SkinnyG's 1977 Chevy Silverado

In other news, to deal with the dead battery issue (and always low voltage reading on the dash), I installed a new 94Amp 12SI alternator for an '84 Camaro 305H.O. (bolts right in). Wow! The voltage gauge never read so high! And wow the truck ran well! And the signal light flash with authority! Impressive.

Dash gauge usually sat at 12-13V at idle, less if anything electrical was on. When the cooling fans were on (30A), the truck struggled to maintain 9-10V on the gauge. Add EFI to that, plus an inverter to run the lappy, then sit in traffic with the alternator at 8V - no wonder the battery died.

For sale: used 10SI alternator from 1977 Chevy C10, low voltage edition.....

Awesome driveway!

The GM 8 pin HEI module uses the VR signals internally, The signal going to the Megasquirt is not a VR signal. I just read the megasquirt instructions and they are very confusing when it come to this.

You can experiment with the distributor with the Qjet still on the truck, drop in the 8 pin distributor, Put 12V on the + side of the coil, Ground the G and B pins. Leave the R and E alone for now.

..Start engine and rotate distributor so base line timing is 8 deg BTDC. As long as B is grounded the engine will run with fixed timing. If you unground B the engine will die because it need the R and E signals to work.

Also keep in mind you need to run a 26 degree offset in megasquirt. The offset allows megasquirt to calculate timing before it actually gets the reference signal. There is some magic done in software to sort all this stuff out.

I only had a 10° offset in TunerStudio, not 26°. But Megasquirt just wasn't seeing a pulse. MS ~did~ see the Tach Output of large cap HEI-4, but not small cap HEI-8.

R gives Megasquirt a tach signal. Without a tach signal, I cannot run the engine - isn't that correct?

Without a tach signal to the ECU, I don't get ignition or fuel pumps.

To get the beast running again, I put the old mechanical pump back on, down by the curb in front of the house. The same mechanical pump that was on when it began starving itself of fuel.

When I got it back in the shop and up on the hoist, and pulled out my Frankenstein fuel/pump/line/surge-tank system, I hosed the old fuel line with carb cleaner and blew air through it. It really flowed well. Makes me think the line wasn't plugged, but that the mechanical pump was failing.

So, today I pulled the mechanical pump off, and spliced in a low pressure electric AC/Delco EP12S I was using with the EFI.

My "falling in love" with the truck is turning into more of a "stepped in it."

SkinnyG wrote: R gives Megasquirt a tach signal. Without a tach signal, I cannot run the engine - isn't that correct? Without a tach signal to the ECU, I don't get ignition or fuel pumps.

That is correct. the R (reference) signal is the tach signal and should go to pin 24 on the megasquirt. Without tach you will not get ignition or fuel pump. E should go to pin 36.

You defiantly need to run the 26 degree offset in the trigger setup for the timing to work in megasquirt. The offset is so the megasquirt can calculate and fire the cylinder before it actually gets the reference signal... if that makes any sense. Also the 26 degree offset is not to be confused with the 8 degree BTDC baseline timing of the distributor.

Anyway what I originally was saying was you can test the 8 pin distributor with the carburetor still on the truck by grounding the B (bypass) pin. With the bypass pin grounded you can get the engine running and set the baseline timing.

Ah I see. That makes sense. Certainly helps me rule out a faulty HEI8. Good tip!

In reply to SkinnyG:

Stupid question but for future knowledge- when you say 'bolt's right in' is the clocking and wiring all the same? I would like to put one of these on my truck with some potential future additions in mind.

Thanks!

The two-pin connector and the battery connector are clocked differently, but not so much that you'd even worry about it. I didn't have to alter anything - wires just hooked right up to their slightly moved locations.

In reply to SkinnyG:

Very awesome. Thank you!

Nope. Not going back to EFI just yet.

But I have been more determined to resolve the off-idle stumble of the Q-jet.

It ~felt~ like it was getting TOO MUCH fuel from the accelerator pump. I had previously doctored this carb according to the Cliff Ruggles book on Rochesters. Great book, by the way. When you got on the throttle, it would ~start~ to rev, but then stumble.

