Rough idle turned to crank then ka-thunk

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Slanty's have timing chains. They actually use the same chain and crank sprocket as the big blocks (cam sprocket is different). The factory cam sprocket had nylon coated teeth. Most aftermarket replacement sprockets were not nylon. The heavy duty slants in some model trucks had double roller timing sets from the factory. If the nylon teeth on the cam sprocket becomes excessively worn, the chain can jump and change the cam and ignition timing.
Also as stated the nylon distributer gear can break, also.
PS: Just a FYI. If the timing chain breaks or jumps on a 225 engine, not likely to cause any other damage. However if the chain breaks or jumps on a 170 engine serious valve damage can occur. The 170 is an "interference" engine, whereas the 225 engine is not.
 
AJ/FormS said:
I read the OP which states prior troubles.
However, my post, as stated, is
"What if."

And I said nothing about "rings not being expanded, and not creating compression due to gaps." That must be your interpretation.
The missing oil I am talking about, is to be
1) firstly, on the ring lands, sealing the rings to the pistons. and
2) secondly, on the cylinder walls, left there by oil-ring design, for the specific purposes of sealing the rings to the cylinder walls and
3) lubricating the working edges so the daym things last 100,000 miles.
4) the gaps are nearly meaningless in this grand scheme of things.
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Thank you for clarification
 
Charrlie_S said:
Slanty's have timing chains. They actually use the same chain and crank sprocket as the big blocks (cam sprocket is different). The factory cam sprocket had nylon coated teeth. Most aftermarket replacement sprockets were not nylon. The heavy duty slants in some model trucks had double roller timing sets from the factory. If the nylon teeth on the cam sprocket becomes excessively worn, the chain can jump and change the cam and ignition timing.
Also as stated the nylon distributer gear can break, also.
PS: Just a FYI. If the timing chain breaks or jumps on a 225 engine, not likely to cause any other damage. However if the chain breaks or jumps on a 170 engine serious valve damage can occur. The 170 is an "interference" engine, whereas the 225 engine is not.
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Thank you for that knowledge that will probably help
 
71drtswnger said:
Thank you for clarification
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No problem, and now I should add that;
1) If the cylinders are devoid of oil, and the throttle is closed during cranking, then the engine will not be able to "suck in" hardly any air at all, and if air is not going thru the venturi, then neither will fuel be.
2) in order for the engine to burn fuel, it has to first be atomized, and there has to be a percentage of it existing as a vapor, to even get it started. Therefore, a fuel that has laid on the plenum floor, for any length of time, all the volatile compounds have boiled into the atmosphere, and the heavy gas left over, while being combustible, is not at all eager to start on fire, even with heat of compression, if you have any, added in.
Once again; I cannot say if this is your problem, but a compression test will prove the concept.
 
Alright sounds like it'll be easy to do


AJ/FormS said:
No problem, and now I should add that;
1) If the cylinders are devoid of oil, and the throttle is closed during cranking, then the engine will not be able to "suck in" hardly any air at all, and if air is not going thru the venturi, then neither will fuel be.
2) in order for the engine to burn fuel, it has to first be atomized, and there has to be a percentage of it existing as a vapor, to even get it started. Therefore, a fuel that has laid on the plenum floor, for any length of time, all the volatile compounds have boiled into the atmosphere, and the heavy gas left over, while being combustible, is not at all eager to start on fire, even with heat of compression, if you have any, added in.
Once again; I cannot say if this is your problem, but a compression test will prove the concept.
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67Dart273 said:
Looks to me like it's time to pull the dist and inspect the drive gear. If that is OK time to evaluate the cam timing

Any idea of the miles on the engine or work that has been done?
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I have pulled the dist and the teath are all there but have a good bit of were in a section to me it looks like a replacement scenario but I'm not sure

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Could it be possible that you have plug wires that are arcing to one another or to ground? I know it's apples to oranges but I had a 4.0 Jeep that was arcing to ground but only at idle. Kept getting rough idle so checked it one night and could see where the fire was jumping to ground.
 
AJ/FormS said:
I thought slantys did not have chains
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What? So all the stories about you having a slant 6 that got 30 plus MPG going uphill in a headwind while pulling a trailer full of fat women was BS? Surely someone of your magnitude who's claimed to have a slant 6 before would know they have a chain. Unless of course all your babbling is just a bunch of BS. I'm leanin "THAT" way.
 
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