400 Doesn't Run Right
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Tuned
Joined: Mar 2004
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400 Doesn't Run Right
I had an oil pressure problem in my 400, so I took it back to the guy who built the engine and he redid some things. The oil pressure problem was due to the cam bearings not lining up, it seems.
I picked it up on Saturday and the idle was rough and the engine pinged quite a bit. So I took it home and did some adjustments to it and I think I made it worse. I plan on calling the machine shop tomorrow who built it, but I wanna get some opinions here also.
He had the timing around 28 BTDC. I lowered this to 10 BTDC and adjusted the idle as needed. I tried adjusting the carb also but I admit that I am not good at this. I took it out on the road and it backfires out of the top of the carb when trying to accelerate. It almost feels like the firing order is wrong. So I took it back to the house and verified that the firing order is correct (13726548). So I am not sure where to go. It runs so bad (it backfires from the top of the carb and when I give it gas it doesn't move hardly at all) that I can't really drive it. I guess that I could bump the idle back up, it would at least let me accelerate and drive to work tomorrow. But I don't like it pinging so bad and that obviously doesn't fix the problem.
Anyone got any ideas? Could it be JUST a carb adjustment out of whack that would make it run so bad?
I picked it up on Saturday and the idle was rough and the engine pinged quite a bit. So I took it home and did some adjustments to it and I think I made it worse. I plan on calling the machine shop tomorrow who built it, but I wanna get some opinions here also.
He had the timing around 28 BTDC. I lowered this to 10 BTDC and adjusted the idle as needed. I tried adjusting the carb also but I admit that I am not good at this. I took it out on the road and it backfires out of the top of the carb when trying to accelerate. It almost feels like the firing order is wrong. So I took it back to the house and verified that the firing order is correct (13726548). So I am not sure where to go. It runs so bad (it backfires from the top of the carb and when I give it gas it doesn't move hardly at all) that I can't really drive it. I guess that I could bump the idle back up, it would at least let me accelerate and drive to work tomorrow. But I don't like it pinging so bad and that obviously doesn't fix the problem.
Anyone got any ideas? Could it be JUST a carb adjustment out of whack that would make it run so bad?
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
Was the distributor vacuum line connected when the timing was 28 BTDC?
Was it connected to manifold vacuum?
If so, then the timing is retarded. You should set the timing to 10 degrees with the vacuum line disconnected.
That will certainly cause the problems that you are having.
Was it connected to manifold vacuum?
If so, then the timing is retarded. You should set the timing to 10 degrees with the vacuum line disconnected.
That will certainly cause the problems that you are having.
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Tuned
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Well... the machine shop has the vaccum lines all GAC'd up. I PM'd Mil1lion for a vacuum diagram a while ago. The machine shop told me that the way I had to vacuum setup wasn't correct, but I am not sure he is right and I know that the way he did it is wrong (because some lines are in different places)
To answer your question, yes I took the vacuum line off when I checked the timing at 28 and retarded it to 10. I held a finger over the line that came off the of dizzy and timed it. BUT the line coming from the vac advance was NOT connected to the manifold it was connected to the back of the carb. I am not sure that is right, which is why I have asked for the diagram.
To answer your question, yes I took the vacuum line off when I checked the timing at 28 and retarded it to 10. I held a finger over the line that came off the of dizzy and timed it. BUT the line coming from the vac advance was NOT connected to the manifold it was connected to the back of the carb. I am not sure that is right, which is why I have asked for the diagram.
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Tuned
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Postmaster
Joined: Aug 2001
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From: Delaware
Originally Posted by kc5hwb
Yes there was.
When you connect that vacuum line it will advance the timing to full vacuum advance.
Some people use manifold vacuum, and there are times when the factory setup puts manifold vacuum to the dist. You have to get the vacuum lines connected right, before you can set it up right.
You could try to plug the vacuum line, and leave it disconnected. It may not run perfect, but it could be a lot better than what you have.
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Tuned
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ok, I will try to do that tonight.
Do you know where I can get a vacuum wiring diagram? Mil1lion said he thinks he has one, but he needs to dig for it and scan it in. I was wondering if you knew of one online somewhere
Do you know where I can get a vacuum wiring diagram? Mil1lion said he thinks he has one, but he needs to dig for it and scan it in. I was wondering if you knew of one online somewhere
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
Originally Posted by kc5hwb
ok, I will try to do that tonight.
Do you know where I can get a vacuum wiring diagram? Mil1lion said he thinks he has one, but he needs to dig for it and scan it in. I was wondering if you knew of one online somewhere
Do you know where I can get a vacuum wiring diagram? Mil1lion said he thinks he has one, but he needs to dig for it and scan it in. I was wondering if you knew of one online somewhere
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Tuned
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I just messed with it again for the last half hour or so. I made sure that the dizzy was stabbed correctly, with the rotor pointing at the #1 plug on the cap while the harm balancer was set at TDC. I also verified the firing order again, that is correct. And I took all the vacuum lines off and plugged everything... the only thing that has a vacuum line going to it now is the C6 tranny.
It runs better than it did, but it still backfires alot out of the top of the carb. I can't accelerate that much at all without a heavy backfire.. and I have the timing set around 20 BTDC right now simply because anything lower than that and it would hardly accelerate at all.
It really seems more and more like the cam wasn't stabbed right. I called the machine shop today and he assures me that it was but I don't see any other explanation for this problem.
It runs better than it did, but it still backfires alot out of the top of the carb. I can't accelerate that much at all without a heavy backfire.. and I have the timing set around 20 BTDC right now simply because anything lower than that and it would hardly accelerate at all.
It really seems more and more like the cam wasn't stabbed right. I called the machine shop today and he assures me that it was but I don't see any other explanation for this problem.
Postmaster
Joined: Aug 2001
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From: Delaware
Pull the valve cover for #1 cylinder, and check the intake valve for that cylinder. It should be closed long before TDC. If it is still closing as the timing mark is coming around to the pointer, then the cam is retarded a lot. The timing mark on the damper or the pointer could be off also, but since the cam was removed it is probably the cam that's off.
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