Need MSD help, have a miss and advance issue

[CGT80]

Philly 87 helped me out in the past, but he hasn't been on in a while and his in box is full. I had typed a message to him. Maybe you guys have run across the same problem as me.


I have what feels like a miss. It will run rough at idle and sometimes will accelerate slowly. Other times it runs like a rapped ape. I pulled one wire at a time and started it back up, but each time it had a far worse miss than it has had. This lead me to believe it wasn't one bad wire or plug.

I changed out my cap and rotor with new MSD parts, but that didn't fix the issue. I changed out the taylor spiro pro wires with a new set but it still seems to idle rough. I also noticed my tach would bounce all over sometimes when idling or driving. It would go from 1k to 5k. I was going up a hill at 70 mph when it happened one time. The timing must have gone way advanced as it started to ping like crazy. Around town and idling it has caused the engine to accelerate a bit when it does this. I also have interference with my radio. I redid most of the wiring in my truck last year. It had been running good since then.

I need to double check the ground to my retard box, but everything else should be good. I was careful with my wiring and made sure I had good connections and clean grounds. I soldered most of my splices and used dielectric grease on everything.

The HEI coil is original to the distributor, which is from 2003 and has 150k+ miles on it. The shaft of course, is only a year or two old since msd sent a new one. I have replaced the pickup before. The retard box seems to work when I use the knob in the cab to retard the timing.

I need to put a timing light on the engine to verify it is still where I had it. I kind of skipped that since the distributor hasn't moved since this engine was rebuilt last summer. It only has 4k miles on it since the rebuild.

Here are my parts:

MSD 8365 distributor
MSD 84281 vacuum advance stop plate
MSD 8782 adjustable timing control
Moroso 72315 adjustable vacuum advance canister

Thanks,
Chris

 

[dyeager535]

I'm not familiar with those parts, but if it appears to be a timing issue, can you bypass the adjustable timing control and rely on vac/mech advance only?

 

[AR_K5]

What truck/motor is it?

I know a lot of folks who have spent piles of cash on colorfull MSD stuff and another bunch who'd say "well there's your problem, throw that thing away". Again

 

[4X4HIGH]

Disconnect your tach and see if the problem goes away, I had a tach fail on me one time years ago and had the same symptoms you're having now.

 

[CGT80]

i would have to rewire the dizzy to bypass the retard box. it replaces the module in the dizzy. Engine is a sbc 406 10.2:1 blue printed and balanced, forged crank which has been trued/blueprited and all roller valvetrain. comp 262 or 264 hydraulic roller cam, aluminum heads and intake and both have major porting work. The engine has 4k miles on it now and was running great. I am not willing to dump the msd setup since I have a bunch of money into it and the engine is far from stock. I will fix or replace what needs it. Estimated for about 400hp and 525 tq. It only gets run to 5k rpm most of the time. The low end torque is great as it was built for that.

The tach is an autometer ultralight procomp 5". It seems to work fine. I can sometimes hear the ignition make sound when i turn the key on. It makes me wonder if the ignition module in the retard box is messing up. That box does conrol the retard so maybe it can advance if it malfunctions. The mechanical weights felt fine when I did the cap and rotor.

i called phil at msd yesterday and left a message. I haven't heard back and I didn't try msd in general yet. I will try them on monday.

 

[ryoken]

yup, annoy tech support till you get a resolution...

 

[4X4HIGH]

yup, annoy tech support till you get a resolution...

Better yet would be to disconnect the tach to see if the issue is still there. I've had the exact same issue before and the tach was the culprit. Yes Autometer is probably the best there is but that doesn't mean they can't fail just as any other brand. At this point it is the easiest thing to try and doesn't cost anything to do so.

 

[AR_K5]

What fuel delivery system?
Have you started it in the dark to look for jumping fire?
Have you looked at the plugs?
Any smoke?

 

[CGT80]

I changed the cap, rotor, and wires. I wondered if it could be a plug. I haven't checked them yet. I think I did get new plugs when I put this engine in...........of course it doesn't mean they couldn't fail. Pulling some of the plugs is a royal PITA with those headers and the AC so I didn't go there yet. I had the noise issue and rough condition with bad wires before. The tach is a good and free idea.

