My car is lacking among other things the air dam. I've decided to make one since I need one by Saturday for my trip from Columbus, Ohio where I am now to South Dakota for my summer job. I've been driving at night which has kopt my car (carbed 250 bored 60 over) from running any hotter than it needs to (currently at 230ish on the stock guage with the fans on). However, the last owner of my car must have removed the air dam because not only is it missing but the bolts are as well. So, are they english or metric? Also, what thread are they? My first guess is that they are 5/16x18 but I can't pass anything through it because they are prety corroded. I was planning to clean them up with a tap but I don't want to pass the wrong thread size tap through.

Thanks.

Oh, and if anybody has an air dam for sale in Columbus, Ohio, please PM me.

 

I am also missing my air dam on my 91 RS 383. I found one on e-bay for 33 bucks. http://cgi.ebay.com/ebaymotors/82-92...spagenameZWDVW
The previous owner removed it but left the bolts in. They were 10 mil, but I have no idea what thread size as they were very badly rusted. I am going to install my new dam with slightly oversized self tapping bolts. I am hoping that I will then run closer to 210 rather than 230. Hope that helps a little.
Dave

 

The bolts that were used to hold my Air-Dam (or what was left of it) on was 4 large body screws (the same as what is used to mount the hood latch panel) but the holes were stuffed so I drilled them out to 10mm and put 4 bolts with nuts on the inside.