Unknown "thingamajig" on my 351 - Ford F150 Forum

GL~ · 11-13-2009, 03:49 PM

What is this thing called and what is the purpose of it? It appears to heat the EGR up for some purpose plus it isn't on the carb, it is mounted to the manifold. Why is there an unused vacuum point on it? There are three plugged vacuum lines on top of my engine, where should that line go to? Also...my engine is orange...erm, it IS a 351 right?

**FOMOCO466** · 11-13-2009, 06:13 PM

show pic of the whole motor, and more of the intake / carb setup

GL~ · 11-13-2009, 07:02 PM

Heres my engine. This truck gets impossibly bad gas mileage so I am thinking it has something to do with something not hooked up transmission-wise(vacuum line?). At 45mph I am at 3000rpm, that can't be right.

1985f150 · 11-13-2009, 07:27 PM

hi..that's just the heat riser....if you live in the south it has really no purpose...but up north you better keep it attached..i just put on a set of headers and completely removed mine....aint no big deal.....hope this helps..

**FOMOCO466** · 11-13-2009, 07:42 PM

that new carb dosen't have the bowl overflow capped off either... if it floods it'll spit gas right onto the dist and POOF!!!!!

you REALLY need to hook up the vac modulator up to the vac tree behind the carb, if it isn't hooked up the tranny wont shift into high gear untill the motor is rapped high... shifts like a rock from 1 to 2 dosen't it...3,000 then SLAM.... that is cause the vac mod isn't hooked up. 1 note.... make sure tranny fluid isn't leaking from the vac mod on the pass side of the tranny, if that seal inside starts going bad the motor will suck tranny fluid from there and burn it giving you smoking conditions! been there done that!
there is also a tiny set screw inside the hole that the vac line pushes onto the modulator... that will set how hard or soft the tranny shifts... and to an extent how long it stays in passing gear before it shifts out of it!

GL~ · 11-13-2009, 07:54 PM

I will plug the large one up front immediately! I don't want a POOF! situation! This is my families only vehicle.

In the first picture you can see two unused vacuum points that are unplugged. One is on the carb in back and the other is on the EGR valve itself. Is there a diagram showing what goes where?
It feels like there should be less RPMs at 45 and up. At 55mph it will be running 3500rpms, let off the gas and it decelerates like the brake is being depressed.