'71 302 Will Not Start | Timing Issue??

[JayM_71Bronco]

Hey everyone,

I am sure there are 20 million thread floating around on a 302 that will not start so please forgive me if i did not come across the same issue or find the solve from another thread. Here is what I am experiencing on my end and hoping someone can help me or at least point in the right direction.

Bought my '71 this summer and have only driven it once, it started and ran only if the idle was sky high. After driving it for a few minutes it completely died and i have never been able to get it started since. I decided that it was time to start going through everything and still nothing.

Vaccum Lines: Started here and capped off anything that wasn't being used currently. (heated choke) and made sure to replace the other lines across the motor. Brand new pcv valve is installed and new hose for that as well.

Replaced the valve covers, new valve cover gaskets. Took the intake manifold off and replaced those gaskets. New carb gaskets and tried to clean the carb as much as I could without taking the entire carb apart. Installed a new thermostat, new starter (mine sounded like it was going). Before I drove it I installed a new mechanical fuel pump as well. Brand new battery and replaced the coil as it seemed mine was going with a Red MSD Blaster 2.

I have been trying my best to go through the timing. The timing marks are almost impossible to see but found DTC on compression and made sure the rotor was pointing to plug #1 and made sure the firing order was correct which it seems to be.

When I crank the engine it just cranks and cranks but nothing happens except a puff of air and it never starts. Not sure what else to check at this point but I have spark, clean new gas, no vaccum leaks to my knowledge so I am thinking it has to be the distributor, the timing or the carb?? Any ideas would be beyond appreciated. I can try to add some videos and pics if that is helpful. (just need to figure out how).

Thanks for the help all!

 

[71 CA Bronco]

Dumb a few tea spoons of fuel down the carb and see if it fires. And stop replacing parts. You could be adding to your troubles.

Where do you live. Might be someone near you that could help.

 

[langester]

What distributor are you running?

 

[JayM_71Bronco]

Will give the gas in the carb a try.

Only replaced the starter because it would not crank anymore and was draining the battery badly every time I tried to turn the key. Replaced the coil after testing it out. But totally agree makes it harder to pin point if I keep changing.

I am south of Boston if anyone is in the area and wants to take a peek.

Thanks!

 

[JayM_71Bronco]

What distributor are you running?

Not sure to be honest. It was on when I bought the truck. Will add a few photos to my gallery tonight.

 

[langester]

Not sure to be honest. It was on when I bought the truck. Will add a few photos to my gallery tonight.

Perfect, I will check them out.

 

[mrdrnac]

Just a wild guess, but distributor looks way advanced?

 

[hatleyjm]

Just thinking back to when I took an auto mechanic course at my local Tech Institute, the instructor said an engine needs 3 things to run: Air, fuel, and fire. Unless there's some major issue with the air cleaner, we can probably eliminate air as one of your problems. I would probably first do what 71 CA Bronco said and try to bypass the fuel pump by putting fuel directly in the carb. I prefer to use starter fluid but gas will also work just fine. If it starts and runs for a bit it's probably a fuel pump/line issue. If it doesn't, you probably need to further evaluate your spark situation. If it does fire, determine if you are even getting fuel to the carb (i.e. bad fuel pump, clogged lines, bad sending unit, etc). Once you are satisfied that fuel is definitely making it to the carb, proceed to fire. IMHO, it really sounds like a fuel issue. I replaced an almost brand new fuel pump recently after it failed. Had to install a new pump to move it out of storage then it sat in my garage for a bit. When I went to start it again, the pump had gone bad. That was a fun conversation to have with the wife..."What? You have to replace that part again...?" But I digress. Make sure you have fuel filters before your pump. Trash from the tank will destroy the pumps.

From what you wrote, it seems like your mechanical/spark timing is good enough that it should run (although it may need to be adjusted once you get it running). The high idle issues could be a carb adjustment. What kind of carb do you have? It probably needs a complete rebuild just to be sure you got all the junk out of it...

 

[gr8scott]

Here are the pictures from his gallery:

 

[hatleyjm]

From the photos that gr8scott posted, your carb looks like an Autolite/Motorcraft 2100. I rebuilt mine recently and it was probably the easiest carb i've ever rebuilt. If it's sat for awhile I would make that top priority once you figure out why it's not running. There are lots of youtube videos showing how to do it if you need any instruction.

From the look of the vacuum advance, it looks like your distributor is rotated pretty far toward the passenger side fender which might indicate the spark timing is advanced. Thats just a guess because someone may have clocked it in that direction to clear brackets or other engine components. I believe mine pointed more toward the driver's fender before I clocked it to make way for some accessory brackets.

