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Chapter 17: Piston slap, more dialing


Well, over the summer TurboStude has slowly been getting developed.

It now has a 650 cfm Edelbrock AFB clone richened out to #19 combination (really rich http// ) on the primary side, with 0.100 inch secondary jets, very firm step-up springs, and the plugs are still not black. The transition circuit is coming in better now, and with some further monkey business, the advance curve will be set. Now for the electric fuel pump which will be in series with an ‘inertia switch’ which will disconnect with any jarring of the car. These are very simple and are present in the trunks of most Ford passenger cars (and on the firewalls of the Ford trucks…. Despite the engine rebuild (by someone I thought I could trust) I think there is some piston slap (no, not detonation) and I’m going to a thicker oil to see what happens….

Anyhow, I’m wondering if I might gain something by using my “auxiliary” exhaust outlet, which I originally welded on to the output housing of the 2.2 TO-3. It was used temporarily before adding a more professional 2.5 inch exhaust thru the fender utilizing the factory 90 degree outlet and doughnut. I could plumb the added on outlet thru a gentle curve to attach to the other one. The turbine is 0.48 and the compressor is 0.42

I don’t know why I didn’t do it before, but going richer on the secondary jets was a big improvement. Ted Harbit suggested that I go to the ‘big squirt’ setting on the accelerator pump, and this probably helps too. At the Stude nationals, I got a look at the regulator on Jon Myer’s dual supercharged ‘Spooky’ Lark. It is boost referenced and is plumbed to regulate the fuel as it is being bypassed back to the tank,and is not acting as a restriction in the fuel supply to the carb (it works off a ‘T’ in the line between the pump and carb). I wonder how much the regulator impedes fuel flow in some of the cars we are building, making us think that we need more and more fuel pump or bigger float needle and seat assemblys. Also I have heard some rumblings about the counter-weighted butterflys above the throttle butterflys not opening fast enough or not at all, some people wiring them open. Maybe the mechanical relationship between the primary opening and secondary needs some scrutiny? secondary is allegedly supposed to open at 60%, but maybe that’s not right for blow-thru turbos?

10/01  Now the electric fuel pump is wired in thru a fuse box, an inertia switch and an oil pressure switch.  It is mounted back near the tank with a filter before it, and then continues on to the mechanical fuel pump, then to another filter, the regulator and then the carb.  I added a digital voltmeter on a little bracket in line of sight.   This is attached to the O2 sensor.  The ideal voltage on WOT would be 0.9 to 0.95 volts, but I still can’t get up to more than about 0.83 volts. 

As far as piston slap is concerned, I used a rod and a piece of tubing to try and trace the noise.  It is not detonation.  It may be that there is some noise being generated by the additional oilpump.  I will try a different batch of oil and try removing individual plugs to see if there is any difference. 

Speaking of plugs, though I don’t hear much if any real pinging, I have noticed tiny little globs on the sparkplug insulators.  I have gone to AC R-45SX plugs which have a longer reach and are less shrouded by the cylinder head.  I’d better work some more on the distributor.  Right now, it seems to run better without any vacuum line.  I think my boost retard is getting too retarded, as it starts about the time I begin to pick up boost.  I now have a tachometer which indicates that I’m reading about 2-3 pounds at the turbo outlet at about 2500 rpm.  I expect that I shouldn’t need retarding until I reach about 10-12 pounds of boost, which occurs briefly, now, at about 4500 rpm.   I expect that things may change with further jetting and ignition adjustments. 

Added a voltage dropper now, and again have 6 volts for the gas gauge and temp gauge.  Speedo again hooked up, and reads odometer, but not speed?!  Frustrating.

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