Need Help With Engine Diagnosis

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harrisonm

harrisonm

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Sorry for the long post, but I figured you’d need specifics. 69 Barracuda, 340, 4 speed, 3.55 gears. About 15,000 miles on 12 year old rebuild by myself. Comp 268XE cam lifters and springs, headers, Eddy Air Gap, 750 CFM Eddy and MP ignition system. For years, I could melt the tires with this combo, and it drove great. In 2013 I blew the car apart for a complete restoration. There was some coolant leaking under the heads, so while out of the car, I replaced the head gaskets. The car is all together now. It starts right up, it idles fine, and it cruises down the road OK, but it doesn’t have near the power it did. I have to slip the clutch more than before from a stop or the engine bogs, and if I stomp on it, it falls on its face and sputters at about 4000 RPM. I put in new plugs, the timing is set at 33 degrees total at 2500 and I put a can of Sea Foam in a fresh tank of gas. Per a suggestion from Mopar Performance years ago, I unhooked the vacuum advance. It ran fine without vacuum advance for years. It acts like either fuel starvation or ignition. I thought I’d start off with a compression test and then replacing the fuel filter. Is there a way to check the MP ignition system? Also, can a carb go bad and cause this by sitting around for three years? I’m pretty sure it isn’t a head gasket, because the oil is clean, and with radiator cap off there is no surge in coolant.
Thanks in advance for any help.
 
Sure the metering rods can be gummed up and not richening up the mixture

You can easily pull the metering rods out and check them. Go to the Ed website, you can download the manual and exploded view for the carb

Also, did you replace the cam drive? Maybe? You unwittingly changed the cam timing.

You should easily be able to swap in something "borrowed" for ignition, that should not take much, if you suspect that. A timing light will tell you what the advance is doing, stuck, rusted, etc, and even just "flicking" the rotor with your finger will tell you if the advance is "free" You should be able to 'spring' the rotor CW with your fingers and it should snap freely back on the advance springs.
 
edels are famous for no gaskets under the fuel level, but they do get powdered if they sit with no fuel in them, the Accelerator pump piston can dry out of its the leather style. Ez enough to clean them, just pull the rods and shoot carb cleaner with the straw right into the floor jets. Also make sure the step up springs is still working, they should pop the rods up wjen you take the little covers off them. You may have disturbed the timing or chain tooth off?
 
Thanks. I'll try those out as soon as I can. I don't think the cam timing could have changed. All I did was pull heads off, put on new gaskets and put heads back on.
 
With todays crappy gas, it can really screw up a Eddy carb. I rebuilt my 1406 cause I let the car sit to long without running it. Afterwards it ran great again. After sitting 3 more months when i cranked it, it ran like crap again. I took the carb off andtook the top cover off. I was shocked at how quick it got full of **** again. I now only run ethanol free gas and I add Stabil to it.
 
I had a Carter 2bbl sit for two years, had a problem when I got it running. Found the needle had somehow slipped out of the jet. In retrospect, the carb had sit upside down for some period of time.
 
These engines when new were expected to have the carburetor rebuilt at least once every few years. I recommend a rebuild at least once every 10K miles, every two years for a Holley, and at least once a year cleaning of the reusable air filter if you have one. You'd be amazed how much crap ends up in the air bleeds and little passages even with a good air filter, nevermind something high-flow.
 
Unfortunately, it's going to be a few more days before I can dig into the carb. But I did want to answer a question. I used some Fel Pro Head gaskets that were advertised as great at stopping leaks they 'may' have been a teeny bit thicker, but nothing that would cause a significant drop in compression. Plus, the way it falls on its face and sputters after 4000 or do RPM, I doubt that could be it. I am leaning towards carb or ignition.
 
4000 is quite far up in the rpm band.
Question is; does happen under WOT only, or under all throttle settings?
If it's gas pedal related, it's almost a sure thing that it is a carb issue.But if it still happens at part throttle, it could be mechanical.
If it just quits reving at 4000 no matter what you do with the pedal, and you don't have a rev-limiter, then it's most likely to be lifter pump-up. This is easily proved by immediately putting it in neutral,and allowing the engine to return to idle.If the lifters are pumped up, it will stall,and be extremely hard to restart.
But if, after backing off the throttle, she will motor through 4000, and continue to 5000 and beyond, then it is very likely to be a fuel issue. The very first thing I would then do, is a fuel volume delivery test.I would fill the float bowls, and then plumb the fuel delivery line straight into a mimimum 2Qt container.Then I would time how long it takes to pump 1Qt (or about)of gas into it at idle.A good system will pump that in 1 minute. An excellent system will pump that in 30 seconds. If it does that, I would move to the carb.
To find out which circuit is guilty, I would disable the secondaries, and try again.Obviously, if it now works fine, then the secondary side needs a look-see. But if it still pukes, then it's very likely to be in the power circuit.
I'm a little concerned about the earliest comment,about requiring to slip the clutch out more than you remember.Between this and the other, I can easily see a faulty power circuit; either a stuck piston, or oxidized rods, or some other fault.
You don't mention fresh gas tho, so even tho Seafoam has stabilizers in it, it cannot bring stale fuel back from the dead.Oxiginated gas goes stale very rapidly when left in an open-to-atmosphere container.The ethanol portion evaporates, leaving the heavier gas behind, which,over time becomes a syrup,and eventually turns to a solid varnish.This can begin to be noticeable in as little as a week in lawn and garden equipment, and certainly noticeable in your V8, in 2 weeks.The length of time that the entire process takes, depends on how much fuel you start with.If you started with a half tank two and a half years ago,most of it will be varnish or syrup today, unless it was Seafoamed back then.However,Seafoam has a limited life as well, and after a year, it loses a great deal of it's effectiveness.So if the fuel ain't FRESH, get rid of it.The crusty white powder in your carb is the residue left by the evaporated oxiginated gas.That powder will be everywhere in your system,everywhere that liquid gas was not. If the tank was allowed to evaporate to empty, then it is everywhere (not so much on galvanized surfaces and more so on aluminum),But worse is that the pick-up sock will be varnished up, cuz it sits at the lowest point.
Good luck
 
If it ran like a raped ape, then you tore it down, maybe the timing chain is off a tooth? any popping etc? You pretty much have to verify timing while tuning the carb anyway. A vacuum gauge will tell you a lot also.
 
I took my wifes car out the other day and stomped it after second gear it started doing the same thing you described, It turned out to be the Orange ignition box I put a spare stock box an it ran fine.

Jeff
 
WOW! Thanks. I had a busy week and did not get to the garage. I will work on it next week. I'LL POST RESULTS
THANKS
 
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