So, since you mentioned having to "convince" the passenger-side mount into place, it sounds like you may be mixing and matching mounts, and this could potentially locate your engine incorrectly, causing the header tube clearance issue. We know from experience with our SuperNova project car that it is possible to force the heavy-duty engine mounts to work with the standard-duty frame brackets (we had 307 brackets from the junkyard after ditching the six-banger). However, when that car was converted to the proper heavy-duty-style frame brackets, the engine fell into place, rather than having to be wrestled into submission.
Although we've provided part numbers, you aren't likely to get the frame brackets from GM at this point, but the good news is that Original Parts Group carries the heavy-duty-style frame brackets for your car. Hopefully, this is the problem you're having, in which case the right parts should alleviate the header clearance issue.
Squeezing The WindsorOn a stock 351 Windsor (Genuine Ford Parts head gaskets, pistons, and rods) a 64cc combustion chamber head will obviously decrease the already docile compression ratio (stock heads can be as small as 58 cc and still retain an 8.8:1 compression ratio). What is the most practical, cost-efficient way of raising the compression to about 9:1 without milling down the new 64cc aftermarket heads?Branden KoehnGrande PrairieAlberta, Canada
There aren't many methods for altering the compression ratio on an engine. You can mill the heads, deck the block, install different pistons, or change the thickness of the head gasket. Decking the block requires the engine to be completely disassembled, and installing new pistons obviously means you're probably looking at a complete rebuild. That leaves milling the heads, but you've stated that you don't want to do that, so you're left with swapping head gaskets. Since you're only looking for a slight gain, this would seem to be the simplest way to achieve your goal. Most head gaskets are a composite design (like the ones your engine is currently using), sandwiching different layers of material, and these are usually around 0.040-inch thick when compressed. For significantly thinner gaskets, you're looking at a steel-shim design. This is basically just a sheet of thin-gauge metal that has embossed ridges to form the sealing rings, and most are around 0.015-0.019-inch thick when compressed. Some auto manufacturers used shim gaskets from the factory (many Chevy V-8s, for example), so in theory, reliability should not be an issue, though shim gaskets are not able to cope with surface imperfections common to used engines the way a composite gasket can.
We started to think this discussion was moot once we tried to find a steel shim gasket for your engine; apparently, no one offers one. We kept searching and did find that SCE Gaskets offers a relatively thin copper gasket for the Windsor engine in its Pro Copper line. The SCE Pro Copper line actually includes a broad range of thicknesses, since one of the intended purposes of these gaskets is to alter the head/deck relationship, either to gain or reduce clearance/volume. The thinnest offered for the Windsor is PN 036062, which has a compressed thickness of 0.021 inch.