IFthe engine has high miles, I would suspect a jumped timing chain.
X25,xxx miles. Supposedly 125,xxx but who knows?
A backfire could've been the "power valve" inside the Carb at the metering block took a dumpthey just scew into the block, easily replaced NBD......how does it run right now when you start it up.....?
You can pull off the bowl, gasket and replace it to see if that might help.....IDK - just a thought and clean up that rocker arm and pushrod or replace them ....can't be good for peerformance you know...
Carb was recently done by a friend who used to run a carb rebuild shop. Not to say he didn't make a mistake but I think he probably did a good job. Since it was rebuilt maybe 1,000 miles ago, it ought to be fine I think. It has "popped" since I first got it, though, so maybe it needs different jets...?
Originally Posted by Robs79BBbronco
Carter's have power valves?I'm wondering what the backfire could have damaged to make it run like that...I'm stumped as well.when was the last time you messed withe Carb?
Originally Posted by American Thunder
I'd do a compression test, and check all the plugs while they're out. A lot can be determined by these 2 simple checks. Also, check ign timing.
I asked a couple of locals if I could mooch a compression tester and the only one who has one is out of town til this weekend. :doh0715 The plugs I bought are spec'd at the right gap for the stock tune. (One good reason to buy Motorcraft.). Stock gap was .045". Wasn't able to do a compression test while the plugs were out but I still intend to run one this weekend.
Could it be bad gas? You just filled up. Was it a gas station you normally use?
Fair question, but I've bought there numerous times, including for the '04 Excursion which I would suspect to be less tolerant of crap fuel.
Reinstalled all rocker arms and push rods after cleaning up the rusty one. Cleaned up the nasty old valve cover and hit it with some paint. Replaced the spark plugs with new Motorcraft platinum deals. Decided to inspect the carb like you guys suggested and -- sure enough -- the blowback closed the choke part way. It's a good stiff choke, too. At any rate, that was the cause of the odd lack of power under load. It was getting enough air at idle and modest throttle, but once it needed a lot of airflow, it couldn't get it with that choke closed half way. The thud remains unidentified but I drove it ten miles tonight without incident.
Anybody know if California will pass you on a smog check if you have a crankcase breather on the passenger side instead of that thing returning the gases to the air cleaner?
Cleaned for reinstallation.
Churched up the stock valve cover a bit to match the air cleaner.
Thanks for the help, guys!