Help - RSR Clone Engine Not Firing
 

I need some suggestions from the collective experts here...

My RSR clone engine is a 3.0 twin plug with MSD, Bosch dizzy, 10.5 CR, headers and 46 mm PMO's. The engine has performed flawlessly for over 10 years with only normal maintenance.

I took the car out for drive with the wife this past Sunday and all was good. Car running perfectly as usual. I parked it, we went for a walk and came back about 2 hours later. The car started very roughly and could not be driven. It felt like it was running on one or two cylinders and there was a strong smell of gasoline. I had the car flat bedded home.

The next day I tried starting it in the garage. There were a couple of backfires but no start. I went back behind the car to find that fuel had been spewing from the header outlets. Lucky no fire.

I checked the sight glass on the PMO's and one bowl on each side of the engine did not show a bubble. I drained the fuel from the bowls, replaced the drain plugs and ran the fuel pump to observe the bowls filling. The same two bowls filled past the top of the sight glass. So I figure needle valves stuck open. This could make sense as I was running low on fuel and maybe some contaminants made their way into the valves. So I removed the carb tops and cleaned the needle valves out with carb cleaner. I reinstalled the carb tops and checked the bowl filling to find that all bowls filled to the mid level of the sight glass. Problem solved I figure.

Not so. While the raw fuel spewing is gone, the car will not start and only pops and sputters. So I think, maybe blocked idle jets. After all, whatever got into the needle valves could be blocking the idle jets. Running the car too low on fuel in the past has resulted in partially blocked idle jets. So I remove them and blow them out with compressed air.

No difference after cleaning the idle jets. I am thinking maybe something else in the carbs may be contaminated. Anyone have some suggestions where to turn next?

Maybe you have layers of things going on here? Could the reason the car wouldnt start after cleaning out the jets be that your plugs are now wet and not sparking?

I might try...
- Getting the garbage out of your tank.
- Changing/installing a better filter. I run 40 micron then 10 micron filters ahead of my carb and have never had a problem.
- Double checking your jets are clear again and your floats are at the right level
- Pull your plugs and check the gap and that they are dry
- Charge up your battery
- Then start it.

John

Thanks for your reply.

I did remove the top plugs, clean and check for spark. I also checked compression while I had the top plugs out. No problem there. I run three filters with this set up. One downstream of the pump and one each at the carb inlets. I am planning to try starter fluid into the air horns while my wife cranks to see if it's fuel or ignition.

Any other idea welcomes

Tom, i feel a bit like the grashopper talking to the sensei, but is the fuel pump on your car one that has to have the outlet pressure stepped-down for the carbs? If so, is it possible that the regulator has failed, allowing has to enter the carbs at too high of a pressure, and thus buggering up the action of the floats? Best of luck, John

John

Thanks for your input.

I am running a Holley Blue pump in the smugglers box with an in-line downstream filter without a regulator. I can't think of a scenario where the fuel pump pressure would suddenly increase. I will keep your suggestion in mind.

Won't start...
 

Tom,
Seems like you have gone through the fuel system. If you no longer smell fuel, maybe the fuel issues were coincident with something electrical? Did you say that the plugs were arcing correctly? Could the twin plug dizzie have moved? Any way to check the MSDs? It's either fuel or spark.... :)

Speedo

sounds like the floats are hung up. if the window has no sign of a bubble the floats are too high and allowing fuel to gush... not likely to drop back down with the bowls full of fuel no matter what you do. drain the bowls again and look into how the floats are set, maybe more clues will be revealed.

Lars

Thanks for the input. I have checked for spark by pulling the plug wires and grounding a new plug against the fan shroud while my wife cranks. Looks like a strong white spark.

Car 311

I have corrected the float problem and now have good float levels. Still does not fire.

replace the plugs

I'm thinking an issue with the MSD.. We had similar symptoms on a Colombo V12 with upgraded ignition and it turned out to be the MSD.

MSD on a Colombo V12? I dont mean this harshly but holy cow...talk about time warp!

Yep.. makes them fire very precise and clean... of course the box is hidden from view. ;)

'73 so I take it no cat that could plug up?

Well still no joy today.

