408 Stroker Conversion - 1974 Bronco

[lars]

I have a Blueprint 408 in mine. Heavy Bronco, 5300 pounds on the scales. 35" tires, 4.56 gears. Transmission is an NV4500 (.73:1 overdrive) yielding around 2400 rpm at 70 mph. When I swapped in the 408 after 20+ years with an Explorer 5.0, I found myself glancing at the shifter when on the freeway to see if I'd shifted into 5th, because it pulls so hard. As heavy as my Bronco is, it doesn't feel like a torque monster, but there is adequate power everywhere, even loaded with camping gear at 8000 feet.

I'm about to swap in a built 4R70W. Big change, and slightly taller overdrive. Which I won't mind because I drive mine long distances to remote locations. I expect I will still be happy with the 4.56 gears because of the output of the engine and the way I use my Bronco. But I agree with Broncobowsher; if you aren't going to put in long highway miles I'd go 4:88.

As for break in, Blueprint runs the engine on their dyno before they ship, and since they are roller cams, no cam break in needed.

 

[1969]

I have a Blueprint 408 in mine. Heavy Bronco, 5300 pounds on the scales. 35" tires, 4.56 gears. Transmission is an NV4500 (.73:1 overdrive) yielding around 2400 rpm at 70 mph. When I swapped in the 408 after 20+ years with an Explorer 5.0, I found myself glancing at the shifter when on the freeway to see if I'd shifted into 5th, because it pulls so hard. As heavy as my Bronco is, it doesn't feel like a torque monster, but there is adequate power everywhere, even loaded with camping gear at 8000 feet.

I'm about to swap in a built 4R70W. Big change, and slightly taller overdrive. Which I won't mind because I drive mine long distances to remote locations. I expect I will still be happy with the 4.56 gears because of the output of the engine and the way I use my Bronco. But I agree with Broncobowsher; if you aren't going to put in long highway miles I'd go 4:88.

As for break in, Blueprint runs the engine on their dyno before they ship, and since they are roller cams, no cam break in needed.

Do you run EFI or Carb?

 

[DirtDonk]

Lars has been Ford factory EFI almost longer than it’s been a thing. And on the 351 was a very early adopter (adapter) of the distributorless ignition from the Explorer.
I assume that’s what he’s got on the 408, but don’t remember for a fact.

 

[Aggie Charlie]

I have a Blueprint 408 in mine. Heavy Bronco, 5300 pounds on the scales. 35" tires, 4.56 gears. Transmission is an NV4500 (.73:1 overdrive) yielding around 2400 rpm at 70 mph. When I swapped in the 408 after 20+ years with an Explorer 5.0, I found myself glancing at the shifter when on the freeway to see if I'd shifted into 5th, because it pulls so hard. As heavy as my Bronco is, it doesn't feel like a torque monster, but there is adequate power everywhere, even loaded with camping gear at 8000 feet.

I'm about to swap in a built 4R70W. Big change, and slightly taller overdrive. Which I won't mind because I drive mine long distances to remote locations. I expect I will still be happy with the 4.56 gears because of the output of the engine and the way I use my Bronco. But I agree with Broncobowsher; if you aren't going to put in long highway miles I'd go 4:88.

As for break in, Blueprint runs the engine on their dyno before they ship, and since they are roller cams, no cam break in needed.

Man, thanks for the information, this is good to know. I will be driving the Bronco on the highway a good bit, and am still leaning to the 4:88 gearing, but I am open to suggestions if you think that the 4:56 gearing would be a better fit. I know it is a moot point, but just curious what kind of MPG you are getting. Right now, with my 302 (carbureated) I am getting 11.2 MPG.

 

[Aggie Charlie]

Lars has been Ford factory EFI almost longer than it’s been a thing. And on the 351 was a very early adopter (adapter) of the distributorless ignition from the Explorer.
I assume that’s what he’s got on the 408, but don’t remember for a fact.

The Blueprint 408 that I ordered has the Holly Sniper EFI Fuel Injection system installed on it.

 

[lars]

Do you run EFI or Carb?

Factory Ford EFI, distributorless. Harness and electronic bits are a bastard combination of the 1993 Mustang 5.0 harness that I started with in 2000, plus parts of a 1994 Crown Vic and a 1998 Ford Explorer 5.0 harness, plus Explorer coils. Run via a 1993 Mustang 5.0 A9L ECU with a Moates Quarterhorse chip to tune it. I got the EDIS running in 2005. Been dead reliable. Tuning was easier with the nearly stock Explorer 5.0 engine that I ran until 3 years ago, but eventually with help got the bugs worked mostly out of the 408 tune. With the 408 I needed a different solution for the cam synchronizer; I had designed an adapter about 10 years ago to allow using a 3.8 liter V6 cam synchronizer, had a couple made, finally got to use one when I installed the 408.

For anyone who may want the adapter I mentioned, I gave the design to Garry Vance AKA EFIGuy (and all around good guy) who generally has some available.

