Manifold to C4 modulator vacuum line

[johnbeck]

As usual I've spent hours part hunting, this time for the steel vacuum line that runs from the intake manifold vacuum tree and down the back of the C4 to the single connection on the modulator valve. My Bronco is a 1973. Any source recommendation? What other vehicles would have the steel vacuum line like the one for my 1973 C4? Much Thanks, John B

 

[56f100bbw]

My 76 and 77 have a pre bent steel line

 

[jckkys]

Scott Drake has them here;https://www.summitracing.com/parts/...2145991090560&utm_content=GSAPI+5ba29d0d66458

 

[garberz]

I made mine from 3/16” brake line tubing.

Mark

 

[Rustytruck]

My 1974 has 2 steel lines since it has a 2 port modulator so that 1973 is a 1 year deal and maybe an 49 state 74, 75 too might have it. its not a big deal just bend up a line. At the intake end run it up about 6 inches higher and then back down to the intake connection. small jumper hose at both ends. Just don't use all rubber.

 

[johnbeck]

Summit is out of stock on the Scott Drake modulator vacuum line. What size is the line suppose to be? Where on the manifold does the line start, does it come off one of the connections from the vacuum tree? I only need a foot or so of hose, what is the best to use - bends without crimping, takes the heat, won't slip off. Maybe fuel line? Thanks, John B

 

[Lawndart]

LMC claims stock -
https://www.lmctruck.com/1966-77-ford/drivetrain/fbr-1973-77-pre-bent-transmission-lines

 

[jckkys]

A vacuum hose goes to the vacuum tree behind the carb. Another to the modulator with 90 degree bend to avoid the cross member.

 

[MikeCon]

How necessary is the modulator?Been running without for quite a while.

 

[Rustytruck]

well either you like to manual shift or you like high reeving governor controlled late shifts.

 

[johnbeck]

This morning I took the time to sort through my junk piles one last time and found my TWO modulator vacuum lines. Two years ago they got throw in with the pile of transmission coolant lines, vapor recovery and brake lines. The rebuilder of my C4 put a modulator on with only one port connection. I drove this morning to a friends house and his Bronco has the two port connection modulator. I traced his lines, the front most on the modulator runs up the trans, to the front right(pass. side) vacuum connection on the front base of his 1406 Edelbrock carb.(Same carb as mine). The rear line runs from the modulator up the trans., to the carburator rear base. Can I use the one port modulator? Thanks, John B

 

[Rustytruck]

yes you can since I doubt you are running EGR any more. Green stripe modulator is the preferred one to run.

 

[savage]

I'm running the green stripe on my 74 ,C-4 tran.

 

[Rustytruck]

nice looking set-up. no factory rust preventer dripping all over. mine wasn't that clean at 3 years old and 10,000 miles all socal life.

 

[savage]

That's a picture right after it was installed. when it comes to leak's, it drives me crazy, so I'm always checking;D

 

[Lawndart]

^^^Ha - I new it was fake knews!!

BTW, I run a green one on my 73. Just abandoned one of the lines.

 

[johnbeck]

I attempt to stay in fashion. How do I obtain a green modulator?

 

[johnbeck]

I just rolled under my Bronco and the rebuilder had installed a modulator with green print "Made in USA". Nice surprise! I will discard one of the vacuum lines. Thanks so much for your help. John B

 

[jwk413921]

Just curios, why not use rubber vacuum tube for single port?

 

[jckkys]

EBs I've seen are full of shortcuts by POs to the point they're unrecognizable and don't run as designed. Why make it worse?