To EFI or Not EFI, that, and which one, is the question.

[Ron Tanzi]

So, I swapped the engine, stock '73 oc 351c to '71 cc 351c with mild cam and oil mods w/ blue thunder manifold (+ ~100hp) Hookers (the less expensive painted long tube model) and upgraded from a toploader to (eventually, after a host of problems with the 1st T5) a T5 z-spec. kept the Holley-rebuilt SA670 carb.

No matter how much adjustring, the carb kept popping on acceleration and puffing black soot (only see that when the car is starting to move, I assume it does it at speed but cant see the fine black powder then. I'm told it's from dumping too much fuel) and the electric choke never seemed to work correctly (or the mechanic, who I tend to trust really couldn't get the carb dialed in correctly) Finally, on Wednesday, the car lost power on the parkway, necessitating a tow (thank heaven for Haggerty Driver's club). Turns out choke was jammed shut and the fast idle cam was damaged. He also says the idle adjustment is not working 100% and he thinks there may be internal damage from the small backfires., but it is running well now.

Started thinking about switching to efi (though part of the reason I decided to switch to a muscle car full-time was because I was sick of asking my bmw's ecu "mother may I?" every time I did anything. (Went from 50+ fuses and relays to 7 fuses and 3 relays, and a whole different set of headaches). So, I'm not sure I want to go back to computer controlled engine/fuel, but I am doing my due diligence.

I have read about various issues with the swap, including needing new fuel pump, tank, lines, header issues and needing to swap distributor (I have duraspark now) bringing the cost and frustration factor up there. I am interested in suggestions about whether to swap and if so which manufacturer and model, or if not, whether to stay with the Street Avenger 670 or go to a different carb (I have read a lot of negative comments about the SA carbs0.

Alternatively, if anyone knows a real good carb guy on Long Island, I would welcome the recommendation, and hopefully can get it all sorted out.

Thanks in advance, luckily I always have my horse Chevy to relieve the stress (Mine's the paint on the right)

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If it were my car I would first try a different carb. It is still much cheaper than buying an EFI set up. Be aware Re: new Holleys they have had some quality control issues. I like having my one car that does not require my scan tools to diagnose. I ran a street Avenger 770 briefly many years ago and it did not work well no matter how I jetted it. I returned it and Summit gave me a full refund. I went back to my Holley 80457 600 cfm 4160 that I converted to a 4150 with secondary metering block kit. It still works great after over 20 years.

Ron

 

[jpaz]

Ditch the Street Avenger carb, they are junk! I had 770 on mine and it was very difficult to tune. Get a Quick Fuel or a Summit carb. I went with the Quick Fuel and it was very easy to tune to my engine. My engine is built similar to yours with the Blue Thunder intake, nice cam and headers. It runs awesome!

 

[73' mach 1]

Lots of good stuff available now for EFI. I went Holley Super Sniper. The real question is how much do you want to spend? Even doing it yourself it can be expensive. Sure you can get one of the all in one kits but there are better ways to go. I decided to go with an Aeromotive fuel delivery system. I needed a new tank anyway. I was starting from scratch so my decision was easy but depending on the condition of your car as others have stated you don't want to put EFI on something with other old parts. This is where the rabbit hole is..."I'll just replace this" "well while I'm in here" " just the tip"....next thing you know you're all in!

 

[clevelandcoupe]

I agree with Jpaz, I had a Holley Street Avenger carb also. It was good not great on my basically stock engine, but as soon I added a few goodies it became impossible to tune even by a master carb tuner that happens to live near me. I bought a Quick Fuel 650 about 10 years ago and with a few modifications by the tuner, never looked back......

 

[Arno]

Lots of good stuff available now for EFI. I went Holley Super Sniper. The real question is how much do you want to spend? Even doing it yourself it can be expensive. Sure you can get one of the all in one kits but there are better ways to go. I decided to go with an Aeromotive fuel delivery system. I needed a new tank anyway. I was starting from scratch so my decision was easy but depending on the condition of your car as others have stated you don't want to put EFI on something with other old parts. This is where the rabbit hole is..."I'll just replace this" "well while I'm in here" " just the tip"....next thing you know you're all in!

Got the same tank and efi, where did you end up running your feed and return lines?

 

[73' mach 1]

Got the same tank and efi, where did you end up running your feed and return lines?

Right down the driver's sides frame and over the rear wheel well

 

[Arno]

Right down the driver's sides frame and over the rear wheel well

Ran both there? Steel lines or something else?

 

[73' mach 1]

Ran both there? Steel lines or something else?

Ran both. No steel. Was black braided rubber.

 

[73' mach 1]

Ran both. No steel. Was black braided rubber.

