1968 F100 w/ 240 inline - timing problem?

takehikes · Post by **takehikes** » Mon Nov 19, 2018 2:47 pm

Driving to work today running along just great like it has for four years without missing a beat. Suddenly starts backfiring and power dies, I could sort of keep it going but finally gave up. Oil pressure was good when it did this, I did see some smoke but couldn't tell color as it was dark.
Had it towed home. Plugs good and spark at each one. No sign of oil on any of them though they could stand changing.
I have a DEI style distributor and good power to it.
I pulled fuel line and have great fuel pressure when cranking.
when cranking it almost wants to g but spits fuel back up out of the carb. I suspect timing is the issue but how could it happen in an instant (distributor is bolted down tight, didnt appear to have moved).
Timing gears (supposedly were replaced by the PO).
I did find one vacuum port on the carb with nothing on it and it looked like maybe a cap fell off so I plugged it, no change (vacuum is port closest to engine facing forward)....I need a vacuum schematic if anyone has one).

Suggestions?

takehikes · Post by **takehikes** » Mon Nov 19, 2018 5:16 pm

I pulled distributor cap.
Turned crank and rotor has a spot where it does not move at all and crank is.
I'm wondering now if its distributor gear or timing gears.

takehikes · Post by **takehikes** » Mon Nov 19, 2018 5:48 pm

Pulled distributor, gear looks good, oil pump shaft good.
I really dont want to pull the front of the engine unless I am absolutley sure its timing gears.
Any 100% way to be sure?

cep62 · Post by **cep62** » Mon Nov 19, 2018 8:29 pm

takehikes wrote:Any 100% way to be sure?

One trick is to see if the rotor points to number 1 "Before" you pull the dist.

You can bring the engine up to TDC on the compression stroke and put the dist back in and see if it starts and maintains timing.

You can start an engine with a slipped timing chain by advancing the timing , but it will slip again soon.

Did you check inside the cap for any faint cracks ?, that'll make an engine backfire.

takehikes · Post by **takehikes** » Mon Nov 19, 2018 9:01 pm

240 has no chain, gear set only. Factory gear was phenolic and known to fail.

cep62 · Post by **cep62** » Mon Nov 19, 2018 9:20 pm

Do you have a Ford Duraspark with a module bolted to the inner fender? they have been known to fail.

You say you have spark but I'd check the timing and look for a cracked cap It'll look like a someone drew a line with a pencil, and the spark can follow
that line. Was there heavy moisture in your area recently?

Busboy · Post by **Busboy** » Tue Nov 20, 2018 12:30 am

The man said his distributor rotor stops turning even when cranking the engine. This is the issue. Pull the front cover. It couldn't be easier.

cep62 · Post by **cep62** » Tue Nov 20, 2018 10:06 pm

Busboy wrote:The man said his distributor rotor stops turning even when cranking the engine. This is the issue. Pull the front cover. It couldn't be easier.

I saw that , but thought he was going back and forth, with a little slack.

Seeing as the distributor is out look down the hole , and look at the drive gear on the cam for a bad spot.

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1968 F100 w/ 240 inline - timing problem?

1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?

Re: 1968 F100 w/ 240 inline - timing problem?