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06-03-2015, 06:34 PM
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#1 |
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Registered User
Join Date: May 2015
Location: Warroad MN
Posts: 41
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Plug/Head Mystery
The sticker on the fan guard and the manual agree, my Dad's 72 250 C10 wants an AC R46T plug. Problem is the plugs that are in it are AC R45 XLS which are a larger and longer thread than the R46T. Dad remembers doing something to the head in the late seventies but doubts it was replaced. My suspicion is the PO may have put a different vintage head on it. Any ideas for IDing this?
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06-03-2015, 07:44 PM
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#2 |
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Senior Member
 Join Date: Mar 2003
Location: Colfax-California
Posts: 8,528
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Re: Plug/Head Mystery
Pull the valve cover and get a casting number. Does the spark plug seat look like a peanut plug tapered seat or the larger gasketed one?
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06-03-2015, 07:45 PM
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#3 |
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Registered User
Join Date: Jul 2010
Location: MD
Posts: 1,937
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Re: Plug/Head Mystery
R46T is the tapered seat plug (5/8" hex). R45XLS is the gasket seat plug (13/16" hex). Look closely at your head to see which it needs.
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06-03-2015, 09:17 PM
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#4 |
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Registered User
Join Date: May 2015
Location: Warroad MN
Posts: 41
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Re: Plug/Head Mystery
The plugs in it are R45 XLS which fit correctly but I don't know whether they are correct for my year/motor. I'll pull the valve cover and get that number tomorrow and post it. i got a great deal on the other plugs on the bay but lol of course they don't fit. I'm used to this kind of stuff. Thanks
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06-04-2015, 11:59 AM
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#5 |
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Registered User
Join Date: May 2015
Location: Warroad MN
Posts: 41
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Re: Plug/Head Mystery
Casting numbers are GM2, A153, and 3824437. Are these decoded the same as the cast numbers on the block?
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06-04-2015, 12:07 PM
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#6 |
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Senior Member
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,528
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Re: Plug/Head Mystery
www.inliners.org/tech/heads/headindex.htm
according to this you have a 230 head which would take the larger plug |
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06-04-2015, 12:48 PM
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#7 |
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Registered User
Join Date: May 2015
Location: Warroad MN
Posts: 41
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Re: Plug/Head Mystery
Thanks. Guess I'll check the block number now and see if the engine is a 250. The truck definitely is a 72.
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06-04-2015, 08:43 PM
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#8 |
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Registered User
Join Date: May 2015
Location: Warroad MN
Posts: 41
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Re: Plug/Head Mystery
The block number is 3994257. Some searching around shows it to be a 250 block so my guess is that the head was changed at some point and that a 230 head fits a 250. Is there any way to find out how the R45 XLS compares to the R 46T? Hotter...colder?
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06-04-2015, 09:17 PM
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#9 |
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Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Plug/Head Mystery
A 46 is one step hotter than a 45
R means they are resistor plugs
__________________
My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
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06-05-2015, 07:32 AM
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#10 |
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Registered User
Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
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Re: Plug/Head Mystery
The 230 engine was equipped with type 46N spark plugs
__________________
68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
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