Install thread- Holley EFI Sniper on '72 402 big block

[Ekliptix]

Part 1 Video https://youtu.be/ZOTmKqEPsHo

Moving the truck into the shop
https://i.imgur.com/kYFBqg2h.jpg

Old vs New
https://i.imgur.com/PWgIN4nh.jpg
https://i.imgur.com/UUTYdyuh.jpg

On the engine. Vacuum and throttle/trans cable connected.
https://i.imgur.com/gK33MXwh.jpg

3/4" hole drilled for O2 sensor. It's 10+ degrees above horizontal and near the collector.
https://i.imgur.com/wFpb0Aih.jpg

Derp. Included 2.5" exhaust clamps for O2 sensor mounting don't fit my 3" exhaust. I'll need to go buy some 3" clamps:
https://i.imgur.com/YLZqP9th.jpg

Draining some coolant to install the new temp sensor
https://i.imgur.com/KCowmx7h.jpg

Temp sensor install location. May need to relocate it as I've read the reading back there can be too low.
https://i.imgur.com/Y5ElynKh.jpg
https://i.imgur.com/BJeprTUh.jpg

To be continued!

[Skrilla]

God I love your truck, soo nice :drool:

[SKR]

I'll be following along, I want to do this to my truck too.

[Ca_Silvia13]

Very interested in how you end up running the fuel. It's the #1 thing holding my back on swapping the 455

[Ekliptix]

Very interested in how you end up running the fuel. It's the #1 thing holding my back on swapping the 455
For the fuel source side (tank to elec fuel pump to throttle body) it should be straight forward.
For the return (throttle body to tank) I have a place near the tank where I plan to add a simple T fitting to a rubber hose (shown in video), but I have not yet figured out a hole in the cab where I want to run the return hose.

[Sentry]

Boom.
https://www.amazon.ca/Fuel-Diesel-Gasoline-Tanks-Black/dp/B01F4CA0FS

Thank me later. :D

[Ekliptix]

Boom.
https://www.amazon.ca/Fuel-Diesel-Gasoline-Tanks-Black/dp/B01F4CA0FS
Thank me later. :D
I don't need to cut my tank to do this install, if I'm understanding the purpose of that thing. If I'm missing the point can you explain?

[Sentry]

It's a quick easy sump, if you want to sump the tank instead of using 45 year old lines.

[Ca_Silvia13]

For the fuel source side (tank to elec fuel pump to throttle body) it should be straight forward.
For the return (throttle body to tank) I have a place near the tank where I plan to add a simple T fitting to a rubber hose (shown in video), but I have not yet figured out a hole in the cab where I want to run the return hose.

I didn't see the inline pump previously. Looks like a very complete kit, would you agree?

[Ekliptix]

I didn't see the inline pump previously. Looks like a very complete kit, would you agree?

It sure is. So far, the only thing lacking is the exhaust clamps for the O2 sensor being suited for 2.5" dia exhaust, while I have 3". I bought the optional fuel kit with the EFI system. If I was going more hardcore, I'd get a new rear fuel tank with a build in electric fuel pump. However, this kit has the in-line elec fuel pump, hose, filters, fittings, etc.

[90_Shelby]

Is the system strictly for fuel delivery or can it control timing as well?

[Ekliptix]

I don't believe to, but this part can be connected to the Sniper EFI computer to control timing: https://www.holley.com/products/ignition/distributors/parts/565-100
It's on my 'later' list of things to add.

[CUG]

Looks good.

[carson blocks]

Nice project. If you're switching to fuel injection, have you considered doing the tank swap to a frame mounted tank? Keeps the gas and associated smell out of the cab, bonus points for safety if you're in to that sort of thing, and clears up room behind the seat for subwoofers, gun racks, whatever floats your boat. They make nice clean tanks for those that sit between the rear frame rails, and are already set up for FI.

[Ekliptix]

Nice project. If you're switching to fuel injection, have you considered doing the tank swap to a frame mounted tank? Keeps the gas and associated smell out of the cab, bonus points for safety if you're in to that sort of thing, and clears up room behind the seat for subwoofers, gun racks, whatever floats your boat. They make nice clean tanks for those that sit between the rear frame rails, and are already set up for FI.
I don't have any issue with the factory fuel tank in the cab. I've never smelled gas. If I were starting from the frame up, I'd put a rear fuel tank in. I the case of what I'm doing here, that's too big of a pain in the ass and cost to bother with.

