[bigblockv6]

It runs pretty good as is but is running real rich. Was thinking I needed to tune the carburetor but I think I’ve got the wrong carburetor to start with.
Called Holley today for help id’ing which carb is in my truck. The numbers show I’ve got a 500 cfm model 4412.
Asked what he would recommend and he said a 350 cfm.

Thanks for any advice,
David Cox
Portland, OR[/QUOTE]
Actually there is no advantage using the 350 cfm carb because it does nothing to increase performance and rather has no more to offer than the stock ww 2bbl carb. Yes you may have issues with the 500cfm carb running rich. Everyone here has given you the right advice on how to counteract the issue, also leaner jets would help. When I ran the 500cfm in my 68's 305E I had the timing and advanced over stock settings , also running the GM HEI distributor and had no issues of it running rich.