HELP PLEASE plug? problems with my 69 C10

[aaronblevins]

Need some help. Just bought this truck. Figuring out all the bugs right now. Long 1st post. Sorry.

350

4 or 5 days ago i was misfiring through the passenger side exhaust. Pulled the plugs. Heavily carbon deposited and some oil too.

Kinda makes no sense.... fast fwd to today... truck was misfiring like crazy from both exhaust pipes. Skipping on the HWY, no power. Pulled into Pep Boys... pulled the plugs... all dry fouled. I mean i guess they were dry fouled. The truck was running like shhht. Threw them away at the store. Should have kept them for pics. Anyways... smelled fuel as i was pulling in too. Truck was flooding. Yes i have a new carburetor and more so, yes i adjusted it 4 or 5 days ago. But it hadn't been running rich for 5 days. I just smelled fuel as the truck was struggling to keep running on fouled plugs.

swapped out the plugs... was thinking also maybe the timing was off. Even though it seems to be running smooth when it's got new plugs... well... no mark on the harmonic balancer.... couldn't time it.... yes i could have by ear... but i need this thing exactly right.

So... could the timing be off? It's got a brand new timing chain and the shop I had it in a few weeks ago pulled the motor, compression was good... replaced the rod bearings, timing g chain, sealed the motor all up.

so there's no reason for me to believe the timing is that bad. Though it might be.

I also think I'm hearing some plug knock... detonating maybe... it's actually was whining like a supercharger after I brought it home tonight. It's running hmmm.... pretty good most of the time... but then goes south quik.

I will answer any more questions you might have getting into this. Need some major help.

[engineer_gregh]

You could trying adjusting the timing with a vacuum gauge. Also what carb are you running?

[aaronblevins]

Hmmm. Hadn't thought of that. But no sideways stuff here. I'm going to do this right. I want it to run correctly and timed correctly. No shortcuts. I just need to know if km heading g in the right direction or even which way to go with it.

Holley 600

[engineer_gregh]

I'm sure some will tell you that using a vacuum gauge is the best way to set the timing. I don't believe Holly's are as sensitive to fuel pressure as an Edelbrock. Maybe one of the Holley guys will chime in on how to set the mixture screws properly. If a shop had your motor out and did all of that work how did they set the timing when they re-installed it?

[aaronblevins]

Yeah I'm positive they set the timing. I'm not saying don't use a vacuum gauge for timing. I'm saying most of the time you advance or retard the timing when you have a light on it. Also reading vacuum I guess. When I set the mixture screws the other day. I did it just as holley suggests. With a vacuum gauge. Reading the highest amount of vacuum while making equal turns to get the highest amount until you pretty much make no more positive change. Set the screws all the way in... backed them out a turn and a half and went to work.

[SCHRUMGMC]

Sorta like the issue I am having with my truck

[engineer_gregh]

Just my .02 cents, but I would take it right back to the shop that did the engine work. How did they time it if there is no mark on the harmonic balancer? Why did they re-assemble it that way?

[aaronblevins]

Well. They painted the motor. I'm guessing they f*ct me for good and painted it after they timed it. I really hate auto mechanics. No offense to those that are. But my truck was a state away and I wanted it fixed. So i paid to have it done. Regrets abound.

[litew8]

you should still be able to see where the line is, unless they coated it so thick that now you can't. Crawl up under there and feel for it then scratch the paint out of the line, use a yellow paint pen to mark

[CC69Rat]

Check the firing order. 1-8-4-3-6-5-7-2

If you're standing in front of your truck. ..looking at the engine. The odd numbered cyls will be on your right. Even on the left. Counting from the front to back.

Ex. #1 - first one drivers side. #6 - third one back, pass side.

Trace your spark plug wires and make sure they follow 1-8-4-3-6-5-7-2.. (clockwise) but notice something about this firing order. 5 and 7 and very close to each other. It is possible these plug wires are crossed up.. its easy to do. Also its possible to have cross arc misfire between the plug wires. If you have them in a wire loom / tie wraps make doubly sure #5 and #7 are not right next to each other. It can give you weird issues like this that make you think 'timing'.. also check to see if one of your spark plug wire boots are melted. Maybe they got too close to the exhaust /headers and the plug is not getting fire. The plug wire arcs to the header and not the electrode on the plug.

New motor, ..just typical bugs you gotta work through. You might need a different plug boot, shorter plug (I use NGK for this but Accel does make a shortie plug)

My bet is #5 and #7 are crossed or cross arcing.. but just my .02

Hope this helps.

[litew8]

Make sure your plug wires are seated properly.

[GASoline71]

So this is all on a stock 40 year old engine? I'd be curious to know what the compression numbers are. I'm betting they are lower than they should be. No way should a shop yank a 40 year old stock engine, huck new bearings in it, and call it good.

You're fouling plugs possibly from ring blowby, and the timing is off, and the carb sounds like it's too rich.

Get the compression check numbers from the shop.

Gary

[Hawghauler]

How old is the cap and rotor? I've seen cracked caps do this very thing. Sometimes so bad it won't even run, then cooled off ran fine. Also, was it raining? Water in the cap is a popular issue with the old style dizzies.