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Ok got the engine rebuilt with new rings and bearings. I also lapped the valves cause they leaked but just a tiny bit. I put the engine back in and it runs exactly the same as before. Misfire at idle and nothing under load. But I have to say it’s got a lot more power now though. I added a couple more ground wires to no avail. What do I do? Really stuck, could use some help.
I haven’t posted for awhile but I’ve made some serious progress. The cylinder walls were really glazed over. And the rod bearings were pretty bad but the last main bearing was the worst. But I got the cylinders honed and have parts on the way.
I want to thank everyone who helped me. I am planning on taking the engine out tomorrow and possibly tear it down. I will update you guys periodically during the rebuild. Thanks again.
Alright, will do the wet test on all cylinders, when I get time. Is this the source of the misfire you think?
This is low compression right? I Googled this and there are people that say it’s bad and people who say its not bad. Just to save you guys the math, the difference in cylinders from the lowest to the highest is 12.2%.
I want to thank everyone for helping me, I will definately use all this knowledge in the future. I figured it out (I think). The 460 has very low compression. Here is the picture of my test. I only did a wet test to one cylinder to make sure it was the rings. I don’t think I put enough oil in, but it when the up, that proves to me that the engine has worn rings and most likely worn cylinder walls. Thanks everyone for your help. I will definately post back when I’m done rebuilding the engine.
I sprayed brake clean around the shafts and nothing happened. I tried to wiggle them while the engine was running but they don’t wiggle at all. I think while runing they make a seal. They don’t wiggle much at all, but they do wiggle. I just didn’t see any difference when I sprayed around the shafts.
Thanks, I’ve replaced the timing chain already. And I’ve set the timing how it says too on the emissions label. 8* btdc with vacuum advance unplugged and blocked. I’m leaning more twords worn rings, cause it has low steady vacuum and I’m not sure, I need to test this again but pretty sure when doing the throttle snap test the vacuum goes to zero and only goes to about 20 inches. Again not sure, will test again and post my findings. Thanks again.
I just did another vacuum reading and thought I would tell you guys what I get for readings. At idle I get about 15 inches and it occasionally drops to 14 inches (most likely when the engine has a big misfire). Just wondering if 15 inches is not enough. I took brake clean and sprayed all over. I sprayed the bushings for the secondaries and nothing, sprayed the intake manifold gaskets and the idle gets a little lower, but I have to spray a ton, to the point that there are puddles of brake clean on the manifold, I’m thinking the change in idle might be from the fumes being sucked into the carb, from spraying so much. What do you guys think?
Thanks, if it can cause vacuum leaks than it probably is a vacuum leak. I’ll see if I can get the Bush kit for it and see if it helps.
Are the throttle shafts supposed to have play, I can shake them up and down with quite a bit of play, would that cause a vacuum leak? The primary throttle blades don’t have play in them. Just curious.
I was told to test spark by taking off the main wire coming off the ignition coil, from the distributor and lift it up so the spark jumps to the distributer and see if the spark stops when the misfire does? They said I might have to use my slow motion camera to see if the spark stops? I just can’t get those exhaust bolts off, I’m thinking I might have to break them. I’ll see if I can take my torch to it and see if I can get it off that way. Thanks, you’ve been a great help.
Everytime it misses, it sounds like it comes from the passenger side (where the exhaust leak is) but it’s really hard to tell. I got a new carburetor base gasket, but it didn’t help, but I did need to replace it because the old one was really bad. I’m trying to find my fuel pressure guage but I just can’t, and I’m gonna have to wait till I get paid Thursday to rent a compression tester and spark tester. I was told about the pcv valve? It rattles when I shake it, so it’s good right? I looked a little closer and found that the exhaust leak is coming from the collector, maybe just tighten it? It’s just so rusty, not sure that bolt will move. Thanks.
Okay, I tested the charging system. With the truck off the battery is at 12.6 volts, with the truck idling I get 14.4 or so, and when I turned on the radio the blower the wipers, and the lights, it dropped to about 13.2 then I reved it to 2000 and it got worse (around 12.7). Is that supposed to happen? I’m not sure that will cause my misfire though.