Monday, February 17, 2014

Machine work for the Spec Miata 1.6 engine rebuild

Having never had need for a machine shop before, I asked around to various local Miata enthusiasts to find a trustworthy machine shop.  I also checked Yelp and Google'd to find reviews on different forums.  I discovered that some shops only work on American cars.  Long story short, I settled on Victory Machine in San Jose mostly due to Yelp reviews and proximity.  Proximity b/c work and life is getting busy again so I don't have time to drive an hour away to shops some recommended shops.

Originally, I had wanted to measure the parts myself but after doing more research, I decided not to.  Turns out that accurate set of measuring devices are very expensive.  It would have cost me about $500 or more to buy the tools to measure this stuff myself.  I watched some videos with guys using cheaper tools to measure and the steps they had to take to find the level of inaccuracy and take that into account with each measurement.  That would drive me fucking nuts.  After speaking with Victory Machine, I decided I'd just pay a professional with the proper tools to do that part.

I drove over to Victory and spoke with the owner about my plans for a budget rebuild.  Turns out that they have done Miata engines before for other racers that I apparently haven't yet met.  He educated me about different options and suggested some base work to clean the parts (hot tank) and measure everything to ensure all the hard parts (block, pistons, crankshaft, head) were re-usable.  Much easier and faster than me attempting to do this.  More accurate too.  Pricing was acceptable also.

Machine shops typically start by hot tanking the engine block and parts to get all the dirty, carbon and oil off the parts so that they can be accurately measured.  Next they measure everything and compare to factory specs.  From there, they know what parts can be re-used and what parts cannot be re-used.  Once they figure out what parts are going to be used, everything gets thoroughly cleaned again and assembled.

A week later, I had some shiny engine parts :)  I'll get some pics up soon.

I had originally wanted to rebuild the head myself along with the bottom end but the technician started rebuilding the head accidentally.  Their pricing was fair so I had them finish it.  The bottom of the head was resurfaced, valves were cleaned and refinished and everything was assembled.

All together, machine costs with the head rebuild totaled around $800.  Not a bad deal but more than I had planned on spending.

Now I need to clean out the oil passages in the block and crank to get it ready for assembly.  As mentioned above, this finish cleaning is always necessary after machine work.  Next post will deal with cleaning.