|10-13-2012 04:57 PM|
I thought I would post an update about this problem. I took all of my plugs to a mechanic and he told me there was something wrong with the distributor. Either the coil, or the module, or something not right with the pickup, even though it was bought new. He said he had seen several of the Mallory distributors bad out of the box.
The distributor was only around $125 new, so trying a new coil, then maybe a module, and then maybe even a pickup would add up quick.
Anyway, I was so tired of it all, I just jumped in with both feet and bought an MSD distributor, 6AL, and coil and that fixed whatever problem it was. I don't usually like throwing parts at a problem, but I figured this should fix the problem as well as being a lot better ignition system for future upgrades. It fired up and runs great. Better cold starting and runs smoother too.
|09-24-2012 10:14 PM|
|Pre-Tuner||Timing light shows 20 with the advance connected or not. Should be good there.|
|09-24-2012 07:51 PM|
|RWENUTS||If it idles pretty high cause of the cam then try plugging the vacuum advance. Even if it's on ported you might be getting a little vacuum to the dizzy pot.|
|09-24-2012 07:23 PM|
|Pre-Tuner||I am using vacuum advance. It is hooked to the timed port.|
|09-24-2012 06:45 PM|
Using vacuum advance?
If so hooked to what?
|09-24-2012 06:34 PM|
I looked into the mystery oil and it seems that is more for older engines that might have some sludge build up. This engine is new, but like I said, I'm gonna try anyway.
One thing I forgot to mention, and I don't think it would matter, but I am using pure gas (no ethanol). It is 93 octane still.
Also, I am running 20 degrees of initial timing, but I don't think that will matter either as it seems right in line with what I hear other people running with a 276hr cam.
|09-24-2012 04:14 PM|
[QUOTE=Pre-Tuner;1593539]The spacer isn't going to work for me because I am already too close to the hood, even with a dropped air cleaner. I'm not sure what that would do for me anyway because the coolant would be cold still. Maybe I'm missing something.
It warms up right quick. You tie it in to your heater hoses. Outlet from the intake.
When you get the motor up to temp check the plenum temp with a temp gun or your finger. See how cold it is! You'll be suprised!!
|09-24-2012 03:40 PM|
The spacer isn't going to work for me because I am already too close to the hood, even with a dropped air cleaner. I'm not sure what that would do for me anyway because the coolant would be cold still. Maybe I'm missing something.
I just checked the cap and it is flawless. All of the terminals look clean and nothing is built up on them.
I started the truck in the garage with the doors closed (don't try this at home) and lights off and couldn't see anything arcing. It was pitch black and I looked very closely.
I'm using a Mallory HEI billet unit with MSD wires. All is new.
The theory behind the Marvel Mystery Oil is that it will free up a lifter if one is sticking? At this point, I'll try anything.
I just tried unplugging each wire with a vacuum gauge connected and the problem goes away so fast I couldn't get to all of them before it went away. I'll try again either later or tomorrow.
|09-24-2012 09:44 AM|
How about a lifter that is haning up?
I had a very similar problem with my 350 where every once in a while it had a intermittent miss and I went through the plugs, wires, vacuum lines, distributor and a few other things trying to figure where it was.
Add one bottle of Marvel Mystery oil into the crankcase and see if the problem goes away.
For me that was all it took and I never had the problem again.
It feels just like an electrical problem and until a good friend mentioned the lifter I had never even thought about it.
Hope that helps Jimbo
|09-24-2012 07:04 AM|
Check for arcing plug wires w/the engine running, hood up, in the dark to see.
What ignition system are you using? Cap spotless inside?
|09-23-2012 09:32 PM|
Ford used to use a heat box under their carbs. You could look into one of these if the rest of your checks don't work out. Easier than swapping intakes.
Carburetor Spacer Plate - 390 IP - Used ~ (1969 Mercury Cougar / Ford Mustang) (c9zz-9a589-b) at West Coast Classic Cougar, inc. :: Specializing in 1967, 1968, 1969, 1970, 1971, 1972, and 1973 Mercury Cougars
|09-23-2012 08:45 PM|
How much drop should there be? The cam is a little lumpy and the vacuum gauge doesn't exactly stay steady.
I already tried a different distributor and I replaced the ground straps when I did the engine. I'll check them though. The battery is bolted to the passenger head anyway, so that should be a hell of a ground already.
Any way I can test the manifold theory before spending money again on a new manifold?
I will try disconnecting the plugs to see what changes.
|09-23-2012 12:06 PM|
|Ruthlessmr||pull spark plug wires while its running and try to see if one is changing the tone more or less when you pull the wire.|
|09-23-2012 10:53 AM|
Typical no heat to the plenum syndrome. Cold intakes don't work well except for WOT.
|09-23-2012 10:41 AM|
I did the standard compression test also, but the carb guy I went to suggested also doing a running compression check, so I did that as well. It's just using the gauge with the engine running instead of cranking at WOT and the plugs out.
The intake is an Edelbrock RPM Air Gap.
You can hear it misfire anytime it has not been run. Under load, at idle, or a little revved up.
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