Saturday, December 22, 2012


You are looking at a very screwed up Saab/Ford V4 engine block. I took this one apart to do a complete overhaul. The piston in the photo IS at top dead center. I rigged the dial indicator to measure how far the crown of the piston is below "deck height" [top surface of the block]. The drill is to get a starting point, so I set the dial indicator at some number greater than the estimated depth of the piston below deck height. I also know the thickness of the steel strap.

 Next is to remove the strap and take a measurent at the piston crown.  I subtract this measurement [plus the amount of the strap thickness] from the first reading. The result was 0.247".  This is a 1698cc V4. We all know [don't we?] that the pistons in the stock 1698cc V4 do not come up to deck height BUT they certainly are not a quarter inch below it! ZOUNDS! Some metally challenged mechanic really did a number on this little engine.
But wait! There's more! It's hard to see in this photo but the cylinder walls are a mess. There is about six jillion tiny hammer marks, all evenly spaced in that shiny area above the piston. What the hell caused that? I am not sure. Perhaps a worn out boring bar [the engine was bored .5mm (0.020") oversize] or an equally worn out hone of some sort.  So what does this have to do with the deck height problem?   Well, sports fans, when I got the sucker all apart I find that the super smart "wrench" who did this work managed to fit [new] pistons for a 1698cc engine onto a 1498cc crankshaft, resulting in the 0.247" under deck height measurement.
This same genius had the crankshaft turned 0.010" undersize on the main bearing journals, and 0.020" undersize on the connecting rod journals, BUT then installed bearings that were ALL 0.010" oversize. That sucker must have rattled quite a lot had had about as much power as an old two stroke Saab with one plug wire pulled off! 

Proving once again that these little V4's are pretty special and require some special knowedge--like factory manuals and 40+ years of Saab experience-- in order to rebuild them correctly. A hack mechanic who once overhauled a Chevy pickup engine has absolutely no business getting within a city block of a Saab V4. This particular rocket scientist managed to make the Saab owner pay TWICE to get his engine overhauled correctly.

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