Gents,
Just wanted to thank the both of you for your advice. Very good stuff and
much appreciated.
Best Regards,
Jim

"Tom in Missouri" > wrote in message
ink.net...
> When standard points ignitions were the norm, voltage was about 15,000 to
> 30,000, depending on who you asked. Gap was .035".
>
> When HEI began, there was 60,000 volts and the gap was .060"
>
> HEI dropped to 45,000 for reliability and the gap went to .045".
>
> See a vague pattern?
>
> If you want to check, set up one plug wire and a plug outside the engine
> where you can see it. Start the engine and let it run at various RPMs and
> see what the spark looks like. A good solid spark that is blue in color
> should give you good ignition.
>
> Shut off the engine and open the gap some. (Or set up a video camera and
> don't shut off the engine.)
>
> Do this a few times and also try closing the gap. When you find the
> strongest spark for the widest gap, go for it. The idea is that a wider
> gap
> exposes more spark and thus more initial flame to the air/fuel mixture.
> However, you need a strong spark to break through the mix and to ignite
> it.
> So you have a compromise of wide gap and hottest spark.
>
>
> "Dad" > wrote in message
> ...
>>
>> "Drink" > wrote in message
>> ...
>> > Hi All,
>> > Quick question: After modifying the ignition system, is there any
>> > logical method or rule of thumb for changing the factory-recommended
> spark
>> > plug gap?
>> > Engine in question is an '86 Corvette 350cid V8 engine with [305
>> > heads]
>> > TPI, HEI ignition, headers, high voltage coil, "performance" 8mm plug
>> > wires.
>> > If anyone can shed more light on the effects of the 305 V8 on the 350
>> > block, I'd appreciate that as well. I think the head casting number is
>> > 62426.
>> > Best Regards,
>> > Jim
>> Any additional gap will depend on whether or not you can produce the
> voltage
>> required to jump the gap and still maintain a strong spark.
>>
>> If you think you have that available open it up a bit and try it. Not as
>> good as knowing what results you will get because of the work required
>> to
>> take them out and regap. Go to some of the after market ignition sites
>> and
>> see what they recommend and at what voltage level.
>> --
>> Dad
>> 05 C6 Silver/Red 6spd Z51
>> 72 Shark Black/Black/4spd
>>
>>
>>
>