EFI to Carb - Ford F150 Forum - Community of Ford Truck Fans

EFI to Carb

Thread Tools Search this Thread
Old 04-25-2017, 11:14 AM   #1
Junior Member
Thread Starter
Join Date: Apr 2017
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Question EFI to Carb

I'm taking out my 300 6 cylinder motor and dropping in a 351m. The 300 is electronic fuel injection and the 351m has a carbureator. What all do I need for my truck itself to change it over so that the carb motor will work?
caseythomp99 is offline   Reply With Quote
Old 05-18-2017, 10:24 AM   #2
Junior Member
Join Date: Jan 2015
Posts: 27
Thanked 1 Time in 1 Post

You will need a fuel pressure regulator they have special ones for EFI to carb swaps with built in bypass and the associated hoses and fittings. Or you will have to pull your fuel pumps and get an exterior fuel pump. New distributor either a hei distributor or duraspark setup. You have to wire your fuel pump to a 12v ignition wire. That should be it as long as you have a manual trans or an older automatic. I swapped my 302 from EFI to carb last year....I think with the 351 you will have to get another radiator, hoses, and motor mounts.
5-SPEED is offline   Reply With Quote
Old 05-20-2017, 11:27 PM   #3
Junior Member
Join Date: May 2017
Location: Seneca, SC
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts

A couple of comments on this:

1) If it is a 351M you will need to change the transmission because they will not bolt up. 351M use the big block bolt pattern for a 429/460 while your 300 uses the small block bolt pattern.

2) unless the 351M has been rebuilt recently I would check the bearings. Those engines are notorious for wide bearings and having no oil pressure because of it. After 150k on my rebuilt 400 I ran into that problem myself.

3) You really would better off getting a 351W due to the transmission issue, even if used it will probably have a longer service life.

4) Other than the engine itself, you would have to get all of the non-EFI components as with any engine swap - it's been done a bunch before so you probably can google someone else's work on it.

lairdt is offline   Reply With Quote
Old 06-15-2017, 09:03 PM   #4
rbohm's Avatar
Join Date: Jan 2016
Posts: 44
Thanks: 0
Thanked 3 Times in 3 Posts

best bet is to dump the EFI fuel pump and go with a carb pressure fuel pump. i tried using a pressure regulator, two of them in fact, when i swapped a carb for EFI on my old 83 grand marquis, and the pump just blew the fuel past the regulators and flooded the carb as if the regulators were not there.
rbohm is offline   Reply With Quote

300 i6 engine swap to 351, 351 modified, efi carbureator, small block

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -4. The time now is 05:13 PM.

Copyright 2006 - 2017 F150Forum.com We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: