Project No-Flight Update
January 2008
Working on the last few open items before I can try to start the car and see if the EFI will run is to install the radiator hoses and coolant and the belt for the water pump and alternator. I used the bendable stainless steel radiator hoses since a stock Corvette lower hose would not reach with the motor setback. The lower hose installed and worked fine. The upper gave me a few re-tries to get it to not leak. Since the hoses are only available in 1-3/4", they supply a reducer insert for the 1-1/2" upper fittings. The "reducer" is a slip-in rubber piece. The first time I put the couplers and hose on I thought it was correct, but the inner rubber piece had actually rolled back on itself and would leak when I filled the system with coolant. Since the inner rubber piece was inside the outer coupler hose it wasn't visible, and I replaced a couple plugs and gaskets before I traced the actual source of the leak to the insert.
In the "I should have done that earlier" department I decided to go ahead and clearance the rear frame cross member for more drive shaft clearance. I'd check the clearance a couple times during earlier fabrication and it should "just" clear by about 1/8" at full suspension droop without the notch. That just seemed too close, so I finally went and installed a notch in the rail and re-touched the paint. It's not a perfect match, but is hard to see the difference from under the car.
21 January 08 - First Start
Well, kind of. I put gas in the car to prime the fuel system and check for leaks. Switching the ignition on the fuel pump would run for 5 seconds as set on the ECM, but I couldn't get the fuel pump to prime. The fuel pump, at about 2" above the bottom of the tank, was too high to self-prime. So, time to drain the fuel from the tank and move the fuel pump lower.
I fabricated a drop bracket (I'll go back and add another brace later) to bring the bottom of the pump flush with the bottom of the tank. Of course that required new fuel lines to and from the pump. Luckily I still had a few lengths of aluminum fuel line tubing setting on the rack. Once it was all together I put fuel back in the tank. Then, the pump leaked. I drained the tank again, (did I mention it is a pain to drain the tank to remove the fuel pump?) I had disassembled the pump earlier to rotate the mounting bracket on the motor and in the process had mis-keyed the bottom plate which has one register bushing taller than the plate. After fixing the fuel pump leak and with the pump in it's new lower location the system finally primed up to pressure. The only leak was on a fitting at the pressure regulator which needed tightening.
Finally, I took the plunge and hit the key. Cranked but no fire. I gave each injector stack a shot of prime, cracked the throttle a bit more and it fired right up. A quick glance for leaks, then look inside for oil pressure ... and no oil pressure. Quickly shut it off. I had primed the oil system a couple of times before installing the engine using my test gauge so I knew the oil pump was ok, but I'd never checked the dash gauge. So, I pulled the distributor, put in the primer drive and turned over the oil pump with the cordless drill. The gauge came right up to pressure. I re-installed the distributor just to make sure it was in all the way down and fired it up again, but still no pressure. I pulled the distributor again and checked the depth to the oil pump drive with the primer, then compared it to the distributor. Sure enough, the distributor reach is about 3/8" less than the primer. I guess the Hilborn manifold sits higher than a normal manifold, and is one thing I had not checked before. I'm going to have to either find a longer reach dual sync distributor, or most likely see about having mine machined to take an adjustable distributor collar then try it all again.
The motor only ran for probably 60 seconds total with the two starts so I doubt it did any damage. I re-primed the oil pump again while turning the motor over and still get 50 psi. I'm going to need to set the throttle stops up higher, as even at idle I needed to hold a little throttle (I removed the return springs from the linkage so I could work it by hand easier). So, one step forward and one step back and it's on to the next problem. Oh yes, did I mention it sounds pretty mean with a good lope and the distinctive header ring. It's pretty loud running in the garage, and may need a bit of additional muffling put into the side pipes but it's not as open headers so measuring the sound level will have to wait for another day.
A machinist friend was able to mill off the old distributor collar and I installed a new adjustable one. It took several install-measure-remove-adjust-reinstall cycles before I was able to get it to engage the oil pump drive and not be bottomed out against it, but once adjusted I now have 75 psi at idle.
On starting session #3 I finally made a little progress, but am probably nearing the limit of my EFI sorting ability.
It really is a bit much for one person to juggle everything at the same time.
I was able to let it run long enough to start checking some of the ECM settings and
bring it up to full operating temp. The air temp was only in the upper 20's so it was pretty cold.
I reset the TPS end points on the ECM as it was showing 20% TPS position when against the idle stop
setting from the prior start. I also enabled the closed loop fueling (I don't know why it would have been set to off) and turned on the manifold surface temp sensor.
The first attempt to start it brought no fire. I thought I had messed something up and was about to reload the prior ECM program when I noticed there was no fuel pressure. The tank level had dropped enough that the pump wouldn't build pressure.
I put more fuel in the tank and now the pump was running at 60 psi. It had
only gotten to about 40 psi on the prior starts so I thought the regulator was
ok, but in retrospect it just had too little fuel in it to fully feed the
pump. I adjusted the regulator down to 45 psi and it fired up.
The smoking is way down now, probably equal parts of being less rich with the fuel pressure dialed down and burning out the storage oil.
In retrospect the total prior running time was only 1-2 minutes (although it seemed much longer at the time as I tried to juggle adjusting the throttle, checking the gauges,
looking for leaks and worrying about all the smoke) which was not long enough to really clean it all out. The water sputter out the sidepipes
also went away once the motor got some heat in it (I'd never seen that much
water before but had never been standing next to sidepipes either).
Once the motor went to closed loop (it has a couple minute delay after start before going to closed loop and I'd never let it run that long before) but was still somewhat cold it would slowly hunt between 1000 and 1500 RPM. Once it fully warmed up and the thermostat opened it didn't seem to want to idle below
1500 RPM. The ECM target idle speed setting is at 800 RPM when warm so I'm not sure why I couldn't get it to idle at a lower RPM once it warmed up.
Still a few mysteries to try to figure out before the next attempt or I probably will just take it to the shop to have them try to set it all.