Engine Misfire - The Saga continues

[Rick Parker]

Do you have compressed air? Blow some into the air bleeds.

[Terry Stapley]

Last evening after receiving all of the great suggestions from forum members I went to the garage and dove in!! I:

Checked that the plug wires were indeed in the correct firing order - check

Checked Dist. cap again for anything abnormal - raised the spring steel contact a bit just to make sure of contact - check

As per suggestion I removed the alternator belt - check

Used Carb Cleaner again on the air bleeds - the idle air bleeds(Toward the outside ?) were clear on both the primary and secondary sides - The high speed air bleeds (Center two ?) on the secondary side were clear but the primary air bleeds kept blowing back carb cleaner so I perservered and finally got those two clear

Checked the plugs on the two offending cylinders and they were a little dark but not wet - check

I did the MSD instructed spark check for the 6AL box - good spark - check

I then fired the engine and it ran fine but was idleing a lot faster then it used to so I lowered the idle with the idle adjust screw - I let it warm a bit and shut if off to put the alternator belt back on - Fired it again and again it ran fine - All header pipes were hot enough to flash water sprayed and the RICH exhaust smell was gone (Wife was happy with this)

I did all of this in about an hour and 15 minutes as I had another commitment
and I will fire it again this evening to see how it runs, but as for now it seems okay!

I really have no clue as to what the issue was as I changed more than one thing at a time because of the time constraint but the idle speed being different leads me to believe that the carb was the culprit.

Thanks for all of the suggestion!! You guys are the best!!

[sharpe 1]

Maby it was a stuck float in the carb???? and flooding those cylinders.

[will butterwort]

moisture in distributor cap, will cause those symptoms, and/or a cracked distr. cap can cause misfire. A lot of good suggestions here, good thread.Good luck. Let us know. Will-alabama

[byron w]

Bobcat, What is the actual name of the MSD voltage/spike protector that MSD sells that you referred too in your previous post?
I can't seem to find it in Jeg's, Summit or on tne MSD website. I am not sure what I am
looking for.

Terry, I am not trying to hijack the thread.

Thanks,
Byron W.

[patrickt]

Originally Posted by byron w

What is the actual name of the MSD voltage/spike protector that MSD sells that you referred too in your previous post?

It's just a big-ass capacitor -- MSD #8830. Here's a shot of mine mounted next to my MSD box. You can get it from Summit for $39 -- here's a link:
http://store.summitracing.com/partde...700+4294922537

[byron w]

Thanks Patrickt, I didn't have a clue what to look for but I figured with a 100 amp alternator that I may need this thing for my MSD ignition.

Thanks again,
Byron

[Bobcat]

Byron ... you should be more concerned with voltage spikes than current , as voltage fluctuations/transients are what kill the MSD system ... and other electronics . This normally happens , for example , if you jump start your car ( connecting/disconnecting the jumper cables ) or switching some accessories on and off . This causes your voltage to do weird things ( transient spikes ) that can hurt the MSD . For lack of a better description , this is a noise filter ( surge suppressor/clipper ) and it must be located such that it filters the power going to the MSD system .
You could probably get one at the local Radio Shack ( around 25 k to 50 k microferrads and 16 vdc ) , but in all honesty , the MSD unit is such a neat package and comes with instructions and mounting hardware , it`s hard to beat .

[Ronbo]

Actually the best filter would be a combination of a choke (coil) in series and a capacitor in paralell. Chokes work much better at blocking the pulses than caps do.

If you have a 2-way radio shop near you stop by and see if they have any of the Motorola filter kits. The car battery is basically like a huge capacitor and provides most filtering in your electrical system but high frequency spikes can still ride on the system. The choke filters by magnetic fields as opposed to static fields like caps.

The secondary (low voltage) winding on a power transformer will also work.

[byron w]

Thanks Bobcat. The spikes are what I am concerned about. I just figured with the 100 amp alternator and external regulator that the spike protector would be a good safety precaution. I will use the MSD product.

Thanks again bobcat and patrict t
Byron

[Bobcat]

Ronbo .... don`t disagree at all with what you said . My warped logic was that MSD recommends this a surge suppressor . If there are any problems down the road , you can say that you are using their recommended protector and that takes away one possible stumbling block to any warranty issues .
I got to be more familiar with transients than I ever wanted to as I used to design DC power supplies for the steel mills and Titanium plants for vacuum arc melting . These put out 10,000 amps DC @40 load volts and during arc strike conditions , you would see some horrendous voltage transients . Our input voltages were either 4160 VAC or 13.2kv and direct short circuits gave us currents as hi as 40,000 amps and voltage at zero until the arc was re established and then the voltage spikes went crazy . We also used everything from capacitors to crowbar circuits to Klipcells .... some worked and some didn`t , but if something was used we didn`t recommend , we voided warranty . That`s why I recommended the MSD capacitor .... again , I don`t disagree with anything you said as you are correct . This was just my reasoning .
Byron ... you`r welcome and this capacitor from MSD is cheap insurance . Good luck !