Wednesday, June 6, 2007

Diagnosis: rejected transplant!

Engine builder Mauricio Velasquez found the problem when he pulled everything apart, and it's not a valve lifter after all. In the course of the overhaul we needed to replace one cracked piston, and by sheer luck I was able to locate a single NOS 83mm flat top piston that fit the bill. Make that bad luck: turns out that replacement piston was a few thousandths of an inch taller than the others -- enough that it just barely contacted the head at top dead center. We were actually hearing the piston hitting the head. Luckily the head wasn't damaged, but now I have a decision to make. Scrounge another original piston, either NOS or good used? Look for a matched set of four 83mm flat top pistons? Or go with my original plan of upgrading to 85.5mm pistons and cylinders, forgoing a little originality for the better performance of a 1600? Hmmmmmmmmmm...

5 comments:

Alf said...

If you want originality and value you have to keep that original motor. If not, then you might as well try that STi donk for fit.

Scott said...

I've decided to go ahead and keep it bone stock for now (for those very reasons), but I'm keeping in mind the option of building a performance engine in the future that could be dropped in whenever I feel the need for more than 54 horsepower. Best of both worlds.

Anonymous said...

I'm floored by the very idea of doing an engine swap on a whim. I'm incredulous and jealous at the same time.

Anonymous said...

machine the piston to the sama shape as the other. check and adjust also the weight.

however 1500 kits are available around. maybe you can locate a set of 1500 piston in first oversize.

Scott said...

Machining the piston was discussed with the machinist, but he recommended against it. I'm going to find an NOS or new set of 1500 pistons and try to reuse the original cylinders.

With regard to engine swapping, yes that's one of the primary benefits of an old VW. Complete engines can be swapped out easily in a day, by one person working alone if need be.