topher455

iTrader: (6)

Im curious. My lq9 has 243's on it which puts it at 11:1 roughly with a 230 236 cam. So I figured I should run a cooler plug. I used the ngk tr6 and it seems to miss alot at lower rpms and they are carbon fouled. The afr is kind of sparatic too probably from the missing. Im thinking they are a bit too cold and thats the problem. They are gapped at .045 and idle timing is ~17*


Open to opinions. Tks.

pt109

iTrader: (2)

I only have 9.5:1 compression and use TR55's @.045.
You say you only have 17 degrees advance at idle.
Is that including vacuum advance?

Ken

NemeSS

iTrader: (127)

usually i use tr55. the plugs may be to cold.is the car misfiring at idle?

topher455

iTrader: (6)

23* including vac advance.

Yea it misses at idle and low rpm. Im gonna swap them out for tr55 plugs. They are spec'd for ls2's which have 11:1 so I figure they should be fine. Any suggestion on gap? Factory spec is .040

I went through a few things on the carb tonight and it all looks good so I think its the plugs at fault here.

pt109

iTrader: (2)

That doesn't seem like nearly enough to me.

I have 30 degrees plus 6 degrees vacuum advance at 800 rpm.

I have a L33 with a dual plane edelbrock, msd6100, holley 600 with vacuum secondaries and comp cams xr269 cam.

I am using a 5 speed manual with 3.88 gears in a 2800 lb car with no knocking or pre-ignition and rarely using 1st gear. My total lead at WOT is 32 at 2000rpm, 34 at 4000 rpm and 36 at 6000 rpm.

I was having problems with the engine loading up with less advance as well. This seems to work for me.

I know that a lot of people say that LSX motors like a lot less advance, which is true for injected motors, but this works for me.

Ken

http://hatfield.homelinux.com/porsche_v8.html

billyflantos

iTrader: (6)

NGK R TR55 V-POWER....SET THE GAP AT .030.....before anybody says anything about the gap remember were running msd box's and with my experience they run better with a short gap....

forcd ind

iTrader: (7)

i run the tr6's, with a carb, and run it rich, never a prob.-i have around 30 degs timing at idle, back it down under boost-i think your problem is something else

topher455

iTrader: (6)

The car was really fat at first. Cruise and pri afr was 9-10 afr so that probably blackened the plugs. But after I leaned it out they never cleaned up. It is my understanding that if a plug is the correct heat range it will self clean. I am gonna pour some more timing to it like I had it with the 5.3 I backed it down a bit when I dropped the new motor in since I was being cautious. I have a bit more money in this one than I did in the 5.3...

Im gonna throw the tr55's in and retune the idle circuts step down the pri jet 1 or 2 and add some more timing. I'll let you know how it goes.

topher455

iTrader: (6)

Ok so I changed out the plugs yesterday. Only cyl 1 and 2 were fouled 3 through 8 were actually a bit too lean. I checked everything to figure out why those 2 were fouled but everything is fine. I suppose it may be because it is a 2 corner idle carb and it was idleing really rich when the headers were open. Maybe they just got too fouled to clean up.

So I put the plugs in and retuned the idle. I also stepped the pri jet up one step since the plugs were so white I may have been getting a lean miss. Lastly I threw a bunch more timing at it. It has about 31* at idle nowincluding vac advance. It runs freakin awesome now. I just have to get some time to dial in the acc pumps and maybe lean out the sec jetting. FYI jetting is at 68 74 Thanks for the help guys.