351M poppin and thumpin

[LEB Ben]

Alright fellas, just got done tinkering with the Bronco, she sounds sickly. Now she is randomly popping, almost like a back fire and sounds like it has a thump to it too. This is only coming from the passenger side, and gets worse as the rpm's raise...but as I said, it's completely random. Here are some pics of the plugs if it would help in the diagnosis:

Driver's side...looks a little lean and yes the 3rd cylinder does burn oil:

Here's the passenger side...the rear two plugs look lean again...but the first two look like they've been drug through coal or something:

Anybody have any ideas on where to go next. This engine will be junked in the next few weeks and will be replaced by a 400...but I have to get the damned Bronco through a 5 hour drive to get home first.

 

[hollenjoe]

oil in a plug, as seen in your plugs is definitively a head issue, try changing your hats plus some o rings (ive used this on worn engines before with succes), you have a couple of engines right? try swapping carbs, check for intake leaks, not vacuum but port leaks...

 

[LEB Ben]

Thanks for the input Joe. Right now, I'm just trying to figure out what is wrong with it...so I know how to baby it...all the spare parts are 5 hours away...so I have to get it there first.

 

[LEB Ben]

Anyone think that the popping and thumping and misfires might be a distributor issue?

 

[flareside_thunder]

It could very well be a dizzy issue, I know the pickups like to take a dump at the worst possible time. Also, don't rule out the coil either...check the connections on there and make sure you're getting spark to all cylinders. Hell, buy a new one they're only a couple bucks.

 

[F 150Cobra]

put MSD on it and floor it till home..


this might help ?
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

 

[LEB Ben]

Alright...thanks fellas...I'm just gettin sick of this whole fix it, it runs, it breaks, fix it, i runs, it breaks.......But she's 30 years old...comes with the territory I guess.

 

[TexasNomad]

I'd say Dizzy to, but I've never heard of ignition making the engine make a thumping sound... I'd really like to hear this...

 

[surewhynot]

Ben, the plugs you say look lean actually look right to me. The others look fouled. I'd clean the plugs, re install them and see how she does.

 

[LEB Ben]

Thanks Tony...the reason I thought they looked lean was because those have less than 500 miles on them...so I thought for the time they were in, they looked a little burned up. I did give them a clean, an nothing happened.


Just realized there was a busted clasp on my dizzy...possible problem, kinda fits the syptoms?

 

[TexasNomad]

Hmm I know a fix for it! drive it west about 1200 miles to a dusty little hole called Lubbock

 

[surewhynot]

That could be the problem Ben.

Here is a pretty good plug chart to help read plugs-

http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

 

[TexasNomad]

This reminds me of some thing, I need to change my oil...

 

[LEB Ben]

Hmm I know a fix for it! drive it west about 1200 miles to a dusty little hole called Lubbock

Tell ya what...lemme drive east 250 miles, get the engine swapped, then you can drive about 1500 miles east and you can pick it up.

That could be the problem Ben.

Here is a pretty good plug chart to help read plugs-

http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

Thanks Tony...just realized the clasp on the back side of the dizzy was broken and that explains alot.

This reminds me of some thing, I need to change my oil...

How does a spark related thread remind you about oil.

 

[TexasNomad]

I dunno........ Why do I think of Pudding when I watch a Aflak commercial..

 

[LEB Ben]

Alright fellas...just wanted to say thanks for the help...it basically came down to my own lack of maintenance. The ear on the back of the dizzy cap that's used to be clamped down...was busted off. Then once I took the cap off, noticed that 2 'contacts' were completely gone, and the others were severely worn. The rotor also had a good bit of corrosion and rust. So a new cap and rotor later, the Bronco is running as good as it can.

 

[TexasNomad]

Hey Ben how much do you think it would be to ship that old 351 of yours to Lubbock?

 

[LEB Ben]

Hey Ben how much do you think it would be to ship that old 351 of yours to Lubbock?

Dunno...figure a radiator was $40 to go 250 miles. Figure I send you a long block, that should lighten it up to about 450-475lbs...so probably a few hundred...unless you have some place that I could send it to you at a freight rate...then it would probably be in the $150 range.

 

[1985 Ford F-150]

Glad ya got er fixed Ben.

 

[UNRULEE]

Good job Ben. I bet your happy it was something simple and cheap.