I may replace my old stamped metal air cleaner assembly currently on my '77 non-turbo 300D with an aluminum air cleaner assembly from a 240D. The 240D air cleaner top does not have the hole for the vacuum pump inlet line, but that's not a problem to drill a hole and fit a grommet for the line.

The big difference is my old air cleaner cannister has a metal grid/support piece connected to the base of the air cleaner cannister that fits snugly to the inside of the air filter - like if it is not there the inner part of the air filter would/could be sucked into the intake manifold, through the intake port into the combustion chamber, and then disaster. However, why does the 240D air filter not need the inner support grid? Granted the 240D has less displacement and one less cylinder than the 300D, but the draw from each cylinder would be equal on the intake stroke for both engines because they both share the same 91.00mm piston and stroke (from the specs I've seen) - given that the non-turbo 300D's extra cylinder means there is a 20% increase in air drawn into the intake manifold for the extra cylinder and when the extra cylinder is on the intake stroke there would be more draw on the air filter. The draw on the air filter would be greater on the 300D than the 240D as the RPM'S increase. However, the air draw on the air cleaner is not constant because of the 4-stroke cycle. Also, the 240D and the non-turbo 300D share the same air filter (I checked on this from several different sources) - meaning the 240D's air filter does not need some kind of reinforcement to maintain its structural integrity despite the fact it does not have the inner grid/support piece like the 300D air cleaner cannister has.

I could remove the inner support grid from the 300D's air cleaner cannister and mount it to the 240D's aluminum air cannister base somehow. Or, simply put the grid into the air filter (not mount it), and then remove it from the old filter and put it into the new filter when the replacing filters.

Has anyone used the 240D aluminum air filter cannister on the non-turbo 300D? If so, did you use the inner grid/support from the old air cleaner? Or, did the later non-turbo 300D's use the same kind of aluminum air cleaner cannister the 240D has without the inner grid/support piece like the old stamped metal air cleaner cannisters have?

Thanks,
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.