TBucket Engine Project (Dart SHP)

I hope that helps you isolate and solve the problem,
please let us know how the testing goes,
hopefully thats not some other defective distributor
 
I did look thru some of their comments that dealt with that distributor and didn't find
anything negative. I will probably be the first to have problems. :(
 
weird situation interested to see if it is even the distributor here causing the ignition cut out. Did you test that it was cutting spark at said rpm using a timing light Rick? That was how my first engine acted when the cam went south.
I am firm believer in a trigger system for spark now trying to stay away from dizzy as much as possible allot to be had from accurate timing.
 
For your vacuum advance connection, manifold vacuum is manifold vacuum.
So if you require a full-time vacuum connection for your needs (vs. ported/timed),
you can make that connection to ANY manifold vacuum source - a port on a carb spacer,
tee into your PCV line, add a fitting to the intake directly, etc.
It does not have to be connected directly to the carb.
 
Hey Rick, let me tell you a story that might help.
My 95 GMC K1500 truck has a 305 TBI engine with the small body distributor and remote coil.
Occasionally and randomly the engine would stutter and one day in a winter storm on my way
to work at night, it cut out completely. No doubt it was lack of spark.
Long story short, it turned out to be the rotor. The spark burns a path through the center of the rotor
and it gets grounded out to the center post of the distributor. So spark comes into the cap from the
coil, but never makes it out to the plug wires. That arc path on the rotor is nearly impossible to see.
You need an eye loupe.
To test, you should be able to connect your timing light to the coil wire, remove the rotor, and crank the engine
to check for strong spark. Or just try another rotor.
But with the tests you already did, like you I'm thinking the rev limiter inside the distributor is faulty.
 
Did you test that it was cutting spark at said rpm using a timing light Rick?
No, not at this point, but the Tach go crazy when it starts cutting out.

For your vacuum advance connection, manifold vacuum is manifold vacuum.
I'm still wondering why there is gasoline in the vacuum diaphragm. Maybe it's been there since the first time I started when I didn't realize how rich it was running until the choke started to come off.

That arc path on the rotor is nearly impossible to see.
You need an eye loupe.
I did look at under 4 power desk light, but wasn't sure what I was looking for. I should take another look at it with my eye loupe (8x).

MSD responded yesterday and they want me to check the voltage at the coil's positive terminal at idle and above. FedEx says the distributor will arrive on Aug 10th, but I can't see it taking that long, it's only coming from Arizona to Oklahoma. It's being sent FedEx SmartPost service. The shipping was free.
 
Hey Rick, let me tell you a story that might help.
My 95 GMC K1500 truck has a 305 TBI engine with the small body distributor and remote coil.
Occasionally and randomly the engine would stutter and one day in a winter storm on my way
to work at night, it cut out completely. No doubt it was lack of spark.
Long story short, it turned out to be the rotor. The spark burns a path through the center of the rotor
and it gets grounded out to the center post of the distributor. So spark comes into the cap from the
coil, but never makes it out to the plug wires. That arc path on the rotor is nearly impossible to see.
You need an eye loupe.
To test, you should be able to connect your timing light to the coil wire, remove the rotor, and crank the engine
to check for strong spark. Or just try another rotor.
But with the tests you already did, like you I'm thinking the rev limiter inside the distributor is faulty.

I have always sprayed the cap and rotor with silicone inside and out and let it dry a bit and was told it would stop the burning and corrosion of both by the hot spark. Also with water proofing from rain and such. Once wires are on, spray them at the cap to seal good so water can't get get under the boots.
 
That coil look good to me.
I would never buy a distributor with a electrical circuit inside NEVER.
The high voltage inside the distributor ionize the air wich in turn corrode the internals very quickly.(do not appear to be your problem in your case).

The magnetic pickup has a polatiry on the MAGNET(and you need to set the gap between pickup and rotor/shaft). If you put the magnet backward on the pickup it wont work correctly.(i know, probably not your case here.). And of course the wires have polarity too.

MSD want you to check the supply +12V at the coil. Probably just trying to rule out any electrical wiring problem since the ignition draw more current at higher rpm AND to have a guess if it work at all at different rpm.

