combustion problems - HELP
- Thread starter cobra_2_76
- Start date
I popped a dist. gear roll pin a few years back. I couldn't figure out what the problem was as I just drove 45 miles!! Turned a corner and pop..... BANG! I it sounded like a gun going off. I parked and pissed with it a while and found nothing. Every once and again it would go off like a gun. Load the exhaust with raw gas and hit the fire while an exhaust valve is open and look out! I guess my oil pressure fuel pump shut-off paid for itself. I wasn't getting gas except when I turned the key.
I got a tow and scratched my head for a bit. I had pulled the cap and hit the key and the rotor moved so I forgot about it and moved on to other things. Later a friend said to recheck it and I pulled the cap and this time grabed the rotor and gave it a good twist! A $.15 roll pin cost me a 25$ tow. Don't underestimate the power of a very tiny part binging things to a stand still.
Good luck finding the cause. I hope it's an easy fix for you.
Tim
I got a tow and scratched my head for a bit. I had pulled the cap and hit the key and the rotor moved so I forgot about it and moved on to other things. Later a friend said to recheck it and I pulled the cap and this time grabed the rotor and gave it a good twist! A $.15 roll pin cost me a 25$ tow. Don't underestimate the power of a very tiny part binging things to a stand still.
Good luck finding the cause. I hope it's an easy fix for you.
Tim
Wasn't the pin. Pulled the distributor last night, gear was tight. Decided the best way to check to see if the pin was sheared to was to try and drive it out. Three taps and out the pin popped intact :damnit: , hole real nice adn round. Put it back together, so tonight I tear the front of the engine down....weeeeeee.
Dave
Dave
Wart said:
99% sure yes, there's always that lingering doubt/possibility something was overlooked.
I'm tearing down the front end tonight and at a minimum I'll at least be able to eliminate a variable. You did remind me that the alignment pin wasn't as tight as I expected and from the perspective of FINALLY identifying the problem, hope it has moved and caused the problem. At least I can then fix it and again start terrorizing the neighborhood!
And our local Buckeye Mustang Club has rented NRP and I was really hoping of getting out there and seeing what it would do.
I guess I'll put it back together, re-check all parts of the distributor, lube it up. Recheck MSD box is working, re-align the distributor to #1, and re-check the carb.
Start over with evaluation too.
Wart: correct my logic if I'm wrong. If the weights on the relulctor stuck then the whole distributor would be advanced requiring the initial advance to be retarded to compensate before it would run. Opposite of what I thought I saw?
Thanks everyone for all the ideas.
Dave
cobra_2_76 said:Bad news....nothing wrong in timing chain area. Cam pin intack and properly aligned. AAAA...HHH
Crank gear and key intact?
Well, yeah, theres 20 - 30 degrees of mechanical advance in the distributor, if it got jammed it could cause problems, I thought the distributor was A-1.
Key way fine....I even took a hack saw to it...now just cut a small groove between both sides of the harmonic balancer halves to make sure it's not moving.
If the 30 degrees of advance got stuck and it would only run with 30 degrees of initial advance, then moving it to 10 degrees should make it run better not worse? I'm not positive on the logic, is my sense right or wrong??? Maybe was the key to the problem.
Dave
If the 30 degrees of advance got stuck and it would only run with 30 degrees of initial advance, then moving it to 10 degrees should make it run better not worse? I'm not positive on the logic, is my sense right or wrong??? Maybe was the key to the problem.
Dave
you mentioned balancer being like 30 degrees off I had the same problem with mine on another thread.
use the positive stop method and find TDC and bump it up to your current balancer bet you will find there is nothing wrong other than the marks being in the wrong place.
IE... not a II specific part .
your marks should be roughly in the 10:00 position when TDC
good luck I'll search for the thread It might be you situation if you balancer is not stock...
use the positive stop method and find TDC and bump it up to your current balancer bet you will find there is nothing wrong other than the marks being in the wrong place.
IE... not a II specific part .
your marks should be roughly in the 10:00 position when TDC
good luck I'll search for the thread It might be you situation if you balancer is not stock...
