#1  
Old 07-07-2019, 05:37 PM
MJVAUGHANS MJVAUGHANS is offline
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Default 1955 spark plug question

I have a 1955 GMC with the 287 V8 that I am getting ready to fire for the first time after a rebuild and I am trying to decide which spark plugs to put in it.(Or at least to start with) It has the stock cam, stock heads, is bored .060 over and has flat top pistons. I think it should be 8:1 compression. Bendix-stromberg 2 barrel carb. I am only looking at ACDelco part numbers to keep it simple.
The plugs I already have on hand are: 43,44,44s,45,45s

  #2  
Old 07-07-2019, 07:17 PM
Bill Hanlon's Avatar
Bill Hanlon Bill Hanlon is offline
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The "s" plugs designate a longer electrode for better electrode cooling during heavy acceleration while still offering the same heat range (ie. 45 vs. 45s) for normal driving. I used the 45S (actually R45S) with an HEI in my '57 GMC with 347 V8.

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Old 07-07-2019, 08:08 PM
chrisp chrisp is offline
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i Have 1 box NOS of each 45LS & 45NSX if in need.

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Old 07-07-2019, 09:59 PM
MJVAUGHANS MJVAUGHANS is offline
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I think I will start with the R45S and see how they look after I break it in and run awhile. I was just concerned about them being a little too hot.

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Old 07-07-2019, 11:07 PM
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Bill Hanlon Bill Hanlon is offline
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One thing. The S series plugs are a little longer. Install one, then manually turn over the engine a few revs. Remove the plug and make sure it has not contacted the piston.

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Old 07-08-2019, 12:37 AM
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Jack Gifford Jack Gifford is offline
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45S is definitely not too hot for your engine.

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Old 07-08-2019, 10:48 PM
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blueghoast blueghoast is offline
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I run the 45's that are avalible today in my 57 Pontiac, no problems

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Old 07-09-2019, 12:13 PM
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unruhjonny unruhjonny is offline
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Just in case anyone here cares, I believe the last time I looked the R43S & R45S was a readily available plug.

I collect 44/44S/R44S plugs, and if the price is right I will also buy 43 and 45 heat range plugs in the same configurations - it's the "44" plugs that have been discontinued for a while...

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