Fuel is an edelbrock mechanical pump and an edelbrock performer 600 cfm carb. The carb might need a kit again. The accelerator pump was crappy when I put it back on the truck, but the fuel seemed to get it back into shape. There was some crap in the bowls. I had a hard time starting it over the winter, although it doesn't get below 40 during the day here. Now it starts fine, so maybe it was just my choke. I though that maybe the fuel was leaking through the bottom of the bowls as I have been told there are plugs in that carb that are prone to leaking.

I haven't noticed any smoke. I do have a 3" single exhaust system with a cat and flowmaster 70, that exits in the stock location. It has tri y thorley headers. I wonder if the cat would hide any smoke.

The new cap and rotor come with two different buttons for the coil. I used the one that had less resistance with my multimeter. They both looked the same, although msd's instructions state that one is all bronze and one is black with a bronze stripe. Both of the new ones looked all black. They state that the button will sometimes cause problems if it has too much resistance. I will have to ask them if I may have got the wrong ones, although this problem popped up with the old cap and button (which worked fine in the past).

My initial timing is 11-12 degrees advanced and ported vac advance so it idles at 11 degrees. Centrifugal is another 21 degrees and should be all in at 3500 rpm. That gives me a total of 32-33 under load and I think my vac advance stop is set for 16 degrees. The vac can is set so that it doesn't advance with less than 7 inches of vacuum.

Thanks for the advice guys. I doubt I will get to mess with it tomorrow, but maybe Monday I can try some stuff and call MSD again if needed.

 

[chulisohombre]

If you still have the stock plug for hei you can just plug it into the distributor like normal to bypass the msd box and run the dizzy without it to see if it is a distributor problem or msd box or advance. It will eliminate those two and make sure the dizzy is sending correct spark without the box. I have a stock diz though so I'm not sure how the msd one hookup compared to a gm.

 

[CGT80]

If you still have the stock plug for hei you can just plug it into the distributor like normal to bypass the msd box and run the dizzy without it to see if it is a distributor problem or msd box or advance. It will eliminate those two and make sure the dizzy is sending correct spark without the box. I have a stock diz though so I'm not sure how the msd one hookup compared to a gm.

That won't work. To run that retard box, you have to take the ignition module out of the bottom of the dizzy and wire the pickup right to the retard box. The box has a module built in. I originally didn't take the module out of the distributor and I had issues. I got msd to clarify that I did have the 4 pin module in the dizzy and not the 5 pin, which could have stayed. I was counting the ground as a pin. I would have to reinstall the module in the dizzy and cut and splice wires, so it is not quite that easy to do.

The 8365 dizzy is the same as an HEI, but in my case, the module is removed to run the retard controller. It takes stock parts rather than the parts that most of the other msd's take. The pickup is stock style. MSD has a pickup that says it works on all msd distributors, but it doesn't work on the HEI, so now I have one sitting on the shelf in the garage with no use for it.

 

[Chevy305]

Why do you need a retard controller? You don't run crazy timing or have super high compression so I can't imagine you need it for faster cranking/starting.

I'd find an ignition module and bypass the box to see if that's you problem.

 

[AR_K5]

Have you been on any rough terrain?
The reason I ask is the floats in those Edelbrock 1406's are prone to bending if they get bounced very much.

My truck had that same carb when I got it. It was great on the paved roads, but worthless on the trail. I tried resetting the bowls and using the spring loaded needle valve, it was all for not. I junked it and got a new (rebuilt) Q-Jet

This may be totally unrelated to your issue but is something to consider.

 

[chulisohombre]

Ok I see. Them it kinda sounds like maybe that is having issues. I would double check all my connections again and see if something is loose. Bad power or ground to the msd box on mine and it has a misfire. It will also make the tach bounce like you are saying. It has to have a solid power supply or it will sent a weak signal to fire. I wired mine in so if the msd box goes out I can just unplug the pickup and put it back to stock hei and run itself separate of the box. I have a older 6a from the 90s also. I heard some of the newer boxes have a lot more issues.

