CRATE 502/502: WHICH SPARKPLUGS?
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,715
Likes: 1
From: VASS, NC, USA
CRATE 502/502: WHICH SPARKPLUGS?
INSTRUCTION SHEET SAYS #4 DELCO RAPID FIRES (LARGE GEAD), WEBSITE SAYS R43XLS (LARGE HEAD), PARTS STORE SAY GO WITH 454 PLUGS (WHICH HAVE THE SMALL HEAD) WHILE THEY WILL ALL FIT, SOME HAVE LARGE OR SMALL HEAD, SOME HAVE DIFFERENT REACH
I HAVE THE R43XLS. GOOD TO GO?
I HAVE THE R43XLS. GOOD TO GO?
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Re: CRATE 502/502: WHICH SPARKPLUGS? (MELVIN)
Melvin,
Don't know what you mean by 'large head'? There are a few factors determining spark plugs:
Gasket or taper seat. The aluminum heads you have take gaskets.
Long or short reach. Aluminum heads use long reach.
Projected tip or regular tip. With flat top pistons, use projected for better burn.
Heat range. I have found an aluminum head big-block likes rather cold plugs.
I'm running AC Delco FR2LS, which is gasket seat, long reach, projected tip in heat range 2 (cold). My heads are the edelbrock aluminums, basically identical to your 502/502 heads.
Not sure exactly what the difference is to the R43XLS, but if they are gasket, long reach and projected tip they should work fine. Heat range (3) is good.
Don't know what you mean by 'large head'? There are a few factors determining spark plugs:
Gasket or taper seat. The aluminum heads you have take gaskets.
Long or short reach. Aluminum heads use long reach.
Projected tip or regular tip. With flat top pistons, use projected for better burn.
Heat range. I have found an aluminum head big-block likes rather cold plugs.
I'm running AC Delco FR2LS, which is gasket seat, long reach, projected tip in heat range 2 (cold). My heads are the edelbrock aluminums, basically identical to your 502/502 heads.
Not sure exactly what the difference is to the R43XLS, but if they are gasket, long reach and projected tip they should work fine. Heat range (3) is good.
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,715
Likes: 1
From: VASS, NC, USA
Re: CRATE 502/502: WHICH SPARKPLUGS? (zwede)
By large and small head spark plugs, I meant the size socket that is used. The large head takes a 7/8" socket, and Im not sure which size the small does. I wasnt sure of the correct terminology.
Im thinking the R43XLS are correct ones?
Im thinking the R43XLS are correct ones?
Safety Car
Joined: Nov 1999
Posts: 4,466
Likes: 0
From: Paducah KY
Cruise-In I Veteran
Cruise-In II Veteran
Cruise-In III Veteran
Cruise-In IV Veteran
St. Jude Donor '03
Re: CRATE 502/502: WHICH SPARKPLUGS? (MELVIN)
The engine comes stock with ACDelco #4, part number 25164642. Recommended gap is .035"
Le Mans Master
Joined: Oct 2000
Posts: 6,563
Likes: 2
Re: CRATE 502/502: WHICH SPARKPLUGS? (MELVIN)
Melvin,
I kept fouling out #1 & #3 plug with the rapid fire 4's, so I switched to R43XLS----runs fine ........
:chevy
I kept fouling out #1 & #3 plug with the rapid fire 4's, so I switched to R43XLS----runs fine ........
INSTRUCTION SHEET SAYS #4 DELCO RAPID FIRES (LARGE GEAD), WEBSITE SAYS R43XLS (LARGE HEAD), PARTS STORE SAY GO WITH 454 PLUGS (WHICH HAVE THE SMALL HEAD) WHILE THEY WILL ALL FIT, SOME HAVE LARGE OR SMALL HEAD, SOME HAVE DIFFERENT REACH
I HAVE THE R43XLS. GOOD TO GO?
I HAVE THE R43XLS. GOOD TO GO?
1st Gear
Joined: May 2016
Posts: 1
Likes: 0
Any new shiny plug is going to run fine for a while. Its after they get fouled a little and have a harder time cleaning up. Seems to me the hot ticket is to order Rapid Fire 5s
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