 

[Arno]

Did you run through the wheel well or avoid it?

 

[Arno]

Front that is

 

[Kilgon]

I used steel for both other than tying in at the tank and efi. Took a couple of hours to bend and fit. If you do run steel get a decent bender. You can use your old line as your return if it's in good shape and just add a new supply line.

 

[Arno]

Awesome! Looks like I might be going up the trans tunnel. Two questions
1- how did you wire in the sender off the Aeromotive tank? Factory two wires?
2- where in the stream are your filters?

 

[Blayne9067]

The 71 429cj cars came with a high volume return to tank mechanical pump system, the factory installed return to tank helps manage fuel temperature and works nicely. Not sure if any other Mustangs came with the return to tank system? I‘m running an AED 850HO-AN-BK, no wires, no computer, no extra fuel lines or modified fuel tank. My fuel pressure is a steady 7psi with no regulator. My car can sit for weeks and fires right up with a few pumps of the go fast pedal.

 

[Ron Tanzi]

Tuning a carburetor is an art. Unfortunately, there are not too many artists left! Fuel injection takes all the guesswork out of it and will be better in most applications, IMHO. Someday, when I can justify it, I'll make the switch to EFI.

I have been called an artist due to my carb tuning wisdom. I am also old. LOL.

Ron

 

[tpj71mach]

I used steel for both other than tying in at the tank and efi. Took a couple of hours to bend and fit. If you do run steel get a decent bender. You can use your old line as your return if it's in good shape and just add a new supply line.

I am buying the same set up the Holley Sniper and the Aeromotive fuel tank with in tank pump. I bent two new 3/8" feed lines using the original feed line as a template, and plan to follow the factory path down the drivers side rocker and in to the engine compartment and feed the EFI from the corner of the engine compartment to the back of the engine. I am hoping that will work as I have not gotten the engine back from the Dyno yet and he's backed up so it will be another couple of weeks. I am going to wait until I have the engine installed and the Sniper in hand before I commit. I am planning on drilling a second hole right next to the original and using the same rubber bushing for the second line going in to the engine compartment so they will look like they both should be there. If any of you guys who have already done this set up and have any tips I would appreciate any info I can get on this, thanks.

 

[Kilgon]

I am buying the same set up the Holley Sniper and the Aeromotive fuel tank with in tank pump. I bent two new 3/8" feed lines using the original feed line as a template, and plan to follow the factory path down the drivers side rocker and in to the engine compartment and feed the EFI from the corner of the engine compartment to the back of the engine. I am hoping that will work as I have not gotten the engine back from the Dyno yet and he's backed up so it will be another couple of weeks. I am going to wait until I have the engine installed and the Sniper in hand before I commit. I am planning on drilling a second hole right next to the original and using the same rubber bushing for the second line going in to the engine compartment so they will look like they both should be there. If any of you guys who have already done this set up and have any tips I would appreciate any info I can get on this, thanks.

If you plan on going to the back of the sniper by the firewall I would drill a hole there where it first passes into the wheel well into the engine bay. If you follow the original route all the way to the front where the mechanical pump was you will have to double back to get to the rear. I think Fabrice and someone else has gone the route I'm referring to. I followed the original route upto where they entered the wheel well. I decided to go under the front torque box so I could go straight up the back into the engine bay. I took a small piece of steel u channel to cover the lines and protect them where they crossed over the torque box at.

 

[tpj71mach]

If you plan on going to the back of the sniper by the firewall I would drill a hole there where it first passes into the wheel well into the engine bay. If you follow the original route all the way to the front where the mechanical pump was you will have to double back to get to the rear. I think Fabrice and someone else has gone the route I'm referring to. I followed the original route upto where ther entered the wheel well. I decided to go under the front torque box so I could go straight up the back into the engine bay. I took a small piece of steel u channel to cover the lines and protect them where the crossed over the torque box at.

I see how you routed it might be easier. I'm sorry I wasn't clear, I meant to say that I am planning on running to into the first hole area where you would install hose to the extra length that goes back out into the wheel well and down to the mechanical fuel pump. but not use that extra length of pipe just stay in the engine compartment and route hose along firewall to the rear of the engine to the back of the Sniper.

 

[Kilgon]

I see how you routed it might be easier. I'm sorry I wasn't clear, I meant to say that I am planning on running to into the first hole area where you would install hose to the extra length that goes back out into the wheel well and down to the mechanical fuel pump. but not use that extra length of pipe just stay in the engine compartment and route hose along firewall to the rear of the engine to the back of the Sniper.

That's what I think @Fabrice did. I'll try to find his for you.

 

[tpj71mach]

That's what I think @Fabrice did. I'll try to find his for you.

Thanks