Replacing spark plugs, 924S
 

I just checked the spark plugs in my recently purchased 1987 924S. The plugs that are in the car now are Champion RN10PYP4's gapped at about 34 thousands.

I've read a few of the posts about plugs and I think that I'll replace the Champion's with Bosch WR7DC's (if still available) and I will gap them at 28-30 thousands.

So the question is, once I put in the Bosch plug's with the correct gap will I have any noticeable changes in my car's performance? If so what changes in performance should I expect?

None. You may get better combustion and fewer emissions.
FWIW I use NGK BPR6ES, just a little longer lasting and maybe a better spark.

If you want a little better performance, replace the wires if old, new air filter and check the compression.

If the previous records do not show any engine work, a new head gasket and a complete valve job will give you a little more power.

GL & welcome.

J_AZ

I get the Bosch WR7DC's from Lindsey Racing. Mine were quite worn, and after replacing plugs, cap and rotor bug (and lines) I've noticed some improvement in acceleration but more so in mileage

Thanks for the responses. Darn, I was really hoping for an immediate and noticeable increase in performance. :-)

Try ********.com for WR7's & WR5's.

Plugs seem to last a long time in these cars, but if your plugs are worn you might notice a small (very small) increase in gas mileage and "performance."

From an old Haynes: 2.5 liter 1983-1987 Bosch WR8DS or Champion RN10GY 2.7 liter WR7DC 3 liter WR5DC Gap-0.028-0.031 in (0.7 to 0.8 mm)
I had my valves,valve guides redone and the power increase was noticeable. My 2.5 normally aspirated was a bit more "peppy". But a lot more than changing plugs goes into getting the max power out of your engine. Besides changing plug wires,do a leak down test or a compression test to see if your rings or valves are worn. Then of course fuel/air intake systems must be in good shape,condition of the overhead cam, properly adjusted timing belt, transmission fluid clean and you got the picture. It's still a sports car and needs TLC.

+1 on the copper NGK. . .