L31 Extreme Budget Build

[L31MaxExpress]

Getting really close to being able to fire this thing up and have it move under its own power again. I was fighting the engine mount bolts, I had installed the wrong motor mount pad and forgot the spacer on the driverside. I located both OE parts in the shop. I had to drill through the pad to be able to bolt on the oil cooler line bracket.

I updated the Proflow4 firmware to the newest version and went through the basic startup tuning settings again. They ship the Vortec version of this setup calibrated for 15* initial and 36* total advance at 3,000 rpm, nope, wrong, try again. Set it up for 10* initial and 29* total @ 3,600. I set the thing for 15* vacuum advance. Kind of helps to know what these heads generally like. Reset the target air/fuel ratios, they had the idle calibrated in the low 13s and cruise in the upper 13s. Now set for 14.1 or stoich at idle and 15:1 for cruise as the targets. Fattened up the WOT target to 12.6:1 from 12.9:1. Lowered the target idle from 800 to 650. Saved the base map and the adjustments to my phone for easy backup if needed. Looked over all the ECM data it was spitting out. All looks pretty close, although the fuel pressure sensor seems a bit off, it has Zero fuel pressure. Should not be a big deal though, I unplugged the sensor, went to 149 psi, then plugged it back in and it shows the same, so it is not wiring/connection issue. I was afraid the ECM was not recieving a signal at all from it, but it defaults to a high reading rather than a low one. On a side note, atleast it is 25* warmer in the shop than outside and no wind chill. It is actually kind of nice working in that crisp 55ish shop rather than the usual 80-90+. It is odd but it stays about 20-25F cooler or warmer than the outside depending on the season inside the shop with the doors closed.

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[L31MaxExpress]

Well I started to build that harness and second guessed the fan, right back to a clutch fan. Just keep it simple and better cooling if needed. S10/Astro fan blade clears with plenty of room to spare.

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[L31MaxExpress]

Well the front is back together. I ran out of the Gates Green Line style heater hose clamps. I have a 90* 5/8" barb style metal heater control valve on the way. Lists for a lot of 70s GM vehicles including a 1975 Corvette. I will put it in where the tight 90* is next to the alternator right after the water outlet. This thing never had a water shut off valve, but since this has all vacuum controls, all that it requires to function is a small vacuum line plumbed into the line going into the recirculation door. I will get a small roll of the rigid nylon tubing from the parts store to plumb that. Heater core is plumbed just like an OE Vortec now and the hoses have ample clearence with anything moving. In theory the engine should warm up a little quicker than forcing circulation in the cool side radiator tank and lower hose with a cold engine, I meant that is why GM did that on the Vortecs in the 1st place, to get the heater going more quickly. I looked for the TBI silicone hoses but everywhere that carries them appears fo be sold out. If and when they come back into stock, will swap out the radiator hoses for them at a later date. I prefer the silicone hoses as they are alot less likely to fail.

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[GrimsterGMC]

Getting close now mate.

 

[Sean Buick 76]

Clean work!

 

[L31MaxExpress]

Getting close now mate.

A little bit at a time. I am not rushing the process. I want to make it look somewhat factory with cleanly routed hoses, wiring and the like. Make sure everything has ample clearence from heat, moving parts, has room to flex with the engine movement, even though that should be minimal because it does have poly mounts, and the like.

I still have a fuel tank to swap, need to install the shorter filter tube in the TH400 with the filter, and add fluid. Change the rear diff oil while the fuel tank is out and a few other things. Still on the hunt for a battery tray that is not a 3 piece unit like mine was.

Also still have the engine harness yet to build, but that is like all of 12 wires out of the C100 plug. Starter, Ignition, keyed power to the TH400 kickdown relay, ground to the TH400 detent switch, battery hot to the fuel pump relay, oil pressure, coolant temp, and an alternator turn on signal is all the C100 plug needs to carry. The firewall side has a couple of empty spare pin slots to hook up the TH400 kickdown ground.

Then I need to wire the battery charge wire ans main power connection to the junction post. i am upgrading the junction block from the tiny 1/4" or so post GM used to a 3/8" double post to be able to carry the necessary amperage without melting like the OE GM units do. For the main power, I am going straight to the battery rather than to the starter like it was factory. The battery is 1-foot from the C100 plug and junction post GM used to power the van, yet they ran the power feed all the way off the starter and tied the alternator into a wire that goes to the junction block. Alternator thus having a solid 15-20 ft of wiring when you include the battery cable itself it had to send power through to charge the battery. I bought 10 ft of 6 ga wire to update the alternator wiring and battery feed wiring. it was like 10 ga stock. Still need to find some 10 ga fuse link wire to fuse those circuits. I found some 14 ga fuse link wire for the 10 ga connections that need to feed the 2 power feed connections in C100 plug.

 

[L31MaxExpress]

Clean work!

Thanks I want to try to keep it well organized and somewhat clean. I would rather spend my time routing everything right than spend it on the side of the road or in a parking lot redoing the work because something rubbed through or otherwise was chewed up or melted.

 

[L31MaxExpress]

I actually was looking at terminals and a junction block. Just ordered these. Stepped back to a 5/16" stud unit, but a 4 post instead. Allegidly will carry 250 amps, much more than this application will ever need by a good 100 amps. Much easier to find the smaller 5/16" post terminals in the needed 6 awg and 10 awg sizes. I like that it has a nice, removable cover over the top, something the undersized GM single junction terminal did not. 1 stud for the battery, 1 for the alternator, 1 for both the C100 power connections to the under dash fuse block and the last one to power the high blower relay.

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[L31MaxExpress]

I spent a good amount of time into the early hours today working on more stuff. Pulling new wire, replacing a few damaged or broken connectors on the part of the old harness that will remain. The fuel pump harness connector was being held together by a crispy zip tie that exploded when I touched it.

Dropped the TH400 pan, installed the filter with the correct shouldered short pan filter bolt and the matching short pickup tube I had acquired. I modified the bracket on an OE vacuum cruise control servo from a TBI van I had laying around. Going to re-install the OE cruise control setup for now. I may eventually go with the fully electronic servo motor style like the GMT400 trucks have, but a project for a different time. I modified the air cleaner for the 1/2" PCV vent hose. I have the new heater control valve and vacuum hose to operate it installed and plumbed. Took visiting 3 different Oreilly stores to get the Gates Green Line clamps I need. Apparantly they are doing away with them.

The engine is full of oil, the cooling system is filled and the transmission is filled to the full mark.

I am going to swap the fuel tank later today and then I will be out of town for 4-5 days. When I return, I will have the remainder of the stuff I ordered and finish the wiring, install a battery tray and fabricate the battery cables. At that point it will be a quick re-inspection of all the work and show time. Light this pig off, check for leaks, set the timing, warm it up, adjust the throttle opening for the IAC, recheck all the fluid levels and roll it around for a short test drive.

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[L31MaxExpress]

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