I have been trying to come up with a good combo for a 400 build to put in my '69 Bronco. I am looking for some input from you guys as to what I should do cam-wise.

My Bronco will have 35" tires, 4.56 gears, an NP435 tranny, and a beefed up Dana 20 xfer case. It is going to be about 50/50 trail rig and street driver.

I want a motor that has a lot of low-end grunt. I am going to be putting an aftermarket MPFI system on it. I want to be able to run mid-grade pump gas.

I have been looking at all kinds of combinations of cams, CR's, and a few heads in Desktop Dyno. So far, I like the DEH255 cam numbers the best, but I have been getting differing opinions on the ability to use that cam with pump gas. So, I have also looked at the DEH265, but I have been getting differing opinions on that one as well.

So, there it is. How would you build it to achieve these goals?

Thanks,

Devin

 

With 4.56 gears, I would go with the 265DEH cam.
What RPM range do you expect to see?

Use the Mass-Flo throttle body for EFI. Don't get that Holley crap.

Look at http://www.massfloefi.com/

 

Well, I want to be able to drive this thing around, including some highway time when I am driving to the trails. So, with my setup, my cruising RPM at 75 MPH would be ~3300 RPM. Now, I wouldn't be out on the interstate very often - just the occasional trip up to Colorado. The majority of the highway driving would be at 2900 RPM or below.

Why do you not like the Holley throttle body?

 

Holly and most of the aftermarket systems are Speed Density systems. They measure the manifold vacuum and use a look=up table to determine the amount of fuel required, along with other variables. This is essentially the same thing that a carb does. The problem is that they can't supply the exact data that belongs in the table, because it is engine dependent. The data must be determined by tuning, which requires Dyno time. Many people who try to use them give up and go back to a carb.
BTW, Accel is supposed to have the best of those.
They work well for racing where the thing is running at WOT all the time, but for cruising where the manifold vacuum changes slightly with load, they are hard to get right.

The Mass-Flo system is a mass air system like the 5.0 Mustang Ford system. It uses a mass air sensor and is much more sensitive to air flow changes. It also uses a table to convert air flow to fuel requirements, but that table can be supplied by the vendor of the mass air sensor. It still requires a little tuning, but that can be done on the street.

 

The 255DEH is a good cam. It will produce maximum torque at low RPM, but the torque falls off after 3500 RPM. A better cam for high RPM is the XE256. It will still produce near maximum low end torque, but make power above 3500 RPM. The 265DEH will produce a little less torque at low RPM, but will stay strong to about 4000 RPM.

I strongly recommend head work to improve head flow. That will help any cam run at higher RPM.

Watch the Dynamic Compression Ratio with the 255DEH and the XE 256 cams. If your static CR exceeds 9.0:1, you could be close to detonantion with low Octane fuels.

 

i just installed a 400 in my 79 f150 4x4 using the 265deh and tims stepped dish pistons and stock heads. havent had time to fine tune it yet but it is quite impressive so far. Currently running 33's and 3:50 and seems quite manageable where the tired 351 i took out really worked for it around town. i figure 4:10's and 38's are about equivalent however i have 35's and 4:10's going in which will help me all around gaining a couple hundred rpm over speed.... So far this build seems perfect for what i wanted which is some 4x4 and DD. As for being a fairly modest build I think you'd like it to unless you were planning on using different heads and had higher horsepower goals.

 

What is your compression ratio? Did you have any work done to your heads? Do you have to run high octane?

 

With the T Meyer 14cc stepped dish pistons and stock (open chamber, 2V) heads, compression should be 9.5:1. With the open chamber heads providing relatively little in the way of quench, this might invite some detonation with the lower octane pump gas.

Off that subject, have you considered a T19 instead of the 435? You lose the granny low gear of the 435, but if you source one of the close-ratio Ford T19 units (4.02:1 first gear), you will have a really streetable four speed (and actually be able to launch out of first gear, instead of second). This gearing of the T19 duplicates the gear ratio of the NV3550 (obviously minus the 5th gear/overdrive).

 

Yeah, I considered it. I wanted the 6.69:1 first gear of the 435. Plus, I scored the NP435 that I have for next to nothing. I have had T18's in several of my other trucks and didn't mind starting out in 2nd.

 

Can't give you actual final comp. ratio although I'm pretty sure Tim's #'s were for 9.3:1
Been running on midgrade just fine and it ran fine on the chevron 87 that was in it. Be nice to see the results of other builds with these pistons but haven't come across any posts indicating that.

 

How can it be done on the street? With a Tweecer?

 

Yes, with a Tweecer, a laptop, and a Wideband. You simply run at WOT and log it. Then correct the MAF transfer function until you are getting the AFR that the computer is commanding. A race track or drag strip is the best place to do this. A Dyno will work as well. You can get the idle and closed loop operation tuned on the highway.

 

Just out of curiosity, how dificult and expensive can it be to create your own fuel injection system out of ford parts? I have the holley and as Danlee mentioned I took it off and went carb. Still new with all components wide band as well. Lucky for me it came with the truck when I bought it so no money out of my pocket sitting in a box.

 

Sell the Holley crap on Ebay. Keep the wideband. Get the Mass-Flo setup.

You can do an all-ford setup. The difficult part is the Intake Manifold and the Throttle Body. You will need a Single Plane Intake Manifold, and a Throttle Body Adapter.
You will need an EEC-IV Computer and Harness, as well as all the Sensors and Injectors and MAF. You can eliminate all the emissions related controls. Then you will need a way to tune it. I use a Tweecer and a laptop.

You should contact the people at Mass-Flo about buying their TB and MAF setup for your DIY system.

I modified my own manifold using Bungs purchased on Ebay, and having the manifold bored at a local machine shop. I then used High Temperature Epoxy to install the bungs into the manifold.

I made my own fuel rails by buying a length of Extrusion and having it threaded and bored for the Fuel Injectors at the same machine shop.