Happy ending to a LONG story...

[vls]

Posted a need for a vacuum diagram of my 79 F250 400. After weeks of frustration with crappy idle and high smog readings, I finally got it running right. Original problem was a factory defect on the intake manifold, causing a huge vacuum leak. Fixed it and reinstalled it. Ran better but still a very bad idle. Carb rebuild did nothing, blah blah blah. Finally decided to replace the plugs and coil. WOW! Runs smooth as silk and smog readings are way below the limit.

Without some sort of analyzer, is there a way to test a coil? I replaced the platinum plugs with regular Autolite 25 plugs gapped at 44. Could that have helped? I'm not going to go back and try to figure out whether the coil or plugs fixed it, just curious.

My only remaining issue is that fifteen years ago I installed a dual exhaust system. 2 cats, 2 mufflers, etc. Now that I'm a "gross polluter", I have to return it to it's original setup, so it's back to a y tube and one cat/muffler. I LOVE California!!! Yeah, right!

 

[O'Rattlecan]

A truck that age isn't exempt?

Ryan

 

[Fellro]

Platinum plugs on a lower power coil system like that don't fire that well. I am a firm believer in sticking with what an ignition system was designed with. Platinum really is not an upgrade fro a copper system any more than running copper plugs on a platinum system is a cheap alternative. It is cheap, but it won't take long to burn out the plugs. So after you replace the plugs many time to the one time a proper platinum plug would have been, you don't save anything.

 

[clutch]

on the plus side, doesn't look like you'll need to plow anytime soon...

 

[vls]

Good old California requires smog 1975 or newer. And if it was a lousy exhaust system when it was built, it has to stay a lousy system.

Clutch, You're right about the plowing. Good thing I only do it for a hobby or I'd go broke this year (so far). I kinda think it's gonna be one of those years where we get hammered in March or April. Can't wait!

 

[O'Rattlecan]

Tough luck on that one my friend. Too bad your state is so commie!

Ryan

 

[Mil1ion]

Hopefuilly I helped some

I use Bosch V-Grooves in my 429

these provide twice the spark.


You can test a coil with a multimeter.

http://autorepair.about.com/od/troubleshooting/ss/coil-test-ohm.htm

 

[primetime]

Just because you have to have a y-pipe doesn`t mean it has to be "stock".
Get yourself some mandrel bends and some pipe in say, 2 1/4" pipe, a Flowmaster y collector, (FLO-Y214300 is a 2 1/4 into 3 for example), a 3" cat and muffler of your choice, build the y-pipe out of the bends, plumb the rest in 3", and Give CARB a big ole finger.

Oh, and just for future reference, Edelbrock Performer 400 #EDL-3771 is listed as an EGR intake for 351m/400 engines. I`ll just about bet it`s got an EO number also. With an appropriate year 4v emmisions carb, or the stock 2v, you might be able to sneak something by.

Glad to hear you figured it out though.

 

[vls]

Thanks again to everyone who helped me though this "ordeal". Especially Mil1ion. I found a lot of things that needed attention anyway, and the smog stuff is now up to par. I haven't run the "sniffer" test again, but after the Y-tube install, I'll let you know what it tests at. Hopefully the next post will be a huge YAY because I'll be legal for another couple of years. No snow yet, but I know it's on the way sometime! Last year we had 10 ft by now.

 

[vls]

Well, here I am back with the good news. I PASSED!!!! Allowed CO 200, measured 20, allowed HC 250, measured 40.

Here's what I did to finally get it so low. Rearranged the vacuum line to the thermactor to manifold vacuum instead of ported vacuum so that the air pump is supplying air all the time (dilutes the exhaust gasses). Opposite with vacuum advance. Ran it off of ported vacuum instead of manifold vacuum so that there is no vacuum advance at idle. Too advanced timing raises HC and too rich mixture raises CO at idle. Set timing at 6 deg per spec. After I set up, it was totally gutless, but the smog readings were great. When I got it home, I advanced the timing at idle to about 20 deg (no vaccum on the advance unit) and when I'm on the road, the ported vacuum adds even more advance and the power is better than it has ever been. No pinging at this altitude, but if I drive to a lower elevation, I'll probably have to back off the advance some.

Anyway, HAPPY CAMPER!!! Thanks again for all of the help. Maybe my story will help some other poor schmuck who has to deal with the People's Republik of Kalifornia! Now we just need some snow!

 

[Mil1ion]

On the 79 engine with vacuum to the dist VA attached to the VCV the VA on the distributor should have manifold vacuum all the time instead of just warming up period.

 

[vls]

Wrong diagram

That's not the right diagram. The one you posted on 12/24/11 is. The vacuum advance was connected to a 4 port VCV that has the vacuum from the bottom of the carb port E (full manifold vacuum) going to the vacuum advance through a restrictor when cold. After warmup, it bypassed the restrictor. The reason I had to replumb it was because with any advance at all beyond the 6 BTDC called for, the HC reading was too high at idle. I'm still not sure why, but it passed. Now that I have it running great, I'll probably leave it as is. Then next smog time, I'll just have to back the timing back to 6 again.