StarDiero75":3sec6anl said:
jamyers":3sec6anl said:
I've got almost a year experience with the Holley Sniper on a stock Chevy 350, glad to answer any questions you've got about the system.
How was getting it all tuned up and dialed in? Did you have any issues? How'd you fix them?
These are the things that I've learned, mostly from experience ('cause I'm sometimes a moron)
Installation:
1. Make DAMSHURE your ignition system is 100% from top to bottom - the slightest ignition misfire will be amplified by EFI because it will interpret it as a lean condition, add fuel, foul the plugs, misfire more, interpret it as a lean condition, add fuel, misfire more, etc, etc, etc.
2. Make DAMSHURE your exhaust has ZERO leaks. The slightest crack / loose fastener will let outside air in (and I thought exhaust gasses only leaked out, silly boy), and the EFI will then think it's too lean, add fuel, etc, etc, etc.
3. Pay CLOSE attention to the wiring instructions, and go overboard on the quality of connections, the number of grounds, and wire routing - keep it AWAY from the alternator and sparkplug wires - Holley (and I don't think anybody else) does NOT do a great job shielding their systems from EMI/RFI, which will cause all sorts of havoc with the system.
4. One thing that the all kinda gloss over is the "Target A/F Ratios". They'll say something like "enter your Target AFRs here..." then move right on. The thing is, the Target AFR is going to be unique to each engine, and a difference of .2 can make a major difference (especially at idle, where EFI seems to like a much richer AFR than you'd think (ours is 13.0 AFR, 600rpm, 23' vacuum). My suggestion is to search the internet for Idle, Cruise, and WOT AFR ratios for similar engines, but those are only starting points - you've got to experiment and see what your engine likes best - which takes time and some driving around.
5. Once you get the system installed, started, and some halfway-decent Target AFRs entered, it's a pretty darned good upgrade - starts as fast as the best carb engine I've ever had (1/2 second cold starts, just bump the starter when warm). Idle is dead smooth, and driving is very nice. Gas mileage in our '69 Chevy C10 (stock 350, 700R4, 3.73 gears) went from averaging 10-11 to 13-14.
6. The Holley Sniper online forums are pretty good, just be ready for people to tell you to make sure your grounds, wiring, etc are good first. Lots of good info there (like OEM replacement part numbers for sensors, etc), just keep in mind that the Target AFR is the "King" of the whole system.
7. EFI in General CONS: * cost, *complexity (troubleshooting can be a real PITA,
8. Holley Sniper CONS: *less than great EMI/RFI shielding, * some components aren't highest quality (like the temp sensor, pressure regulator)
Other stray thoughts...
* get some spare components to keep on hand for replacement or troubleshooting: TPS, IAC, O2, Temp sensor, etc. Some parts may be OEM, but (like the IAC) won't be stocked on hand at your local store.
* I'd recommend getting an in-tank fuel pump over an inline external one. We got the external one, and it's noisy (plus we murdered it recently (not the pumps fault), so we're switching to an intank pump which should longer, be less likely to be murdered, be quieter, etc. The kits people sell seem overpriced to me - I'd think you could source the AN fittings, hose, clamps, pump, etc online for a good bit less.
* Oh, and if you decide to get a Holley, I *strongly* recommend getting it through
https://www.efisystempro.com/
They've often got great deals, and they are known for their after-the-sale support.