good spark from the coil...  but not from the spark plug wire.. pull the cap and rotor again.. check for burn thru marks..  examine the burn marks on the inside of the cap terminals.. make sure the burn marks are even. that the distributor shaft did not get bent when the cap got knocked off.

no bright blue snappy spark from the coil wire..

clip a test light clamp to the positive coil terminal..  shove the probe into something to ground it.. turn the key on.. do you get a medium bright light??  crank the engine..do you get a brighter light.. return the key to the run position..the light should go back to medium..

this is an ignition system trouble shooting procedure..   lets you isolate the trouble fairly quickly..

an orange spark might be a failed/burned out ignition coil.. you might want to identify the type of coil and measure with it disconnected from positive to negative ..  then from positive to the high voltage connector..  or is it negative to the high voltage connector.  measure all three ways. . takes an extra few seconds.

[57larry]

both dist & coil have 5,000 miles on them.

thank you Wayne, you know your stuff, I'll see what we have

[Beck]

I stopped and helped a guy on the way to the NATS several years ago with ignition problems. He was running a normal coil, 8 volts. He did not have a balast resistor. After a few hours run time the coil overheats and shuts down. There are 12 volt coils that don't require a resistor. Check what he has.

The guy I helped was very lucky. His coil was mounted inside the car under the dash. It was hot enough to blister fingers. The car could have gone up in flames. The sad thing is the guy wouldn't believe me. After sitting a while the car would restart. He would go 5 to 10 miles and it would stop again.

[chimp koose]

I wonder if the module didn't get hit with a few errant sparks when the cap was mis aligned . that could be enough to ruin it .

[57larry]

just got an update from Fred, got spark from dist & coil. changed coil and put in a new Pertronix module. still doesn't start. battery is new & charged. now when he cranks, gas shoots out of the top of the carb.

the SBC has a high torque mini starter the really turned the engine over, now it still cranks, not as fast and just doesn't sound good

I don't know what to tell Fred, he's frustrated. thanks, Larry

[chimp koose]

Fuel out the top of the carb says float/needle and seat problems. That must have been some huge bump he hit .I have had a holley with the side hung floats hang the needle/seat open after a burnout at the track  . Spark, fuel and compression, in a no start, one of these is the problem . You now have spark ,compression is unlikely to be lost hitting a bump , so fuel is next. If it is shooting out the bowl vents you know you have fuel , now the level needs to be regulated .Could be as simple as something grungy being dislodged by the bump and finally working its way to the needle/seat area .

[wayne petty]

he probably has the distributor installed 180 out of phase..

2 turns of the crank to one of the distributor gives you a 50/50 chance of getting it right..

if he did not take out the distributor.. when he bounced it thru the pot hole.. there must have been enough frame flex/body movement to not only knock the cap off but to break the distributor housing /shaft.

decades ago.. working in an horrible transmission shop doing R and R.  the guy in the next bay pulled the trans out of a corvette.. snapped the distributor off.

could have also when the distributor cap and rotor impacted sheared the roll pin..  so the distributor no longer turns with the gear..

an inspection is needed..

don't forget.. there is also a chance the timing marks on the damper DON'T line up properly.  

http://i1207.photobucket.com/albums/bb476/waynep712/ignition%20system/sbc400damper_zps7b6410dd.jpg

you can see that the 2 different dampers both fit the crank woodruff key at the same position.. but the mark on the damper is in a different location..

http://i1207.photobucket.com/albums/bb476/waynep712/chevybalancermarks.jpg


this is a 2 o clock timing mark..
http://i1207.photobucket.com/albums/bb476/waynep712/8inchTimingMarks.jpg

the 3 bolts on the inner will always align in the same location..


if gas is FLOWING out the fuel bowl vents..

if it has an electric fuel pump.. turn it off...  if it has a mechanical fuel pump and a rubber fuel hose section on the fuel pump inlet .. squeeze that with a pair of needle nose pliers or small long nose vice grips. that will stop the fuel from being pumped up to the carb.. get the engine started..  after  the engine has run for 15 or 20 seconds.. release the pliers...  if it still starts flowing out the bowl vents.. pinch it again.. take the engine RPMS up to about 2000... when the engine starts to die.. release the pliers again.. a full speed rush of fuel will come thru the wide open needle and seat and may clean the debris out.

whacking with a plastic screw driver handle. usually works also. .

[enjenjo]

On that SBF boat motor that would not start, the problem was traced down to a broken roll pin in the distributor gear. It put the rotor out of phase with the terminals on the cap when cranking.

[UGLY OLDS]

On that SBF boat motor that would not start, the problem was traced down to a broken roll pin in the distributor gear. It put the rotor out of phase with the terminals on the cap when cranking.

  Was there any pieces of valve seal found in the oil pan  VERY common problem with Fords .. Oil pump will suck in a piece of valve seal & jamb just long enough to shear the pin..then continue spinning like nothing happened ...

Bob ...  

[chimp koose]

I tore down a 460 once that ingested hard chunks of valve seal in the oil pump, thus twisting off the oil pump drive instead of breaking the dizzy gear. All came to a halt just before the bearings wore through to the steel shell.

[57larry]

we pulled the distributor and found that the top shaft is bent. $250 for a new Pertonix dist. may put an old points dist back in