Alright, I ended up with a 1990 F700 with a 4v 429 engine on a deal recently. The engine was out of the truck because it had a bad valve or something. Cant remember the story. Something to do with the heads.. The original owner had the block machined, the crank polished, the heads decked, and the valves ground. He then put the engine back together. New pistons, cam, bearings. Unfortunately he wasnt an experienced mechanic, at least it didnt appear so..

So Im not sure where to start here.

Heres the problem. I went ahead and put the engine back in the truck. When it first started I was happy to hear a nice smooth running engine, but when I went to break the engine in I noticed that it was smoking heavily from only side. It doesnt smoke at an idle, just when accelerating, decelerating, or holding anything over 1000 RPM.

The smoke doesnt smell like coolant, and I dont seem to be loosing any. It smells like fuel.

Not sure what to do. You think the machine shop messed up when grinding the valves? Something spark related?

Any ideas would be greatly appreciated.

 

pull the spark plugs and look to see if you can figure out which cylinder is the problem.
Also a compression test on that side of the engine won't hurt either.
once you have rulled out compression and valve timing possibiltys.
If you have figured out which cylinder it is swap plugs from cylinder to cylinder on the that side and see if the problem cylinder moved with the plug.
Do the same with the plug wires.

Is this a E.F.I. engine.? if so do the same with the injectors and see if the problem cylinder moves.

You can find it, just got to dig to find it.

 

Its a carbureted engine.. That adds to the confusion because of the unbiasedness of the carburator and the intake manifold.. if this was a diesel Id be all over the injectors.

thanks for the input. Im gonna start with it in the morning.

Ill let yall know what comes up

 

Pull the valve cover and check the valve train on that side. Maybe a pushrod has fallen out of place.

 

Didnt get a full day, but I did spend a couple hours. Haven't got the problem yet.

I pulled the valve cover, and all the push tubes were moving, as were the rockers.

I replaced the spark plugs.

Changed the carb with a different edelbrock one.. Thought I may have blown a power valve out of the Holley.

I did a compression check and they're all at 120.

Also played with the fuel regulator. That didnt seem to do anything.

After changing the carb I noticed that the smoke wasn't really only coming from the right side. But it seemed to be pouring equally out of each side.

The spark plugs are turning black, and #3 even comes out wet.. Ive leaned the carburator down as far as it will without dying..

Would this all be because it hasn't been broken in yet? Ive got a great hill to drive this truck up as soon as I think it will make it. Ive just never seen an engine smoke so bad right after a rebuild. Hopefully I havent already smoothed out the lapping on the cylinder walls. Ive easily run the engine for 30 minutes, probably an hour trying to figure this out.

Im in need of some direction here. Im not sure what is going on? This is very confusing, mainly because I didn't do the rebuild. Hard to look back when theres no history!

You all think that if the guy had the machine shop cut the cylinder walls .010 or .020 then put regular pistons and rings in that it would cause incomplete fuel burn?

The amount of smoke coming out of this thing is ridiculous. It engullfs the whole yard with smoke after just 10 seconds or so at 3500. If it was coolant I would expect to have added some by now. Its still right at the top.

Im gonna go check the oil see if theres more than a gallon in there. See how much fuel has mixed into the oil.

Also, what happens when the cam is put on wrong? Maybe just a tooth off? Would the engine still start and run ok just not letting the fuel burn completely?

 

what type of tranny do you have ? if a Allison then your modulator could be bad and sucking up tranny fluid !

 

CJ06 is correct also pull the vac line off and see if it has fluid in it.

What coolor "smoke" and what does it smell like?
Black and will burn your eyes is fuel.
I'd keep eyes open for vacume leaks if you have that one.
Steam (from coolant) smells a lot like coolant but won't burn you eyes nearly as fast. This on kind of explanins itself (no quick fix)
Blueish is usually oil. either burning it (see it on plugs) or its getting in the exh AFTER the combustion chamberfrom like the exh valve guides.

I'd pull ALL the plugs and and compare which one are rich or very different and thn see if you see a patteren.
The intake is divied into 2 sections.
1st section is: 2 center cylinders on one side of the engine to the outer 2 cylinder on the other head and
2nd section is just the oposite.

 

370s/429s sometimes suck oil from under the intake. I've had a few that were hard to seal some of the rebuilder intake gaskets leave something to be desired.

Just A Thought-------Hotwrench

 

Hmm. that would make sense. When I went and drained the oil there was much less than I put in. But the lifters may have been dry? Im not sure how much they soak up?

Im glad you posted that. I was about to pull the engine out and just tear it back down and restart. I should have done that before I even put it back in the truck. This is such a waste of time..

Infact Ive pretty much convinced myselft that, that's the only way Ill ever trust the engine again.

I would hate to sell the truck and then have a pissed off client that bought a truck hoping to work it, just to be let down. Then Id have to do the work any way, and still have ruined my rep.

Plus working the engine with this unknown problem may ruin parts, if they arent ruined already.

 

Found the cam was late 1 tooth.

What a pain!