Randy's Ring & Pinion
 Message Forum
 Photo Gallery
 Event Calendar
 Book Reviews
 Bronco Wallpaper
 Bronco FAQ
 Link Back to CB!
 600+ Bronco Links!
Search All Bronco Links
Buy / Sell
 Classifieds / Want Ads
 Vendor Forum
Bronco Tech
Recent Tech Articles
  Holley Carb Tips
 Aussie Locker
 C6 203 205 Doubler
 4 Link
 Clutch Replacement
 Early Turn Signals
 C4 Improvements
 Threaded Dipstick
 NV3550 5 spd
    More Tech...

Welcome to the ClassicBroncos.com Forums.

You are currently viewing our boards as a GUEST which limits your access to viewing only. To take advantage of all the forum features please take a moment to register. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact the admin. If you've lost your password click here.

Go Back   ClassicBroncos.com Forums > 66-77 Ford Bronco > Bronco FAQ > Engine FAQ's

FAQ Tools
6 Cylinder to V8 Conversion 6 Cylinder to V8 Conversion
For Those Thirsty For More Power
This thread is intended to provide a checklist of parts needed and point you to a write-up on how to convert an Early Bronco equipped with the stock inline 6 to a small block V8.

First, A Word Of Advice
Basically, this project involves eliminating everything forward of the transfer case and replacing it with V8 specific parts. Do your homework in advance and don't begin the conversion process until you have ALL the parts required. Otherwise you run the risk of stalling out on your project due to confusion, lack of funds, time scrounging for parts, or just life in general getting in the way. With the all necessary parts acquired and a good gameplan in place, this process can go quickly and minimize the amount of downtime for your Bronco. If only I'd done this, I could have at least still been enjoying a slow 6 cylinder Bronco instead of no Bronco at all for a long time. I now adhere to this principle when undertaking any moderately sized or above project.

Checklist of Needed Parts
Small Block Ford V8- Keep in mind there are no engine parts that are interchangeable from 6 cylinder to V8. You are going to need a V8 complete with intake, carb or EFI, air cleaner, exhaust, fuel pump, fuel lines, ignition, plug wires, starter, water pump and timing cover, accessory brackets (ok, you can re-use the alternator, and A/C or power steering if you have), pulleys, belts and if applicable, bell housing, clutch disc, pressure plate and motor plate. I'm sure I've left something off. The easiest swap is an engine directly from an Early Bronco as it should already be set-up with the appropriate water pump, timing cover, and pulleys. 5.0s and 5.8s can be installed, but may require further ingenuity to make clearance between the front dress of the engine and the radiator. In my opinion, the Explorer 5.0s make the best candidates for V8 conversion because of their short style water pump and timing cover.

Transmission- don't even think about using that stock 6 cylinder tranny
Tramission Adapter (aka Intermediate Housing)
Transmission Output Shaft (aka Spud Shaft)
There are numerous options here depending on your desires and budget. I was able to get the above transmisson pieces as one unit free of charge from a great member on this board. People are always upgrading so check the For Sale or Free Parts section in the Classifieds and you might get lucky like I did.

Shifter Linkages
V8 Clutch Fork
Clutch Linkage- 3 pieces here, if you're swapping in a 5.0 you're also going to need a EFI clutch equalizer bracket (Wild Horses) so that the equalizer bracket has a place to mount to the engine
Motor Towers (Frame Brackets)
Motor Mounts- standard or extreme duty available
Radiator- the smaller 6 cylinder rad will not adequately cool the V8
Radiator Hangers- because the V8 radiator mounts completely different than the I6 radiator
Upper Radiator Hose
Lower Radiator Hose
Throttle Linkage - instead of going with the stock Bronco linkage, you can instead choose a simpler, better looking throttle cable available from BC Broncos or Summit Racing

The Actual Conversion Process
This link will provide an awesome write-up on the how-to process and is very comprehensive. http://www.lonestar-ebc.com/Tech/TechItem.asp?TechID=19 I don't want to be repetitive of his great write-up and I don't think there's anything I'd add to it aside from the above mentioned throttle cable option versus the stock throttle linkage.

If you have anything to add to this post, feel free to add below.