Dano78
Founding Member
Seems as if you've covered most the stuff! I've had the dist. gear shear off before. Was a real head scratcher for a while. Also had a cam chew away 1/2 the dist. gear and jump time. Came to find out the damn cam bolt had loosened up and backed out enough to cause the cam to "walk" but still work the eccentric! Took a couple of days to figure that one out.
Think you might have problems with the centrifugal weights/springs inside the dist.? Still a possibility of an ittermittent short in the MSD box. Might want to bypass the MSD system and see if that corrects it. Usually I stuff a points dist. in the car for this, real simple to set up the points without butchering your current wiring for the testing purposes. That, and they are cheap, if you don't have one.
I've also seen Hi-pressure oil pumps, when revved, over pressure lifters causing the valves to hang open. But I don't think yours is in this area.... at least I don't think it'd alter the timing that greatly.
Think you might have problems with the centrifugal weights/springs inside the dist.? Still a possibility of an ittermittent short in the MSD box. Might want to bypass the MSD system and see if that corrects it. Usually I stuff a points dist. in the car for this, real simple to set up the points without butchering your current wiring for the testing purposes. That, and they are cheap, if you don't have one.
I've also seen Hi-pressure oil pumps, when revved, over pressure lifters causing the valves to hang open. But I don't think yours is in this area.... at least I don't think it'd alter the timing that greatly.
about a year ago i replaced my distributor with a remaned unit.
the car was running pretty good then the performance started to decline. this spring i check the msd box, coil, plugs, wires couldn't really place my finger on the problem. then i started to have the same problems you are having. swapped the carb out, tried different chokes, went thru the dstributor top to bottom, advance kit, everything.
so after watching this thread i decided to barrow and msd distributer from a friend of mine. no vacuum advance, just a straight up distributor.
car runs great.
the car was running pretty good then the performance started to decline. this spring i check the msd box, coil, plugs, wires couldn't really place my finger on the problem. then i started to have the same problems you are having. swapped the carb out, tried different chokes, went thru the dstributor top to bottom, advance kit, everything.
so after watching this thread i decided to barrow and msd distributer from a friend of mine. no vacuum advance, just a straight up distributor.
car runs great.
Short answer it runs!!! Seems the coil was not dead,
worked but just barely enough to hide its
problems....here's what transpired.
Well went back to the drawing board and started over
with the spark. Re-checked the magnetic trigger on
the box and got a good spark with a plug in the coil
wire.
Next decided to check the wires from the MSD box to
the distributor. Stuck two tabs into the female side
of the Duraspark distributor connection and used a
screwdriver to make the trigger jump. Again fantastic
spark with a plug in the coil wire.
Next put the coil wire on the cap, aligned the rotor
with a plug terminal, pulled that wire off at the head
and installed a spare plug. Then ran the screwdriver
over the terminals again to trigger the plug.....hit
six times THEN it started discharging in the MSD box
not at the plug. OOOOOO, shades of a bad box?
Tried several times with same results. Re-checked
cap, no cracks.
Friday morning called MSD and discussed findings. Of
course electricity finds the closest ground, so
concensus was box was ok. Said to check coil. Now
the instructions say if the ignition FAILS to replace
the coil and if it still doesn't work return the box
for service. They gave me the ohm spec's for the
primary and secondary windings.
My ohm meter on my Craftsman diagnostic box failed so
Friday I take an eary lunch to Radio Shack and they
don't carry one in those ranges, darn. Off to my
favorite parts store and get one there. (Should know
better and stay with a sure thing.)
Take off early from work, (one of the few benefits of
being salaried!) Get home and check the ohms.
Supposed to be .7 for primary and 4.7K for secondary.
The coil registers 1.2 primary and 4.3k secondary
Hummmm, call MSD back and they say the coil is bad.
OK, off to Summit, three and a half hours later return
with the coil. Ohms match, install and still won't
run. ****.
