i was wondering what the difference on gapping too tight and or wider. i was told to gap at 32 with ur5's and it makes my car run like crap but when i gap at 35 it runs fine. can somebody enlighten me on how this works. when running 32 the car detonates at top end of each gear. at 35 it just pulls and pulls and pulls thats where i have it now. why is that?
spark plug gapping
- Thread starter TurboBusa
- Start date
The gap sets the min firing voltage and the initial Flame front size, ie kernel. For some reason, your car needs a larger kernel for it to run right. One such reason could be particulate matter in the chamber, ie oil. Weak rings, faulty PCV system would be causes.
What did the old plugs look like?.
When you change plugs, and set up in performance, it can be an indicator that there is an ignition problem. The plug materials differ in their erosion properties, and it's the erosion, that allows for the *trace* to build, that allows for the spark to actually jump. A *softer* plug, allows for an easier trace to form, but the plug wears out quicker. The AC's, and Autolite's are proven plug, if you use something else, and it really works better, then either of those, your curing the sympton, rather then the problem.
What did the old plugs look like?.
When you change plugs, and set up in performance, it can be an indicator that there is an ignition problem. The plug materials differ in their erosion properties, and it's the erosion, that allows for the *trace* to build, that allows for the spark to actually jump. A *softer* plug, allows for an easier trace to form, but the plug wears out quicker. The AC's, and Autolite's are proven plug, if you use something else, and it really works better, then either of those, your curing the sympton, rather then the problem.
i went back to AC from ngk. car seems to run much better. the plugs looked like it was running lean, which what it was doing on top end. the o2's would start at 840's then on top it would drop to 600's to 700's. i changed the blm's for richer and trans plus to run much richer but when i did this it would cut out on the top end. but the o2's would be around 830's it felt like the something blew the fires out of the candle. with the AC at 35 the car runs fine. with the ngk's at 32 car would come out like a bat out of hell but the top would fall on its face it got a little better at 35 gap but not as good with the AC's at 35. i will also check the pcv. I checked the plugs for oil and the only oil i saw was around the thread of the plug, but saw what it seems like detonation which explains the leaning out but even when rich it would pop. this is a fairly new rebuild it has 4600 miles on it. thanks Bruce.
abner
abner
Look for just a slight gray *hue* on the center porclean, as an indicator of oil. 4600 miles, rings may have not seated. Too much boost too early can glaze a ring and really slow down the seating process.
Your welcome.
Might get serious and get a WB to be sure of where your at.
Depends on the type of ring, and final grit of the honing stones.
*Soft* rings, and a rough final cut, 500 probably would do it.
Low tension rings, fine hone, might take 15,000 miles.
Precise machining, torque plates and a sharpe machinist/ assemblier, 5 mins on the dyno could do it.
Do what your machinist recommends, if he doesn't have a firm recommendation, find another machinist.
If you're doing your own *honing*, and moly rings, I'd say 1,000 min..
It's better to be cautious, rather then glaze a set of rings. I've only seen 2 engines never break-in, they were glazed so bad, but it was enough of a PITA to want to avoid that.
i have a very slight gray on them but no blue smoke coming out the tail pipes. i hope their not glazed. as for the WB, its next on my list. i did a compression test on it also yesterday and they are pretty high. maybe carbon build up or something cylinders are within 182's to 185psi, checked it hot. but to think about it, it's always been like that.
