Engine Trouble

[broncodawg]

I tried to take my Bronco out today for the first time on trial run to break in the new 351. I made it about 20 feet down my driveway and it starting spitting black smoke out the top of the carb and through the air cleaner. Several times I could see a flame through the filter element. It sputtered but continued to run for about a mile and then stalled completely. It would not re-start or even catch at all. Any ideas? :huh:

 

[Yardape]

Sounds like a timing issue to me

 

[Shadow_D]

^X2

 

[Bully Bob]

Yep, as above..,

351 firing order is diff. than 302... just in case.,

Was the dizzy stabbed all the way down & locked..?

Assume timing chain/gears are all new..?

Start over.. TDC # 1 compression stroke, on thru to ea. plug wire location.

 

[broncodawg]

I used the firing order from my Chiltons Bronco manual for a 351W. 1-3-7-2-6-5-4-8.

Everything is new, the distributor was locked down.

 

[Bully Bob]

Did it run smooth at first., then take a squat..?

Reason for asking.., I've heard of the electronic "boxes" going south....

Did you check for spark..?

 

[Yardape]

I used the firing order from my Chiltons Bronco manual for a 351W. 1-3-7-2-6-5-4-8.
Everything is new, the distributor was locked down.

Assuming everything was installed correctly, sounds like your dizz has been installed out of time. usually if it barks back up through the carb like you described the distributor is out 180 degrees. How long did it run before this happened?

 

[broncodawg]

It ran fine at idle for an hour after I got the motor put in (listen to the link on you tube). As soon as I put it in gear and hit the throttle it started

coughing and shooting smoke. I had to clean the plugs twice after I installed it cause they were fouled. After it ran about a mile it backfired, stalled and would start again for about 5 seconds then stall out again. Now it won't start at all. I don't know much about building engines and had a friend helping me but hes gone back to Iraq and I'm stuck.

 

[Bully Bob]

Two things come to mind...,

1.) 1 backfire thru a holley will destroy the power valve. (there's an anti-backfire kit for that)

2.) Somewhere, back a few posts.., someone mentioned when you cam-up a 351 you need to use the 302 firing order.

I've not re-worked a 351 so this is not my strong suit.

I heard the recording B/4 & something doesn't sound right....hard to tell from that..maybe it's the headers making that sound.

And again.., the placement of the dizzy is pretty critical. And the setting of the advance prior to hooking up any vacuum advance. Do you recall where that timing was set..??

 

[Shadow_D]

I just listened to that vid and something don't quite sound right, subtle but off. Maybe missing on a cylinder???

 

[broncodawg]

I've got a guy I work with stopping by after work tonight to check it out. I'll let you know what he tells me. Thanks for the advice, it put him on the right track.

 

[Bully Bob]

Good Idea.., & if you're still scratching your heads....talk to James Duff in Tenn. They've done many 351's.

(sometimes the harmonic bal. has to be changed..., {4 to 3 bolt} & the timing marks are diff.)

865-938-6696

jamesduff.com

 

[broncodawg]

I feel like an idiot. Two of my plug wires were mixed up and the distributor was on 180 degrees out. My friend from work had it running smooth in about 20 minutes. It starts right up and you can tell a difference in the sound at idle and when you rev it. Thanks for all the advice.

 

[Bully Bob]

Another satisfied customer....... :-}

 

[broncodawg]

One last thing..I tried to drive it to work this morning and its still spitting black smoke out of the carb. As long as I stay down on the throttle it runs pretty good, otherwise it sputters and backfires. One friend says too much fuel going in, another says my carb's too small for the motor and I at least need to change my jets. Any ideas on that one?

 

[Shadow_D]

Black smoke is usually a sign of too much fuel. Sounds like the carb may need to be adjusted a little... Also the backfiring through the carb could have done damage to the seals so you might want to make sure they are still good.

 

[Bully Bob]

Adjusting.., I doubt will help that. (save the float level) I wouldn't change the floats W/O looking inside to visually see the fuel level. Seems some of those carbs have a sight glass.. does yours..?

".....carb's too small for the motor "

Naw.., I had the same carb on my 405 chev. big block...worked fine.

"..at least need to change my jets"

Naw.., no mountains in Texas.....(the carb is new right)...? (or re-built..meaning it didn't come out of a cubby-hole in a garage did it..?)

Again.., the power valve may have blown due to the backfiring. That would create flooding condition.

Lastly.., if the carb is old, or used....there's a couple other things that need checking.... or., if you didn't have the fuel properly filtered.

Just noticed this...."still spitting black smoke out of the carb" Is this true, or did you mean out of the tailpipe....?

 

[broncodawg]

There are no tailpipes, I'm running open headers right now for the Mud Drags this weekend. There are black puffs of smoke and coughing noises that come right out of the top of the carb and through the air cleaner. I did not see any flamesthis morning. It runs fine at idle and I even pulled the linkage a few times myself last night and it revved up no problem.

I have a new 140gph electric fuel pump with a new regualtor. I'm waiting on the pressure guage to come in now so I'm not sure what psi the fuel is being pumped in.

The carb came straight off the built 302 that I had in before I did the swap to the 351. It did fine on that motor but I was running a mechanical fuel pump.

I took the air cleaner off again thois morning and there's a layer of black carbon on the inside of the venturis of the carb

 

[Bully Bob]

"...a new 140gph electric fuel pump with a new regualtor"

The pump came with specifications...i.e. pressure ratings.

(elect. pumps are usually more press. than you need)

The reg. should have settings. I think that carb calls for 4-7 PSI (don't quote me) so you may be overpressurized.

You could un-plug the pump & see if it (the eng.) settles down for a while B/4 it (the eng.) runs out of fuel.