Technical > Matt Shaff's Engine Shop

stupid question?

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L79_Acadian:
  Hi, just wanting to know what oil weight to use in my stack injected small chevy. Its on methanol. Also
what plugs are recomended for the same setup. I need 3/4"  reach,gasket seat plugs, for a magneto.
   Thanks in advance
       Roger

Frontenginedragsters:
Rodger:
 I will assume this is a compression ratio around 12 to 1.
If the bearings clearances are typical bracket race: .0025-.003" we use 10-40 Brad Penn racing oil.
Everybody will have a different view on this but we have used that oil with ZERO problems.
Spark plugs are also a topic of preference. We have been using NGK plugs for the few years.
They are very easy to read and not over priced.
I would start with a R5671A-7. The short number is: 4091.
Tighten up the gap to .016-.018" for the mag.

Thats my 2 cents:
Matt

ricardo1967:

--- Quote from: Frontenginedragsters on May 27, 2014, 07:59:22 AM ---"...I would start with a R5671A-7. The short number is: 4091...."
--- End quote ---

That's interesting Matt, I've been afraid that NGK heat range '7' was too warm for such application. I'm currently using '9' (R5672A-9), but definitely going warmer on my next set of spark plugs.

gordon:
-9 is two steps colder than the -7. NGK runs colder as the number goes higher on that series.

ricardo1967:

--- Quote from: gordon on May 27, 2014, 08:23:17 PM ----9 is two steps colder than the -7. NGK runs colder as the number goes higher on that series.

--- End quote ---

That's correct. As a matter of fact, I believe this applies to all NGK series.

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