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351C Engine Won't Stay Running


Okay, so I have my car ALMOST done and of course I run into a problem. One I can't see to get around. I have a 351C 2V engine from a 1975 Ranchero, Edelbrock 2V 4 Barrel intake manifold, with a Summit Racing 600CFM Street/Strip carburetor. At this point the timing sounds correct or really close when it runs, I just cannot keep it running. Sometimes it will run longer than others. It runs fine, runs fine, then all of a sudden will just shut off. I am guessing some sort of fuel problem, but if you look at the primary sight glass, it always stays half full. I checked the power to the coil, and it seems to be getting 12V consistently. Can someone please start throwing some ideas out there?? Thanks!!!

I have almost the same setup, only Ford 302. Same carb and intake, same headers. That engine, at least on the movie clip, does not run good at all. A couple of things to try. First, mark with a Sharpie your distributor setting then advance [turn clockwise] just a small amount; about the width of the line you just drew. Second, turn in your idle mix screws about 1/4 turn. When mine was adjusted too rich it would stumble, then stop right after starting. Be sure you have the vacuum advance plugged into the correct port on the carb. Use the maniflod port, not the timed port. It took me a while to get mine adjusted. Was pretty good at doing that 40 years ago when we still had carbs on cars.
Could be several small things. First raise your idle speed. That flame out the carb could be the timing or firing order. What type of fuel pump are you running. If the pressure is too high, it will over ride the needle and seat. Let us know what you find. By the way the sight glass should be at the bottom of the hole, gas visible when you rock the car. After you raise the idle, adj the idle jets. Make sure you have all the vacuum ports capped.
ellis8500 why did you use the manifold port instead of the timed port for the distributor vacuum?? Also, the timing was set up like you described. I am pretty sure the timing is really close. I turned the mixture screws all the way in, 1 turn out, 1 1/2 turns out, and 2 turns difference. Talking to Summit's tech support, they think it may be a vacuum leak. Could be how I have my advance vacuum set up currently if what you say is correct.

railroad, the idle screw is turned where this thing should be cranking when at's not set too low. You can even pump the jets to give it gas, and it dies. I am using the mechanical fuel pump. The gas in the bowl should be in the middle of the sight glass according to Summit...and it is their carb, so I am sure they know. ;-)
Either timing is off or carb too lean. Sounded if it was running on all 8 cyls. Did you rebuild engine or someone else? Could have put timing gears in wrong. That is the only thing that will make an engine back fire. {TIMING} {PLUG WIRES ON WROMG} {Broken Valve spring/Valve/Rocker Arm}
The engine is from a running 1975 Ranchero, and nothing was done to the engine but freshening up the gaskets and dress up. The manifold was changed to an Edelbrock unit made for the 2V engines, to support a 4 barrel carb. The plug wires were triple checked to be correct. When the valve covers were off, I rotated the engine through a few cycles and noticed nothing wrong with the valves/valve springs at all.
The timing is probably slightly off, as it has been moved around a bit from initially setting it to try and adjust the running, but it is not completely off. If the engine would stay running I could actually set it. LOL
Check firing order. Ford changed the firing order when they went fuel injected/roller cam engines. If you still have the original 1975 cam shaft the firing order will be different than a newer engine. The timed port is used as part of an emissions control system; which our engines do not have. Use the manifold vacuum port on the front of the carb and be sure to cap-off the timed port. Backfire can be a sign of insufficient timing advance. Start with idle screws 3/4 turns out and see if it will run at all after it comes off fast idle. Advance the distributor a little each time until it starts good with fast idle set. Leave it there and let the engine warm up to operating temp.
I am using the firing order for the old 351C/M and 400 engines I believe... 1-3-7-2-6-5-4-8. As long as it is that, my timing was triple checked. It could possibly be something with me using the wrong port for the timing maybe?? I am going to check that, and check for any vacuum leak. I am just hoping the manifold is sealed properly, and I am not getting a vacuum leak on the underside of the manifold in the lifter valley. That would suck. LOL
Also, use WD40 or starting fluid and lightly spray all around the intake area, but not toward the carb intake. If the engine speeds up or changes, you have a vacuum leak.
The firing order is right. If Summit says half the hole, good enough. You cannot say the idle screw is set right, unless you are viewing the throttle blades and the transfer slots, and then there is nothing chiseled in stone about the number of turns on the idle speed or idle mixture jets. A vacuum leak does not have to be external. The manifold or carb base and gaskets may be an issue. If you will turn up the idle where you can keep it running long enough to diagnosis and tune it, I think you will get it to clean up. Block off the vacuum advance for now. You can decide whether you want to plumb it to the manifold or ported later. Turn up the idle and put the timing light on it, adj the carb and see what it does. Good luck,
I froze the video, while looking at the dist cap. It looks like you have the 1-5-4 firing order on the wires. I may be wrong, and cannot see all the wires. Verify that, also when you pumped the carb a couple of times and it ran high idle, I thought you had the throttle opened, but it did not move. That high rev, with enough raw gas is usually a vacuum leak. Let me know on the wiring. Good luck,
I am thinking it is a vacuum leak at this point...just have to get to the garage and mess with it some more. Let me find a pic of my cap, I am pretty sure its just how it looks.
If the number 1 wire is just to the left of the back cap retaining clip, you are OK.

On the back top of the intake, in line with the float adjuster on the carb, there is a threaded hole. I cannot tell if there is a pipe plug in it or not?
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Looking at the picture of the dist, something don't look like the diagram. If #1 is correct, the next one (to the right) should be #5 and looks to be run to the wrong side.? This picture is suppose to be on a 1975 C engine. Right or wrong?
I just found another firing order like the one described in post #9. Confusing. I really doubt if it was wired like the diagram that I pictured, it would even run at all. My mistake.
Backfire thru the carb is definitely timing/ignition I would think, but it only did it once, sooo...

I assume you have verified that the timing mark on the balancer lines up with the zero mark on the timing tab with #1 cylinder at TDC on compression stroke and the rotor pointing at #1 terminal on the cap? If you advance the dist just a tad from that point, it should be close enough to run smooth. If it's ok, and the wires are correct, then I would suspect fuel before worrying about the cam timing. Try a known working carb in place of yours. See what happens. Process of elimination. .

Regarding the coil, you are getting 12V even when it's running? You should get 12V for starting then it should drop to 7-9v while running. You may have a bad coil or voltage regulator. I would change that out also.
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Lean a/f can result in popping back through the carb, ie big vacuum leak. He needs to try bumping the timing up and raising the idle, so he can tweak it.

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