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Discussion Starter #1
I have a set of heads i just put on my sbc they are cast 194's. I think they are from a corvette. I went to buy sparkplugs for it and they asked me if they were tapered or not I have no idea. How can i tell which plugs i need? Looking at the spark plug hole it's hard for me to tell what im looking at without a comparison. If someone could send a pic of both types or has a good explanation that would be cool the guys at napa are only so helpfull.
 

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I dont have a picture, but if the area just above the threads have a 45* taper there, about 1/4", you need tapered plugs..

If there is a larger flat area, about an inch accross, you need the larger washer type plug.


Now, you just have to figure out the heat ranges.................. :confused:
 

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I can't vouch for the source, but I recently read that Chevy changed to tapered plugs in '70.
 

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MI2600 said:
I can't vouch for the source, but I recently read that Chevy changed to tapered plugs in '70.
In my experience, all of the 70 model GM's I was familiar with used the 13/16" plugs with the washer. Most of the 71 models had the 5/8" tapered seat "PEANUT" plugs.
 

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Discussion Starter #7
I cant really look at the numbers on the heads anymore since i already put the valve covers on and forgot and or lost the numbers.And thank you poncho. That sounds easy enough to determine. I remember there is no obvious taper on them and i seem to remember there being a flat area around the holes so im thinking washer type plugs. Any words of wisdom to figuring the heat ranges?
 

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tinman386 said:
Any words of wisdom to figuring the heat ranges?
I always had great success with the AC R44, but since it is unavailable now I find myself switching between the R43 and R45.
 

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Discussion Starter #9
What does everyone think of ngk's? In my motorcylce years ago and still in my old boat they are the only thing that runs good. I was hoping to run them in my sbc.
 

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I have gotten the best life with AC Delco's or Bosch Platinums.

Since you have gotten satisfactory life in other applications, try the NGK's.
 

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Discussion Starter #11
I can't really say i got good life out of the ngk's. but they seem to start easier and run smoother. i had champion's in an old 75 honda and it wouldn't run i put ngk's in and it ran like a top. I have bosch platinums in my 88 caprice. And it runs the same as it did when i changed the plugs which were in bad shape. As a matter of fact 1 of them looked like the original plug. You know the 1 on passenger side in the back thats hard to get to. Some one changed them and left that 1 in. So maybe i'll try the ac's if not the ngk's.
 
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