 

[71 CA Bronco]

I'm going to go out on a limb here. Fuel in the carb will fire it up. And its the fuel filters and/or power valve on the carb. Check the simple stuff first. ;D

 

[JayM_71Bronco]

From the photos that gr8scott posted, your carb looks like an Autolite/Motorcraft 2100. I rebuilt mine recently and it was probably the easiest carb i've ever rebuilt. If it's sat for awhile I would make that top priority once you figure out why it's not running. There are lots of youtube videos showing how to do it if you need any instruction.

From the look of the vacuum advance, it looks like your distributor is rotated pretty far toward the passenger side fender which might indicate the spark timing is advanced. Thats just a guess because someone may have clocked it in that direction to clear brackets or other engine components. I believe mine pointed more toward the driver's fender before I clocked it to make way for some accessory brackets.

Correct, do believe it is a 2100 model and have a great carburator shop by the house they have rebuilt the carb on my 76 BMW so I may take this there anyways for a double check.

Here is a video of the start, too me it sound like timing is way way off or something. Excuse the very squeaky clutch pedal in the video but you can hear it puffing and cranking and not even getting close to firing.

https://vimeo.com/456604430

Thanks all!!!

 

[hatleyjm]

Yeah i can see why you'd think the timing was off--it seems to be backfiring up through the carb. Here's the way I'd approach this if it was my own vehicle:
--First make sure that your distributor is set correctly--turn the crank until #1 cylinder (most forward cylinder on the passenger side) is on the compression stroke then again until it reaches Top Dead Center (TDC).
--Set your distributor, making sure that even when it meshes with your cam gear, the rotor bug is pointing at the correct place on the cap where the #1 plug wire will be. Sometimes it takes a couple of stabs to get it right.
--Make sure your wires are in the correct order on the cap (For non-HO 302's, it should go 1, 5, 4, 2, 6, 3, 7, 8) and going to the correct place (Ford orders them #1-4 front to back on the passenger side, then cylinders #5-8 front to back on the driver's side)
--Once you've got your spark timing right, put a bit of fuel down the carb and crank it and see if it fires up.
--One thing you can't check without doing quite a bit of work is to check and see if the mechanical timing is right. This requires removing the water pump/timing cover and all related/in-the-way accessories. I'm not sure how often these jump teeth or get loose enough to affect the mechanical timing (i.e. valves) but I would think it'd be pretty rare and I wouldn't consider tearing into it until i'd exhausted all other possibilities.
--If it still doesn't fire after doing the above recommendations and adding new fuel to the carb, i'd check and see if I was getting spark.
--If it does fire and runs for a bit then dies, I would start looking at the fuel system (pump, hoses, sending unit--in that order).
--Also, don't worry about setting the ignition timing until after you've figured out and fixed what ails the Bronco--having your ignition timing a few degrees off if it's just running in the garage won't hurt anything.

I don't mean for the above to sound belittling or patronizing. I was raised working on Chevy's and when I started working on my lone Ford I found out pretty quick that ole Henry does things a bit different in regards to cylinder and timing order.

 

[JayM_71Bronco]

Yeah i can see why you'd think the timing was off--it seems to be backfiring up through the carb. Here's the way I'd approach this if it was my own vehicle:
--First make sure that your distributor is set correctly--turn the crank until #1 cylinder (most forward cylinder on the passenger side) is on the compression stroke then again until it reaches Top Dead Center (TDC).
--Set your distributor, making sure that even when it meshes with your cam gear, the rotor bug is pointing at the correct place on the cap where the #1 plug wire will be. Sometimes it takes a couple of stabs to get it right.
--Make sure your wires are in the correct order on the cap (For non-HO 302's, it should go 1, 5, 4, 2, 6, 3, 7, 8) and going to the correct place (Ford orders them #1-4 front to back on the passenger side, then cylinders #5-8 front to back on the driver's side)
--Once you've got your spark timing right, put a bit of fuel down the carb and crank it and see if it fires up.
--One thing you can't check without doing quite a bit of work is to check and see if the mechanical timing is right. This requires removing the water pump/timing cover and all related/in-the-way accessories. I'm not sure how often these jump teeth or get loose enough to affect the mechanical timing (i.e. valves) but I would think it'd be pretty rare and I wouldn't consider tearing into it until i'd exhausted all other possibilities.
--If it still doesn't fire after doing the above recommendations and adding new fuel to the carb, i'd check and see if I was getting spark.
--If it does fire and runs for a bit then dies, I would start looking at the fuel system (pump, hoses, sending unit--in that order).
--Also, don't worry about setting the ignition timing until after you've figured out and fixed what ails the Bronco--having your ignition timing a few degrees off if it's just running in the garage won't hurt anything.

