Topic: need help!

[Rick Fox]

78 400  will run ok until it warms up.  once warn it begins to miss badly even through acceleration.  I've plugged all the vac ports off thinking I had a bad vac accessory.  I've sprayed carb cleaner everywhere and get no increase in idle. I have a new cap and rotor,  new plugs and wires, new carb from BFIC,  motor is timed at about 14°....... any ideas?

[oldskoolubr]

Ignition Module?  Does it die on you or just run poorly?  Are you sure of the Timing?

[Rick Fox]

 doesn't die, just runs poorly after warm-up.  I'm certain on the timing.

[eroc022]

Choke adjusted properly ?

[Rick Fox]

 seems to be.  It snaps close on cold start after pushing throttle.  After its warm it opens up. 

[eroc022]

Is it fully open at warm up though ? Meaning it is vertical

[Rick Fox]

Yes.  I'll also note that when I put a vac gauge on the intake port I was getting a solid 20 inches.  When I hooked it to the carb base I was getting 20 inches, but it fluttered rapidly.  Both are manifold vacuum so I'm not sure what's up.

[Amtrak]

What is the timing at 3000 rpm?  it should be around 36 with the vacume advance un hooked
have you tried a new coil  does your coil have red and white wires or red and yellow wires?
have you tried a new pickup coil? did you get the right one   pontiac pickup coils  have opposite
magnetic polarity from chevy pickup coils  and have you tried a new dist module as refereced
in a prior post

[oldskoolubr]

Hey Eroc shouldn't you be able to test the module?  I know I took mine to Oreillys and they put it on a machine and gave me the readings...

[rhino33]

check the condition of the weights and springs on the distributer

[Rick Fox]

I haven’t checked the timing other than at idle.  As for the distributor internals I thought everything either worked or didn’t.  I checked the weights and springs and found they were slightly seized.  I removed them I got them freed up. Now they extend and retract easily.  I’ll have to check the coil wires tonight, but I think I have a red and white.  What’s the difference in the color of wires?

[rhino33]

red is batt pos and the white is tach. let me know if that was the issue, i had the same issue with my 400, and i even installed an adjustable vacuum to dial in how many degrees of timing i wanted, check out crane cams vacuum adjuster, i just fabbed my own based on the idea, an adjustable timing light will be required
cheers

[Rick Fox]

So replacing the coil fixed your problem? I guess the winding could become loose and become worse after it gets warm....... I'll keep you posted.

[rhino33]

no i never changed the coil it was the springs and weights on the dist that were bad on mine

[eroc022]

Hey Eroc shouldn't you be able to test the module?  I know I took mine to Oreillys and they put it on a machine and gave me the readings...

Yes but it's normally like an on off switch, either it works or it doesn't. It's odd for it to be intermittent.