So Ive been doing a lot of mods to my car this summer and I'm about to start an engine/trans swap to a 406 with a summit stage 3 1223 retro roller ls firing order cam https://www.summitracing.com/parts/sum-1223#overview and a 2004r overdrive trans. I have been trying to do my research on whether a throttle body fuel injection setup would be a beneficial upgrade for me and being that I'm fairly handy with electrical systems and I need to upgrade my carb setup anyway with the new engine I am thinking the fuel injection would be the way to go. I am also running dual electric rad fans and it looks like many of these systems will control the fan relays as well.

Im considering either a holley sniper 2 setup or the summit setup.

The sniper setup says it can control the timing with the hyperspark distributor I would have to think having a computer control the timing would be an ideal upgrade especially on a vehicle that will spend some time cruising in OD with 3.55 gears at lower rpm?
anyone have any thoughts or input on this? vs going with a summit setup and just running my cheap hei?
I also have a mechanical tach in my 74 so the other question is if I swap to the sniper and hyperspark can I just swap in a tach from say a 75? or is there more to this?

I do have a polished air gap clone I am planning on running with an open spacer which I heard will work fine with the TB setups as long as the cutout or open spacer is in place.

Mainly looking for feedback from others who may have gone down this road but all feedback and opinions welcomed. Thanks.

 

I see that a number of FiTech re-sellers (including Summit) are advertising FiTech's latest multi-port injection kits......but 'Stack' injection, not throttle body air valve. Doesn't seem to be any availabilty, tech info or images showing yet. Might be interesting to see where this all goes?

 

A good read about FAST TBI systems here.

 

I use 20 year old Holley Commander 950 and 1 year old Megasquirt. The spark tables are small and very hard to tune. I use stock distributor on the Holley. I use electronic spark control on the Megasquirt. I recommend staying with stock ignition. The injection is great. Here is current thread on this forum about injection. Good Information. https://www.corvetteforum.com/forums...level-2-a.html JP

 

I scanned through that threa and theres a lot of very in depth tuning and such going on. It is my understanding that the new sniper 2 version has a much smarter learning ecm and I wouldnt have to do as much playing around with a laptop. even the summit TB system seems to imply this.
I am kinda looking for feedback from owners as to whether its true or not. I realize not as many will be running the latest and greatest systems but..

 

Im now also looking at other systems such as the jegs system which appears to be comparable to the summit setup.

 

At some point I would go to modern dizzy with a digital tach. You can always sell your tach drive dizzy

 

There are 2 distinct schools of thought here.
There is no dening that with computer controlled engine management near optimum engine running conditions can be met.
Then there are 2 thoughts on that. Are you truly capable of getting this setup to this level considering every engine is different?
And in a weekend toy, will you actually know the difference?
Between this near perfect ign. timing and say a really well setup distributor?
There is the want for the perfect running engine on the one hand. (But the complexity of achieving it).
And the "keep it simple stupid" thinking on the other hand.

 

augiedoggy,
I'm a converted carb to EFI guy, and it's hard to sum up the last 5+ years of my conversion experience. The Holley Sniper for Dummies - Level 2 thread (LINK) has been a year plus recording of that. Upgrading to an EFI throttle body system or tuned port system will be an upgrade in terms of your ability to control vastly more tuneability and recordability than any carburetor fuel delivery system. You should definitely include the timing control with this. The upgrade isn't wholly realized unless you do both fuel / air / timing control. The biggest mistake people make when they convert is assuming the EFI unit will learn its way out of your engagement. It doesn't matter what system it is. Almost all of them only learn modifications to the base fuel table. That may be good enough for those who don't engage the other parameters, but if you do start getting into the weeds of what your EFI system is doing, you will find that your engine is telling you what it wants. Then you can make those adjustments and really make that engine run. Data logs will paint the picture, and you can make the adjustments. If you simply desire to bolt on some parts and have the engine run, aftermarket EFI will not be for you, and I would recommend against moving away from the carburetor. The Sniper 2 still only learns to the base fuel table. In that regard, it is no better than the Sniper 1. So, I will unfortunately smash that myth. The Sniper 2 does not learn any better than the Sniper 1. There is still no learning to acceleration enrichment, coolant enrichment, startup enrichment, AFR tables, idle tables, air temperature enrichment...

So, to sum up the last bit of too much writing: if you are going to go EFI and treat it like a carburetor, save your money and don't do it. If you want to learn and engage the technology, get into the weeds, do it, you won't be disappointed.

KT

 

I have a early MSD Atomic and I eventually added timing control. The timing control made a big difference. If i had to do it all over again i would have stayed with a good carb set up. Latest and greatest is to hard to understand for us old guy's.....Ray

 

Now the Aces setups look to be the best value... I can get the whole setup with fuel pump and timing controlled distributor for about $1500 Im reading up on the different parameters and such... The multiport setup they have is nice too but it seems to be setup more for racing than a street cruiser with a powerband starting at 2500 if Im reading that correctly. (EDIT I now see in the sniper thread that running a single plane with fuel injection gives the advantages without the disadvantages they normally come with on a carb setup)

https://acesefi.com/collections/all-products

 

How much of a difference timing control will make will depend greatly on just how good your current ign. system is dialed in.
People are always asking us how much of a difference it will make if they have us Dyno tune their bike for instance. The answer of course is that is directly related to how far out your current tune is.
A really well setup ign. system may be improved on but seat of the pants, probably not by much. But if replacing a distributor that came out of Mom's station wagon. Yup, the difference should be huge!

