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Timing Chain?
https://slantsix.org/forum/viewtopic.php?t=50078		 Page 1 of 1
Author:  Purple Valiant [ Sun Oct 14, 2012 4:43 pm ]
Post subject:  Timing Chain?
This is my second week with a Slant. I admit to limited knowledge of this motor but, all ignition parts are new or good and I can't get it to idle. It idles okay at startup but horribly rough when warm and it takes a tic for the engine to respond to throttle and even then, pretty gutless. The water pump looks like it has never been touched so I am just 'assuming' the timing chain cover has never been off.

So, am I freaking out and it could be a vacuum leak or something just as simple?

Thanks ahead of time
Author:  sandy in BC [ Sun Oct 14, 2012 4:50 pm ]
Post subject: 
Do a tuneup and adjust the valves.
Author:  Purple Valiant [ Sun Oct 14, 2012 6:37 pm ]
Post subject: 
Quote:
Do a tuneup and adjust the valves.
Thanks. I just did a tune-up. Timing mark jumps around a bit.
Will do the valves tomorrow and report back.
Author:  Slanted Opinion [ Mon Oct 15, 2012 11:34 am ]
Post subject: 
While you're there tighten the nuts that hold the carb to the manifold. It's a common source of vacuum leaks. Beyond those things it's time to do some methodical troubleshooting.
Author:  Doc [ Mon Oct 15, 2012 11:39 am ]
Post subject: 
Is it a Holley or Carter carb?
DD
Author:  Purple Valiant [ Tue Oct 16, 2012 7:47 am ]
Post subject: 
Quote:
Is it a Holley or Carter carb?
DD
Carter.

The valves were close enough and no indication of a cam lobe problem. I think the safest course of action is to yank the engine to give it "the once over" and rebuild the carb. Argh.

thanks guys
Author:  Jeb [ Tue Oct 16, 2012 8:30 am ]
Post subject: 
Unless it's smoking, knocking, has low oil pressure, or gives really bad compression test readings there is no reason to snatch your engine out. It's probably something simple.

Done a compression test yet?
Author:  Purple Valiant [ Tue Oct 16, 2012 2:03 pm ]
Post subject: 
Quote:
Unless it's smoking, knocking, has low oil pressure, or gives really bad compression test readings there is no reason to snatch your engine out. It's probably something simple.

Done a compression test yet?
I haven't, no. The plugs look great and it doesn't burn oil but, I know I should. I don't remember who I lent my tester to at the moment.

It has what sounds like a rod knock at low idle but deeper - more of a thump that cycles as the timing catches up to itself. It sounds like it's coming from the bottom end.

My thought in yanking the motor is ease of pulling the pan, oil pump and front covers. The kid I bought this car from had it for 6 years - the last 4 of which it sat unfired. He had no idea what I was talking about and apparently never laid a wrench on it. Just superficial stuff.

I would love if it was something simple. Not a rod bearing and timing chain and believe me, I don't relish the idea of pulling the motor.

In the meanwhile, I will order the carb kit and put out an APB for my compression tester.
Author:  SlantSixDan [ Tue Oct 16, 2012 4:15 pm ]
Post subject: 
Welcome on the board. Water pump does not tell us anything about timing cover. Timing does not "catch up to itself" while engine is running. Check for timing chain slack with engine not running: Pop off the distributor cap and, using the belt and fan blade, manually rotate the engine in one direction until you see the distributor rotor begin to turn, then see how far you can manually rotate it the other direction before the distributor rotor starts turning. Use the timing marks as a guide/gauge to how many degrees the crank turns before the distributor moves. If there is more than a degree or two of perceptible lag, the T-chain is slack and/or the cam sprocket is worn.

If timing is bouncing around despite no substantial T-chain slack, suspect problems with distributor. Still with breaker points, or converted to electronic yet?

Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Give some thought to condition of exhaust system (severe restriction will make engine run poorly even at idle). More esoteric causes include cracks in the intake manifold floor that allow exhaust into the intake tract.
Author:  hantayo13 [ Tue Oct 16, 2012 4:58 pm ]
Post subject: 
stuck EGR valve if it has one..... take exhast apart at manifold ,if exhast plugged will run better once opened
Author:  Purple Valiant [ Wed Oct 17, 2012 5:57 am ]
Post subject: 
Quote:
Welcome on the board. Water pump does not tell us anything about timing cover. Timing does not "catch up to itself" while engine is running.
It may not tell "us" anything but in my garage both these things happen.
As the motor slows down from rev and timing chain slack goes from the pull side to the push side there is a nano second when the distributor shaft is caught with no force driving -as is anything else that depends on the cam for operation- but the crank keeps moving. Once the slack is back on the pull side it has "caught up to itself".
Maybe you could put up a page of Dans Acceptable Terminology. :D
Quote:
If there is more than a degree or two of perceptible lag, the T-chain is slack and/or the cam sprocket is worn.
There is lag there. Most certainly more than the .125 you suggest.
Quote:
If timing is bouncing around despite no substantial T-chain slack, suspect problems with distributor. Still with breaker points, or converted to electronic yet?
Pertronix conversion.
Quote:
Give some thought to condition of exhaust system (severe restriction will make engine run poorly even at idle). More esoteric causes include cracks in the intake manifold floor that allow exhaust into the intake tract.
Headers and DualFlo dual exhaust.
I will check the head once the motor is out.
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