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Discussion Starter · #1 ·
I have a 351W engine with a 750 cfm Holley model 4160 carb, manual choke, and MSD ignition (coil in cap). The engine is very difficult to get started, and sometimes just will not start. I've got 8 psi fuel pressure. The engine will occasionally fire on a few cylinders, but will not start. When it does start, it seems that it fires on maybe 4 cylinders which gets the revs up to 1500 rpm or so and then the rest of them start firing. Once it starts and warms up a bit, it runs just fine and restarts OK. The battery is in the trunk. It cranks OK. When it won't start, it appears to be flooding. Could I have insufficient voltage to the coil when cranking due to the battery location in the trunk? How much voltage do I need when cranking? Any other thoughts?
The plugs are Autolite AR3932. Could they be a cause?
 

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Jim,
If it's turning over pretty fast, I don't think you would get low voltage at the coil. Does it turn over slower when cold than when warm?

When it starts to run on 4 cylinders, does it blow out some dark smoke as it begins to run better? If so that would be a flooded condition on startup. You run 8 psi of fuel pressure. Holley recommends 7.5 psi max. I run 5-6. 8 might make it flood....

Are you using the choke when starting cold?

Let me know....

Greg
 

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I think Greg is on the right track...might be too much fuel pressure. In any case, sounds overly rich. (too much fuel pressure can cause same symptom) Based on your statements, I would focus on the carb...ignition system is probably not part of the problem.
My suggestions in order:
1. Confirm needle and seat are in good condition (while you are there, record jet size)
2. Confirm float level is correct
3. Install an in-line regulator
4. Only pump the throttle once or twice prior to cold start

Good luck and Merry Christmas.
 

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Do you have your choke and ignition circuits tied together? If you do the voltage being supplied to the coil may be too low due to the load from the choke. Disconnect the choke wire and try again.

Jeff
 

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While the engine is running, if you look down the venturis, do you notice excessive fuel coming from the boosters? Turn off the engine and then look down the venturis, is fuel still dripping?

I think everyone is hitting on the cause, too much fuel pressure, poor seating of needle/seat, or issue with float/float level.

Also can you confirm the basic diagnostic steps? Timing, proper advance, no vacuum leaks...

If you believe there is an electrical issue, you can test resistance on each spark plug wire or clip your timing light on each wire to verify spark is going through...
 

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Discussion Starter · #7 ·
Won't Start

Well, now I'm down to won't start at all. A few cylinders will fire occasionally, but it will not start. It has a manual choke. I've tried with the choke nearly closed and with it open. Either way, it won't start. I pulled the plugs, and they were black and some were wet, so it appears that it is flooding and runs rich. I have tried opening the throttle fully and cranking while slowly closing it, but no difference. I put in new plugs with no difference. It has fired back thru the carb a few times now. There are no vacuum leaks that I can find (it only has 30 miles on it). It has always been hard to start, but runs fine once it is started. It is turning over pretty fast and when it did start a few days ago, there was no black smoke when the remaining cylinders caught. The voltmeter reads 12V while cranking. The carb (Holley 4160) has number 70 jets and power valve. It was tuned in Phoenix, and I live in TN, so probably more elevation. Any recommendations on what else to try or how much to downsize the jets? Thanks for your help.
 

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Sounds like you may have more than one issue going on there. If it's firing back through the carb you could be over-advanced. That coupled with high fuel pressure and whatever else you haven't identified yet wil give you a no start. Either clean off your old plugs or get a new set properly gapped, then verify you're initial timing. Get it running then work your way through the carb. Fuel presure, float setting, idle mixture, etc.
Frank
 

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I have (3) Holley 2 bl carbs on my '32 street rod and they will flood with more than 4 lbs of fuel perssure. I installed a fuel pressure gauge set at 3 1/2 lbs and have had no problems since.

