Title: Which spark plug? Post by: davvide on April 14, 2012, 12:26:29 pm Hi guys,
on my engine, 90,5 x 76 with 48 IDA and 9:7:1 rc, I used untill last year NGK spark plug D7EA. Last year I have reworked the heads (cb 044) but now the spark plug after few km are burned. I know that the heads temperature is increased after the job and now I'm waiting to try NGK D6EA, a little bit hottest than the 7. or maybe is better a coldest one?! Which kind of spark plug do you use on your street/strip engine? Thank in advance! Title: Re: Which spark plug? Post by: richie on April 14, 2012, 15:38:39 pm What is the compression now?
It sounds like it is maybe lean,or to much timing,not a spark plug issue,I have used d7ea in 500hp turbo engines and 12/1 compression N/A without any problems,if you want to try a diffeent plug you need to go to a d8ea not a d6ea cheers richie Title: Re: Which spark plug? Post by: davvide on April 14, 2012, 15:48:42 pm Hi Richie,
thanks for your suggestion. Now the compression ratio is 9:9:1 So is better a coldest one not the hottest? if I have more degrees on the heads I need a spark more cold? Title: Re: Which spark plug? Post by: richie on April 14, 2012, 16:09:52 pm Hi Richie, thanks for your suggestion. Now the compression ratio is 9:9:1 So is better a coldest one not the hottest? if I have more degrees on the heads I need a spark more cold? Higher compression=more heat needs a "colder plug" [runs colder so less likely to create detonation] but you really shouldnt need to move on the heat range from the d7ea,it proberly needs more fuel[bigger jet] how much total timing do you have? cheers richie Title: Re: Which spark plug? Post by: davvide on April 14, 2012, 16:59:21 pm I had 10° to advanced but I need to check it to be sure.
I've 165 for main jet with F7 emulsion tube Title: Re: Which spark plug? Post by: richie on April 14, 2012, 17:06:52 pm I had 10° to advanced but I need to check it to be sure. Total timing try max 30,and what size idle jets?I've 165 for main jet with F7 emulsion tube cheers richie Title: Re: Which spark plug? Post by: richie on April 14, 2012, 17:07:29 pm Can you post a pcture of the spark plugs so we can see what they look like?
Title: Re: Which spark plug? Post by: davvide on April 14, 2012, 17:31:16 pm Yes,of course:
(http://img571.imageshack.us/img571/4075/20120414182611.jpg) idle jet is 55 f10 Thank you very much Richie for your help Title: Re: Which spark plug? Post by: richie on April 14, 2012, 18:18:29 pm Yes,of course: (http://img571.imageshack.us/img571/4075/20120414182611.jpg) idle jet is 55 f10 Thank you very much Richie for your help That doesnt look to bad to me,it really depends on how you were driving it just before you turned the engine off,to long idleing and it will only show whats happening in that period,maybe try a 60 idle and see how it behaves,whan you mentioned it being to hot in the 1st post,do you mean just cruising or when you are pushing it hard? No problem to help,I am supposed to be building an engine,but everyone needs a break for a beverage/Tea ;) Title: Re: Which spark plug? Post by: davvide on April 14, 2012, 21:07:21 pm or a beer! ;D ;D
I haven't this kind of problem on the strip but in that case I usually change the main jet from 165 to 175. The spark burned only in normal use, when I don't go too much fast. Before the job at the heads I had no problem. After that I used for 2 month the car with the same setting but I thought was more rich and I moved to 165 main jet. Maybe the problem is only that ??? Maybe I can try to use the 175 all time and try 185 on strip Title: Re: Which spark plug? Post by: richie on April 14, 2012, 22:39:39 pm or a beer! ;D ;D I haven't this kind of problem on the strip but in that case I usually change the main jet from 165 to 175. The spark burned only in normal use, when I don't go too much fast. Before the job at the heads I had no problem. After that I used for 2 month the car with the same setting but I thought was more rich and I moved to 165 main jet. Maybe the problem is only that ??? Maybe I can try to use the 175 all time and try 185 on strip With normal road use you are mainly on the idle circuit which is why i sugested going up a size on the idle,most of your driving will be done on this jet cheers richie Title: Re: Which spark plug? Post by: davvide on April 15, 2012, 21:37:28 pm I will try when stop raining!
>:( >:( thanks for help Title: Re: Which spark plug? Post by: DWL_Puavo on April 16, 2012, 08:10:58 am I made this cross-reference table for 044 spark plugs as I found out that these were quite often asked in finnish vw forum: http://dwl.fi/044_sparkplugs.xls
I've used D8EA (a bit colder plug) in our endurance racer without problems. Annoying thing BTW is that NGK (as well as Denso) plugs go hotter when the number decreases, and Bosch (as well as Champion and Brosk) ones get colder as their number decreases. Title: Re: Which spark plug? Post by: davvide on April 16, 2012, 19:29:10 pm Hi, I know that NGK became colder when number increase, maybe my reasoning was wrong!
Thank you for sharing, it will be useful and thanks for explain your experience Davide |