[Ekliptix]

Got the fuel tank drained in to jerry cans.
Removed the mech fuel pump.
Assembled the elec fuel pump and filters.

Found a factory return line I intend to use. Need to get a fitting to step down from the 3/8" fuel hose to the 5/16" steel return line going into the fuel tank.

I intend to keep the 2 3/8" hoses (green and red below) next to each other, along the frame rail before running them up the firewall above the transmission, around the distributor into the EFI unit. I'd use the factory hard lines along the frame except they terminate way at the front by the radiator. The headers will be approx 3" away from the fuel line at the nearest point. I suspect this is OK for temps, but I'll look into something to wrap parts of the fuel hose with to protect it from heat as an extra step: https://www.amazon.ca/Heatshield-Products-204002-2-Inch-2-Feet/dp/B004GNLGTQ/ref=sr_1_3?ie=UTF8&qid=1517862195&sr=8-3&keywords=fuel+line+wrap&dpID=41594aFPM1L&preST=_SY300_QL70_&dpSrc=srch

Here's the plan:
https://i.imgur.com/rtj8YUl.jpg

High flow mech fuel pump vs electric fuel pump.
https://i.imgur.com/A0etF0vh.jpg

[carson blocks]

Mounting the fuel pump on the frame under the cab?

[Ekliptix]

Correct. Near the stock fuel hard lines.

[carson blocks]

Nice, just wanted to make sure it wasn't going in the cab with the tank, both for noise and safety.

[Ekliptix]

Part 2: https://youtu.be/hIClWrLBrBA

Got the fuel system installed.

Removed the mechanical pump and used the included plate to cover the hole. The original bolts were too long for the plate, so I had to find some shorter bolts.

The electric fuel pump is mounted along the frame using some existing holes (lucky).
https://i.imgur.com/5VXUn1Nh.jpg

https://i.imgur.com/vJWJmjqh.jpg

I ordered some of these off amazon.
https://i.imgur.com/YdnR4l2h.jpg

And after a bunch of looking found this 3/8" to 1/4" step down to connect to the factory return steel line into the stock tank. From the EFI unit in the engine bay, the 3/8" rubber return hose goes down the firewall, along the frame, through 2 of the rubber retainer clamps, into the 3/8" to 1/4" step down fitting, into a new 1/4" rubber hose, into the factory 1/4" steel return hose which goes into the cab and tank.
https://i.imgur.com/6BLLowjh.jpg

I heat tape wrapped some of the fuel line and post pump filter just as a precaution, and it looks cool.
https://i.imgur.com/mjndZLyh.jpg

Also got the 3" exhaust clamps from amazon so O2 sensor is installed.
https://i.imgur.com/7sszeDIh.jpg

- - - Updated - - -

Made some wiring progress tonight.
https://i.imgur.com/3q2ZNhyh.jpg

This is an optional 10 pin connector. Most of the wires are for nitrous, etc, so I cut and heat shrinked most of them. I only need the brown wire remaining to send a signal to my tach.
https://i.imgur.com/aVkjyksh.jpg

Started getting some things tucked away. I need to buy some black wire loom to cover those 3 wires at the top. I attached the fuse and relay to a screw by that AC box thing.
https://i.imgur.com/L3neJOqh.jpg

Tried to hide the wires as much as possible. This is the power from the battery, ran through the fender.
https://i.imgur.com/L2I07i2h.jpg

What's left is connecting a blue wire (power) to the fuel pump, grounding the fuel pump, ensuring the O2 sensor cable is secure, terminating the yellow wire to the distributor tach signal, connecting the brown wire to the tach, connecting the pink wire to 12v when the ignition is on.

Then put some gas in the tank, follow the start up instructions including priming the pump and dumping gas into a can to fill the source hose with fuel.

The end is in sight!

- - - Updated - - -

Good news and bad news.

The good: The truck is running!!! It idles super smooth and there's no unspent fuel coming out the exhaust.

The bad: There's coolant leaking from the intake manifold where a crack has appeared, likely from me over tightened the heat temp sensor.

