Hi, I have a 74 Maverick 250 6cyl that is finally up & running after 16 yrs of sitting. It runs a bit rough, but after a lot of new parts & cleaning of the sytems at least it's running. Here is a list of parts that were put on: NOS brand new Carb 1974 D4DZ NOS brand new Distributor w/dual vac advanace-D4DZ Wires, Cap, Rotor, Plugs, Oil fitler, Gas Fitler, Fuel pump, Gas tank & sending unit, Egr cleaned out & working. It seems like it has a vacuum leak, there are a lot of vacuum hoses on this thing. Which brings me to my question about these vacuum hoses. Now can I omit a lot of these hoses & put it back to a simpler design, like a 1970 or 71 that did not have the extra emission parts like: 3 Way Solenoid Valve(bolts to valve cover), also the EGR, Temp Control Vacuum valve, Dual diaphram Vacuum Modulator, Ambient Temp Switch, I've looked at some vacuum routing diagrams from a 70 & 71 250 which had far less simplier vacuum, can I route mine the same way & will it run better??? I don't need to worry about emissions(have classic car insurance). Please let me know what you guys think, my buddy wants to buy all new emission parts I mentioned above, but I would like to ditch most of those if I can. Thanks...
On my 1976, it required replacing the exhaust manifold with a non EGR one. I also had to remove the EGR plate under the carb and replace it with a non-EGR plate. After that....all I had to do was remove all the crap you mentioned.
They were trying some voodoo in those years (the cars polluted less, but somehow did this by burning more gas !?!). I don't know that I would do away with the EGR. That does have some benefits, but a lot of the rest of that stuff can go, as you suspect. I would take that dual diaphragm off the distributor, change it to a single and try it hooked up to the vacuum source from the carb. (no advance when the car is starting). You might want to try it with manifold vacuum and see if it likes that switch better. You can probably run a few more degrees of initial timing that the stock specs call for. Also, the advance weights in many old Ford distributors are controlled by one heavy spring and one lighter spring. If you switch the heavy for another light spring, it will wake it up a lot. It will bring the mechanical advance in quicker. There is the possibility of going too far here ... there are aftermarket super-light springs (drag race-only items) ... that will put you straight into detonation. In my experience, two light stock springs works well.
The car is an a/c car, I might have access to a early intake w/o the egr style. Never thought about the dist springs, will look into the 2 light ones. Could I just plug the other vacuum port on the vacuum advance or would I need a new one (for a early car) with just the one port?
I am trying to recall, but I think that one stage of the distributor advance mechanism in that dual setup actually removes advance in some circumstances. Forgive me, but the last time I de-smogged a car was 30 years ago. You might be able to leave one stage open to atmosphere and have the other stage function as a single. I wouldn't cap it, it would probably slow the other stage down. IIRC, the stage next to the dist is the one you don't want.