Hope this helps, Bill
 

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1. Jet size for that carb is 70-72 so that should be good for TN. Power valve N/A.
2. Your fuel pressure is too high. Get that sorted out. What pump do your have?
3. Look in the fuel bowls through the site glasses and verify fuel (float) level.
4. You only have 30 miles on it and it's always been hard to start with backfires? Verify timing is OK.
5. Wet, dark plugs...Timing, weak spark, lots of unsuccessful attempts at cold starts. New plugs no better...you could have a weak component in the ignition, dizzy trigger, coil, wires...

If you want to chat let me know and I will PM my cell number.

Greg
 

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Discussion Starter · #14 ·
Hard to/Won't Start

Thanks for everyone's advice. I haven't ignored any of it. The engine has a Holley mechanical fuel pump. I was getting ready to order a fuel pressure regulator and saw that the more expensive ones have a return outlet. Is this the best type of regulator to get? Do you route the return back to the inlet side of the fuel pump? They also have cheaper regulators with no return outlet.
I finally did get it started after changing the plugs twice and finding the right combination of choke and throttle, and I took it to the painter. It will be interesting to see if I can find that combination again.
I did check the manifold vacuum while cranking and it has about none. It has a fairly high duration, rough idle cam. I guess that is one of the root causes of the hard starting.
 

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You have a lot of factors in play. If you want to eliminate one, change the pump. Go with an old school approach the same as millions of carb cars have done. A simple mech pump with an internal 6 psi regulator. Here's an example.

http://www.summitracing.com/parts/edl-1725/overview/year/1977/make/ford/model/ltd-ii

Free Flow Rate: 110 gph
Maximum Pressure (psi): 6 psi

Notes: These fuel pumps are capable of supporting up to 600 horsepower.

Greg
 

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In addition to everything else, Holley's are very sensitive to bends in the fuel line....With a mechanical pump, make absolutely sure that you do not have more than one 90 degree bend in the fuel line....I know this sounds ridiculous, but if you talk to the Holley tech folks, that will be the first question they ask you.
Good luck.
Edward
 

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I have a 351W engine with a 750 cfm Holley model 4160 carb, manual choke, and MSD ignition (coil in cap). The engine is very difficult to get started, and sometimes just will not start. I've got 8 psi fuel pressure. The engine will occasionally fire on a few cylinders, but will not start. When it does start, it seems that it fires on maybe 4 cylinders which gets the revs up to 1500 rpm or so and then the rest of them start firing. Once it starts and warms up a bit, it runs just fine and restarts OK. The battery is in the trunk. It cranks OK. When it won't start, it appears to be flooding. Could I have insufficient voltage to the coil when cranking due to the battery location in the trunk? How much voltage do I need when cranking? Any other thoughts?
The plugs are Autolite AR3932. Could they be a cause?
too big carb for just 351 CI
and how do you know it is just firing on 4 cylinders
you could be dumping too much gas into the cylinders and hydro-locking the engine or just plain flooding
 

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I just read through this thread again and have a couple of thoughts.
1-I am really surprised that you have 8#s pressure from a mechanical pump. Can you check that w/ another gauge somehow? 8#s is way high if that is a confirmed pressure so must be fixed.
2-In your original post you say you have an MSD ignition. I am surprised no one has mentioned that as a possible problem. The number of MSD failures on this forum is astounding to me. Apparantly MSD has diagnosis instructions on their web site so i would go through them for sure.
 

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Discussion Starter · #20 ·
Hard To/Won't Start

Thanks for all of the advice. I've already replaced the electronics in the MSD ignition which didn't help. I like the idea of using an Edelbrock fuel pump which limits fuel pressure to 6 psi. I've got one ordered. That will at least eliminate one cause.
The car is at the body shop, so it will be a while before I get to try starting again. I'm getting it painted Ford Ruby Red with silver stripes. I'm anxious to get it back and get it wrapped up, then I'll post some pictures.
Everyone at this forum has been a great help. Thanks again.
 
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