What spark plugs for 350 5.7?

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OchoCinco

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Houston, TX
First Name
Daniel
Truck Year
1985
Truck Model
C10
Engine Size
350
Looking to get new plugs, what do you guys use/recommend? What gap are you running?
 

ali_c20

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Austria
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Alexander
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1974, 1979
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C20, K5
Engine Size
350, 350
I buy the standard ACDelco plugs with the specs for my engine. Works for me, I'm mostly cruising and they are cheap.
I tried fancy iridium once but I couldn't tell any difference. Maybe there is one if you have a performance setup.
 

75gmck25

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Bruce
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1975
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K25 Camper Special TH350 NP203
Engine Size
5.7
I used Delco R45TS with stock heads, but noticed that rockauto now shows the R44 as stock.

Ignore the .060 HEI gap recommendations you see in some references, since GM later realized that was too wide. Most folks now use about .040-.045 with stock HEI.

R - resistor
4 - 14mm
5 - heat range ( 5 is the hottest)
T - tapered seat
S - extended tip
 

BillK

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Waldorf Md
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Bill
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1985
Truck Model
Blazer
Engine Size
350
I have always used what the owners manual calls for unless it is a modified engine. AC Delco for me.
 

Raider L

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I've got 1970 Z28 300 HP heads on my 350 so it's always interesting going to the parts store to get plugs. I think, I'd have to go look, they're R45TS or something like that, maybe. Now, if I still had the old 882 2 bbl. heads on it I think they were R44T big plugs, 13/16" size, gapped at .035" That's by the book.
 

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