Which spark plugs in 69 350?

[Driftwood]

Just bought a 69 convertible with original 350/350. Runs fine, but to be safe I'm in the process of changing all fluids and spark plugs. Any spark plug brand and gap recommendations? How about rear diff and tranny lube? Thanks.

 

[MaineShark]

I think the general consensus that's been reached here is plain ol' AC Delco plugs, and GM diff fluid.

Joe

 

[Dave L.]

The original AC plug was an R-44 for a stock 350,hi perf used R-43,not sure if they are still available through AC any longer. You might have to cross reference to an Autolite or other brand. The rear axle lube you are looking for is GM# 1052271 qty 2 and GM# 1052358 qty 1.
Is your trans manual or auto? Manual - SAE 80w-90 GL5
Auto - Dexron II or III

Dave

 

[vets4-2]

ac/mr43t plug

 

[69vettester]

AC 10's Rapid Fires, With MSD 6a module and 8.5mm wires.
I consider this combo optimum ignition in my 69/350.
Tom
PS..you can gap the plugs to 45 or 50 with this setup.

 

[69vettester]

AC 10's Rapid Fires, With MSD 6a module and 8.5mm wires.
I consider this combo optimum ignition in my 69/350.
Tom

 

[JohnZ]

"Rapid-Fires" are a waste of money, and 43's are WAY too cold for street use. I use AC R45S plugs in my '67 convertible and in my '69 Z/28 and have no fouling problems at all. 45's are the best compromise for most normal driving, and if you do a lot of freeway miles at speed, you might get away with 44's instead.

Plugs are plugs - regular vs. marketing-hyped "whizbang" plugs makes no difference at all in power; all they do is light the fire, and the rest of the burn takes care of itself. Just find the correct heat range for your type of driving, gap them at .035", and forget about them, assuming you have plug wires in good condition.

 

[Driftwood]

Spark Plugs

Everyone thanks for the all the input. Maybe I'll start with the AC R45S at .035" and go from there.

 

[Mike Carter]

Driftwood,

I use the 44s , in TX where I live I drive a lot of highway between towns, I think the 45s are good if you drive a lotta city. Also make sure you have good distributor and wires, carb tuned etc.

BTW = I don't do the "special " plug stuff, marketing ploy.

 

[Driftwood]

So far I've been probably 50% putting around town and 50% highway cruising. Maybe I'll try both the 44 and 45-- is the difference only in how clean the plug stays, or will I also tell a difference behind the wheel?

 

[Mike Carter]

Stick with the 44s, normal driving.

Mike

 

[Driftwood]

OK-- thanks Mike.