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High speed miss


nasty51ford
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My "58" B67 has a high speed miss, it's got the END 673, is the best way to determine which cylinder is missing to "crack" each fuel injection line at the pump one at a time while it's idling, to see if I can hear a difference ? The only problem is, it really only does it above 1600 RPM or so, so should I hold it at 1800-2000 while cracking the lines? The engine runs so nice this is aggravating the hell out of me! Lol. I put about a third of a quart of tyranny fluid, and a half bottle of injector cleaner (HEET) in with about 30 gals of fuel to see if that will help.

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If you have access to a hand held laser thermometer, point it at the individual exhaust port while the engine is running and see which one doesn't really match the others. This way doesn't always work but it might narrow down the search.

Or with a long screwdriver, put the tip of the screwdriver on to the top of the injector and the handle to your ear. The "sound" of the injector will sound mushy compared to the others. Not totally full proof either.

Jim

It doesn't cost anything to pay attention.

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A lot of people look for a broke spring or injector but forget valve float from a weak spring will do the same thing and depending on load can be intermittent. Just saying :) Paul

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"OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK"  Thomas Edison

 “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’

P.T.CHESHIRE

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  • 3 weeks later...

Well, I checked the exhaust ports at the manifold on my truck yesterday, and all of them except number 1 were around 195-205 at idle, and number 1 was pretty steady at 175, is that a major difference? I listened to all the injectors through a stethoscope, and they were all clicking away happily. I was thinking maybe a partially clogged or dirty injector? I stopped and got some Lucas top end lubricant/injector cleaner, and it actually sounded a little better by the time I got close to home (an 18 mile drive) I am just curious if 25 degrees difference is enough to indicate anything?

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Not too sure about fuel supply, it seems to be fading a little when it gets to 2000, and has trouble sometimes reaching 2100, I'm going to put a fuel filter in it this weekend and see if that helps at all. If that doesn't help, I'll pull the valve cover and check the valve springs on number 1, but if 25 degrees isn't much to worry about, it may not be number 1 cylinder causing the problem, but still, something is causing it to be cooler than the others.

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yup, pop the valve covers. at worst you you can adjust the valves anyways. even if they run good, they always run a lot better after you adjust the valves. my end707 had a slight miss. I went to adjust the valves and found a bent pushrod. I threw one in from a gas 540 we had layin around as it was the same length and it has been good ever since. ran a lot better with a straight pushrod and a valve adjustment

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Yeah, I cracked all the injectors today, one at a time of course while it was running, and there is a discernible difference with each cylinder. also, it seemed to run quite a bit better on the drive home after that, maybe the Lucas injector cleaner is doing the trick? Whatever is going on, it had quite a bit more power on the way home, and the high speed miss is just about gone!

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