starter works but not firing

[ivansgreat]

Howdy all! So, about a week ago I went on a pretty long drive to Houston from College Station(70 miles), and I had an intermittent problem of my truck stumbling (mini backfires). I had the same problem driving around town when I got back. Finally one day it just wouldn't even startup. I'll turn the key, the starter will start, the fan turns, but there is no firing of the engine going on.

Point gap is fine
I think there is no leak in the carb (hoses look good)
gas is squirting in carb

Any thoughts would be very much appreciated.

(attached are pics of the carb and such)

[ivansgreat]

more pics

[ivansgreat]

One more.

[FORDification]

Backfiring out the exhaust is the result of improper timing 99% of the time. From your description, it sounds like the timing was slowly changing, either from a loose distributor or the timing chain slipping. If it's the original timing chain and gears in that engine, those gears will have a plastic coating on the gear teeth, which was supposed to help the engine run a little quieter. However, over time the plastic will crack and break off, falling down into the oil pan. This will make the chain very loose, causing erratic timing and even possibly even the chain jumping a tooth on the gear.

Have you checked for spark at the plugs? If you're getting a good spark there, then I'd definitely check out the engine timing.

[ivansgreat]

I don't thnk there is spark at the plugs because the engine doesn't even start up.

[FORDification]

You can have spark at the plugs without the engine starting up....it just means your spark is happening at the wrong time. In order to determine whether it's a timing problem or an electrical problem, you need to actually check for spark. If there's spark, then it's probably a timing problem...no spark means it's electrical.

[NM5K]

Another thing that can happen is the pin that holds the distributor gear
on the shaft has gone kaput. Usually you can turn the distributor and get it
running again, but eventually you run out of room to turn..
It may not be that at all, but thought I would mention it. I had the pin
break on my 68 a few years ago, and the timing would drift..
Auto zone had the replacement pin..

BTW, you probably want to make sure the points are actually
operating, and have a gap at the high points of the cam.
I've seen points get loose, and the gap slowly close up, and
pretty much will cause the same problem..

[Jake11]

Turn the motor, by the bolt on the harmonic balancer over to TDC on the timing pointer. Take the cap off the
distributer and see if the rotor points to #1cyl. or 6. If it lines up your ok. If not theres a problem with the chain
or distributor drive. If it looks ok, replace the points&condenser at least and ck for spark at the coil wire.
Keep sluggin, Jake

[willowbilly3]

Also check the point gap. Points made nowdays have a really crappy rubbing block and they can wear away pretty fast, especially from new. I have found them to wear off and go shut in just a few hundred miles, even with proper lube. That changes the timing too plus the weaker spark will make it backfire worse. A petronix is $80 well spent.

[ivansgreat]

Thanks guys. I'll check this stuff out.

[DuckRyder]

Good advice so far.

For it to run you need

spark
fuel
compression
(all at the right time)

Let us start with some basic trouble shooting and figure out whats missing and go from there...

Also, when you get it running, check that the choke is opening fully, looks like someone disconnected your choke pull off...

[ivansgreat]

I've checked everything, and it all seems to be fine. However, I can't tell what the markings are on the harmonic balancer. Does anyone have a pic of what the marks should look like. I can see the marks but I'm not sure where the pointer is pointing at.

[DuckRyder]

I'm not really a small block guy, but typically Fords have.

A deep mark all the way across the dampner that is TDC and will have hash marks every degree with half width marks every 5 degrees and full width every ten from about 30 BTC to 10 ATC.

Edit: did google image search on "302 timing marks" this might help.

http://www.fordmuscle.com/forums/falcon ... y-sbf.html

[Jake11]

Sand it with 220 paper or emery cloth. Then you'll see the marks. Paint it black with spray paint. When dry rub chalk
on the marks. Now you can see then easy.

[ivansgreat]

On my truck I can see (tc 10 20 30 btc). But, when the rotor is pointing to the #1 spark plug the timing shows to be around btc. Will this cause it to not even start? Also, the timing pointer is on the passenger side of the engine. I'm using the straight (drivers side) side of the pointer when I say that it points at btc. Here's a pic.