Holley Sniper

Green411 · #1 (**permalink**) 01-08-24, 04:42 PM

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 · #2 (**permalink**) 01-08-24, 05:50 PM

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.

Green411 · #3 (**permalink**) 17-08-24, 07:35 PM

Sorry David C, for some reason (ineptitude?) have only just seen this.
Sounds like sound advice.

David C · #4 (**permalink**) 04-06-25, 07:19 PM

I'm pleased to report that my 410 is now sporting a Sniper 2 fuel injection unit with hyperspark distributor. First impressions very good other than fairly loud injector tick. A returnless pump went in the tank without too much trouble. I re-jigged the wiring loom to tidy it up and moved the pump relay to the fuse board. The throttle linkage required a fair bit of measuring and a bit of fabrication but otherwise it was surprisingly straightforward.

Green411 · #5 (**permalink**) 05-06-25, 10:10 AM

David, thanks the update.
I hope it works out for you as well as it has done for me. Mine isn't perfect, I occasionally get a stall when pulling away from stop during warm-up if I open the throttle quickly, but that's about it. I've left the programming completely alone ie it's all self-learnt. Maybe a few goes at more throttle from standstill while it warms up will nudge it to learn more in that particular TPS/MAP/CTS/oxygen sensor combination? Or maybe I've got an air or exhaust leak somewhere? Must admit I've never bothered with any data-logging with it.
Also my (Holley in-tank) fuel pump is noisy, even with a full tank. But at least I know it's working!

David C · #6 (**permalink**) 05-06-25, 03:31 PM

I think your pulling away issue has been fixed on the Mk 2. As both butterflies open together rather than one after the other with the carburettor I have to be quite gentle on take off or I get thrown back in my seat with quite a jolt. I haven't noticed huge pump noise but it may be due to all the other noises. There is quite a loud injector tick and I think noise from pulsing in the fuel filter mounted on the inner wing. More fettling and investigation required but it's a very promising start.
I will try to get up to one of the East Anglia meetings so that we can compare notes.

Green411 · #7 (**permalink**) 10-11-25, 02:57 PM

Update:
I mentioned that I occasionally got a pulling-away stall when the engine was cold. This developed into frequent cold stalling, including on the over-run when slowing for a stop, plus increasingly hard cold starting and occasionally dodgy hot starting.
I had a dig around on the Holley Sniper forum and it seems I'm not the only one with this type of problem. Suggestions were to check the Coolant Temperature Sensor reading vs the Manifold Air Temperature via the supplied HandHeld screen, as the OEM CTS have, in some cases, been shown to read high on a cold engine and low on a hot engine. On a cold engine the IAT read 55*f but the CTS read 71*f.....too much of a discrepancy. It's a common sensor type (Standard Motor Products TX3 or equivalent) and I had a spare which was known to be good. I swapped them over and all was good, with now only a 1*f difference.