93 K2500 Suburban 454 Holley Sniper Upgrade

[Erik the Awful]

You're likely going to have some teething issues, and don't rush to blame the Holley. Every issue I had after my Sniper install was something else on the truck suddenly crapping out.

 

[LC2NLS6]

Took it for its first drive, ran fine. I must have installed the new Y pipe donuts crooked, the pass side is leaking, which is highly annoying. AFR stuck at 35.6. I need to clear the Holley learn tables I think, it ran fine in whatever mode it figured out with. Has way more torque, like, I'm sure it has 500+ ft lbs now. It also pulls harder past 3000. I drove it over to the engine builders shop to return the engine lift plate he let me borrow (my leveler is at the house down south somewhere).

 

[LC2NLS6]

Der, of course the 02 is whacked, the donut is sideways, and is upstream of the sensor. Ok, gotta fix that.

 

[LC2NLS6]

I highly recommend Gen V 454's upgrading to this Comp magnum 215/215 roller cam. Lifters are quiet, has a rowdy idle, and tons of torque with the peanut port heads.

https://www.compcams.com/magnum-215...d-lifter-kit-chevrolet-big-block-396-454.html

 

[LC2NLS6]

Must have burned up the O2 wideband breaking the prior cam in. It was stuck at 35.6 AFR. Overnighted a Bosch 17025 from Summit and back in business.

If I had to do it all over again, I think I would have got the Terminator with the GM trans controller built in and the ECU would be mounted in the cab vs on the engine itself. $3000 though just for that.

https://www.holley.com/products/fue..._kits_with_transmission_control/parts/550-408

 

[LC2NLS6]

Cleared the tune, started over, new sensor, she runs well. Added base fueling, set it to target a bit richer. I do think a longer throttle arm would help on part throttle use to make it easier to dial the pedal travel in. I set startup timing to 20 deg idle and cranking, WOT to 33 deg, on pump premium 93 E10 winter blend, which according to my 2009 flex fuel Suburban is 25-40% alcohol...

The Chinese plastic radiator #2 is leaking when cold (I suspect thermostat isn't open and waterpump puts out too much pressure for the Chinesium clamped alum plastic to hold it. Brand new, garbage. I think I'll go full alum made in America now. Had one in my 87 GN, big money, but at least it didn't leak when new. - EDIT - It helps to actually tighten the upper hose clamp - no leaks now...

I added Moroso spark plug wire separators bolt off the stock valve covers.

Painted the 454 valve cover emblems black, then sanded the 454 shiny. Turned out well I think. Removed the air filter tube to pull vac from the driver side valve cover.

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[LC2NLS6]

Had to manually unscrew the throttle stop, now it idles 550. Before it wouldn't go below 780.

Cranking timing at 20 degrees - it did not like that. So I went back to 15 deg cranking timing, all good there.

 

[Erik the Awful]

If I remember right, there's a procedure for setting the throttle stop. I can't remember if it was in Holley's instructions or if it was the procedure that I found from a Sniper guru that was better and more thorough than Holley's. Mine idles perfect and switches from initial high idle to normal like it should.

Holley has a video, though.

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[LC2NLS6]

That's how to do it. The trouble was I was used to my Holley HP EFI that makes you do a manual TPS reset. The Sniper it is key off 5sec then key on like normal. My idle screw was 2 turns in, way too far open, hence the higher than desired idle when hot.

 

[Erik the Awful]

Oh, yeah. It shouldn't be that far in. Mine came like that, but if I remember right, I read the instructions and backed it off to contact and then 1/2 turn in before starting.