Sniper EFI into 78 400cid C-Body - been there, done that - thoughts

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Will repost it here in case somebody may find it useful.
It took me a while to do the install due to work and other factors. But finally it is all in and working.
Started with:
1978 bone stock 400cid C-body with TQ but ELB-delete (poorly) performed eons ago. Canadian spec, so no emissions gear.
It ran reliably, but slowly, starting cold was a funny game.

Installed - Sniper EFI with MSD magnetic distributor, MSD coil driver and in-tank fuel pump.

Used original steel fuel lines (pressure and return) but with new rubber parts everywhere. Kept original "fry pan" air filter housing.

Result - sure start any time, very crisp throttle response, good acceleration from 0 to 85 (have not explored further yet) and pickup at any speed. Allows me to keep up with or stay ahead of traffic with zero effort. No bogging at idle with AC running as before. Fuel economy so far stays about the same.

Now some thoughts:

Worth it - Yay or Nay?
If you are only looking to improve drivability for you summer toy - then firm "NO". Just get yourself a new carb, new wires, ensure there are no air/vac leaks and enjoy your car. The extra expenditure, time and effort simply not worth it.

If you are driven by the desire for better drivability, as well as long range / all weather predictability and superior throttle response - and are prepared to put some 2K into the project - YES, by all means. But also be aware that once you get used to the new set of dynamics, you will want more - sharper and tighter steering, sportier cam, TC with higher stall speed... And did I mention tighter steering?..

How complicated?
If you can rebuild and tune your engine with closed eyes, habitually swap distributors, cams and at least once installed and set up some software or a mobile app - it's a walk in the park. Just RTFM and be prepared to look for extra info on the interwebs.
If you are like me - familiar with modern plug and play cars and comfortable with general wrenching, some aspects will be a bit of a challenge. And here it greatly depends how you approach it - as a mental excersise to keep you grey matter humming or a nuisance that postpones immediate gratifications.

What do you need?
There are at least 2 setups, as I see it.
Basic - you just buy the injector kit with external fuel pump and whatnots, but leave the ignition as is. Worth doing if your ignition has been updated (and not a mess of old hacked wires left from the Lean Burn delete surgery performed 30+ years ago).
All in (that is how I did it) - the injector kit + magnetic distrib, wires, coil/coil driver, in-tank fuel pump... Or any combination of these components, really.

You also need decent set of tools, good wire crimpers, rolls of wires and connectors, million zip-ties, lots of gorilla tape, fuel hose and or copper-nickel pipes, a timing light, and ability to control the hate of imperial units: as someone from the metric universe I totally struggle with all these gages, thread designations, and how to measure up the wrenches - whereas it is immediately clear if 11 mm is less than 13 or 15, with all these x/8 and x/16 it just bends my mind backwards every time.

What not to like?
How the information from the OEM is presented. I realize, that it is mostly aimed at the "experienced" category and serves as nothing more than a general guidance. As a tech writer who spent quite a few years in MFG creating shop assembly and repair manuals for complicated drilling machinery, I'd say a more systematic presentation would be much welcome and make it so much easier for a layman like myself to install and tune it. What especially annoys is that once you start digging, you drown in endless linking to yet another write-up or a video that only confuses you more. Web forum on Holley's own website is not too bad, but the advice from Holley folks is not always very informative and more often than not is a copy-paste of the same set of endless links to writeups that have some more links to click...

Also you lose the cruise control - if it worked. Mine did. I am kinda thinking of trying to connect it (will need a mod to the throttle bracket), but I rarely use this feature even in our everyday cars, so this can wait.

On what and how I did - it will be easier if you ask a question rather than me writing about the whole adventure and trying to recall all steps.

Some highlights:

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twostick

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Worth it - Yay or Nay?
If you are only looking to improve drivability for you summer toy - then firm "NO". Just get yourself a new carb, new wires, ensure there are no air/vac leaks and enjoy your car. The extra expenditure, time and effort simply not worth it.

