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Engine Problems (misfire?)
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TOPIC: Engine Problems (misfire?)

Re: Engine Problems (misfire?) 9 years, 10 months ago #18926

  • BritRacer
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  • Seasoned Racer
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Here are the plugs I changed to at the track they were brand new and only in the car for a single race. As you can see #3 is all black again. It is not wet to touch so is this an indication of it being rich?
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Jason Jane
Norcal

Re: Engine Problems (misfire?) 9 years, 10 months ago #18927

  • joeblow
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  • Seasoned Racer
  • Old Racer
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A quick track test would be to move that injector to another location. If the problem follows the injector well you found the issue. I think it is oil fouled though. Could be valve stem seal, piston ring, cracked block/head.

Start with the injector though. Could be a bad plug lead too which you could swap with another one.
Old Racer!

Re: Engine Problems (misfire?) 9 years, 10 months ago #18928

  • BritRacer
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  • Seasoned Racer
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Thanks Joe.

I was wavering between the 2, but it was not sticky to touch so went the other way but maybe that is just because the car has not been run awhile. Don't think it is the leads as we changed out those at the track and still saw the issue. I am leaning more to valve stem seal.

I plan to do a leak down test after Christmas, which may help in the diagnosis. There is not froth in the water which I hope rules out the cracked head/gasket.

Thanks

Jason
Jason Jane
Norcal

Re: Engine Problems (misfire?) 9 years, 10 months ago #18931

  • joeblow
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It may not be the leads but it also could be the distributor cap. It can be cracked or fouled on one post.

I still think it is oil though.

I have seen cracked heads leak ONLY oil and not pass water. Though it is pretty rare. As a side note. Does the injector itself look dirty? If it is leaking (not closing all the way) it will be very black as well. Of course a leaking valve stem seal will get the injector dirty too. If you pull the intake manifold and see a oily sooty intake port on the cylinder you know it is not the rings too.
Old Racer!

Re: Engine Problems (misfire?) 9 years, 10 months ago #18939

  • BritRacer
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If I find it I be the rings, does anyone have recommendations for replacements? I have read in a few places neither the Goezte nor the Porsche genuine rings are guaranteed to meet the gap requirements on high mileage engines. It looks like Lindsey do a set designed to be filed down to the right gap but are these allowed within the rules. What do people normally do in this situation?
Jason Jane
Norcal

Re: Engine Problems (misfire?) 9 years, 10 months ago #18940

  • tcomeau
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I have no prob with Lindsey piston rings. " aftermarket parts...no change in performance or weight may be used..." PARAgraph 2.1 of the rules. Using these rings can actually help keep some "loose" blocks in racing service.
Tim Comeau
SoCal 944 Spec #22 since Feb 2003.
Let's keep building it!
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