Another point. Reread the direction. Make sure you followed everything perfectly! It makes a huge difference. Mine fired right up. Ran rough until all the air was bled out of the Sniper then ran awesome. Only problem I had was self inflicted. Forgot a clamp on the fuel pump outlet and it bled off pressure.
Holley EFI Sniper vs Street Demon
Hey all, as we move into the holidays, and time off becomes abundant, I’m going to do the efi or new carb upgrade. I was curious to hear Bird Guy’s (and Gals?) thoughts on this modification.
Here’s what we’re working with:
1974 Formula Firebird with 1970 face.
- 455 YC engine auto trans
- I just bought this car in October and I’m not sure what the internals look like, the YC definitely didn’t come in this car, probably out of a bonnevile or Grandville? Maybe even a GTO. The engine is strong and makes the car fly down the road very fast, even with the carb needing rebuild. It doesn’t feel like a 250 HP YC, it feels in the 300 range. I have and have had fast cars so know what to expect. The Idle sounds like she has a mild cam and the exhaust is open. Not sure what muffler it is but under the car it looks very stock. True dual exhaust tho
I bought the Street Demon because I want to drive the car around town and didn’t want to wait till I figured out the rebuild on the quadrajunk. I’ve been lectured since my high school days (I’m 36 now) by the guys who lived The muscle car life in the sixties and seventies that the qjet is trash, and at the same time the best Carb for my Bird hands down if adjusted right. I just want to enjoy it and the street demon seemed like the path of least resistance.
![Automotive tire Motor vehicle Automotive design Gas Automotive exterior]()
here’s the set up the day I got her
![Vehicle Automotive tire Motor vehicle Hood Automotive design]()
Here she is cleaned up
more to follow
Here’s what we’re working with:
1974 Formula Firebird with 1970 face.
- 455 YC engine auto trans
- I just bought this car in October and I’m not sure what the internals look like, the YC definitely didn’t come in this car, probably out of a bonnevile or Grandville? Maybe even a GTO. The engine is strong and makes the car fly down the road very fast, even with the carb needing rebuild. It doesn’t feel like a 250 HP YC, it feels in the 300 range. I have and have had fast cars so know what to expect. The Idle sounds like she has a mild cam and the exhaust is open. Not sure what muffler it is but under the car it looks very stock. True dual exhaust tho
I bought the Street Demon because I want to drive the car around town and didn’t want to wait till I figured out the rebuild on the quadrajunk. I’ve been lectured since my high school days (I’m 36 now) by the guys who lived The muscle car life in the sixties and seventies that the qjet is trash, and at the same time the best Carb for my Bird hands down if adjusted right. I just want to enjoy it and the street demon seemed like the path of least resistance.
more to follow
21 - 25 of 25 Posts
Update!
Car has started and I’ve been getting her dialed in!
EFI is weird man. Had to change the alternator since the stock is 60 amp I think and the car would stay running. Put in a 140 amp and power issue is gone. The self tune is more like self fuel table learn. Everything else I had to dial in. The engine ran super hot because the air Fuel mix was very lean. But its running and I’ve been getting the temps dialed in.
The odd thing is setting the timing and AFR. I’m not sure what the timing is supposed to be at given the instructions don’t match how it’s normally done? I have the hyperspark Distributor, CD box and igniter. I made sure to Phase the Dist according to instructions, 1st cylinder on comp stroke, at TDC. Car started right up. Had to verify the timing control by setting the static timing at 15 and verifying on the Timing marks and adjust. This system allows me to set the cranking Timing, and it’s set at 15. The factory for the car says 10°. I’m a bit overwhelmed with all the new info but it’s new and exciting. Any of you guys that could chime in on the timing stuff would be great.
either way I’m running 15° Idle | 34° cruising | 39°wot
Average AFR is like 13.2
I think my fan clutch is toast because when I come to a stop the temp will creep to 210 and then on the highway it’s at 178 (170 thermostat)
she is leaking oil in two places, front and back of engine. I hoping it’s just the pan gasket, which I have, but need to install. If I have to pull that engine, I’m rebuilding the whole thing
![Tire Wheel Car Vehicle Automotive lighting]()
![Car Vehicle Hood Motor vehicle Light]()
![Car Wheel Tire Vehicle Vehicle registration plate]()
![Motor vehicle Hood Automotive tire Car Automotive design]()
![Camera accessory Camera lens Cameras & optics Font Lens]()
![Wheel Tire Car Vehicle Window]()
![Car Vehicle Motor vehicle Automotive lighting Hood]()
![Motor vehicle Automotive design Automotive exterior Vehicle Auto part]()
![Automotive fuel system Automotive tire Motor vehicle Automotive design Tire]()
![Motor vehicle Vehicle Automotive design Automotive fuel system Auto part]()
Car has started and I’ve been getting her dialed in!
