got a light?
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Junior User
Joined: Jan 2002
Posts: 68
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got a light?
Hey guys I got a problem. I got a 351M in a 79 Bronco with a 2 barrel carb. it runs good ...until I put it in gear and drive it. It seems good the moment I touch the pedal but then as I give it more gas, it acts like it has no power and begins to stumble and sputter! I rebuilt the carb with no change. I checked everywhere for vaccum leaks and fixed all that I found... helped but still not good. I had changed the intake when I installed the motor...I feel confident that I got it sealed properly. All surfaces were clean and i used the provided sealer for the ends of the rubber gasket and a thin film on each port. I am at a loss on this one and thoroughly frustrated! I also checked the timing its at 8 degrees BTC. I would appreitiate any suggestions....thanks for your help.
Senior User
Joined: Sep 1999
Posts: 176
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From: Minneapolis
got a light?
You said that your timing is at 8 deg. I assume that is at idle. When you try to rev it, can you see it advance? Also, if you can get it to rev up to about 3500 rpm, see what your timing is. You should be 34-38 deg at about 3500. If your distributer is trash, you will see problems like you are getting.
It is also very possible that your coil is not putting out enough power to run the engine properly.
By your post, it sounds like you just installed a used motor without a rebuild. Correct?
Do you know if it ran good previously?
When you install a Ebrock intake, throw away the front and rear gasket, and use RTV only. It is best if you have your heads milled properly to get as tight a seal as possible on the intake. If you have more than about 3/16", that will be way too much gap. It also means you are probably not matching up to the heads properly either.
I run vaccume gauges on all of my vehicles. It eliminates any guess work about leaks. It also is a way of monitoring the engine over time for wear.
It is also very possible that your coil is not putting out enough power to run the engine properly.
By your post, it sounds like you just installed a used motor without a rebuild. Correct?
Do you know if it ran good previously?
When you install a Ebrock intake, throw away the front and rear gasket, and use RTV only. It is best if you have your heads milled properly to get as tight a seal as possible on the intake. If you have more than about 3/16", that will be way too much gap. It also means you are probably not matching up to the heads properly either.
I run vaccume gauges on all of my vehicles. It eliminates any guess work about leaks. It also is a way of monitoring the engine over time for wear.
Thread Starter
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Junior User
Joined: Jan 2002
Posts: 68
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got a light?
Ok when I checked the timing it does advance when it is reved. I dont have a tach so I cant say specific RPM but I would say its close to what you said 35 degress at 3500 aprox. I did try a differnt coil and condenser also put a new brain box and fuel pump. along with the obvious wires, cap, rotor, plugs. This is a used motor and it ran but I couldn't tell how well cause it too had a real bad holly on an aluminum intake. Thats why I changed the intake to stock. I did get a warranty along with the fact I got it from a friend so I wasnt too concerned. It runs real smooth with good oil pressure when not under load. Oil pressure is unaffected by load just saying that it seems like a strong motor. I am thinking its the stock Motorcraft carb. It sat about 2 yrs, I tried a carb kit but it didnt seem to really help. As for the vacuum gage i have an old one but I am not sure how to use it. I check everywhere for leaks with carb cleaner and fixed what I found...this was prior to all the above.
thanks for your input!
thanks for your input!
