Crossflow miss-fire / ignition cutting out

[fwester]

I would like to thank all of you for the very quick and specific suggestions / recommendations how to get this fixed. I am half way through the 'shopping list' and keep you posted once I have identified root cause(s). Just getting used to the forum / system and apologies for not knowing yet how to best thank each individual with a response.

 

I have a 1700 Crossflow (upgraded by Roger King - fantastic engine) with an Alpha 3D ignition kit. Unfortunately I have had several intermittent issues recently (not good at the start of the season...) Here are the symptoms / findings:

1) loss of power - feels like the ignition is being cut all of a sudden

2) big bang from the exhaust

3) similar noise from the carburators (40 Webers)

4) occasionally can get the revs up and being able to drive again

5) while obviously (or at least it felt like) not running all al cylinders the rev limiter light comes on at very low revs (light flashing)

6) issue appears with cylinder no. 2 - checked spark plug - wet / oily after several attempts to start

7) exchanged spark plug no. 2 - all 100% ok for 50 miles before issue occurred again

8) checked spark plugs - all ok apart from no. 2 again - showing showing really black carbon surface

 

Stopped playing with it in order to avoid potential massive damage. Not a happy bunny as you can imagine. Any help / advise would be very much appreciated. Thank you.

 

 

Edited by - fwester on 2 May 2012 10:36:19

[6speedmanual]

Lead?

Can be intermittent and temperature related.

If two of teh leads are approx same length, change them over and see if problem moves with the lead. Or get the engine hooked up on a Sun Tuner where teh ignition signal can be put on the oscilloscope.

 

When you get the loss of power is it a full engine cut or a partial reduction in power (which would correspond to one cylinder stoppingfiring)?

 

Peter

[Roger King]

It's worth a quick check of the alternator wiring first. As an initial check, make sure all wires and connectors to the alternator are in good nick.

 

You can also try bypassing the alternator and running on battery only for a short while. Make sure the battery is fully charged first, and if the symptoms go away, the alternator's your problem.

 

Edited by - Roger King on 29 Apr 2012 23:58:45

[Mcalvert]

Could be many things, but sounds suspiciously like the problem I have been chasing on my 1700 x/flow for a while and have just diagnosed. in my case, the bolt holding the trigger wheel onto the crank had come loose, meaning that the trigger weel was stopping in different positions each time I turned the engine over (it is keyed into the crank pulley, but the key pin had sheared under the strain)

 

Worth checking?

 

Otherwise, I suggest

 

- checking that you've got a spark at the king lead and at each of the spark plugs

- changing coil, rotor arm, distributor cap, plugs (all cheap parts, and if they don't do the trick, worth keeping in as spares anyway!)

 

Best of luck Michael

[elie boone]

If it's only cil n°2 plug that is sooty check first your ventury grub scew. Otherwise if you can run without rev limiter to exclude it to be faulty.

[Eugene]

I had the rotating ventury issues as well - a real bugger to spot as it rotated exactly 180 degrees!

 

😳

[Baz Hemsley]

Similar problems with my recent re-build. fault eventuality traced to Aldon ignitor in distibutor. Burtons out of stock and Aldon direct awaiting back order. Redline again to the rescue, with replacment from stock.