I finally took the huge step of swapping motors in my '71 Bronco. A Coyote swap was a bit too much for my intact Bronco thus I took the next best route - A professionally built blue printed and balanced 347 stroker topped off with the Edelbrock Pro Flow 4 EFI system which comes in a very impressive box. Being the DIY type I researched and watch all of John Melton's Nashville Early Bronco videos. I put a 289 in a 65 mustang so I figured I could pull this off with a little help from the internet. Long story short I did pull it off, but I learned a heck of a lot along the way. Here are some of my tips and lessons learned if you decide to take on a project like this.
• Understand what you presently have so you will know what you can, or cannot reuse. It was after I pulled my existing 302 that I figured out it came from a truck. Mine had a front sump oil pan which is extremely tight to get out when simply separated from the bell housing. Broncos use a rear sump oil pan that clears the front frame member much better than what I had. Likewise, I now understand why there was no radiator shroud. It does no fit if you have an F150 18 ½” fan and 1.5 “ fan spacer. In fact, I'm down to a ¼ inch of hood clearance with my present setup (which will be tackled sometime in the near future).
• Hood clearance issues are a pain. If you are working on the body please do yourself a favor and do the 1” body lift. I did not because my 71 already had a 3” suspension lift and it is already a stretch to get in and out of it. I have put in the NV3550 and this new motor. I really wish I would have done the body lift 4 years ago when I replaced all the rubber parts on the frame. My air cleaner is a bit modified so I can close the hood!!! With the 1” body lift I would have options.
• If you have a manual transmission you will most likely need the clutch equalizer bracket from Tom's Bronco Parts or Wild Horses. The 90's roller blocks are missing the mount bolt hole for that clutch equalizer. The kit works but you need to drill the hole before you put the engine in. If you wait till the motor is in and mated to the bell housing you will curse it like crazy because there is no room for your drill! I got lucky on that one.
• Timing covers, water pumps, harmonic balancers, and timing pointers are not all interchangeable! My old motor had the timing pointer at 10:00. The early 90's engines have it at 11:00. I learned the hard way that you cannot use your bronco water pump with a bottom left outlet with a mustang style timing pointer at 11:00. You really want the timing marks at 2:00. There are various ways to solve this. My fancy new balancer now has white stripes painted on it all offset from the laser marked numbers so that I could actually find TDC and more importantly 12' before top dead center! My timing pointer is a white stripe on the timing cover. If I measured correctly I'm within 1 degree at least
• The Edelbrock ProFlow is super nice. Lots of capabilities and features that a tuner would love, but also simple enough for the weekend mechanic Bronco owner. But like Melton emphasizes you need to have your exhaust in tip top shape. I had my O2 sensor welded in at a local muffler shop for $50. It is easiest to do this before you pull your old motor. Duh, pretty simple advice but I see how someone could get excited and forget that you need to plan all those steps, especially when going to EFI, and do them in the correct order.
• Another EFI hint – The 23-gallon tank is great. I had put mine in over a year ago in anticipation of my EFI upgrade. The in-tank fuel pump works well. I can now drop the gas tank and reinstall it in less than two hours. That's because I have done it too many times! There is a reason that the EFI pump has that extra vent port. Do not simply rely on your existing vent lines. If you simply plug that 4th vent line your tank will pressurize and gas will leak from the top once your high-pressure fuel regulator starts to return fuel to your tank!
• My Bronco has 2 tanks. My auxiliary tank is now a transfer tank with an external fuel pump plumbed into the return line. I can use my gas gauge selector to turn on that pump and move 8 gallons into my 23-gallon tank. Several ways to do deal with tanks. Just think thru how you want to do it. Oh yeah, the blue press on AN fittings are tremendously easier to deal with than those fancy braided ones. I absolutely hate trying to cut the braided lines and pressing those AN fittings over that prickly braiding always draws blood.
• My 347 is professionally built with Forged pistons, aftermarket SVE heads (AFR knock-off) and a Ford racing E303 roller cam. Oh, ah. So now you are going to Napa to buy Spark plugs and their question is year, make, and model? You no longer get to say 71 Bronco, unless it is your water pump, maybe… 93 Mustang might be a good answer. 86 Mustang is not good in my case. Most true mechanics know this one already – spark plugs are dependent upon the cylinder head more than anything else. Did you know that the spark plugs in a 86 mustang are shorter than those in a 93? More importantly the Edelbrock ProFlow 4 is great, but you will have serious buyer's remorse if your new motor is barely running and spewing smoke out of the backend on your first drive. 3 days later you will really get to understand all the tuning options to get your super rich running engine into a range that is almost acceptable. You may consider getting a new O2 sensor because that solved the problem for someone in Australia. Or is the MAP sensor that fixed the problem for the guy in Colorado? Guess what – having the correct length spark plug makes a tremendous difference in how your engine runs. As my mechanic mentor told me, “Check the simple stuff first.” I spent days on this one. Now I know why there were carbon deposits on those first sparkplugs the I had bought months ago. BTW SVE aluminum heads need the NGK BKR5E-11. My dirt track racing mechanical mentor insisted on NGK for some reason. His insistence lead to me solving my rich running EFI problem.
• Speaking of spark plugs and small block Fords what is the firing order? Hint – two answers are acceptable. Now which one are you going to use? Hint – your cam shaft selection will dictate this! If you guess wrong then that super nervous but much anticipated first start will be disappointing. It will start with only 3 cylinders firing, but it runs a heck of a lot better when all 8 are firing in the correct order, even if the plugs are too short!
