Help me decide what EFI I want for my Chevelle

[Russell]

I am looking at options for my 71 Chevelle right now. It must remain big block and I want it fuel injected.

I'm trying to decide if I want to get a good 8.1L again with a custom oil pan and modified intake to have the throttle body exit straight out vs up at an angle for hood clearance. Advantages for factory EFI include distributorless ignition, sequential fuel injection, no RFI issues, off the shelf parts from anywhere and OBD PID gauge outputs to the cluster I want for the car on the serial bus. Disadvantages is the clearance issues requiring custom parts, doesn't look stock, low potential for increased performance without tons of really expensive Rylar parts.

Another option is to keep the 454 already in the car and go with aftermarket EFI.

I've more or less decided against the Sniper EFI due to all the issues guys seem to be having with it. Fitech and FAST are not appealing to me due to issues I've had with both in the past myself. I'm interested in the Pro Flo 4 setup from Edelbrock due to the more or less stock appearance and proper sequential injection. All ya'll seem to have had decent results from them as well which means a lot to me.

The final option is to retrofit the 454 with a crank / cam sensor and run it with an LS PCM with distributorless ignition and sequential injection. Being a gen IV big block, there is little aftermarket support for adding the cam and crank sensors.

My biggest worry with the 454 is that aside from knowing it is a 79 truck engine with 72 car heads on it and an edelbrock air gap intake, I have no idea what else has been done to it. It may run like a turd because the engine components just don't work together and no amount of EFI conversion would fix it without a tear down and a whole new set of pistons, cam, heads etc.

I like the aftermarket EFI options for the ability to keep a stock style air cleaner for the cowl induction hood, but beyond that the modern EFI engine that wouldn't require any tuning afterwards is quite appealing still.

Thoughts?

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[sweetk30]

pro flo 4 guy here . and ex sniper user

pro flo 4 selling points for me :
super nice chat forum for tech questions no cut/paste go read this on every single posted up question . people dont tell you your spelling sucks .
the system just needs a min of 8" vac @ idle speed when running . so cam / heads / comp ratio dont play to much in to how it JUST RUNS GOOD .
no stand alone tune each time . play with it as you wish / save tunes / make power adder changes like cam / heads / other stuff it will tune .
100% live adjustments from the blue tooth system . no tiny screen to try and read . no key on/off /reflash to make changes .

i could go on and on but you have read it a am sure already .

go look around in the pro flo 4 section here and find the good info / help and builds guys have done . one guy with a dodge charger ? ? i think just did a huge road trip and only problem 2x was the fuel pump he got in the custom tank . the pro flo 4 was perfect . https://forums.edelbrock.com/forum/pro-flo-efi/pro-flo-4

 

[Bowtie85]

Always thought fitech was the efi of ck5. Guess not any more?


That being said, can’t beat a tuned qjet

 

[beags86]

Mr.BigBlock will guide you into which Holley ECU you need.

 

[mrk5]

What about a Gen VI L29 454 along with it's factory EFI system? Don't know anything about how that would work just throwing it out there if you wanted to keep it a 454.

If it was my car I'd like keeping it a 454 so I'd probably do an L29 with the Edelbrock EFI. Seeing the PF4 in @Bent77 rig, I was surprised how stockish/carburetorish it looked. A factory air cleaner would help with that too.

 

[folkenheath]

That's strange, I got a notification about this thread, but I don't see where.

I vote ditch the 8.1, it's not worth the hassle while still having the limitations in your Chevelle.

If you really are set on the DIS then get a Holley ECU and one of their DIS kits (I prefer the 36-1) for your Gen IV block. This will require syncing the position of the cam sensor on the target wheel, it's also an external target wheel so don't get anything near the teeth when running.

Or find a Gen VI 454 or 502 block and put a GM DIS front timing kit on it(internal target wheel). I would still run the Holley ECU at that point, you could theoretically run any LS ECU, including the Pro Flo 4 system, but you would need to swap the coil wires for firing order or get an LS firing order cam since you can't always change the firing order in the computer like you can with the Holley.

If you really like tuning and want laptop capability go with the Holley, even though it doesn't require a laptop, it has more options down the road if needed.

However, I truly believe that once you get the Edelbrock up and running you won't care its not DIS. It still computer controlled timing that eliminates the vacuum can and mechanical weights, and rotor phasing is taken care of by edelbrock since they include the distributor. So all you have to do is sync it with a timing light using tablet, once that's done everything is through the tablet. If you were all out racing or using a bunch of nitrous the more rock solid timing of DIS might be of benefit since there is no error added through the camshaft and timing chain. But I don't think you'll ever know the difference for what you are doing and it will save you time and money.

 

[dyeager535]

I'm not a Chevelle nor Big Block chev guy, so there may be limitations I dont know. But your clearance and injection issues are ones I've kind of worked through myself.

What I've worked out is a BBC TBI, and in your case, probably an Edelbrock or similar lower profile intake that is fuel rail ready. I plan to run mine off the TPI ECM. If not going crazy on the engine, should be no reason it wont work. Tuning will be a bear, but if everything else falls into place, it seems like a valid option.

The benefit to the factory TBI throttle body is you get to keep the stock TPS and IAC, and if you need kick down/TV/Cruise, it's set up for all that.

I'm not sure what is more low profile than that, the intake really governs it though. Can only sit the throttle body so low on the intake before the linkage starts hanging up.

 

[sweetk30]

i think its around the same or just a bit under stock with carb my self . edelbrock pro flo 4

first pic is a tbi hyperchips salad bowl unit with my old tbi filter setup . and the filter base is cut open to match the salad bowl size hole .

pro flo 4 uses comon gm sensors for the most part . no real problems reported over on the forum i can recall .

 

[6872xtc]

I like my PF4 and how I can adjust lots of settings on the fly, even the spark control. You can't change base maps without a key cycle, but I doubt that you will do that often. It only takes a few minutes to change that anyway.
As far as RFI, the only problem that I have found is that a CB will kill it when you key the mic. I haven't talked with Edelbrock about it yet, but no harm was apparently caused except the engine died and I had to restart it.
I have a '72 350 in a '90 Jimmy so I put the '90 air filter housing on which has a bell style spacer that is the same height as the original one on the TBI system. I do have a picture of the Edelbrock proflo intake next to an Edelbrock performer with a 1.5" spacer/adapter with a TBI on it. I don't know if it will help you with any height idea.
I don't have the cruise control hooked up yet as I haven't gotten it worked out how to install the 2nd stud so that it clears the air horn of the throttle body. The lever is fairly close in its swing path.

 

[Stephen]

My 504 in Wally has a 2000 vintage proflow system that's still working well but I have the itch to make it better so I'm keeping an eye on this. My thoughts so far are just like yours, either put tone wheels on it and go to a "LS" operating system with coil packs or most likely what I'll do is just go to a wide band / self adjusting control system to take the set-it-yourself mapping out of the equation. I could probably put that money into a dyno tuning session or put a wide band on it and dial it in better myself too.

I have an itch to put a 454 into our '74 K20 and would go through all the same questions but given that we just fired it with the 350 today and I really just want to make it go, that'll be a different stage in it's life.