I'm closing in on starting up my 86 460. I've modified most of the smog equiptment and I have questions about vaccuum connections.
Firstly, for the distributor advance, do I pull a vaccuum hose from the carb base or the manifold itself?
Secondly, I need a distributor vac,brake assist vac, and heater/ac vac. Is there another vac connection I have over looked?
PS: The Heddman Hedders fit pretty well but the collector on one side was welded on crooked from the factory and my exhaust connections needed some mods to get the thing straighted out.
If this small project works, I'll buy a pair of Thorleys next year. MUCH NICER STUFF.

 

Distributor advance usually comes from the carb. If you hook it to the manifold, it would always run full vac advance. If you have the C6 automatic, there is probably a vac hose from manifold vac down to the vacuum modulator on the trans. That is assuming they still had vacuum modulators in '86. A vacuum modulator would sense engine loading by vacuum, and vary a control pressure in the trans.

 

does your truck have cruise control? thats the only other thing that comes to mind. generally theres the vacuum tee at the back of the manifold that runs all the important stuff, leave that. but the tee in the front usually runs all the smog crap like egr, etc... i would just rip all that off and plug everything, and then try running the advance both full and timed to see which works better for you. by the way, did you have the truck running before so you could give me an idea how much the headers helped? also, how much did you pay for the heddmans, and other than the misweld, were there any complications? im looking to get a set of headers for my 83 4x4 with a big block.

 

Ah YES....Trans vac. and CRUISE VAC. Thanks..

Yes I've been running this truck for 3 years with an exhaust gasket leak, dreading the root canal job needed to change a gasket. It was all that at the very least.
The Heddmans were dirt cheap. I had the heads off for drilling and helicoils. Jacked the motor some and removed the starter. Everything clears fine so I know the design was good, but the final fabrication at the factory of the collectors had to be off.
I REFUSED to pack those things up and ship back and exchange for new, so I cut and rewelded the exhaust pipe side at the proper angle to account for the mis alignment.
Once I see how this all turns out with the exhaust mod, I might begin adding a bit here and there. Its an 86 F250 king cab SuperCamper/Auto. Rear wheel drive only and non posi. What a beat. My 88 Aerostar has posi and this beast sits on one drive wheel. Thats another project.
The Thorley Headers are MUCH MUCH nicer than the Headmans. Worth the extra 2 bills I think. I'm sure.

PS: What do you mean by running full advanced and timed. I have dropped the distributor in what appears to be the proper spot and expect it to fire pretty eaisly. Don't I need vac. advance in normal operation? I also expect to change the secondary spring to a bit lighter one to relive the bog before the bang.

Thanks for the assist,
Gary

 

As if I didn't ramble enough on the last post,
The DIPSTICK tube now is a NON FIT!!!! My plan is to find some flexible copper tubing of the same diameter, cut to proper length, bend to fit, solder/braze a mounting tab, and be done with it.
UNLESS I can buy a flexible replacement tube. Just post a link if you could !!!

Gary

 

Full vacuum is straight off the manifold.. Timed vacuum is off the port on the carb that is designed for the Dist. Timed vacuum will slowly bring vacuum up to full vacuum as the throttle blades are opened more and more. Full vac., or Manifold vac., is always at it's highest at idle.
When the throttle blades are opened (i.e. you STEP ON IT) the manifold vacuum goes down, which will retard your timing if the dist is connected to this. However, with timed vac, it will increase, so the timing will advance.. which is usually what you want, but not always...
Good luck!

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh

 

 

To do the timed vacuum off the carb, is this the port on the front bottom of my edelbrock 1406 ?

Bert

 

you have two ports on an edel 1406

pass side is IRC manifold vac.....drivers side is the one you want.....ported vacuum

someone please hop in if I have the two backwards....they are two ports below the large one on an edelbrock carb, but Im pretty sure Im remembering correctly. experimenting with both wont hurt anything, but most guys prefer ported Vacuum (drivers side) and not manifold vacuum (pass side)