What is the best spark plug for a stock engine? Darn fat fingers.

 

It doesn't matter. Buy the correct size, and heat range, and the engine won't know the difference.
I normally run AC, because they are often on sale.

 

likely you'll get many opinions.

ACDelco was likely the OEM plug (41-808 platinum - gap 0.035).

However, some ACDelco 'platinum' plugs (e.g. 41-906) where known (I had 3) to loose their platinum 'puck' (dab of platinum on underside of ground electrode), which at best just left the gap way too large.

Unfortunately, ACDelco doesn't make an 'iridium' plug for your engine, which would be the best choice.

And assuming you have an aluminum heads engine, NGK also doesn't make an 'iridium' plug for your engine either.

So assuming you have aluminum heads (see below for clarity if your not sure), I would select the ACDelco platinum and reduce the 'lost puck' chances by replacing them every 25-30k.

Interestingly, NGK's site notes the 1988 engine as having both aluminum and cast-iron head options.

Appears the distinction is the aluminum heads took a flat/gasket seat type plug -- whereas-- the cast-iron heads took a tapered seat (backwards of what I would have expected -- unless of course it's incorrect).

It further calls for either a 5155 (FR4) (NGK v-power for aluminum -- flat/gasket seat) or 6630 (UR4) (NGK v-power for cast-iron tapered seat) or 7401 (UR4ix) (NGK Iridium for cast-iron tapered seat).

The FR4 is 14mm hex, 5/8" thread diameter with a 3/4" (19mm) reach.
The UR4 (& UR4ix) are a 14 mm thread diamater with a .460" reach.

 

will matter if you use a cheap POS like Autolite, stick with AC Delco, Champion, Bosch, etc.

 

For my LT1, I like the NGK TR-55 Double Platinum.

 

Ya think.
I ran autolites in my work truck for 440,000 miles, changing them every 100k.
Different results for different folks I guess.
I can't keep a champion in my chainsaw for more than 1 month, but I bet some will say they are the best thing since sliced bread.
Spark plug opinions are just that. Opinion.

 

I put AC Delcos in my 89. Though they rusted up on the outside where you attach your wrench. I don't know why they did that.

 

I put a set of Bosch Plus 4 Platinums in my 88 about 5 years ago and they are still good. They are supposed to last 100,000 miles. http://www.boschautoparts.com/Produc...lugs/Platinum4

 

When I bought my '92 back in 2000, the previous owner was running AutoLite Platinum plugs and the car had 63,000 miles on it, a new Opti and a new water pump. I kept the plugs on there until I reached 93,000 miles and they never missed a beat.

 

the Platinums are good, and the el cheapo ones are OK for a weekend driver or a non performance vehicle.

 

Thanks for the clarification. I run NGK copper cores in my DD Toyota Camry, but I usually don't run them than any longer than 15,000 miles before swapping them out.

 

I guess it is good we cleared that up.

 

Why, yes. Yes, it is.