While looking online for spare needle and seats I noticed the R-4224 660 takes a different part no. seat assembly Holley 6-508.
The other side hung carbs like 1850 take a Holley 6-506. Both are adjustable and have same .097 metering hole.
Only thing I see different is the 6-508 has the small spring clip to retain needle to float.....is that it and could you use the one without clip if you had to?
Holley 4224 vs. 1850 needle and seat ?
Moderator: Team