Distributor Help

[Tulsa cobra]

I have a Roush 427 SR/TW, about one year old, came with a MSD 6AL ignition, blaster coil and a MSD Pro Billet Ready to Run distributor #8354. Ran like a top, did not have one single problem, however, went to start it about 3 weeks ago, and the engine would turn over and not fire. I used the paper clip test and noted spark from my coil to my main distributor plug, but not from the distributor to the spark plug. Most likely a bad magnetic pick up, this model has to be sent back to the factory, and cant just have the pickup replaced, sent it back, they confirmed that it was actually the small microprocessor chip that went bad, they replaced and sent it back. Prior to sending I marked both the distributor housing with two different scratches on it to align with the block as well as three different points where the distributor was pointing. I replaced it exactly where it was. I never took off the spark plug wires and left the attatched to the distributor.

I turned the engine over, it does not run, but when I give it a little gas, I get a backfire that comes out of the carb.

I called MSD, they told me to remove and clamp the vacuum secondary and plug the end at the distributor, still same problem. I then reconnected and advanced it about every 2 degrees for a total of 50 degrees, then retarded the same, still the engine would never run, just back fire.

I turned the engine to about 14 degree BTDC and removed the distributor cap and it was pointing just before the number one plug, which proves to me that it is correct. I pulled the number one plug and turned the engine over and got a good spark.

Still same issue, never once even tried to run rough, just nothing until a little gas then backfire.


I am at my wits end, I do not think anything else could have changed. When I removed the distributor, I did not move the car an inch, or turned the engine over, i chalked the wheels, applied the handbrake and left the garage basically locked until I put the rebuilt one on.

Because the engine doesn't run I can not check the timing.

Any thoughts. I am not very mechanically incline.


The only thing odd is that it comes with a grey wire used for the tach, but I talked to the builder and said I do not need that wire and can clip it off due to the fact the rpm is controlled by the ignition box,which is the way he had it set up. The one I removed had it clipped off and again worked great.

ANY help is appreciated.

[scootter]

It could just be 180 deg off. That will give you back fire out of the carb.
Scott

[Tulsa cobra]

Hopefully, to correct this, I cant turn the housing 180 because the vacuum would be hitting the block.

Can I switch the order of the plugs on the distributor

[madmaxx]

Turn your engine over until balancer is pointing at zero degrees. You should be pointing towards #1, or 180 out. It sounds like you are one 180 out, so rotate engine to zero pull cap and if pointing to 0 rotate enigne again to zero, pull dist and turn to point to #1.

[grybrd123]

I had a similar experience this summer. I got a new Roush 427SRX, came with the same distributor you have. This was a warranty replacement for my previous Roush 402R (used a quart of oil every 300 miles and could not be fixed). The previous motor came with a different distributor that ran through a 6AL box, no problems. When we installed the new motor with the different distributor it came with (same as yours with both mechanical and vacuum advance) we could NOT get proper mechanical timing with the vacuum disconnected and plugged. I talked with Roush, talked with MSD, etc. We got it to run, but instead of the nominal 16 degree mechanical advance (16 initial, total was supposed to be 32) we got 16 initial and over 40 total. It was worse with the vacuum connected. We fooled around with it and set the mechanical advance at 10 initial, which gave 34 total, and it ran OK, but that's still too much advance, and the idle wasn't very good (too retarded). Ultimately we simply removed the 6AL box and ran the coil directly from the distributor.

Voila! 17 and 31 degrees of advance, problem solved. The distributor has its own circuits so it doesn't need the 6AL to run, and the two don't play well together. MSD instructions for the distributor include a wiring diagram for the 6AL (available on line through the MSD site), and we wired it that way, but it screwed up the timing. The 6AL doesn't do anything above 3000 RPM anyway, so it's not needed.

You can do the same - I bet it solves your problem.

grybrd123

[Tulsa cobra]

I advanced the plugs 4, to simulate that it is firing 180 out, so 6 was the new one. It ran, a little rough, but ran. So I assumed I was 180 out. So I pulled the distributor, then I rotated then engine to TDC, pulled the cap, the distributor was at one, I rotated the engine one turn to TDC, put the distributor and put it back so it was at one again, fired it up and it backed fired again.

Some how I got it 180 out again.

[Tulsa cobra]

Apparently, when i had my wife tap the engine over, it actually went past. I pulled the plug, put my finger on the number one and felt the compressive stroke. Took off the dist and it was pointing at 6, 180, so I pulled it and put it at one, turns over, just need to retime it.

[madmaxx]

Whats the difference between the srx and the sr???