Need to do:
1) replace/fix intake manifold where it cracked.
2) adjust throttle cable to provide 100% open throttle. Reads 85% position at peddle WOT.
3) wait 3 months for snow to melt

Part 3 Video: https://youtu.be/JSnHy1DTm8E

Finished engine bay
https://i.imgur.com/qaTdR0bh.jpg

Running and warming up
https://i.imgur.com/1eLElLsh.jpg

Me "What's that sound?"
https://i.imgur.com/fnm3wZph.jpg

Green juice is good, right?
https://i.imgur.com/iVzCDe2h.jpg

Random pic of chains used to get 1 car and 2 trucks unstuck from my driveway this weekend. 305 studded winter tires, love 'em.
https://i.imgur.com/6fV4j3Xh.jpg

[BerserkerCatSplat]

Fuuuuck, you didn't even bottom out the sending unit and it still cracked the mounting boss. That blows.

[SKR]

How is the truck running now? Is your throttle super stiff?

I had a Sniper put on my truck this spring too, but it shudders and surges at part throttle. It's hard to feather the throttle because it's so stiff so I wonder if it's having trouble learning what to do.

[HiTempguy1]

My big curiosity is what compelled you to go EFI?

Honestly, have grown up on EFI but having owned plenty of carbed vehicles, I love carbs for their simplicity. And a quadrajet can be setup to get almost as good mpg as efi.

[SKR]

My big curiosity is what compelled you to go EFI?

Honestly, have grown up on EFI but having owned plenty of carbed vehicles, I love carbs for their simplicity. And a quadrajet can be setup to get almost as good mpg as efi.

Looks like we're both on his pay no mind list, but I can answer for myself. I decided to change because I wanted better driveability and better mileage than what my carb could do. I went from 6-8mpg on the highway to 13-14, and I can just turn it on and go. You can buy a lot of gas for what it costs so it's not worth it just from that standpoint, but it drives a lot better. I still need to dial the tune in though.

[Zorac]

My big curiosity is what compelled you to go EFI?

Honestly, have grown up on EFI but having owned plenty of carbed vehicles, I love carbs for their simplicity. And a quadrajet can be setup to get almost as good mpg as efi.

i always contemplate it as well. the carbs are so simple. while i have most of the parts to do an efi/megasquirt conversion on my old car, i have resisted so far and stuck with a weber. the weber runs well and is easy to fix. mpg isn't bad and its not like a put a bunch of miles on the car.

[revelations]

Man that thing looks nice and clean, compared to the dozens of vacuum hoses and thus, failure points, I had in my late-80s electronic carb vehicle.

[Maxx Mazda]

Agreed. Thats a nice looking setup.

[Ekliptix]

I replaced the intake manifold and it wouldn't start. I re-baselined the distributor incase I messed up the timing when having the intake manifold off. It'll start now but sounds like it running on 4 cylinders. I'm thinking spark, so I replaced the wires. I need to check if there's spark getting to each cylinder, one spark plug at a time. I'll also triple check all the wiring and fuel, incase I didn't hook something up when I was replacing the intake manifold. I'm a bit pissed since it was idling perfect until the original intake cracked. Now with the new intake, it won't idle. Trouble shooting will continue. I'm confident it's something I did, not the EFI unit.

[HiTempguy1]

Looks like we're both on his pay no mind list, but I can answer for myself. I decided to change because I wanted better driveability and better mileage than what my carb could do. I went from 6-8mpg on the highway to 13-14, and I can just turn it on and go. You can buy a lot of gas for what it costs so it's not worth it just from that standpoint, but it drives a lot better. I still need to dial the tune in though.

That much of a difference eh? That is impressive!

Also, I didn't know a lot about this Sniper system and did a lot of reading on the weekend. I now get it, the pricepoint is amazing for what you get. It actually makes LS swaps sort of irrelevant now IMO, super cool product.

[SKR]

That much of a difference eh? That is impressive!

Also, I didn't know a lot about this Sniper system and did a lot of reading on the weekend. I now get it, the pricepoint is amazing for what you get. It actually makes LS swaps sort of irrelevant now IMO, super cool product.

That's because my carb was a piece of shit though. Most people call a mechanic, I needed to call a priest to work the demons out of that thing.


I replaced the intake manifold and it wouldn't start. I re-baselined the distributor incase I messed up the timing when having the intake manifold off. It'll start now but sounds like it running on 4 cylinders. I'm thinking spark, so I replaced the wires. I need to check if there's spark getting to each cylinder, one spark plug at a time. I'll also triple check all the wiring and fuel, incase I didn't hook something up when I was replacing the intake manifold. I'm a bit pissed since it was idling perfect until the original intake cracked. Now with the new intake, it won't idle. Trouble shooting will continue. I'm confident it's something I did, not the EFI unit.

