78 NYB Holley Sniper install.. the end of my lean burn fun

[73 T&C]

Make sure you keep any of the harness going to the Throttle Body away from the ignition wires, the distributor, coil, alterator and their associated wiring. These components are terribly noisy electronically speaking and will transmit all manner of crap to the ECM which will act on it, badly I might add.

A buddy of mine did a super sanitary install on a 68 Roadrunner. He hid all the wiring inside the factory harness. Beautiful job. Unless you took the air filter off, you would never know it had EFI except it would barely run.

It was picking up noise from the alternator cable and the ECM was reading it as a 2500 RPM wide tach signal. He moved all the EFI stuff away from the factory components and it runs like a new Hemi now.

Kevin

Working on the wire routing now along with the adaptor play we’re making for the throttle connection.

Most of the wiring, except for the temp sensor and coil connection, come out of the firewall side (back) of the unit. I intend to loom it around the fire wall to the battery and for the hand held monitor (which I will pull through and put in the glove box). Finally, the O2 sensor wiring will go to the left side of the engine to be installed right after the cross connector. That should keep the most sensitive wiring well away from the distributor and ignition wires.

As for ignition, without the lean burn computer, I’m putting in a Mopar electronic ignition kit as the first step in the setup. Eventually, I would like to have the sniper control the ignition timing. But for now, I just want to get it running. The basic set up allows for connection to the coil for rpm/tach signal. The base program in the unit should work well initially. But if you know me… I will soon be messing around with the timing.

 

[73 T&C]

Couldn’t help myself just now…..

 

[Knebel]

Do it all at once!!! You wont regret the timing control!

 

[LocuMob]

Couldn’t help myself just now…..

View attachment 579099

Now you're talking!

 

[fury fan]

Now you're talking!

@73 T&C
Check those valve covers on a flat surface before you install. I bought a set many years ago and one had about 1/16" of warp/wobble to it. I knew about it, so was very cautious working my way around tightening it, but I hear a pop as one of the bottom ears cracked. Still usable, but oh-so-disappointing. It was many years ago, maybe I just got a bad one.

 

[fury fan]

Might that be remedied by using a dual-terminal battery, with the normal wiring going to the "top posts" and the EFI wiring going to the "side posts"?

Just curious,
CBODY67

Yes, a dual-terminal battery would serve the purpose.

I was considering connecting to the starter relay batt connection and at the block where the ground cable is mounted. I figured these are both connected directly to the
Battery with heavy enough wire to be almost the same as a direct connection to the battery. Are you telling me it isn’t and that it will be a problem?

From what I read, these type of connection locations were exactly the type of connections the manufacturers (and quoters of, like me) were saying to avoid.
In any wiring circuit, each connection has a slight voltage drop. Add any voltage 'non-drop' (?) at the grounds and they add up.
However, those are akin to whatever battery voltage might be - meaning if you have a 14.3 volt system and .5 volts of total drops that is essentially the same as if you were connected directly to a system of 13.8 with no voltage drops. The ECU must perform across a wide range of voltages, so we know it's not necessarily the voltage drops that cause the problem. And the ECU should be monitoring voltage during operation and adjusting injector cycle times based on that voltage to ensure consistent fuel delivery.

So -
I believe the reason for connecting directly to battery is due to the battery acting as a large buffer, smoothing out the 'dirty' voltage bounce in the system. IIRC this is also why they recommend to NOT disconnect the battery on a running engine to check the charging system, as that causes a voltage spike. I am a decent electrical person but not an electronics person - I suspect we'd see such bounce on an oscilloscope but not on a standard DMM, but that's outside my expertise.

 

[CBODY67]

Regarding minimum voltages and such. About 20 years ago or so, I was working the "night shift" parts for our GM dealership parts dept. One day, right after I came to work, a tech requested an a/c control panel for a late-model car . . . complaint on the RO said "Buttons unresponsive". Then, about 9pm, the same car was dropped off by a wrecker service. Car went dead on the road. So we did a charging system check, using an inductive-pickup Sunn checker. Charged the battery, too.

When we got the car running, I was curious. The battery was good, and the alternator seemed decent in output with little load. But as more and more load was applied, the system voltage kept dropping. When the system voltage got down to about 5.5V, warning light icons on the instrument cluster came on in pairs, then went out, in a sort of sequence, in about 2 seconds. Then the engine died. New ACDelco reman alternator, charged the battery back up, and all was well.

So the real reason the a/c control failed was not a defect, but low battery voltage, it seemed to me.

Possibly some EFI diagnostics somewhere which might mention the minimum battery voltage that system needs to operate the ECU and the fuel pump too?

As to the tank-mounted fuel pump module, the fuel in the tank is also the heat sink for the heat the fuel pump generates. Does the pump come with their fancy "mat" fuel pickup "sock" too?

An alternative, for slight bit less money, is their underhood fuel reservoir/pump to supply the EFI TBI unit. IF you have enough additional room under there. Using the existing fuel pump as a "lift pump" to the reservoir. Might need to relocate the coolant reservoir and such in the rh frt section of the underhood area behind the core support? But the in-tank system better mmics all OEM-style EFI systems, which might end up being the best way to do things.