If you are driven by the desire for better drivability, as well as long range / all weather predictability and superior throttle response - and are prepared to put some 2K into the project - YES, by all means.

These 2 statements seem to contradict each other.

The second statement sounds to me like a textbook definition of improved drivability.

When I built my 493 15 odd years ago, the original plan was 6pak complete, brand new in a box and at the time that was about $2300 from Herb's.

I was starting from scratch so I had no fuel or induction system at all. I got an M1 single plane off the clearance aisle at Summit for I think $150 and all of a sudden EFI starts to make serious economic sense. The Holley Commander 950 TBI system was about $1500 complete and while it's positively stone age compared to the Sniper, it did EVERYTHING better than a carburetor once I got it close to dialed in which in the days of non self learning EFI was a challenge of no small magnitude given the completely wrong camshaft I chose. (MP509). It would cold start and idle first time every time and the throttle response was instantaneous bordering on psychic.

Kevin
 
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These 2 statements seem to contradict each other.

The second statement sounds to me like a textbook definition of improved drivability.

Kevin

Not really.
Just tootling around from one meet to another now and then, or for an occasional drive in sunny weather, like my neighbour does on his '59 Corvette to the tune of annual 200-300 miles, I would not invest in Sniper and such. New properly set carb, and basically a minor tune-up - and be done with it.

We, however, plan(-ned, damn quarantine destroyed all plans and budgets) long hauls to visit friends all over the West Coast, from Squamish all way down to San Diego and so on. And there gains in driveability and consistency of responses and settings would have become noticable and very much welcome.
 

1970FuryConv

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Sounds great. Inspiration to go ahead and rebuild my 400.

By bone stock, do you mean no engine mods or rebuild?

Thanks, Ben
 

Alchemi

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The lack of mpg gain is an interesting note
What are you getting out of it?
What sort of afr numbers are you getting?
I know TQ's are a good bit of kit and if it was set up well then the rest of it will come back to the inherent design of the intake and flow distribution, but im kinda surprised is all given the list of noticeable improvements youve noted
 

Knebel

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I have done the Fitech efi swap. The lack of mpg improvement had me stumped. It was actually 4mpg less than with a holley.

My expierience was very much that I was thinking you install it and it tunes itself. That takes a lot if learning and research and I agree that you go down a rabbithole of information that makes it more and more confusing.

However, the swap has many benefits!
 

twostick

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I have done the Fitech efi swap. The lack of mpg improvement had me stumped. It was actually 4mpg less than with a holley.

My expierience was very much that I was thinking you install it and it tunes itself. That takes a lot if learning and research and I agree that you go down a rabbithole of information that makes it more and more confusing.

However, the swap has many benefits!

Something is wrong with your tune. EFI, especially TBI is no guarantee of substantially better fuel efficiency but it should be no worse.

Does it control your timing?

What is your target AFR at cruise?

Wide band O2 properly calibrated?

Kevin
 

Knebel

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Yep controls timing. Afrs cruise at 3000 and 45kpa is 15:1. Timing is adjusted to 45° cruise and 36° wot and load. The car runs geat and has good power. My AFR values are not adjusted any different than I did with the carb, all in the 14s unless WOT/96kpa. I run a relatively agressive timing curve id say. I idle at 30°...this way I get 12inch HG vacuum. Bring it down to 18 or 20 and ill see 9 inch HG. That is also similar to the carb setup. I ran 16° at idle with the vacuum plugged into manifold.
 
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Something is wrong with your tune. EFI, especially TBI is no guarantee of substantially better fuel efficiency but it should be no worse.
Kevin
My wife and I thought about it a lot. We kind of agreed that most likely, the main reason to the same (or worse) mpg is that before the conversion we tended to drive gingerly, so to speak. And now we just drive it "normally", the same way we would drive our daily vehicles (and them being German sport sedans... well, you know :)).
Improved performance and that wonderful sea of torque only provoke you to step on the gas.
Having said that, I would love to have a mentor who is fluent in fine settings of this Holley gadget to properly set it, as I only went by recommended defaults.
 
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