No adjusting of idle speed, idle mixture, APT, or timing would correct this.

Yesterday I moved the link to the furthest hole, and voilà: Carburetored awesomness.

Nice lookin truck! Love what you were able to do with the paint...tried to roll my 83 F250, didnt work very well:(

I don't think I put an update on the paint here. This is after three Okanagan summers (sunny and HOT), plus Canadian winters. I have never colour-sanded it, buffed it, or waxed it. I washed the truck last year some time (it is June as of this picture).

In reply to SkinnyG:

Ok one final stupid alternator question and I'll get off your case- is there any downside to upgrading the alt on a stock truck? Right now the truck is mechanical fuel pump and still a mechanical fan, but both may have electric versions in their future. I'd like to preempt that extra draw with a better alternator before I add the additional components. Any reason I can't or shouldn't do this?

Thanks again for your sage words of advice!

Other than drawing more current out of the high-output alternater than the existing wiring can provide and thus burn the entire truck to the ground, no - there is no downside.

Upgrade the wiring from the alternator to the battery, and you should be good.

I haven't done mine yet.

But the only thing extra is electric fans (relay off the battery), electric fuel pump, and tunes.

In reply to SkinnyG:

Alright I'll keep that in mind. Thanks!

A year ago I swapped the polyurethane motor mounts out of The Crusty Chevy for rubber, in an effort to chase down a vibration. The poly was not the culprit, but the replacement mounts had their own issue.

Today I swapped them back.

Left to right, you see "Anchor" made in China, "Anchor" made in USA, and the original clamshell with the poly mount installed.

Looking at the ends, you can see the USA mount had completely collapsed and had deteriorated. This mount was actually faulty from day one - the metal supports for the motor were actually touching the clamshell on the inside, producing a horrifying (and slowly increasing) metal-on-metal vibration exactly at cruise RPM under light (cruise) throttle. I finally had enough, and pulled them out and went back to poly.

Great news everybody!  That didn't fix anything.

In reply to SkinnyG :

Look up a Sirometer tachometers and read this

Https://grassrootsmotorsports.com/forum/tech-tips/cheap-simple-nvh-tool-and-write-up/117396/page1/

I seem to have lost the wiper switch.  As exciting side to this, it is not replaced in the aftermarket.  I can use a 78+ switch, but I have to also upgrade the motor as well.

So, I took the switch out and disassembled it, cleaned the contacts, and fixed the springs that made the electrical contact. Stuck it all back together, and boom!  Awesomesauce!

Good thing, too, because my commute today was sheer ice:

Although I had four Michelin X-Ice Radials, I turned around within two blocks to load my six sandbags for winter.

It didn't help that both my fuel tanks were empty too.  Fuelled both up on the way home - $167 of Premium at $1.55/L, which will get me about 300km.

Good news everyone,

The aforementioned vibration has gotten quite worse. It wasn't from the motor mounts as I had previously suspected. I put it up on the hoist today, and had a kid on and off the throttle to make it make noise so I could chase it. It's a nasty "bearing rattle" that I can feel in the floor, and can hear from under the floor.

It wasn't from the back axle, which didn't make sense to me anyway, but I hoped it wasn't.

It's very definitely from the back of the transmission (and zero play in the u-joints, and zero play from the existing bushing - odd).

So I ordered a new extension housing bushing and we'll see if it makes a difference.  If not, that means I have to pull the trans and go in. Again.

Fingers crossed!

I really like the snowy driving shot above.

I like this one, where I got stuck mere feet from my driveway:

Took the extension housing off the trans.  The bushing looks good.  I had replaced it a couple years ago, but it still looks good.  There wasn't any notable play in the driveshaft assembled.

I removed it and installed a new bushing.  Will find out tomorrow if that fixes it.  If it's not that bushing, it'll have to be bushings further in - but I put in all new bushings when I rebuilt the transmission not too long ago.  How odd.

Good news everyone!

The vibration issue is deep inside the transmission.  I am SO looking forward to ordering a rebuild kit and a set of bushings.  Again.

Christmas come early this year - only the coal is in the shape of a TH350.

In reply to SkinnyG :

What about a turbo 400 instead?