This morning go back out and recheck - notice no fuel
in carb. Hummm, I know I re-tightened the cam
eccentric bolt, but no fuel. Try some gas in the carb
anyway, doesn't run. Oh well, I'll get back to it
when I get the eccentric tightened. Get started
tearing the power steering off AGAIN, when I notice my
vice grips hanging under the car. Darn forgot to hook
up the fuel lines to the pump. Hooked it up, turned
over the car to fill the bowls and IT STARTS!!!!
Seems the thing was slowly failing....who would have
guessed. Because it was not generating a strong enough
charge it wouldn't jump the gap in the distributor and
grounded in the MSD box. I guess if I had followed
the MSD instructions I would have saved a lot of
frustration, but darn it was still generating a spark.
OH well it runs great and I'm out of my gloomy
cloud!!!! Summer may be good afterall!!
worked but just barely enough to hide its
problems....here's what transpired.
Well went back to the drawing board and started over
with the spark. Re-checked the magnetic trigger on
the box and got a good spark with a plug in the coil
wire.
Next decided to check the wires from the MSD box to
the distributor. Stuck two tabs into the female side
of the Duraspark distributor connection and used a
screwdriver to make the trigger jump. Again fantastic
spark with a plug in the coil wire.
Next put the coil wire on the cap, aligned the rotor
with a plug terminal, pulled that wire off at the head
and installed a spare plug. Then ran the screwdriver
over the terminals again to trigger the plug.....hit
six times THEN it started discharging in the MSD box
not at the plug. OOOOOO, shades of a bad box?
Tried several times with same results. Re-checked
cap, no cracks.
Friday morning called MSD and discussed findings. Of
course electricity finds the closest ground, so
concensus was box was ok. Said to check coil. Now
the instructions say if the ignition FAILS to replace
the coil and if it still doesn't work return the box
for service. They gave me the ohm spec's for the
primary and secondary windings.
My ohm meter on my Craftsman diagnostic box failed so
Friday I take an eary lunch to Radio Shack and they
don't carry one in those ranges, darn. Off to my
favorite parts store and get one there. (Should know
better and stay with a sure thing.)
Take off early from work, (one of the few benefits of
being salaried!) Get home and check the ohms.
Supposed to be .7 for primary and 4.7K for secondary.
The coil registers 1.2 primary and 4.3k secondary
Hummmm, call MSD back and they say the coil is bad.
OK, off to Summit, three and a half hours later return
with the coil. Ohms match, install and still won't
run. ****.
This morning go back out and recheck - notice no fuel
in carb. Hummm, I know I re-tightened the cam
eccentric bolt, but no fuel. Try some gas in the carb
anyway, doesn't run. Oh well, I'll get back to it
when I get the eccentric tightened. Get started
tearing the power steering off AGAIN, when I notice my
vice grips hanging under the car. Darn forgot to hook
up the fuel lines to the pump. Hooked it up, turned
over the car to fill the bowls and IT STARTS!!!!
Seems the thing was slowly failing....who would have
guessed. Because it was not generating a strong enough
charge it wouldn't jump the gap in the distributor and
grounded in the MSD box. I guess if I had followed
the MSD instructions I would have saved a lot of
frustration, but darn it was still generating a spark.
OH well it runs great and I'm out of my gloomy
cloud!!!! Summer may be good afterall!!
Blue Thunder
15 Year Member
Cool that you found the trouble.
In the future, to check for coil issues, pull the coil wire out of the socket and rest it on top so there's a small gap between the wire terminal and the coil terminal. Run it. The gap will increase resistance and force the coil to put out more current to bridge the gap. If the car runs better when you add the gap, you know the coil is bad. (Don't leave it running for a long period with the wire loose or the coil might eventually overheat and explode like a grenade)
In the future, to check for coil issues, pull the coil wire out of the socket and rest it on top so there's a small gap between the wire terminal and the coil terminal. Run it. The gap will increase resistance and force the coil to put out more current to bridge the gap. If the car runs better when you add the gap, you know the coil is bad. (Don't leave it running for a long period with the wire loose or the coil might eventually overheat and explode like a grenade)
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