[Okie528]

Beautiful Truck!

Love my sniper in my '72 Blazer 350sbc, cold starts, warm starts, throttle response, reliability! You look like you are taking your time and going about it the right way. Not sure if the return line step down will cause a problem, seems like I read something on that once, you may want to research it a little. I ran new 3/8" lines for both of mine. You probably could remove your 5/16 dump on the fuel sending unit, drill and install a 3/8" if you had too.

Here's a little unsolicited, hopefully welcome advice, might save you some time and frustration:

1. Be patient, use the Holley tech support, they were very helpful getting it set up. Let them help you, if you have a question, they have answer. I called twice before I ever started installing mine, and a few times after.

2. There's an idle table that is not listed in the install instructions that they will walk you through if you cant get your idle where you want it.

3. I always let the fuel pump cycle before I start it, warm or cold and it will bump off in a 1/2 sec every time. Restarts can stumble if you don't. (I'm using an in-tank pump so that may be a difference)

4. There's a common whistle on these in acceleration, which they will say is normal characteristic, (it's annoying, unless you like the sound of City bus turbo's). You can totally get rid of it by using the Canton part# 85-154 ($30 on amazon) 1/4" 4 hole Phenolic Carb spacer. I tried a 1/2" open spacer first and caused a big vacuum leak which led to more issues. I'm a big believer in the 1/4" Canton, its proven to work with this set up, and shouldn't cause any clearance issues, I found a lot of guys were using it to eliminate the whistle.

5. Tom Kise with Holley tech has an 11 part post that goes through the most commons issues and how to avoid them on the Holley Sniper EFI owners and tech Facebook group listed under files. Great info!

I had a few issues to work through, some due to installation mistakes, but once I got it straightened out she's been great ever since. I even turned the learning off after a few weeks (Holley Tech recommendation) and unplugged my monitor and threw it in the console. I found myself obsessing over the monitor and wasn't crazy about the look of it, just like an original looking dash.

This is just my experience, I learned a lot from guys that had already gone down this road, reading ton's of threads and facebook post, like I'm sure you are. You'll read a lot of bad stuff on the Sniper and Fitech efi's, but installed correctly they will do exactly what they are meant to do, improve reliability, throttle response, and gas mileage. But, if your engine was having problems and not running right to begin with, it might not run right with efi. If I can be of any help PM me anytime.