In the past month and a half, my bird is getting a slight knock to it if I'm really light on the pedal. It did this last year a lot more, more at top end. I drove a 89 Vette tonight that had the same problem, just a bit more than me. I swear last year that it did it more on 93 octane compared to 87.

Another weird thing is that I picked up 40 more miles to a tank. My gas gauge i sbroke so I strickley go off my tripometer. I went from 200 - over 240 miles/tank. Maybe it is from that 15% metholyne or what ever it is that they add to the gas between certain months out here in AZ.

1. Should I retard the timing a little bit? I think I'm around 8-9 degrees right now.

2. Should I run a lower octane fuel in the summer since the air is hotter and less dense. Is it the higher the octane, the faster the burn rate? I forget.

On another note, anyone else running Bosh platinum +4's. I heard that if you run NOS with them they will melt. I did notice a bit of performance gains and mpg with them. Sone told me that Autolite are the way to go.

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Michael Graeber

My Garage

1)83 Z-28 T-Top: Full cage, 9" w/ lad.bars, Midwest Engine Tech 406sbc,Strip Dominator, 1000-CFM Demon Carb, Phase VI Chevy Bowtie Heads 2.05/1.60, .630" Crower roller set-up, 1 3/4 coated Hookers 3" true dual exhaust th400, fuel cell & still not running

2)89 Formula WS-6 305 TPI Auto Daily Driver: minor motor mods, more suspension stuff. MODS

 

If you ping at all do not use lower octane. Use the highest you can find. I is not a bad idea to bump back your advance but run a tank of good gas first and see if it stops.

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1991 Z28 ZZ4 with LPE superram base, SLP runners, LPE 58mm T-body,Random Technology ramair,TES headers,24#svo injectors,and just about every other bolt on that there is. Just got a ZEX nitrous kit!

 

I just looked at your sig. what kind of compression are you running? You may want to run a little octane boost.

 

As far as your Nitrous question platnum plugs are a no-no. I use NGK TR55's with no problems on a 150shot.

Jeff

 

As far as plugs go, I never have understood why they make those with 2 or 4 anvils. The plug still only makes one spark, but now it is divided up 4 ways (with a +4 type plug). So in essence, it makes 4 weaker sparks. Can someone elaborate?



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Joshua Johnston
1991 Z-28
Flowmaster
K&N
305 / 5spd. (Temporary)

 

Actually the spark only goes to the terminal with the least resistance.

 

however, the 4 electrodes also shield the combustion chamber from the spark more than splitfires or regular plugs so it defeats the purpose of not having an overhead electrode in the first place.
just use delcos they are fine.

 

The path of least resistance theory makes sense. When I bought them, I thought that the design would allow the flame to be able to shoot down further, but it also makes sense that the design would shroud the flame more with electrodes on all sides.

Thanks Guys!

 

The +4 plugs work well in overhead cam motors where they sit at the center, top of the combustion chamber. But like an earlier post stated, with 4 posts, you have that many more chances of covering up the spark kernel in a small block. Some folks will spend a lot of time to "index" the plugs, just to make sure to the plug is open to the combustion chanber. This gives better cusbustion, but is nearly imposible on vehicle with a/c and smog still installed.

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Pat McGrath '89 Formula LB9, T-5

 

I have run +4 on my LB9 for about 8 months and i have seen no improvement.

In my opinion they are waste of money. They are also a hotter plugs(good for high rpm engines)

Just put in stock AC Delco and indexed them. It really did not take much more time, but I guess I just got lucky.

Go with the stock ones.

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89Iroc, 305 TPI, WC T5, 3.08 Posi, Headers, Hooker Y-Pipe, 3 inch over the axle, Flowmaster 80, No Cat, Aluminium Driveshaft, Ported Plenum, Air Foil, K&N, All free mods,