EFI is weird man. Had to change the alternator since the stock is 60 amp I think and the car would stay running. Put in a 140 amp and power issue is gone. The self tune is more like self fuel table learn. Everything else I had to dial in. The engine ran super hot because the air Fuel mix was very lean. But its running and I’ve been getting the temps dialed in.
The odd thing is setting the timing and AFR. I’m not sure what the timing is supposed to be at given the instructions don’t match how it’s normally done? I have the hyperspark Distributor, CD box and igniter. I made sure to Phase the Dist according to instructions, 1st cylinder on comp stroke, at TDC. Car started right up. Had to verify the timing control by setting the static timing at 15 and verifying on the Timing marks and adjust. This system allows me to set the cranking Timing, and it’s set at 15. The factory for the car says 10°. I’m a bit overwhelmed with all the new info but it’s new and exciting. Any of you guys that could chime in on the timing stuff would be great.
either way I’m running 15° Idle | 34° cruising | 39°wot
Average AFR is like 13.2
I think my fan clutch is toast because when I come to a stop the temp will creep to 210 and then on the highway it’s at 178 (170 thermostat)
she is leaking oil in two places, front and back of engine. I hoping it’s just the pan gasket, which I have, but need to install. If I have to pull that engine, I’m rebuilding the whole thing
[Update]
so after, testing, tuning, testing some more, I ran into some Holley Snags
- Holley Sniper throttle bodies come with their internal fuel regulators clogged with metal shavings from the time it was assembled
- the injectors have weak connectors and can come lose from all the vibration, and or it just not being connected correctly at assemble time
these two issues seriously made this install hard, and filled with frustration or not knowing what is causing the nightmare conditions that made me wish I had went with a carb instead
the AFR was consistently wrong and the ECU was doing its best to match the target AFR.This lead to my fuel table being so wrong that it caused unstable idle, temps, and performance.
the injector not working caused the system to over compensate with the other injectors that the system couldn’t stabilize. This lead to rough idle, high fuel consumption, weak vacuum (break booster works so much better now) piss poor performance.
after the fixes were discovered and completed, it’s a whole new car. Breaks work better, the target AFR actually sticks to the Tables, the temp is at 175 whereas it was 190- 210 (to be fair the Fan clutch was on its way out) car is fast again, and the exhaust doesn’t stink like gas (sweet rich smell)
here’s some photo proof and other glamour shots. I’ve also linked the videos that helped me find/fix the issues above.
![Automotive tire Motor vehicle Hood Automotive lighting Automotive design]()
![Wheel Tire Car Vehicle Motor vehicle]()
![Car Vehicle Motor vehicle Hood Automotive design]()
![Automotive fuel system Car Motor vehicle Automotive tire Hood]()
![Wheel Bicycle tire Light Crankset Automotive tire]()
![Tire Wheel Automotive tire Hood Automotive lighting]()
![Automotive tire Sleeve Collar Automotive wheel system Gas]()
![Wood Grass Gas Plant Electric blue]()
![Gesture Finger Thumb Nail Gas]()
so after, testing, tuning, testing some more, I ran into some Holley Snags
- Holley Sniper throttle bodies come with their internal fuel regulators clogged with metal shavings from the time it was assembled
- the injectors have weak connectors and can come lose from all the vibration, and or it just not being connected correctly at assemble time
these two issues seriously made this install hard, and filled with frustration or not knowing what is causing the nightmare conditions that made me wish I had went with a carb instead
the AFR was consistently wrong and the ECU was doing its best to match the target AFR.This lead to my fuel table being so wrong that it caused unstable idle, temps, and performance.
the injector not working caused the system to over compensate with the other injectors that the system couldn’t stabilize. This lead to rough idle, high fuel consumption, weak vacuum (break booster works so much better now) piss poor performance.
after the fixes were discovered and completed, it’s a whole new car. Breaks work better, the target AFR actually sticks to the Tables, the temp is at 175 whereas it was 190- 210 (to be fair the Fan clutch was on its way out) car is fast again, and the exhaust doesn’t stink like gas (sweet rich smell)
here’s some photo proof and other glamour shots. I’ve also linked the videos that helped me find/fix the issues above.
21 - 25 of 25 Posts