All in all, it was pleasing project. My Bronco now performs like my buddies Tesla. It might even be worth more, but it is not for sale – perhaps an even trade for a Coyote based build from Icon or Gateway, but hey at this point I would even have to think on that. After all between paint, suspension, transmission, interior, and EFI motor I'm approaching the $20k mark in parts plus $200K in my labor…. Good luck with your project. Try to keep your labor cost less than mine!
• Understand what you presently have so you will know what you can, or cannot reuse. It was after I pulled my existing 302 that I figured out it came from a truck. Mine had a front sump oil pan which is extremely tight to get out when simply separated from the bell housing. Broncos use a rear sump oil pan that clears the front frame member much better than what I had. Likewise, I now understand why there was no radiator shroud. It does no fit if you have an F150 18 ½” fan and 1.5 “ fan spacer. In fact, I'm down to a ¼ inch of hood clearance with my present setup (which will be tackled sometime in the near future).
• Hood clearance issues are a pain. If you are working on the body please do yourself a favor and do the 1” body lift. I did not because my 71 already had a 3” suspension lift and it is already a stretch to get in and out of it. I have put in the NV3550 and this new motor. I really wish I would have done the body lift 4 years ago when I replaced all the rubber parts on the frame. My air cleaner is a bit modified so I can close the hood!!! With the 1” body lift I would have options.
• If you have a manual transmission you will most likely need the clutch equalizer bracket from Tom's Bronco Parts or Wild Horses. The 90's roller blocks are missing the mount bolt hole for that clutch equalizer. The kit works but you need to drill the hole before you put the engine in. If you wait till the motor is in and mated to the bell housing you will curse it like crazy because there is no room for your drill! I got lucky on that one.
• Timing covers, water pumps, harmonic balancers, and timing pointers are not all interchangeable! My old motor had the timing pointer at 10:00. The early 90's engines have it at 11:00. I learned the hard way that you cannot use your bronco water pump with a bottom left outlet with a mustang style timing pointer at 11:00. You really want the timing marks at 2:00. There are various ways to solve this. My fancy new balancer now has white stripes painted on it all offset from the laser marked numbers so that I could actually find TDC and more importantly 12' before top dead center! My timing pointer is a white stripe on the timing cover. If I measured correctly I'm within 1 degree at least
• The Edelbrock ProFlow is super nice. Lots of capabilities and features that a tuner would love, but also simple enough for the weekend mechanic Bronco owner. But like Melton emphasizes you need to have your exhaust in tip top shape. I had my O2 sensor welded in at a local muffler shop for $50. It is easiest to do this before you pull your old motor. Duh, pretty simple advice but I see how someone could get excited and forget that you need to plan all those steps, especially when going to EFI, and do them in the correct order.
• Another EFI hint – The 23-gallon tank is great. I had put mine in over a year ago in anticipation of my EFI upgrade. The in-tank fuel pump works well. I can now drop the gas tank and reinstall it in less than two hours. That's because I have done it too many times! There is a reason that the EFI pump has that extra vent port. Do not simply rely on your existing vent lines. If you simply plug that 4th vent line your tank will pressurize and gas will leak from the top once your high-pressure fuel regulator starts to return fuel to your tank!
• My Bronco has 2 tanks. My auxiliary tank is now a transfer tank with an external fuel pump plumbed into the return line. I can use my gas gauge selector to turn on that pump and move 8 gallons into my 23-gallon tank. Several ways to do deal with tanks. Just think thru how you want to do it. Oh yeah, the blue press on AN fittings are tremendously easier to deal with than those fancy braided ones. I absolutely hate trying to cut the braided lines and pressing those AN fittings over that prickly braiding always draws blood.
• My 347 is professionally built with Forged pistons, aftermarket SVE heads (AFR knock-off) and a Ford racing E303 roller cam. Oh, ah. So now you are going to Napa to buy Spark plugs and their question is year, make, and model? You no longer get to say 71 Bronco, unless it is your water pump, maybe… 93 Mustang might be a good answer. 86 Mustang is not good in my case. Most true mechanics know this one already – spark plugs are dependent upon the cylinder head more than anything else. Did you know that the spark plugs in a 86 mustang are shorter than those in a 93? More importantly the Edelbrock ProFlow 4 is great, but you will have serious buyer's remorse if your new motor is barely running and spewing smoke out of the backend on your first drive. 3 days later you will really get to understand all the tuning options to get your super rich running engine into a range that is almost acceptable. You may consider getting a new O2 sensor because that solved the problem for someone in Australia. Or is the MAP sensor that fixed the problem for the guy in Colorado? Guess what – having the correct length spark plug makes a tremendous difference in how your engine runs. As my mechanic mentor told me, “Check the simple stuff first.” I spent days on this one. Now I know why there were carbon deposits on those first sparkplugs the I had bought months ago. BTW SVE aluminum heads need the NGK BKR5E-11. My dirt track racing mechanical mentor insisted on NGK for some reason. His insistence lead to me solving my rich running EFI problem.
• Speaking of spark plugs and small block Fords what is the firing order? Hint – two answers are acceptable. Now which one are you going to use? Hint – your cam shaft selection will dictate this! If you guess wrong then that super nervous but much anticipated first start will be disappointing. It will start with only 3 cylinders firing, but it runs a heck of a lot better when all 8 are firing in the correct order, even if the plugs are too short!
All in all, it was pleasing project. My Bronco now performs like my buddies Tesla. It might even be worth more, but it is not for sale – perhaps an even trade for a Coyote based build from Icon or Gateway, but hey at this point I would even have to think on that. After all between paint, suspension, transmission, interior, and EFI motor I'm approaching the $20k mark in parts plus $200K in my labor…. Good luck with your project. Try to keep your labor cost less than mine!