I don't mean for the above to sound belittling or patronizing. I was raised working on Chevy's and when I started working on my lone Ford I found out pretty quick that ole Henry does things a bit different in regards to cylinder and timing order.

REALLY appreciate that! Don't at all feel as it was belittling or patronizing. Learning as much as I can every day about this truck, it is my first Ford. Will certainly give all of this a try. A local shop owner told me his old 72 used to skip a tooth on the timing chain so I wont rule that out but certainly will wait until I try everything else. Will let you know how it shakes out! Thanks a million.

 

[71 CA Bronco]

Yeah i can see why you'd think the timing was off--it seems to be backfiring up through the carb. Here's the way I'd approach this if it was my own vehicle:
--First make sure that your distributor is set correctly--turn the crank until #1 cylinder (most forward cylinder on the passenger side) is on the compression stroke then again until it reaches Top Dead Center (TDC).
--Set your distributor, making sure that even when it meshes with your cam gear, the rotor bug is pointing at the correct place on the cap where the #1 plug wire will be. Sometimes it takes a couple of stabs to get it right.
--Make sure your wires are in the correct order on the cap (For non-HO 302's, it should go 1, 5, 4, 2, 6, 3, 7, 8) and going to the correct place (Ford orders them #1-4 front to back on the passenger side, then cylinders #5-8 front to back on the driver's side)
--Once you've got your spark timing right, put a bit of fuel down the carb and crank it and see if it fires up.
--One thing you can't check without doing quite a bit of work is to check and see if the mechanical timing is right. This requires removing the water pump/timing cover and all related/in-the-way accessories. I'm not sure how often these jump teeth or get loose enough to affect the mechanical timing (i.e. valves) but I would think it'd be pretty rare and I wouldn't consider tearing into it until i'd exhausted all other possibilities.
--If it still doesn't fire after doing the above recommendations and adding new fuel to the carb, i'd check and see if I was getting spark.
--If it does fire and runs for a bit then dies, I would start looking at the fuel system (pump, hoses, sending unit--in that order).
--Also, don't worry about setting the ignition timing until after you've figured out and fixed what ails the Bronco--having your ignition timing a few degrees off if it's just running in the garage won't hurt anything.

I don't mean for the above to sound belittling or patronizing. I was raised working on Chevy's and when I started working on my lone Ford I found out pretty quick that ole Henry does things a bit different in regards to cylinder and timing order.

Well my limb broke. ;D I agree after seeing the video sounds like timing and/or firing order.

 

[Rustytruck]

to check slack in the timing chain turn the crank to top dead center on the timing marks while looking at the rotor under the distributor turn the motor backwards until you see the rotor just move and stop look at the timing pointer and if it move more than 15 degrees or so the chain is stretched or worn.

 

[Timmy390]

Didn't those old timing sets have nylon teeth?

Tim

 

[Rustytruck]

Didn't those old timing sets have nylon teeth?

Tim

yes from the factory but even the stock cast steel all metal silent chain timing sets had issues with wear and stretch. it wasn't solved until the performance chains with true roller chains.

 

[DirtDonk]

Also as a side project... Where does your PCV valve connect to the intake?
It cannot be to a single runner, and must be connected to the common plenum under the carburetor. In '71 there would have been a spacer under the carburetor that had the fitting for the PCV.

You've got the spacer, but I can't see the hose from the PCV connected to it. If that port is open it's a HUGE vacuum leak. And I would not try to diagnose the rest of the engine issues without the PCV connected anyway. It'll run, so it's not your issue to have it unplugged, but the carb is set up to have that valve in play.
And of course, if the port is open then all bets are off.

Paul

 

[DirtDonk]

Oh, and though it does not matter to performance, if you're ever looking at other Broncos and have the question, the '71 would have had the valve in the driver's side valve cover and the clean air return vent elbow in the passenger side rear.
The '70 and prior models used the reverse pattern, and as said it does not matter to how it functions. Just letting you know how yours would have normally come unless it was an extremely early '71.

Which makes me curious now. What month was yours built in?
Just curious, as yours was probably oriented that way to more easily work with the new valve covers.

Paul