Plug gap and cooling

ledslinger29

ledslinger29

Well-known member
I had my plugs gapped at .034, and regapped them to .041 or so after it ran hot and "dieseled" a good bit. I reset my intitial timing to 12 degrees, and it seems to run cooler, and the dieselong is reduced, but it still happens. Could this be the result of a Better burn? Also, I've got all of my coolant leaks resolved, only to find that I have an oil leak as well. I wasn't able to spot it before, because I used Brad penn, and its green. I'm hoping it's the front of the oil pan and not around the balancer....
 
Gap them @ .045" & what plug are you running??? Probably too hot or too high a curb idle speed & or run a higher octane fuel.
 
What's your compression and on 87? Dieseling can be caused by having the idle screw set too high and the timing too low. If you can up the timing without pinging you should. And that will bring the idle screw out. As you get into the transition circuit by having the butterfly open to far, fuel and heat cause the engine to diesel. When compression is good this becomes easier to occur, like a diesel, and I suspect modern fuel is more prone to spontaneous combustion and boiling evaporation ect. Is the engine getting hot running? Retarding the timing will raise the engine temperature. What kind of ignition system are you running?

For the oil leak, did you put any sealant in the crank keyway or on the balancer bolt head/washer?
 
Econoline":39o0qn0j said:
What's your compression and on 87? Dieseling can be caused by having the idle screw set too high and the timing too low. If you can up the timing without pinging you should. And that will bring the idle screw out. As you get into the transition circuit by having the butterfly open to far, fuel and heat cause the engine to diesel. When compression is good this becomes easier to occur, like a diesel, and I suspect modern fuel is more prone to spontaneous combustion and boiling evaporation ect. Is the engine getting hot running? Retarding the timing will raise the engine temperature. What kind of ignition system are you running?

For the oil leak, did you put any sealant in the crank keyway or on the balancer bolt head/washer?
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I tuned the idle using a vacuum gauge, im idling up around 900 - 1000 RPMs, I can't keep it running at 750. SCR is about 9:1, I'm running 89 octane. The engine is running cooler ( I think since I regapped the plugs, if thats possible)

I didn't use any sealant on the bolt or the keyway. the leak starts after the engine is warmed up, but doesn't happen if I just take it around the block. Its either the front pan gasket or the balancer. Once the engine is hot it drips from the bottom of the front lip of the oilpan where it goes around the front main pretty steadily, I just can't see EXACTLY where its coming from. Oil pan gaskets are a pain in the Bronco too, because I've got a front differential in the way...
 
Howdy All:

Hey, another basic question for Slinger- Why won't it idle at say 500 or 600 rpms? What carb are you using?

Dieseling is almost alway caused by the curb idle set too high.

Opening the spark plug gap should not effect how hot your engine runs. too little initial advance could.

Opening the gaps to .045" could very likely reveal other weakness in the ignition system, especially old and/or cracked carbon core spark plug wires. IF you get any misses or miss fires with the gaps wider start checking for electric leaks somewhere in the ignition system.

On the oil leak- bummers. I feel your pain. If it's leaking that much there is no easy fix. Sorry.

Adios, David
 
Howdy Again Slinger:

I just checked back to find that you are using the original Autolite 1100 with LoM distributor with Petronix.

Here's another thought- check carefully for a vacuum leak. A vacuum leak could account for not being able to get the idle down to 500 rpms or so as well as adding to a lean burn condition that could cause the engine to run hot.

How long since the carb has been rebuilt?

Adios, David
 
Hi, as mentioned, the idle is high, which will allow run on. Vacuum leak? What is the vacuum reading at idle? Is it steady? I'm wondering if you could have a valve tightened down a little too much, and a high idle to compensate for that or something else. Does the idle mixture screw have any effect? If the throttle is open too much the mixture screw will not do much. Good luck
 
CZLN6":30aaigjc said:
Howdy Again Slinger:

I just checked back to find that you are using the original Autolite 1100 with LoM distributor with Petronix.

Here's another thought- check carefully for a vacuum leak. A vacuum leak could account for not being able to get the idle down to 500 rpms or so as well as adding to a lean burn condition that could cause the engine to run hot.

