Holley Sniper

[Green411]

Thought you might be interested in an update after 18 months or so.

The car still has the original Torqueflite 3 speed auto transmission and original back axle. With the original carb I got 13-14 mpg imperial on a run and about 11-12 mpg running around locally with 10-20 mile drives. Driveability left a lot to be desired and starting under most circumstances was poor.

With the Sniper I get 15-18 mpg on a run (absolute best of 19mpg at no more than 60mph and no harsh acceleration) and 13-15 mpg running around, all imperial.
Drivability and starting are greatly improved on top of the 10-15% fuel consumption improvement.

It's all based on the Sniper's self-learning, with no manual tuning done. The original ECU failed after about an hour of running, but Holley accepted liability immediately and I got a free replacement from Summit which has been fine.

I've had a couple of instances of a spit-back through the throttle body while pulling away during warm-up. This was traced to tbi mounting bolts loosening up for some reason, presumably causing a slight air/vacuum leak.
I use the recommended sealing plate between the square-bore throttle body base and the stock spread-bore intake manifold. Have tried it without it, but got an air leak.

Overall I'm very pleased. Would I do it all again? Yes, in a heartbeat.

[dwomby]

Thanks for the update. Tempting.

David

[David C]

Very pleased to hear all is still well. I have been keeping an eye on the internet for tales of woe about the updated Sniper and have seen few if any.
My installation of overdrive gearbox on the 410 has dragged on for various reasons but I hope to have it back on the road in the next week or so. If all goes well then Sniper and Hyperspark will be next.

[Green411]

I forgot to say in the last post that the fuel pump is a bit noisy, too. I used a Holley 12-131 returnless drop-in fuel module, which has a 255 lph in-tank pump. I added a Hydra-Mat, too, in lieu of a reservoir/swirlpot. All seems to work very well.

[David C]

Do you think it would be a good plan to put some neoprene or similar under the fuel tank and also between the straps and the tank?
Perhaps a bit of Dynamat on top of the tank to damp any ringing.

[Green411]

Hmmm......I must say I hadn't considered anything between straps and tank, or below tank, but I have put as much sound deadening as will fit between the tank front and seat back, and above tank.

[David C]

Next time you have access I suggest you place a hand on the top of the tank with the pump running. If you notice any lowering of noise level then one or two pieces of Dynamat or similar about 6" squareish may well help. If you can feel the pump vibration then decoupling the tank from the bodywork with something resilient is worth a go.