 

[Aggie Charlie]

Factory Ford EFI, distributorless. Harness and electronic bits are a bastard combination of the 1993 Mustang 5.0 harness that I started with in 2000, plus parts of a 1994 Crown Vic and a 1998 Ford Explorer 5.0 harness, plus Explorer coils. Run via a 1993 Mustang 5.0 A9L ECU with a Moates Quarterhorse chip to tune it. I got the EDIS running in 2005. Been dead reliable. Tuning was easier with the nearly stock Explorer 5.0 engine that I ran until 3 years ago, but eventually with help got the bugs worked mostly out of the 408 tune. With the 408 I needed a different solution for the cam synchronizer; I had designed an adapter about 10 years ago to allow using a 3.8 liter V6 cam synchronizer, had a couple made, finally got to use one when I installed the 408.

For anyone who may want the adapter I mentioned, I gave the design to Garry Vance AKA EFIGuy (and all around good guy) who generally has some available.

Lars,

The 408 that was ordered from Blueprint is coming configured with a Holley Sniper EFI system already installed.

 

[rocknhorse76]

Lars,

The 408 that was ordered from Blueprint is coming configured with a Holley Sniper EFI system already installed.

I certainly hope that the Sniper works out for you. It’s better than most carbs, but will never stack up to a multipoint EFI system. I run a nearly identical setup to what Lars has, and it’s pretty awesome. I wouldn’t even think about going away from an SEFI setup.

 

[rocknhorse76]

Factory Ford EFI, distributorless. Harness and electronic bits are a bastard combination of the 1993 Mustang 5.0 harness that I started with in 2000, plus parts of a 1994 Crown Vic and a 1998 Ford Explorer 5.0 harness, plus Explorer coils. Run via a 1993 Mustang 5.0 A9L ECU with a Moates Quarterhorse chip to tune it. I got the EDIS running in 2005. Been dead reliable. Tuning was easier with the nearly stock Explorer 5.0 engine that I ran until 3 years ago, but eventually with help got the bugs worked mostly out of the 408 tune. With the 408 I needed a different solution for the cam synchronizer; I had designed an adapter about 10 years ago to allow using a 3.8 liter V6 cam synchronizer, had a couple made, finally got to use one when I installed the 408.

For anyone who may want the adapter I mentioned, I gave the design to Garry Vance AKA EFIGuy (and all around good guy) who generally has some available.

Lars, I started out with a Ron Francis EFI harness many years ago, but not much of it remains now. I’ve chopped it up to incorporate EDIS, Exploder coils on the firewall, a newer ECT sensor, and a slot style MAF sensor with integrated ACT sensor. I do have one of your cam sync adapters that I got from Garry, and it has been working great!

 

[bronco italiano]

I would do a Q-jet before sniper.
Sniper can run great and then run terrible.
Ford is more prone to RFI noise with sniper
There is a huge Holley sniper group on FB, a guy out of Texas, Mad science motorsports, seems to have a good reputation for remote tuning/troubleshooting.
Make sure you install many good grounds and follow the Holley install instructions to the letter, especially on main power and grounds.
Best of luck with the build/run

 

[DirtDonk]

Is it pretty much accepted practice nowadays to add an RF shield between the distributor and throttle body? Or is that not a cure for everything yet?

Paul

 

[Aggie Charlie]

I would do a Q-jet before sniper.
Sniper can run great and then run terrible.
Ford is more prone to RFI noise with sniper
There is a huge Holley sniper group on FB, a guy out of Texas, Mad science motorsports, seems to have a good reputation for remote tuning/troubleshooting.
Make sure you install many good grounds and follow the Holley install instructions to the letter, especially on main power and grounds.
Best of luck with the build/run

Thank You for the information. I will look up the group on FB, and reach out to Mad Science Motorsports for help if I need it.

 

[Broncobowsher]

Isn't the new Sniper2 supposed to fix a bunch of known issues?

 

[Aggie Charlie]

Isn't the new Sniper2 supposed to fix a bunch of known issues?

Yes, that is what I have heard. Unfortunately, I got one of the last Sniper 1 Systems, due to the lateness in shipping. Hopefully everything will be OK with it.

 

[.94 OR]

Is it pretty much accepted practice nowadays to add an RF shield between the distributor and throttle body? Or is that not a cure for everything yet?

Paul

What are people using for shielding?

 

[DirtDonk]

I think we’ve read here of experimenting with everything including blocks of wood! But I believe the most common would be a sheet of aluminum.
Probably 16th inch thick, or perhaps it’s measured engage. 16 gauge maybe?
Formed to fit between the two components, and usually I’ve read of them being grounded. Not just by the mounting bolts, but by an additional grounding strap from the sheet aluminum to a good ground.
Not sure if it changes things by grounding it to the body, or directly to the battery, vs the engine, but it’s a thought.

Easy to experiment with. You’re just trying to put something between the front of the throttlebody, where the computer computer is, and the distributor, where the electrical action is.

 

[gnpenning]

Some shielded the wire. Similar to the shielding in coax. In fact you can remove it from old coax and put your wires inside.

 

[73azbronco]

Apples to cumquats, I have factory 4.88 in my rubicon with a 3.6, it is a rocket off the line, and takes 7% hills in 8th when it used to take 7/6th on 4.11 gearing

 

[.94 OR]

Apples to cumquats, I have factory 4.88 in my rubicon with a 3.6, it is a rocket off the line, and takes 7% hills in 8th when it used to take 7/6th on 4.11 gearing

How about uphill? Same results?

 

[Broncobowsher]

How about uphill? Same results?

The comment states 7% grades.