71 LS5 Big Block general questions on oil/plugs

[Jeffro]

Just purchased a this nice, previous 2 owner CA & AZ 71 LS5, 83K orig miles, all matching numbers, Factory A/C, basically all the options except for the LS6 basically. I am not a collector or a Corvette expert, just always liked the C3 Stingrays and wanted one, so finally was able to purchase one.

Have a couple questions:

1) Only familiar with SB 350's, had a questions on oil weight, engine is all orig stock. The previous owner said he ran synthetic 10W30, seems a little light weight to me for AZ, should I run 10W40 or even 20W50 Synthetic?

2) For plugs, I see the AC Delco site has like 5 different PN's for my application: Rapid Fire 1 which I think is for more like if you had MSD type ignition, 41-817 Platinum, then a CR43TS & R43TS and then a R44TS. My guess is maybe the 41-817 is the upgraded platinum version of the stock plug?

Appreciate if I can pull on some of your corvette expertise,

 

Jeffro-Phx

[corvettech]

20w50 is going to be a bit on the heavyweight side, im sure youd be safe with 10w40 though. im not sure on the plugs, (all the experience I have is on fuel injection) hopefully one of the old school techs can chime in

[Two Fangs]

The '71 LS5 was only at 8.5:1 compression, so I would not worry about running anything as cold as a 43 plug.  Start with 44's, and if they want to foul, go ahead and step up to 45's.  As far as oil, the engine would do well in the current heat with a 10w-40, then maybe a 10w-30 in the winter, if an oil change is required.

Sounds like a great car, good luck!

[Azmotorhead]

I'll agree with 2 Snails. Though with todays crap gas if you have detonation drop down to the R43 plugs. Lower the # the colder the plug

[Bromley's Corvettes]

I use NGK plugs and Pertronix elec IGN upgrade and black MSD wires. Also Pertronix black coil.

[Jeffro]

Thanks for the replies, think I will definitely switch to 10W40 oil and maybe the 44 plugs, need to verify what's in it currently, seems to run good now. Want to keep it stock and not add any aftermarket upgrades, even though there are some good ones that are tempting.

[Buccaneer]

I used to use 20W50 year round in my 383 Gen I C3 motor, but changed about a year or so ago to 10W30 Amsoil and seems to work just fine. I did notice that the oil pressure is slightly lower at idle when warmed up with the 10W30, but it's still well within spec. Since I have a flat tappet cam I went with the higher Zinc content oil which is a good idea if you are not running a roller cam, cheap insurance IMO.