My Five-Minute Engine Swap (318/340)

[dibbons]

Actually, just swapped the air cleaners on a BBody. The unsilenced '68-'69 340 air cleaner, using my custom aluminum two-barrel carb adapter, now sits about and inch and a half higher than the '72 factory single snorkel 318 air cleaner.

The 340 air cleaner is just kissing the hood insulation pad. The easiest way to find a bit more clearance (in addition to solid motor mounts) would be to find a filter element measuring just a shade less high than the CA 305 (Fram) called for here, which is 2 3/4" tall.

 

[dibbons]

Update:
Found a WIX website where one can search for filters by size. Found a WIX #42070 which is listed for a 1967 Dodge Charger 426 CID which is the same diameter as the AF-305 but is shorter at 2.120" which will give me .63" of added clearance (2.75" - 2.120"). Perfect! Also fits 360, 383, 413 from the '60's. Two of these were used on the dual quad 426 CID Maximum Wedge motors.

WIX rates their #42044 @ 160 CFM and the shorter #42070 @ 120 CFM.

How much clearance does one need anyway? In my case, even with the shorter element the lid of the air cleaner is just kissing the hood insulation pad.

 

[Dana67Dart]

WIX rates their #42044 (AF305 equivalent) @ 160 CFM and the shorter #42070 @ 120 CFM.

Just out of curiosity. is the CFM rating per square inch of filter material?

If you have a 500cfm carb wouldn't a 160cfm filter severely restrict air flow? I'm not the most knowledgeable on CFM and airflow

 

[dibbons]

I don't know where WIX gets those CFM figures, maybe someone else will chime in.

 

[Dana67Dart]

Do you have a spacer between your carb and intake? might get a bit more clearance.

Also after you shorten your filter you might want to redo your interference test but with the trans in drive (and later in reverse) and your left foot planted on the brake and briging the RPM up to max comfort level. you might have engine rock that could cause some issues as well