Please keep us posted on the install and performance benefits (starting, throttle response, fuel economy on the road), too.

Just some thoughts,
CBODY67

 

[fury fan]

IIRC many relays have a drop-out voltage of around 8 volts, so that might have been the cause rather than ECU diagnostics per se. Fuel pump surely would've turned off.
I'm surprised it made it down to 5.5 volts.

 

[Knebel]

My expierience is that you really need a good battery and a good charging system. These systems don't seem to respond well to lower voltages!

Id recommend upgrading your chargewire and alternator wire to some 00gauge! This way you have less drop when cranking. This dreaded drop while cranking can cause all kinds of no start or start/stall issues! Believe me I was chasing it haha

 

[70bigblockdodge]

Watch those valve covers on cast iron heads. Cast iron heads are notorious for uneven gasket surface, and those valve covers do not bend like originals.
Lots of luck with EFI, not my bag.

 

[LocuMob]

Lots of luck with EFI, not my bag.

You simpleton.

 

[70bigblockdodge]

You simpleton.

I must say I will be watching this thread because if anyone can sort out this pressure carburetor it will be Javier.

 

[73 T&C]

Yesterday’s fun:

Worked on making an adapter plate to mount the old linkage to the new throttle. Will take pictures tomorrow. But reading and watching install articles and videos have noted the need to plan this part of the integration carefully.

We threaded the largest mounting hole on the sniper throttle such that, together with a roll pin guide mounted next to it, the adapter plate should give me a safe and secure linkage connection (with the added benefit of one bolt removal).

Of course, as mentioned in one video, I approximated the distance between the main throttle shaft and the accelerator link to maintain the same range of operation and lever arm distance. I even adapted the cruise control throttle lever from the Thermoquad to work the same on the new adapter plate.

Ordered a new sending unit for the dash gauge to replace the lean burn temp sensor ( that sensor only switches on/off at 160 degrees). I intend to use the original temp sensor location for the sniper temp sensor so I needed one for the dash gauge.

Pulling those old sensors may be a challenge… already hit them with penetrating oil…but I have a feeling I may need to bring out the torch to loosen them.

Todays progress.

New fuel sender in and tank is now up and lines connected. It happened after I left.

O2 sensor installed.

Ordered a square to spread bore adaptor plate…. Should be in by tomorrow….. I hope.

Need to get the battery tomorrow as well.

New sender is a match….

 

[Ripinator]

Couldn’t help myself just now…..

View attachment 579099

Ten more horsepower right there!

 

[73 T&C]

Ten more horsepower right there!

Lol….. but only when you get it with the extended chrome wing nut bolts!

 

[73 T&C]

Picture time and progress… from back to front:

Went with relief cut for lines rather than separate penetrations for the lines. Simpler is always better. Cover is going to be important for this bit.

In-line filter… will need heat shield.

O2 sensor in. Will need some reworking of connector to avoid extreme kink and better support of the wiring. Will be bending that flange to get it out of the way.

Noticed that the neutral safety switch line needs some love and better support.

Used the hard line up to the firewall and then intercepted it. Supposedly, the 550-511D does not need a return with the supplied in tank fuel pump…. We’ll see, but that’s what the Holley man said.

Lots of extra high pressure fuel line. Waiting on the new valve covers….and the cool pressure guage.

My frankenlink…. Looks like it might work. I had to switch the kickdown link to the other side of the return spring knuckle but it aligns very well. Not shown for better look at adapter plate (of which I’m quite proud). I’ll get a shot of kickdown link in place to add to this thread tomorrow.

Different angle. One bolt and off she comes with links and all.

WOT position and the cruise lever works as intended.

Detailed and sorted a few things on the roadrunner too last night…. Just to relax.

Adapter plate for base arrived today.

Hopefully replacement coolant temp guage sensors arrive tomorrow

As always, any comments and suggestions are welcome.

 

[73 T&C]

Well, at least one thing arrived today.

I think I’ll get some carb studs. These loose bolts held by the base setup is no bueno. Have no idea what the two long studs are for.

 

[Knebel]

Nice work!

 

[70bigblockdodge]

Long ones are for a quadrajet. The bolts captured in the adapter actually work well unless you gorilla tighten them pulling up on the plate. If you have the inside holes on the sniper I would just stud all the way through, cleaner and simplest.

 

[73 T&C]

Coolant temp sensor arrived yesterday.

I’m putting the sniper coolant temp sensor where the original gauge sensor is and replacing the LeanBurn sensor near the water pump with a new gauge sensor. The sniper coolant temp sensor looks to be a match for the existing sensor.

Also arrived, proper direct connection 7/16”valve cover bolts and two studs per side. Should make install easier with the studs.

And…. Also arriving yesterday: Fuel pump cover plate. Chrome of course… for that extra horsepower. Lol. It was actually cheaper than the cast alum option.

Thinking about wiring. I think I’m going to take the LeanBurn wiring apart for use in connecting the engine start and run for both the Sniper and the new ignition module. Instructions do not mandate anything regarding location just that it provide power during cranking and running. I’ll look at the wiring diagrams to confirm.