Additional Sources: Tom's Bronco Parts catalog, Wild Horses catalog  

Last edited by bfoldy; 07/26/06 at 11:54 PM..
alien74 on 09/27/07, 11:17 PM
using a 6cyl tranny

22years ago I bought a 6cyl Bronco and after a couple of years conv. to a v-8 351W without much knowledge of the diff. between the two other than the intermediate housing was shorter.

Well needless to say butchered my tunnel and changed the local of crossmember. Well for a couple of years I struggled with breaking carriers and 1st gear in those trannies, I just thought that with 4:11 gears and 38' swampers doing holeshots on hard pavement @ 5 or 6 grand was the culprit and gave up and put an automatic

Well that was 16 years and I have not had any problems with it at all considering almost 400hp but not as much of a led foot.

I wish I knew then what We know now!!!!!!!!!!!!!!!
Reply With Quote
Bargain Hunter on 05/18/09, 04:32 PM
I have a 68 with a 170 inline 6. I'm in the process of converting to a 302. I know the output shaft has to be changed to use the factory transmission, but I couldn't help but notice you saying DONT EVEN THINK ABOUT USING STOCK TRANNY! Maybe a dumb question, but why not? This is my first Bronco, just bought it, so expect a few dumb questions.
Reply With Quote
wynn68 on 06/26/11, 07:29 PM
Did you ever determine if you had to change the transmission for the inline 6 to v8 swap? I am working on my first bronco project as well. I would like to keep the PTO winch if possible.
Reply With Quote
bfoldy on 08/21/11, 07:56 PM
You don't absolutely have to switch transmissions, but you would need to change the transmission to transfer case adapter because the i-6 and v8 transmissions are different lengths. The main reason it's not recommended to use the original 6 cyl trans is because it was not built to handle nearly as much power as the v8 RAT or RAT trannys. In my opinion, it's just as easy to find a v8 3 speed tranny and swap it in than it is to fool with swapping transfer case adapters.

- Sent from my iPhone using Tapatalk
Reply With Quote
wyowheeler on 05/12/14, 10:23 PM
The lonestar link above above is no longer a valid address. Anybody know of any similar addresses? I amthinking about swapping my 66 half cab's 6 cylinder to something better. Probably a 302 but have also wondered about a V-6 from a Ford Ranger. Those have decent power and I like the idea of taking the motor, tranny, and tcase all from the same donor, but V-8s Are tough to beat. Can anyone shed some light on this? Thanks
Reply With Quote
biofused1 on 01/29/15, 04:56 PM
Doing a 351 motor swap in 66 bronco donor vehicle is 93 ford f150 motor and harness making the change on harness to be mass air have not bought ecu or transmission yet Question 1 the speed density motor and harness that I have can I use the 94-95 mustang ecu. plus is the 94-95 ecu pin locations the same as 88-93
Question 2 If I can use 94-95 ecu does it require anything else on the motor other than the mass air that is needed for the 88-93
Question 3 If I can use 94-95 ecu my harness has a plug for the transmission that is for a e4od is it possible to change plug connections to use 4r70w transmission
Reply With Quote
cshepherd70 on 09/23/15, 01:27 PM
Does anyone know how to locate "steps to convert a 6 cylinder to V8 on an early bronco" like the lonestar (from 2006) link states (but not available)? Thank you.
Reply With Quote
mynous on 10/12/15, 02:10 PM
for anyone looking for the lonestar-ebc writeup. the wayback machine managed to save a copy (not all pictures are available).

Reply With Quote
chrlsful on 06/29/18, 08:10 AM
the 6 cyl 3.03 has 500 HP capacity (local circle trackers use it in tube chassy race cars as it's light'n strong). The RAN v RAT may B about ease of mate-up/length/etc, don't know.
Reply With Quote
chrlsful on 06/29/18, 08:11 AM
How bout a bent8 to i6 swap like some of us do (250/4.1 or 300/4.9)?
Reply With Quote

  ClassicBroncos.com Forums > 66-77 Ford Bronco > Bronco FAQ > Engine FAQ's

FAQ Tools

Forum Jump

All times are GMT -6. The time now is 02:23 AM.

Bulletin Board Software by: vBulletin
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

This site created, owned and maintained by Jon Hanna
Copyright 1996-2019 All rights reserved. Privacy Statement
ClassicBroncos.com is not affiliated with Ford Motor Company

Page generated in 0.35536 seconds with 69 queries