JeepsAndGuns
04-04-2006, 08:14 PM
Well I think I am haveing a problem with my 401. For as long as I can remember (since I built this engine that is) I have had a jumpy vaccume reading on it. no matter what I do I can not get a even reading at idle. I checked it yesterday agan and the needle jumps really ast really viloenty from nearly one side of the guage to the other. I can rev it up and it will straighten out. I am haveing some running issues the past couple days (think its carb related/ un related to the vaccume problem) but I finally broke down a did a compression test today. This is what I found:
1. 180
2. 160
3. 160
4. 175
5. 175
6. 180
7. 175
8. 180
All the plug seem to be uniformly colored except for #8 with was slightly darker than the rest. And from looking at the plugs it appears I am running slightly rich (but I can fix that) #'s 2 and 3 have me worried, is that too mutch of a diffrence? If these cylinders were side by side I would suspect the head gasket being faulty. but these are on opposite sides of the engine. Could it be valves? How do you test to see if its the valves being burnt or whatever?
I also want to add in a couple more long questions if its not too mutch for one post.
Here in the past month or so I have been haveing a intermittent no start problem. It seems to only do this after sitting for a while (sometimes a week, sometimes over night, sometimes in the afternoon after sitting all day) there seems to be no pattern or anything to when it does it, except for it only seems to do it cold, it is usally always fine after starting. But what it does, I will crank it and crank it and it will not start, BUT when I let off the key from cranking it, it will kinda chug or sputter. Best way I can discribe it would be "dieseling" It takes for ever to start, it will diesel every time after letting off the key when it is haveing its no start fit, and usally backfires real lightly through the carb. Evenutally after cranking it long enough it will start up like nothing happend, no spittering or sputtering to life, it just starts perfectly. A couple time it backfired when it finally started but thats probably from the un burnt air fuel mixture in the exhaust. I have had a few suggestions on what it might be. The only thing I have replaced so far the the electric ignition switch on the base of the steering collumn. I thought that was the problem because it never done it agan for a couple weeks. but this past weekend it done it to me twice agan. Suggestions I have been told are coil, dist pickup, and solonoid. I hate just spending money replaceing parts that "might" be bad, I prefer to find out exactly what the problem is and replace just that part.
My last and final question for the night. Just starting sat night it is running funny. It did its no start thing. (it sat since the weekend before like it always does) but when driveing it I noticed it didnt want to accelerate right. It felt like it was hesatateing or stumbleing. It didnt spitter or sputter or miss or anything like that while doing it, it just did go right when I hit the gas. It also seemed to slightly surge while driveing constant. But it is a verry slight surge, almost like a split second miss. I got it out yesterday and messed around with it. I drove it and the miss or surge wasnt there, but the hesatation was. The hesatation is ther almost through all the accelaration unless I hit the gas and it will kinda go away upward of 2500 rpm. I hooked a vaccume pump the the vac advance to check it and watched to make sure it moved. I could pump it and it would take a fair ammount to make it move, but it did move, but would instantly go back down. I started the engine and left the vac pump on the advance, I pumped it and the idle went up somelike it should and it didnt leak back down, it stayed put untill I released the pressure. Dont know if thats the way it supposed to be or not. I checked the vac port on the carb and it was working like it should. No vac at idle, only when reved. But I didnt put the guage on it, just used my finger. I am wondering if the backfireing through the carb might not have blow out the power valve. (I thought the holley truck avenger carbs had a guard to keep this from happening) but I still dont know exactly what a pv is and what it does when it goes out. But somebody told me a way to test it is to take your finger and cap off the bowl vant tubes, it the engine stalles its bad. I tried that and it keps running fine, but dont know it that really proves anything. About that point I stoped, the only thing I done to it today was the compression check. And broke two spark plugs :(: getting them loose because they were tight as hell. So now I need to get two new plugs.