That sucks, hopefully it's something easy to figure out.

[revelations]

That's because my carb was a piece of shit though. Most people call a mechanic, I needed to call a priest to work the demons out of that thing.



Was it one of those units with emissions and vacuum hoses going in 32 different directions? A small or intermittent leak (eg no issues at idle, but leaked during driving) usually meant hours of troubleshooting. I ended up replacing every, single, fucking hose on mine because it was easier.

It would, literally respond opposite to what you would think during troubleshooting and even then intermittently. Demons indeed.

[Ekliptix]

I spent a couple hrs on the truck today. Got it running after confirming wiring was correct, 12v everywhere it was needed, then:
a) plugging all the vacuum hoses and ports. It wanted to turn over, but didn't start until I,
b) turned the dist cap as advanced as it would go.

Once running, it sounded normal, all 8 cylinders. If I dialed back the timing by turning the dist cap, it would back fire a little, so I left it as advanced as I could with the cap position.

I hooked up the timing light and it appears ~12 degrees ahead of 0. But the weird thing is the timing light was not flashing steady, the light seemed to skip some revolutions. This is making me wonder if spark is actually travelling to Cyl #1 on every revolution, or if there's an issue with the distributor. You can see this action in the video. I don't think there's an issue with the timing light because I used it on the Blazer this morning and it was normal.

So, next steps are:
a) reconnect one vacuum line at a time and see if/which line is causing a leak.
b) remove the dist cap for inspection/replacement.

Overall, I'm happy it's running again even though there are a couple bugs to work out.
https://youtu.be/uSN6lzK4BdA

[BerserkerCatSplat]

Only 12 degrees advance with the distributor maxed... are you sure the dizzy wasn't installed one tooth off?

[Ekliptix]

You could be right. When I was lining it up, there was some room for error. I'll also try the timing light on each plug wire to see which ones are not consistently flashing, sending spark.

[BerserkerCatSplat]

Timing gun pickups can be a tad flakey, but either way it's worth the effort reset your distributor location. No idea if you bought them as a package, but double check your cap and rotor are making good contact as well - I saw one time where a guy was having really random spark loss issues and it turned out he'd received the wrong rotor and it was juuuust too short, and was only making intermittent contact with the cap when warmed up.

[Ekliptix]

I believe there is still a problem with the distributor, but it's running now. I've easily started the truck a few times and brought it up to operating temp. Using the timing light, I check each plug wire. Strangely, they all appear to be flashing normally at this moment in time. I'm still suspicious of the distributor. I have a spare dist from the original 350 engine, but the timing curve is different in it.

I reconnected each vacuum line, one at a time. The engine appeared to run/idle the same with all vacuum lines connected vs all plugged. The vacuum at idle is only 6 inches according to the factory gauge, very low. I plan to try blowing into each vacuum line when the engine is cold to see if I get any leakage.

I took a risk and drove the truck down my driveway and back, about 1 mile. Everything was fine. I tried stomping on the gas and it lit the tires up from a stop through 1st gear and 1/2 way through 2nd gear. So, it's making more power now vs with the carb. I have no idea if the timing is optimal, plus the throttle is only opening a max of 85% until I adjust the throttle cable. Still, I was happy and felt some gratification feeling the new power and responsiveness the holley Spiper is going to give me once things are 100%.

Last night I installed a new starter as the existing one somehow got out of alignment and the gear teeth were shot. Got it lined up and done. Was a tight fit and lesson in patience trying to do it all on jack stands.

Fired up first try.

https://youtu.be/J5CxfMAJR5U

To do:
1) check for vacuum leaks.
2) determine why distributor is unreliable to deliver spark to each plug. Potentially replace distributor or at least, distributor cap.
3) figure out why brakes are so weak. This has been an issue since the 350-->402 swap. It may be the vacuum is too low, or another reasons.
4) install converter lock up wire + switch to 700R4. The vacuum line does not seem to engage the lock up, currently.

[Sentry]

#3 could be as simple as the added weight in the nose from a big block vs. a small block lol. Have you put a gauge on it to see how much vacuum you're getting?