'71 302 Will Not Start | Timing Issue??

[Timmy390]

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.

I remember Dad having to get a timing set change on our 1967 Mercury Comet station wagon due to the chain jumping.....

It's clearly a timing issue in my eyes. Fuel, air ad spark all seem to be there. I base this off the backfire through the carb and the sound the engine is making when trying to start. It's catching to a point or trying to.

Timing set, distributor moved........I would start with bringing #1 to TDC on compression stroke and see where things point.

Tim

 

[Rustytruck]

with this motor cranking hard and spitting and the distributor in the position looking so far advanced all bets are off. could be the wrong firing order the distributor a tooth off or just plain adjusted wrong or just plain crossed wiring for the plugs. even with the obvious fuel available its not firing off, so someone needs to stop guessing and go from basics. top dead center #1 and suspect total failure everywhere else. these old broncos parts get swapped, they get installed wrong, cams get changed so you have 2 different firing orders to deal with. I would like to see a picture with the cap off, rotor in and out while the engine is sitting top dead center #1

 

[DirtDonk]

A relatively easy way to test the firing order is to find TDC on #1 and then with the plugs removed from #3 and #5, see which one builds pressure first as you continue to turn the crankshaft clockwise.
If it's number 5 you have the old 302 firing order. If it's the 3 then you have the 351 and more modern HO firing order.

Then you know your wires are off, because it looks to me from here like yours are in the 15426378 order running counter-clockwise on the distributor. Can't verify that all 8 are correct from here of course, but you can do that quickly at your end.

Good luck.

Paul

 

[hatleyjm]

That's a cool way to check the firing order, Paul. I hadn't thought of that...As the Bronco's accumulate more PO's this will be more and more helpful since you can't always tell what someone did to the innards from the outside.

 

[cofferjl]

In my experience as a technician I have seen similar issues before, and I would also agree that it is a timing issue. I do not think that the firing order is wrong as the engine started and ran for a little while. I wouldn't be surprised if someone dropped the Dist. a tooth off and then compensated by "timing the engine by ear" throwing all other adjustments out of wack and lacking power at lower rpms. Here is how I would proceed if you are willing and able to do the work.
1. Find top dead center.
2. Pull Dist. and make sure to reinstall with the rotor pointed at the #1 position, with the Dist. in the middle of the adjustment sweep. This may require repositioning the oil pump shaft.
3. Attempt to start the engine, if engine starts use a timing light to set the engine to the correct timing marks. If engine does not start pull valve covers to watch the action of the valves as the engine is turning over. If they are not this would indicate timing chain issues.
4. Adjust the carb to the correct settings at this point.

Also if fuel is suspect at anytime I use brake cleaner to spray into the engine. Works like ether/starting fluid but isn't as hard on the engine and less chance of a spill causing a fire like the gas pouring method.

If you don't or can't handle this I suggest taking it to a good, trustworthy mechanic. NOT THE CHEAPEST. Keep this rule in mind. Any fool can buy a stethoscope but it doesn't make him a cardiologist and any fool can buy a wrench but it doesn't make him a technician.

 

[71 CA Bronco]

I just thought of something else to check. Its possible the roll pin on the distributor sheared. I had a boat years ago that back fired and sheared the roll pin. It was doing the same thing and as we turned the distributor it would fire then the same issue would occur. Pulled the distributor and found the sheared pin. Hard to find but an easy fix.

 

[JayM_71Bronco]

Hey guys,

First off thanks so much for all of the suggestions, super helpful. I pulled the distributor and set the engine to 10 degrees BTC. Reseated the distributor and plugged all the wires in and she started almost instantly. I am guessing the guy who had previously installed this new distributor when I bought it from him installed it on DTC on the exhaust stroke, not compression. Sounds great now, just need to dial in the timing and make sure the carb is right. Running a bit rich right now.

I can post an update video if anyone cares to see it! Right now it only has half the exhaust system on as I need the rear pipes bent so they come out the side behind the rear tires instead of straight out the back, so it is very loud but sounds good, engine isnt shaking, no knocks or anything. Appreciate all the suggestions, you guys rock!

 

[hatleyjm]

Glad to hear it worked out and didn't cost you anything but time!

 

[cofferjl]

Congrats, I bet it was a good feeling when it fired off immediately.

 

[gr8scott]

I can post an update video if anyone cares to see it!

Yes please!........

 

[JayM_71Bronco]

Trying to post some videos but not sure why they wont post? Maybe becuase they are vimeo links?

 

[JayM_71Bronco]

Trying to post some videos but not sure

https://vimeo.com/459175728

https://vimeo.com/459175697

https://vimeo.com/459175617

 

[cofferjl]

The idle sounds like it may be set a little high, but in that first video it starts right up great. Good looking Bronco too.