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2/3/12 7:59am - Original Message: 'Correct Spark Plugs and Octane'
Former Member
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New Philadelphia, OH - USA

1977 T-Top Coupe, Black with Buckskin Interior. Restored.

Joined: 1/19/2012
Posts: 8
From the VIN # of my '77 I have learned that my car has a std. 350/180HP motor. When I bought the car the spark plugs that were in it were R44TX AC plugs but the Haynes manual says that it should have R45TS plugs. I know these plugs have a longer reach than the R44's
so I am afraid to replace them as I don't want to hit the tops of the pistons. Which one
is correct? Also, can anyone tell me what the correct octane gas should I be using? The previous owner said that he used 87 but that just doesn't seem like the best choice.
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2/3/12 9:29am - Reply: 'Re: Correct Spark Plugs and Octane'
DaveM Lifetime Member
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Flanders, NJ - USA

1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2531
There's no need to use anything but Regular gas in your car. As far as the plugs go, I would check with several local parts stores and see what they say, if they all say to use the same one, then that's what you need to put in there.
Good luck,


Lifetime Member #116
Dave's '82

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2/3/12 12:33pm - Reply: 'Re: Correct Spark Plugs and Octane'
nosal1 Gold Member
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Dunedin, FL - USA

1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.

Joined: 3/21/2006
Posts: 240

Good Morning All, I suggest using AC45TS (they are not to long unless you have domed piston which you do not) and set gaps at .042 instead of .045 as recommended by the books.These are used for continued street use (start and stops in city).. For performance engines that run the track or is used on long road trips at high rpm we use depending the use i.e. strip use AC42 TS series,next hotter plug is AC 43 TS,for combination some street. For freeway(California folks) use AC44 TS.Daily driver with an occasional highway drives use AC45TS and all with the gap of .042. I have evaluated all these on various engines and race cars over the last 30 years with much success. As far as octane of fuel,unless your engine is timed at 4-6 degrees advanced you would want to use at least 89 octane,however I did a study on my '72 Chevy 1/2 ton pick up with a 360 hp 350 engine and found that while burning premium fuel I burned less fuel (15 MPG as opposed to 12 with 89 Oct.)   I would not consider burning 89 in my (370hp 350) Vette and in fact I have located a couple of service station that have NON ethanol fuel..That's just me and all the people here that I have built performance engine. Have a great day and happy motoring...Sal C


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