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Project: BIG
BRONCO 
Custom Modifications (Pics near bottom)
I am documenting all my modifications here, in an attempt to better provide others, seeking to do similar modifications, with accurate information of what each mod is and how it performs. I have devoted a lot of time and effort to researching the ford 351 and 400 M-block motors, and despite hearsay, have found it to be an excellent choice for my buildup.
Engine Modifications
presented in the order I did them (to better gauge their individual effects)
1) Tune-up! This is typical maintenance. I changed the plugs, wires, cap, rotor, oil, battery, air filter. Effect: Not much noticeable but I believe slight performance gain overall. I used synthetic blend oil, high performance 8.5mmplug wires, and a Wall Mart 1000 crank amp max battery. The battery helped starting a lot, and now I can have the radio on when I start the motor and the radio never goes out. Gas mileage increased slightly to about 8.5 mpg.
2) Edelbrock 750 CFM carb and Edelbrock Performer Intake manifold. Effect: After a long ordeal of tuning and timing adjustment I gained significant mid to upper power. Off idle power was about the same or slightly less, but the motor seemed not to run at idle speed perfectly. This is probably due to the carb being too big. I was planning on having a 400 crankshaft installed and with everything I though 750 would be the right choice. But I am fairly sure now that a 600 should do better, especially on the low end. Gas mileage still increased, even with the big 750 4 barrel! Averaging slightly over 9mpg. That stock ford carb really sucks lol! I am sure with a good tuned 600 I could probably break 10 mpg.
3) Installed summit brand 5" tall x 14" air filter (I believe they use K&N), and Dynomax full length headers, and a custom made (by me) dual 2.5" exhaust with glass packs and side exit in front of rear tires. Effect: OK! We are starting to notice some power now. After retuning the carb and advance (still not perfect) I noticed a decent gain in power across the entire rpm band, but more so at the top end. Also a decrease in gas mileage, now at 8.5 - 9 mpg. I noticed in neutral the engine revs much quicker, indicating a more free flowing exhaust. The exhaust also became much louder (still using the same glasspacks) but the tone changed. I actually liked the 'gurgle' of the manifolds and exhaust that were on it. Now its more of a loud 'blat'. Still debating on putting mufflers on. Still have off - idle problems though... need to try smaller carb.
Things to come: 400 short block, 302 Cleveland Australian heads, msd ignition system, and comp cams extreme energy camshaft.
Check out the 351M 400 power drive!
Also here are some links to pages that discuss high performance options for the 351M / 400:
http://home.earthlink.net/~bubbaf250/ Bubba's M-block Ford V8 workshop, "The most comprehensive source of information about Ford M-block (351M/400) engines on the Web."
http://www.projectbronco.com/Technical_Articles/Technical_index.htm Lots of good info on the M-block motors
Photo album of my upgrades
Edelbrock parts and some chrome to put on.
Custom linkage I made to connect the throttle kick down rod.
Carb bolted on, with the linkage I made. I really need to paint the engine
compartment next time I pull the motor out!
Nice shiny Dynomax headers, unfortunately these didnt fit.
Header installed but it blocked the front driveshaft from being hooked back up
to the front axle yoke.
302 Cleveland Australian heads I plan to rebuild. They have large ports and
closed chambers, should be about 10.75:1 CR when bolted on to my motor.
All that chrome and my motor still looks like a mess. Well, I got a lot more
dress up to do yet.
This webpage originally born on 10-8-02. Last updated on 10-8-02
Thank you for viewing my web pages!