 

yeah I was assuming this also. On the system I was looking at you calibrate the distributor by setting it to 15 degrees BTDC and then it sets a default timing curve which you adjust using a graph and laptop.
I feel that will be easier to play around with and adjust that the constant messing around with adjustable vac advance cans, weights and springs no?

they have an integrated CDI setup for an extra $400 not sure I feel Ineed that but then again I dont NEED fuel injection..

 

I know an in the tank pump is ideal but will that require a new fuel tank with the chambered design or can I use the stock tank? Just trying to get all my ducks in a row for what I would need to purchase. from what ive learned now I would be replacing the dual plane with a single plane intake and getting benefit there although I dont really ever take it above 5k rpm

 

I am another Holley EFI system user. I have the Stealth Sniper on my 427 in my 1968 Corvette and I love it. I also used the In-Tank fuel pump assembly to simplify the installation. I had planned into my budget a new fuel tank as I thought you needed one. The folks at efisystempro.com convinced me to use the factory tank and use the in-tank fuel pump, pressure regulator, fuel level sending unit and the awesome piece of Holley Hydra-Mat which is something you want to use if you are cornering hard. They make the fuel tank modules for Corvettes from 1963-1982and are listed at the efisystempro.com website. The fuel pumps they use are the same ones (Walbro) used in the C4 Corvettes from the factory.

I was able to buy the entire Stealth Sniper (1st gen) and the fuel tank module for way less ($600 less) than I had budgeted. I bought the entire system and had it in my hands two days later from the folks at efisystempro.com. The reason I bought from them was the 2 years of post sale support they give you and they have a very highly trained Holley Tech on their staff. If you choose a system that can control the timing then go for it. Without timing control it is just half way using a EFI system. The engine should be able to pull timing to control engine speed more accurately. The Holley EFI systems have a great software package that is online and allows you to custom tune the engine. I am not sure what the others provide but the Holley does an outstanding job on the software and quality of the parts.

The Edlebrock Pro Flow systems are fairly nice as well. I would use them if I went to a multi-port intake with individual injectors. I am very pleased with the Stealth Sniper as it does a good job looking like a carbureted engine. It fits on my C3 with a factory L88 hood and wedding cake assembly. I have used Holley parts for decades and they "know" fuel systems! With the awesome support from the seller I have never had to ever call Holley for any kind of support.

Hello augiedoggy, I am using the Edlebrock RPM Air Gap dual plane intake manifold under the sniper and it works well. I have no whistling or other noises from the Air gap intake. I also have a great Data acquisition capability built into my Sniper using a cable from the system connecting to my laptop that is in the car. I use the laptop every time I use the car to keep track of the learning process. A very handy feature indeed. Overall I am very pleased with my system and I stay in touch with my new buddies at efisystempro.com.

 

I think it was Jebby that said he has installed numerous TBI fuel injection setups, and he recommends the ignition control. Maybe he will stop by and chime in.

 

that hydramat looks to be about the same cost as a replacement fuel tank with the baffles I can get for $320

I should be able to utilize the factory steel lines correct? with a regulator in the engine compartment.

 

Ya know Augie, your definitely a regular on here. Certainly you've seen a fair few threads on EFI conversion.
I ran one a couple years back, "77 EFI conversion".
Lots of others have run threads as well.
Stock fuel tank, home made baffle for me.
Stock steel lines? Poor idea. Fuel regulator in engine compartment? Some do. Many of us run the regulator in the rear of the car.
Lots of ways to do this. I suggest you read some of the old how to threads on here. Really do your homework before you order part 1.

 

Oh, thought I'd add. I've tried a couple different intake manifolds. First a Performer RPM. Seemed just fine. Then same manifold with divider removed. Didn't really notice a difference. Then a single plane as everyone said it would make a difference.
It didn't.
Car runs great, starts great, warms up perfectly. Accelerates, decelerates , runs cool in high temps in traffic and generally goes really hard with all 3 types of intake manifolds.

 

Strangley I thought I remembered you saying the single plane was the ticket to making it run right on your car multiple times in other threads but it must be someone else im thinking of.. Maybe Rescue?

I never really read any of the fuel injection threads it was out of my budget for years and honestly I had reservations about another throttlebody corvette like my old crossfire car but it was reliable.. Crazy thing is I just saw my old car for sale on facebook and its got another 80k on it since I sold it almost 13 years ago.

I do plan on doing my homework. most of what ive read so far has indicated most of theses efi setups recommend having the regulator at the engine bay were it can be properly measured and regulated plus gives the advantage of re circulation the fuel for cooling. I would think the steel lines would be saver than running rubber lined under the car as long as they are in good shape of course.