Ct1987

Hi all,
Need some input and ideas. I have the 305 carbureted engine in my 87 formula and was thinking of going to EFI. I have looked at most of the systems and I keep going back to the Edlebrock Atomic EFI system. One of its features is that it does not need a return fuel line. They use a PWM in line fuel pump that eliminates the need for a return line.

The mount it has is the Holley square bore. The only way I can mount this system on my Rochester manifold is to use a conversion spacer or replace the manifold.
Talking to the Edlebrock tech, he suggested I go with a dual plane low profile manifold to get best results.

What are the pros and cons of what I am thinking of doing.??

Big question, the EFI has it own ECU unit that controls all the features that were controlled by the factory unit for the electronic Rochester. What do I do with the factory ECU? What else does the factory computer control or monitor?

Louis

aliceempire

iTrader: (14)

The return line isn't really a big deal. Not needing one just means you'll either remove the existing one or have a useless line on the car.

If looking to retain your current intake manifold (it probably isn't restricting that LG4 in the least if stock) then you could go with this https://www.holley.com/products/fuel...SABEgLIePD_BwE That's probably the one that will need the least amount of work to convert your car, at least as far as aftermarket "kits" are concerned.

PRO's? Possible easier starting and better fuel economy. But a proper functioning electronic quadrajet do both very well. Problem is many have forgotten or never knew how to fix or maintain them.
CON's? A lot of effort for a low powered 305 with minimal gain. AND the probable problems associated with changing something to an aftermarket system. High cost, low returns.

The factory ECU controlled some fueling aspects and timing. The aftermarket system has greater control of fueling. Sometimes they do not have timing controls unless added. Either way, the distributor needs to be changed as the factory one won't be compatible.

There's probably a bunch more I could add. Others may chime in with facts and opinions I don't have.

Ct1987

Hi Aliceempire, thanks for the info. The Holley looks like a good unit. This is one that I missed in my search.
As far as the Rochester goes, I have rebuilt several and they do run fine, if you know the workings of them.

Thanks,

Louis

Drew

iTrader: (58)

The only issue I see with all of the EFI systems that mount to the intake like a 4bbl carb, is that they're kinda like TBI. You're not going to get all the benefits of a multi port fuel injection, like a TPI, LT1, LS1, etc. Seems like a lot of trouble for not a huge benefit.

Most of the Qjet cars have that problem with the spread bore carb flange. The GMPP ZZ4 intake is nice because it takes either a spread bore or square bore carb, and it has all the provisions for all the stuff that bolts to the stock intake. There are other intakes out there with the relatively universal carb pattern, but sometimes they require a small adapter, and often the throttle cable bracket, or other brackets won't bolt up. FWIW.

Ct1987

Hi Drew,
thanks for chiming in.the GMMP intake is a good unit, I agree. Right now, this is the research stage. If I go through with it, it won't be till spring.

Louis

Drew

iTrader: (58)

Ok, I'm confused now... Digging a little bit, Atomic EFI is the MSD/Holley system, and it looks like Edelbrock's EFI systems are all marketed as Pro-Flo? Unless I didn't dig deep enough, it looks like Edelbrock's systems are primarily of the 8 injector - Multi-port variety, while the MSD/Holley is 4 injectors in a compact unit styled like a Holley 4bbl?

I would think that the style with 8 injectors and fuel rails and a throttle body mounted like a carb on top of the intake, would have all the benefits of EFI. It's not as covert as the MSD/Holley style, but it'd allow a person to keep a standard style aircleaner. Takes a few seconds for the fuel rails to tip off a passerby that it's not a carb, but more obvious than the other...

Ct1987

Thanks again Drew. I did not look at that unit.

Will do my DD on that. Really appreciate your help.

Louis

Ct1987

Hi, still doing my DD, I will need a return line from the efi unit back to the tank. I don't have access to my car now as its in storage. Looking at the fuel pump sender unit, I see at least 4 pipes. Obviously one is the fuel output, what are the other three. I had thoughts of using the canister vapor line as a return but not sure it this will work.

Does anyone have any ideas?

Thanks, Louis

Drew

iTrader: (58)

Without looking, I want to say the carb fuel system incorporates a return line. If it's inadequate, the easy fix is to get the feed/return lines from an EFI parts car. By now, one of the aftermarket tubing vendors probably offers a repro. Could bend one too... But I'm *ahem* Thrifty, so I'd get a set of used lines. TBI and TPI use the same lines, V6 are close but bend a little differently under the hood.