Can anybody HELP, all this crap seems to be happening at once and it starting to overwhelm me/ drive me nuts. I know my sig says I am gonna swap in a caddy 500, but I have to completely overhaul it first, and have a couple big projects in front of that, so I am gonna be keeping my 401 for atleast another couple years and I want it running right, HELP
1. 180
2. 160
3. 160
4. 175
5. 175
6. 180
7. 175
8. 180
All the plug seem to be uniformly colored except for #8 with was slightly darker than the rest. And from looking at the plugs it appears I am running slightly rich (but I can fix that) #'s 2 and 3 have me worried, is that too mutch of a diffrence? If these cylinders were side by side I would suspect the head gasket being faulty. but these are on opposite sides of the engine. Could it be valves? How do you test to see if its the valves being burnt or whatever?
I also want to add in a couple more long questions if its not too mutch for one post.
Here in the past month or so I have been haveing a intermittent no start problem. It seems to only do this after sitting for a while (sometimes a week, sometimes over night, sometimes in the afternoon after sitting all day) there seems to be no pattern or anything to when it does it, except for it only seems to do it cold, it is usally always fine after starting. But what it does, I will crank it and crank it and it will not start, BUT when I let off the key from cranking it, it will kinda chug or sputter. Best way I can discribe it would be "dieseling" It takes for ever to start, it will diesel every time after letting off the key when it is haveing its no start fit, and usally backfires real lightly through the carb. Evenutally after cranking it long enough it will start up like nothing happend, no spittering or sputtering to life, it just starts perfectly. A couple time it backfired when it finally started but thats probably from the un burnt air fuel mixture in the exhaust. I have had a few suggestions on what it might be. The only thing I have replaced so far the the electric ignition switch on the base of the steering collumn. I thought that was the problem because it never done it agan for a couple weeks. but this past weekend it done it to me twice agan. Suggestions I have been told are coil, dist pickup, and solonoid. I hate just spending money replaceing parts that "might" be bad, I prefer to find out exactly what the problem is and replace just that part.
My last and final question for the night. Just starting sat night it is running funny. It did its no start thing. (it sat since the weekend before like it always does) but when driveing it I noticed it didnt want to accelerate right. It felt like it was hesatateing or stumbleing. It didnt spitter or sputter or miss or anything like that while doing it, it just did go right when I hit the gas. It also seemed to slightly surge while driveing constant. But it is a verry slight surge, almost like a split second miss. I got it out yesterday and messed around with it. I drove it and the miss or surge wasnt there, but the hesatation was. The hesatation is ther almost through all the accelaration unless I hit the gas and it will kinda go away upward of 2500 rpm. I hooked a vaccume pump the the vac advance to check it and watched to make sure it moved. I could pump it and it would take a fair ammount to make it move, but it did move, but would instantly go back down. I started the engine and left the vac pump on the advance, I pumped it and the idle went up somelike it should and it didnt leak back down, it stayed put untill I released the pressure. Dont know if thats the way it supposed to be or not. I checked the vac port on the carb and it was working like it should. No vac at idle, only when reved. But I didnt put the guage on it, just used my finger. I am wondering if the backfireing through the carb might not have blow out the power valve. (I thought the holley truck avenger carbs had a guard to keep this from happening) but I still dont know exactly what a pv is and what it does when it goes out. But somebody told me a way to test it is to take your finger and cap off the bowl vant tubes, it the engine stalles its bad. I tried that and it keps running fine, but dont know it that really proves anything. About that point I stoped, the only thing I done to it today was the compression check. And broke two spark plugs :(: getting them loose because they were tight as hell. So now I need to get two new plugs.
Can anybody HELP, all this crap seems to be happening at once and it starting to overwhelm me/ drive me nuts. I know my sig says I am gonna swap in a caddy 500, but I have to completely overhaul it first, and have a couple big projects in front of that, so I am gonna be keeping my 401 for atleast another couple years and I want it running right, HELP
