posted February 21, 2003 06:43 PM
Distributor shims when do you need to use them and how do you check to find out how thick of shim to use? Never used these shims before. Got a 350 sbc with heads milled down about 12.5 to 1 comp. Thanks for any info.
dirtbuster Dirt Freak
Total posts: 353
posted February 22, 2003 11:11 AM
I assume you mean shims between the intake and the dist flange not gear shims.
The main thing is to keep the dist gear from bottoming out on the oil pump shaft before the dist is seated on the manifold. I have tried to measure with calipers and do the math and figure out how much clearance there is but the easiest way i have found and the quickest is to place the dist in without a gasket or shim and make sure it is all the way down. It should leave a little gap between the intake and the dist flange. AT this point the gear is bottomed on the shaft so all you have to do is either measure the gap with feeler guages and then find a combination of shims and gasket that is greater than this by about 0.030-0.040 or so. Another quick way is to do the same as above then lift the dist slightly and slip the edge of your gasket/shim combination under the dist flange and make sure the dist is down on them, then pull them out and you should be able to see/feel the dist drop a little bit indicating there is clearance with that combination. I am sure there are more scientific ways of doing this but this has seemed to work well for me and it is fairly simple and quick.