Tips on replacing 2bbl with 4bbl

Reply Subscribe

Thread Tools

Search this Thread

May 4, 2018 | 11:58 AM

Brandon Hartness

Thread Starter

New User

Joined: Mar 2018

Posts: 3

Likes: 0

Tips on replacing 2bbl with 4bbl

I have a 1973 2wd F250/390 with a stock 2bbl setup and headers, and I just picked up a used Edelbrock 7105 manifold, and a Holley 0-80457SA 600CFM 4bbl to go with it. I'd love to hear any tips on the conversion, including:

Removing the current boat anchor of a manifold
Tips to insure no oil leaks
Potential linkage issues
Vacuum port issues
Fuel pressure issues
Which switched 12v to tie the electric choke into

I believe there's a pan under the manifold. Do I need to remove that and replace the gasket, or do I simply replace the manifold gaskets?

Thank you in advance
Brandon

May 4, 2018 | 01:39 PM

HIO Silver

Fleet Owner

Joined: Dec 2009

Posts: 20,678

Likes: 83

From: NorCal

Tips.

An OE FE intake weighs 80 lbs. Place a piece of plywood on the fender so ya can set the intake on it upon removal. Alternatively, use a cherry picker. Another alternative is to put a board between the engine and the fender.. then the intake can be dragged out instead of lifted off.
You may need a single-port coolant fitting if deleting the 2V carb de-icing plate. Visit National Parts Depot's early Mustang catalog and spec the fitting for a 68 with a 390.. about $10.
Drill a 1/8-inch hole on your new thermostat's flange to allow a means for trapped air to escape.
I used Gasgacinch to keep the intake gaskets in position.
China walls.. use RTV instead of the cork gaskets. Position the 7105 in place to gauge how tall the RTV needs to be. Remove. Now wipe the china walls with acetone for an uber clean surface for the RTV to stick. Apply the RTV to look like a sweet TIG weld rather than a long worm. I use the "daub-move, daub-move, daub-move" method at a height that will seal. Allow to out-gas for about 10 minutes before squarely setting the intake in place. If RTV oozes out, then ya used too much. It should just squish and slightly bulge. Torque in the specified sequence.
New throttle return springs are **nice** to have.

May 4, 2018 | 03:46 PM

colonelmustard

Freshman User

Joined: Sep 2012

Posts: 35

Likes: 0

From: Flagstaff Az

I have same truck as you. I installed the same set as you and it has been a real sweetheart for the last 20k. I had one problem with the carb. The accelerator pump adjustment was way off. Found a thread here that told me how to adjust it. I put a 2bbl Street Avenger on my 360 and it was 100% plug and play. I am sure you will love the set up.

May 4, 2018 | 04:01 PM

1STFOX

Mountain Pass

Joined: Apr 2018

Posts: 101

Likes: 4

Not sure on an FE Engine, But I always use studs to guide the intake for proper alignment. Your Holley may or may not have
automatic Kick down linkage, If it does, your rod will probably need to be modified. Holley makes an extension kit. Use a quality
thick gasket, this sometimes helps vapor lock issues...

May 5, 2018 | 12:31 AM

wyrm73

Laughing Gas

Joined: Oct 2015

Posts: 991

Likes: 114

From: Dallas, OR

Quote:

Originally Posted by 1STFOX

Not sure on an FE Engine, But I always use studs to guide the intake for proper alignment.

No studs on a FE- the bolts are at an angle so it won't work.

x2 on HIO's suggested china wall method. I didn't check the gap beforehand and didn't get enough sealant and it leaked like a sieve. I ended up doing a VERY ugly spackling job/ smear sealant all over the manifold and china wall just to avoid pulling it back apart for a while...and it is starting to leak only a couple month's later. Sealant or cork gasket, both are a royal pain.