I use an ITC foam air filter, not an air box, and I'm not sure about the clearance measurement. The specs for the ram pipes and air filter were provided by a manager at ITC, who dug into the company parts bin so he could test his recommendation before emailing me. I thought his service above and beyond the call of duty. Here are excerpts from what he wrote:
"We do have a distributor in the US who deals with the kind of filter you will be after, Coast Fabrication over at Huntington Beach. They may be contacted on 714 842 2603 or via e-mail at
[email protected] - this may have recently changed, if you don't get through on this address drop me a line and I'll get it sorted for you.
"Before you get in touch with them please send me some details of your engine, carbs and clearances etc and I should be able to give you some further insight into which components you will require."
Email #2: "The 22JC50 is the standard baseplate we list for your Alfa engine, the hand written 22 part denotes the specific application and is hand written because we are still a relatively small firm and are too tight to get lots of different labels printed.
"I pulled a 22JC50 and an old TWM ram pipe off the shelf to do some checking and I reckon it might be quite tight on no. 4 ram pipe when the filter is actually fitted, full radius ram pipes throw up loads of problems with internal clearance, typically 80 -90mm od compared to 60mm od for standard style ram pipes. As you are cutting your own plate this should not be a problem, it looks as though you still have a bit of space at the back of the engine bay and you would only have to move it back by around 10mm to get the necessary clearance inside.
"If you can fit the JC50/S/75, that will be the better filter to go for, the extra height will always be a help, especially on no.4 cylinder where the domed part of the filter will curve slightly over the rampipe. This filter should cope with about 500bhp so the extra airflow available won't really make a difference - it'll just help with the clearance inside and make sure all four cylinders can breathe easily and evenly."
Best regards,
Andy Jackson
Parts Manager, ITC
I did use the JC50/S/75, as noted here:
http://greend.com/Specifications.htm