Sniper EFI - Fuel Grade

[PVCsnorkel]

Considering the price of Fuel this is probably the wrong time to ask this...
For those of you with Sniper EFI, do you use regular (88/89) Fuel or premium?

My sniper setup has a slight misfire like idle and I'm wondering if it's cause I've been running regular.

 

[cruisermatt]

That’s not your cause.
High octane fuel lets you run more ignition timing and higher engine compression ratio without detonation. It’s not “better”. Running higher octane fuels won’t hurt anything so the fuel companies calling the different octane ratings “regular/premium” simply as marketing.

As for properly diagnosing your misfire, start with an infrared temperature gun across your exhaust manifold and see which cylinder running cooler then the others.

 

[Dirt Boy]

I run regular in my 40 with sniper EFI. No problems. FWIW.

 

[Lead Head]

Unless you have modified your distributor's ignition timing or your sniper is controlling spark, there is no reason to run anything but 87 in these engines.

 

[PVCsnorkel]

Unless you have modified your distributor's ignition timing or your sniper is controlling spark, there is no reason to run anything but 87 in these engines.

My ignition timing is a bit messed up. I did the MSD springs to adjust for my desomg. Then learned they make it worse...

 

[franklin40]

i agree with above. fuel octane is related to compression and timing. not “how” the fuel is injected. whether it’s a carb or efi these lower compression engines should run just fine on regular. the ethanol in the lower grade fuels though will gum things up if left to sit for a long time but if you’re running it regularly and putting fresh gas in every now and again that shouldn’t be a problem.

i had some sniper issues when i installed it on my chevelle. i had a bad injector so part of the manifold was gettting a lean mixture while the rest were trying to over compensate. it eventually took my O2 sensor out which made it really hard to diagnose. oh and i had a vacuum leak too. . just go through your systems one step at a time so you don’t change too many variables at once. otherwise you’ll never know what actually fixed the problem. i’d also start with base lining your distributor too if that’s something you played with