This morning I changed the top plugs out and disconnected the bottom plugs at the distributor. I figure the top plugs should be enough to fire the engine and removing the bottom plugs takes away one variable. I removed the air cleaners and sprayed starting fluid into the air horns while my wife tried to start the car. No start . Only pops and flame out the exhaust.

So I figure I've narrowed the problem to the ignition.

So, I figure that I created another problem in my efforts to fix the original stuck needle valve issue. The only thing I did to the ignition was to remove the plugs, plug wires, cap and rotor. So I figure maybe I disturbed something in the ignition wiring. I removed the top plug wires and checked them for resistance, I know from previous experience that the combined resistance of the wire and Beru connector should be around 5-8 K-Ohms. I found 3 of the 6 to be shorted or in the M-ohm range. I think the connectors at the distributor were not robust enough. so I replaced the wiring and connectors in all leads until I had 5-7 k-ohms in all leads. So I cross my fingers, install all the refurbished wiring and try to start the car. No difference still a couple of spurts out of the exhaust but no fire.

Ideas??

I assume there are two msd units with the twin plug set up? are the connectors for each msd to the motor harness the same, and/or are they clearly defined? with all due respect could you have plugged box A into box B's harness connector?

that or buy a single msd box crimp it all up with fancy connectors and swap them out one at a time...

Green Distributor Wire?

I am running a single MSD driving two MSD Blaster coils. I have verified that I have spark by removing an ignition wire lead and connecting it to a grounds spark plug while the engine cranks. Clearly visible spark.

It seems like a weak spark or a timing/firing order problem.

Have you checked the distributor rotor for cracks or burn marks? Also clean the post inside the distributor cap.

I had similar issues as you, but cleaning the jets and draining the bowls cleared everything up, mine was a result of rain so now I only use the rain hats.

I had to clean the jets a few times, I used some thin wire and then blew air through.

I did check the rotor for damage and used a small wire brush on a Dremel to clean the contacts on both the rotor and the cap. I also checked the contacts on the rotor and cap for continuity.

Cap on 180° out?

I wish it was that simple. The cap has a mistake proof locating pin that allows it to go on only one way.

I had a bad MSD once. I sent it to MSD and they turned it around really quickly and the service was very reasonable. I dont think I had any spark though when it went bad.

A few more ideas:

Swap the MSD box for a known good one

Jumper 12v power directly to the MSD to bypass ignition circuit

Check valve clearances

Sounds like you have thought of everything, perhaps the ground wire on the MSD could be failing? Fully charged battery?

Check the plug wire sequence again, you might have them mixed up.

Check the timing, maybe your distributor turned, pull some timing out to get it started.

I really don't think it's ignition related, I think you have a fuel problem, pull all the plugs see if they are wet. Pull the tops of the carbs again and clean out the bowls and jets.

I'm no expert, but if a bad MSD could cause out-of-time ignition pulses, it could completely destroy an engine. This seems like a very unlikely failure mode. The fact that you're getting regular spark pulses suggests to me that your MSD is fine.

You can test for weak spark easily; just vary the distance at which you hold an empty spark plug wire from a ground. It's easy to shock yourself with this test, so either man up or take precautions. :) You are looking for the spark to jump a good 10-20mm.

I would not adjust timing, thus complicating your diagnosis, but make sure the dizzy isn't loose, check for shaft play, etc. This also seems unlikely to be the source of your problem.

I would check each plug to see if the problem is limited to certain cylinders and to verify fuel delivery. Sometimes we use a laser thermometer on each header, just past the flange, to more quickly identify the quality of ignition in each cylinder.

Did you fuel up during the last successful drive, before parking the car for dinner? Is it possible that you got some bad gas, or water in the tank? Hold a rag over an empty spark plug hole and try to start the engine, to eject fuel into the rag. Sniff the rag. No, not that deeply. ;) Does the fuel have a strong scent?

Problem solved. I checked the timing and it was advanced at 35 deg BTDC while cranking. I removed the distributor and reset the static timing to about 10 deg. It fired right up and ran beautifully.

I will be changing out all (3) fuel filters as part of the spring tuneup this week.

Thanks for all the input.

Tom, I was about to ask for an update. Glad she's fixed. John

Did the distributor slip? I had that happen once.