How long since the carb has been rebuilt?

Adios, David
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Thanks David, I'll go around with some ether and see if I can find anything. Carb was rebuilt last fall...
 
B RON CO":3t5nakpr said:
Hi, as mentioned, the idle is high, which will allow run on. Vacuum leak? What is the vacuum reading at idle? Is it steady? I'm wondering if you could have a valve tightened down a little too much, and a high idle to compensate for that or something else. Does the idle mixture screw have any effect? If the throttle is open too much the mixture screw will not do much. Good luck
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I may need to adjust a valve, and i put hydraulic lifters in it and am still using the adjustable rocker arm, and set them to light pressure when I first put it back together. Problem is, with all my coolant leaks, and now an oil leak, everytime I get it up to temp I find somehthing else I don't like before I get to the part where I check the rocker arms for tightness. The idle screw is definately making a difference, though.
 
If you have oil on the back of the balancer it's probably not the pan gasket, but more likely the seal in the timing cover and/or the balance is grooved and needs a speedy sleeve or to be replaced. If the oil is on the front of the balancer it is what I referred to above and will only leak at high rpms.
 
Econoline":37g8dh94 said:
If you have oil on the back of the balancer it's probably not the pan gasket, but more likely the seal in the timing cover and/or the balance is grooved and needs a speedy sleeve or to be replaced. If the oil is on the front of the balancer it is what I referred to above and will only leak at high rpms.
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The steady drip leads me to believe it isn't the pan, and it appears behind the balancer running off the top passenger side corner of the pan, which is the direction oil leaking from the timing chain cover seal or keyway would be sling. No oil on front of balancer. New balancer, so maybe it's just the keyway. Guess the best way to tell will be to jerk the radiator and pull the balancer and see what's wet.
 
ledslinger29":2villcq1 said:
I had my plugs gapped at .034, and regapped them to .041 or so after it ran hot and "dieseled" a good bit. I reset my intitial timing to 12 degrees, and it seems to run cooler, and the dieselong is reduced, but it still happens. Could this be the result of a Better burn? Also, I've got all of my coolant leaks resolved, only to find that I have an oil leak as well. I wasn't able to spot it before, because I used Brad penn, and its green. I'm hoping it's the front of the oil pan and not around the balancer....
Click to expand...

You might try using a thick carb base gasket like was used on the mid 70's up engines or you could build a plastic (or hard wood) carb insulator to help the carb from getting too hot. Good luck :nod:
 
The leak wouldn't be from the keyway if it's on the back of the balancer, maybe the seal got damaged installing the balancer or maybe it is the cover gasket.
 
Hi, you can change the seal with the cover on the engine. If it won't pry out you can drill a small hole for a sheet metal screw, twist in a screw and pop the seal off using the screw for leverage. Use a very big socket or just tap the new seal in. Good luck
 
Thanks fellas, I'll be checked mg all this stuff out sometime in the next couple of days, and I'll update here if I figure anything out
 
Been out for a few weeks, hurricanes, work and all that other real life stuff gets in the way. So I've got her idling down around 900, she shudders a bit, but runs. My #6 cylinder was running a lot cooler according to the IR gun, and I reach down and touched the plug wire next to the coil and got woke up a bit, so I've got s new set of wires inbound.
Also found a small leak with ether, where the throttle shaft goes into the side of the 1100. What are my options here?
https://imgur.com/gallery/foPrg
 
Also, just to update, I opened up the plugs to .045 and adjusted the valves with the engine warm, man she's quiet! Now I just have to figure out my oil leak and vacuum leak at the carb. Thanks for the link Bill, hopefully I can do something with that.
 
Well, I've now got her idling down around 800, with new plug wires even with the vacuum leak at the carb. It doesn't stumble anymore, those wires were about fifteen years old. Found my oil leak too, pulled of the balancer and the front of the timing chain cover was dry, put a socket on the oil pan bolts, and I guess I was a little too careful about that cork gasket, the first few up front weren't even snug anymore. Went all the way around the pan tightened them all a bit, and the leak is gone. That't the kind of oil leak I like, operator error. Bill I may be sending that carb to you in the coming months when i put that DSII distributor I got from you in there.
 
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