dixie wrecked

iTrader: (6)

Howdy, Ive been fighting some major gremlins with my t/a for a while. 85 t/a, 310, eddy performer rpm dual plane, holley 4160, heddmans with true dual straight pipes, Delco point type dizzy, factory spec 7mm wires, tpi heads (was tpi factory).

She runs alright, holds idle at around 750 (fluctuates 735-760), tho I can dial it down. Under 3000 rpm, she runs fine. Over 3k, she starts popping out the pipes getting progressively worse. I'm running 8-10° base timing, no amount of advance or retarding changes it.
6.5 power valve, carb rebuilt.
I just changed my intake gaskets again (thinking they were causing a vac leak, I think they still may be as well as sucking in oil), problem didn't change. I noticed my plugs are all covered in carbon as well.

The only things I can see are either my plugs being fouled, secondaries not opening (which raises a question as to why), or my manifold gaskets are still leaking causing a vac leak. My idle mixture screws also have no effect at all, all carb gaskets are good, new PV, and no known external vac leak.

In park, she will rev till the needle bounces, I can manually open my secondaries and they spray nicely, with the only popping occurring around 7000. Pcv hooked up, tho I can unplug it and vac advance, leaving them unplugged, and my idle goes up but otherwise runs the same.
I'm leaning towards plugs and a vacuum leak somewhere,
Though its just a guess at this point

RedLeader289

iTrader: (2)

You already covered timing so I think it sounds like a plug problem. Do you have the means to swap them out (or at least swap out the worst ones?)

dixie wrecked

iTrader: (6)

Yes I do, I can get to all my plugs (though 3 and 5 are a PITA!!).
Somehow cyl 3 plug gap was .50+.. the rest still at .35

RedLeader289

iTrader: (2)

Mmk, see what happens with some fresh plugs. If they come out looking just like the current ones then you can cross that off your list.

dixie wrecked

iTrader: (6)

New plugs, Delco r43t's, no change.
All but cyl 7 had carbon build up.
obviously running rich, but with no way of tuning the carb..

Damon

Tell me more about this points-type distributor and how you have it wired in.

dixie wrecked

iTrader: (6)

New Factory delco Dizzy and coil. 12v from batt -> switch -> 10a fuse -> resistor -> coil pos, coil - to dizzy, plus a tach. Ignition is on its own circuit, as is fuel pump.

dixie wrecked

iTrader: (6)

Anything?

Damon

Bypass the ballast resistor (temporarily) and see if the situation changes. I'm assuming the points are dialed in precisely using a dwell meter already.

dixie wrecked

iTrader: (6)

Have not tried that, also that assumption would not be right.
Its out of the box specs, I don't have a dwell meter. Or a vacuum gauge. Before this it was an Accel vacuum advance hei, no computer, and it was the exact same. Using accel, Borg warner, even mastercrap..no change

Damon

OK, so it's almost certainly not ignition. That leave carburetor and valvetrain.

Does it do it at that same RPM regardless of throttle position? I think you said you can free-rev it without problems, but under load, it's popping and breaking up past 3000. That would tend to rule out valvetrain (which would happen at the same RPM regardless of load).

So, your problem is likely fuel. To be specific, you're probably outrunning your fuel system. Badly.

dixie wrecked

iTrader: (6)

I thought of that, but I'm not sure how to test it. I originally had a Precision brand (Orileys) inline pump, 20 gph I believe, and if did this. Switched to a cheap *** one from a 86 bronco (old one crapped out. Dont buy precision brand ones..), and now a specra brand one, 30gph, 7psi I believe. Every time I check my float bowls, they're right at their mark (raising em above and below the mark doesn't affect anything). I've considered switching to a Holley Red or blue, to see if its a volume issue.
Any idea how I could test if its a volume issue? Short of dropping $100+ for a holley or carter.

And yes, I can free rev it till the tach bounces, only popping at redline, even manually opening my secondaries. While under a load, I noticed its less pronounced if I accelerate slowly, though it still kicks in above 3k. Straight flooring it leads to popping

Damon

FP readings at idle are meaningless. You need to see what it's doing under load/WOT.

Get a remote fuel pressure gague setup- somewhere you can read the pressure WHILE DRIVING. I have one I carry from car to car- just a 3/8" inline connector with a port for the small 1/8" gague line fitting, a coil of soft copper gague line and a cheap fuel pressure gague on the end of it. I install it just in front of the carb and snake the line to where I can (temporarily) duck tape the gague to the OUTSIDE of the windshield.

Make a run while watching the gague and it will be OBVIOUS if you are outrunning the fuel supply. Fuel pressure will nose dive shortly before the motor noses-over.

dixie wrecked

iTrader: (6)

It would appear not. Resting PSI is 8-9, accelerating normally (granny driving, under 2400 rpm), drops to about 7, cruising 60 mph @ 1900 rpm is about 7.5, and full throttle drops down to just below 6. I'm suspecting an intake manifold gasket leak,
It would explain why my idle mixture screws have no effect, as well as a source for a major vacuum leak

dixie wrecked

iTrader: (6)

Also about half an hour ago, she randomly died. Flooded out, to be specific. Cranked my float bowl down 1 and a half turn, held throttle down and she fired. A dude at the gas station actually asked if it was a diesel, based off all the black smoke

dixie wrecked

iTrader: (6)

Changed manifold gaskets, very little change. Idle screws still unresponsive, still popping above 3000, though not as bad. Still burning oil.. I wonder if perhaps my secondaries aren't opening?

midias

Any chance you blew out the power valve?

dixie wrecked

iTrader: (6)

I thought the symptoms matched a PV as well, alas, nope. Even with a brand new one, no change.