 

[CGT80]

Why do you need a retard controller? You don't run crazy timing or have super high compression so I can't imagine you need it for faster cranking/starting.

I'd find an ignition module and bypass the box to see if that's you problem.

The distributor mechanical advance was not working right when I did the first 406. It was advancing way too fast. I ended up getting a new shaft with weights and springs from Phil and that solved it. The retard control for in the cab was to address that issue (which I wasn't aware of because I assumed I was getting what the chart showed) before I knew I had bad parts. The truck weighed 6500 pounds or so with my tools for work and it would ping when the weather got at all warm. I also have a toy hauler trailer that weighs about 9k pounds which I tow with this truck. The first build of this 406 was supposed to be 10:1. It obviously didn't like that quick of an advance.

I set my timing to be all in at 4500 rpm IIRC, the slowest curve, and pulled my trailer after I got the new dizzy shaft. It pulled just fine. I probably don't need the box now, if I keep the advance rate slow. I have however stepped it up a couple notches for everyday driving as it responds better, so I might need to retard it a tad if I pull the trailer.

Have you been on any rough terrain?
The reason I ask is the floats in those Edelbrock 1406's are prone to bending if they get bounced very much.

My truck had that same carb when I got it. It was great on the paved roads, but worthless on the trail. I tried resetting the bowls and using the spring loaded needle valve, it was all for not. I junked it and got a new (rebuilt) Q-Jet

This may be totally unrelated to your issue but is something to consider.

I have only been off road once since I got the engine back in. I am thinking it is time to check the carb and put a kit in it. It sat for a few months while the engine was built so it had some build up and the accelerator pump had shrunk.

I was considering rebuilding my 795 q jet and running that. The first version of this 406 was still pulling vacuum at wide open throttle, which seems to mean it wants more air. I would have to tune the q jet to be able to pass smog. The carb is legal but it is tuned for a performance engine without regards to smog.

Ok I see. Them it kinda sounds like maybe that is having issues. I would double check all my connections again and see if something is loose. Bad power or ground to the msd box on mine and it has a misfire. It will also make the tach bounce like you are saying. It has to have a solid power supply or it will sent a weak signal to fire. I wired mine in so if the msd box goes out I can just unplug the pickup and put it back to stock hei and run itself separate of the box. I have a older 6a from the 90s also. I heard some of the newer boxes have a lot more issues.

I wondered about bad connections. I made sure to clean the grounds to the coil from the hei connector on the dizzy. The other wiring was cleaned up when I put the engine back in. I do have a relay tied into the power for the ignition. I tried another relay, but I could put a jumper wire in the socket to bypass that possible issue.

Another odd thing: My gear vendors overdrive will randomly shift out of overdrive and the lights indicate it is waiting to shift but hasn't reached speed. I have had to pull over and shut the truck off, then restart, and it then works fine. It seems more like maybe there is interference with the gear vendors computer than a bad connection.

I have the original ignition module for the dizzy. I just hate pulling or even working on the distributor. It kills my back to work on the back of the engine. If it comes down to it, I can go that route. I have all the wiring neatly covered in split loom and taped up with rubber tape. The under-hood paint is new two stage satin black. It looks very nice and factory like, and I also don't want to dig into that again. I took time to reduce splices and I soldered and heat shrinked most of the splices that I did have. I would be surprised if the problem is in that wiring, but I might have to get back into it if the other ideas don't show anything.

 

[chulisohombre]

Sounds like you did all the wiring good and shouldn't be the problem. Anywhere you can check voltage that's uncovered at the coil and grounds you can do without pulling your other wiring out. You can just check the voltage across the relay by voltage meter on the input and out put side and see if there is a voltage drop. With the msd box it has to have full power to it or will not work correctly. Mine won't even fire is the voltage is below 11.5 volts. Jump start it it pops right away. Something else to think about. On my stock hei I left the module in and just hooked up the electronic pickup to the msd. That way it's still usable if need be but out of the system and running off the msd. I'll have to look at the msd dizzy and see how that one is wired up. Good luck. Wiring is a mess sometimes.