Am pretty sure the new distributor will fix your problem.
You changed spark plugs too?(did you change anything else?) did you go from non-resistor type to resistor type or vice-versa?
I use to run non-resistor(cuz thats all i could get at the local store), but resistor type are better for your onboard and neighbors electronics(thats what am switching to, R5674-6 to ur6(7773).. but then again some CDI ignition don't like resistor type(usually not a problem with MSD). Still worth checking to me..
 
Last edited:
I have always sprayed the cap and rotor with silicone inside and out and let it dry a bit and was told it would stop the burning and corrosion of both by the hot spark. Also with water proofing from rain and such. Once wires are on, spray them at the cap to seal good so water can't get get under the boots.
Are you talking about a silicone lubricant? What do you use?
 
I would never buy a distributor with a electrical circuit inside NEVER.
Gosh, what would you buy? Surely not a points type distributor...... right?

The magnetic pickup has a polatiry on the MAGNET(and you need to set the gap between pickup and rotor/shaft). If you put the magnet backward on the pickup it wont work correctly.(i know, probably not your case here.). And of course the wires have polarity too.
It has run just fine and the magnetic pickup and magnet were not loose when I removed them. There were no changes before the problem and the change in spark plugs was the only change, which did NOT effect the problem. MSD tells you about the magnet and they also paint two stripe on the magnet so you can install it correctly. Of course they could always label one incorrectly. That happened on the MSD forum and they had to use a compass to determine polarity.

MSD want you to check the supply +12V at the coil. Probably just trying to rule out any electrical wiring problem since the ignition draw more current at higher rpm AND to have a guess if it work at all at different rpm, if it short out or etc.
Hopefully the alternator has not gone bad. Can't remember what the voltage gauge has been reading.

You changed spark plugs too?(did you change anything else?) did you go from non-resistor type to resistor type or vice-versa?
Yes I changed spark plug from Champion to NGK (7373) FR5 and it is a resistor type plug.

https://www.ngk.com/product.aspx?zpid=9759

Thanks for the comments!
 
I use a magnetic pickup distributor with external electrical box(6al)

What was the champion plug type, resistor too? I know i did the crossreference, it should be the same type.
 
The reason I used the NGK 7373 FR5 was it cross referenced to the Champion RC12YC. The Champion is recommended by Brodix as a starting point. I was able to confirm this on the NGK website and my Excel file, although it does not look like an exact match. They give several possibilities. Going to a colder plug is certainly worth a try.

Check out the Cross Reference Excel file below:
http://garage.grumpysperformance.com/index.php?threads/spark-plug-cross-reference-excel-file.11698/

NGK Cross Reference
https://www.ngk.com/Automotive-NGK-l1411.aspx

FP03_SparkPlugCompare_6366.jpg
 

Attachments

  • Nomenclature_NGK_Info.pdf
    82.8 KB · Views: 0
the difference in seat diam. is not critical to the plugs function.
looking at the picture above it looks like you've got significant fuel ash or fuel additive residue built up,
on that ground electrode and just looking at the picture makes me think that plug heat range is a bit hotter,
than what Id guess might be ideal,
as the porcelain and ground electrode seem to extent a good distance out into the combustion chamber.
now the plug from what I can see does not look like its running hot , ill easily admit that ,
but Id like too see several other clear detailed pictures from several perspective angles
 
I beleave the stock ACDelco for the sbc 350 is the R45TS wich is equivalent to the NGK heat 4.
NGK - 5 is usually a great choice for most NA motor or NGK - 6 , not any colder unless you run nitrous or a turbo/blower then a 7 or 8 will do.
What do the NGK look like? do you think they are too hot?
I was running NGK - 8 to be on the safe side with the blower/break-in but it was way too cold so am switching to ngk 6.
 
Rick, I was reading an article in Sept 17 CarCraft - "Swapped & Boosted", pg 62.
I tried to find a link - NADA.
An engine being tested would not rev beyond 5500 rpm.
On page 64, the article says, Eric's tuning experience came to the rescue. In the past, he's seen digital rev limiters become confused, causing ignition cutouts at lower than specified engine speeds. We had set the MSD box at 6800 rpm, but the limiter shut the engine off below 6000 rpm. He raised the limiter speed to 8000 rpm, and on the next test, our Tiny Dancer twirled right over 6500 rpm and peak power jumped to 502 hp at 6400 rpm.

Sounds similar to your problem. Eric is Eric Rhee at Westech Performance Group. 951-685-4767 WestechPerformance.com
Maybe you can contact him and pick his brain.
 
Back
Top