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65 Skylark find won't start


Newbuickguy

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My name is Max and I really need some help diagnosing a 65 Skylark I found. It is in great shape with 39k miles, 310 ci, 2 barrel Rochester carb, auto transmission with a console. Had been "sitting" for about three years with only quick starts and very short garage moves during those years. Started work on the car three days ago. The Skylark started hard but ran smoothly for at least 30 minutes after that. Got 10 gallons of new gas and added lead substitute. Then the heater core dumped all over the carpet. It was replaced yesterday. Started again and ran for 15 minutes. Everything is looking good - no leaks. It runs perfectly. Pulled out of the garage and it died while idling. It started again and ran for two seconds then died again. Now it just turns over. We guessed float issues so tapped the carb. Now it won't fire at all. We've got spark to the plugs, we have good fresh gas squirting from the jets, all butterflies are moving smoothly, we have compression, changed the coil and condenser, we have a good battery that will spin it, (once in a while it will fire.) The tops of the cylinders are gas covered and the plugs are dry when we pulled them. So, we have spark, gas and compression. It won't respond to starting fluid. We have even watched the plugs fire when hooked up and out of the block. It has been airing out so it isn't flooded. Let it sit for three hours- still nothing but a spinning engine that won't fire. What are we overlooking? I'm ready to change the carb because it seems like an air or gas issue. Also, when testing the plugs, the spark is weak but there - you can see it. Maybe timing? Maybe air leak at carb? Maybe weak spark? We've got pressure at the gas line into the carb and the gas looks normal we put in a cup. Any suggestions appreciated. 

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It won't start on starting fluid, you confirmed spark, check for a vacuum leak, broken supply to the brake booster, It would have to be something causing a lot of air to be pulled in, An old vacuum hose could have cracked and split under load from the few times starting and running. The starting and stalling could be many things on a car that was dormant for years, but the starting fluid test would and should  narrow it down as to spark or fuel

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I had another thought. A weak point on these engines is the timing gear set if still original. The cam gear originally was coated ( for noise) with a phonetic (plastic) coating.  Over the years the  coating breaks up and falls off making timing impossible. Replacement timing sets don't have the coating so a one time replacement is all that is needed. To check this see how much slop there is when rotating the crank before the rotor moves.

 

Another long shot is the ignition lead. It is a connection atop the engine side of the fuse box where the engine wiring harness plugs in. If memory serves, it is either a red wire or orange wire. There is a small screw holding the connection together. If loose or dirty it could cause intermittent stalling issues but you wouldn't have any spark if it isn't connecting.

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this is a tough one- not sure if i would change the carb yet, if its squirting in gas it should fire maybe would run poorly

 

i would double check points- are they dirty- correct gap-check with dwell meter if possible, and focus on maybe a weak spark or timing issue- check timing- any way the spark plug wires could have got crossed after it was running and died-

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3 hours ago, ol' yeller said:

I had another thought. A weak point on these engines is the timing gear set if still original. The cam gear originally was coated ( for noise) with a phonetic (plastic) coating.  Over the years the  coating breaks up and falls off making timing impossible. Replacement timing sets don't have the coating so a one time replacement is all that is needed. To check this see how much slop there is when rotating the crank before the rotor moves.

 

Another long shot is the ignition lead. It is a connection atop the engine side of the fuse box where the engine wiring harness plugs in. If memory serves, it is either a red wire or orange wire. There is a small screw holding the connection together. If loose or dirty it could cause intermittent stalling issues but you wouldn't have any spark if it isn't connecting.

 After reading the authors coverage and what he did it seemed like the basics were being covered so like you the timing chain jump came to mind too. Just a FYI on the nylon coated aluminum gear : The coated gear had nothing to do with sound reductions, but rather cam harmonic's. I didn't realize until yesterday that the high performance FE 427 425hp Fords came with nylon gears too.  

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Well can just pull the distributer cap and see if the rotor is turning smoothly. Lose a timing gear and it won't. Said there was fire at the spark plug but did you check dwell ? GM distibuters of that period were deigned to be able to set dwell with the engine running.

 

However if you have fire and fuel than the only thing left are mechanical problems. Seems like if you lost a timing gear you would feel blowback through the carb.

 

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It could be something as simple as a weak spark due to a bad coil. Remember it was stalling out after a good run bringing it up to temperature, and not restarting. Maybe that component  just flat out failed. 

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First eliminate everything you thought worked and start over from ground zero. "It Ain’t What People Don’t Know that Gets Them into Trouble; It’s What They Know That Ain’t So "

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Check plug wires. Coil wire.

I have had spark plugs that would fire on the block but not under compression.

By the way, what is the compression?

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Do a compression check - in fact do two of them:

 

First check compression on dry cylinders - all of them - with the spark plugs out of all, and record each cylinder

 

Then go back, and one at a time, add a tablespoon or three of oil to each cylinder - one at a time - and record each compression

 

1. a notable increase in compression after adding the oil will indicate worn or broken piston rings

2. A very low reading on a particular cylinder can indicate stuck valves or broken pushrods

3. Low readings between a pair of cylinders could indicate a bad headgasket  (or possible cracks in head or block - less likely)

 

Get an older copy of a MOTORS MANUAL

Get a Vacuum Gauge 

Read the pages which show you how to diagnose a multitude of problems from how the Vacuum Gauge reads or fluctuates - this is a gem of a way to diagnose, but too long to list here

 

Actually, I found you a video which shows this: 

 

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5 hours ago, padgett said:

For those too young for vacuum gauges. MAT on a scan tool is the same as manifold vacuum just may be metric.

 

..... are you calling me "old" just because I am?

Maybe I was raised in a vacuum?

 

sorry, just couldn't resist

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If the car ran originally and now doesn't, it is unlikely that the compression changed that quickly.  Yeah, it's possible that a valve stuck, but it would still run roughly on seven.  The OP has apparently checked all the most likely causes (spark and fuel), so timing chain would also be my next guess.  A chain that skipped teeth due to a worn cam gear will STILL spin the distributor, however, so simply looking for the rotor to be turning isn't a sufficient test.  The best thing to do is to put a timing light on the engine and check the timing while cranking.  Yes, the engine doesn't need to be running to check the timing, just turning over.   If the timing is close to correct, the chain isn't the problem  If it's way off, start pulling the front cover.

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I owned one years ago. I had 2 failures that were similar to yours.

One: GM had a plastic toothed cam timing gear that would fail. The engine stopped suddenly and obviously wouldnt start. Fortunately, that engine will not eat valves when this happens.

Two: instant coil failure.

 

My 2 ¢ worth

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On ‎4‎/‎21‎/‎2016 at 1:23 PM, helfen said:

 After reading the authors coverage and what he did it seemed like the basics were being covered so like you the timing chain jump came to mind too. Just a FYI on the nylon coated aluminum gear : The coated gear had nothing to do with sound reductions, but rather cam harmonic's. I didn't realize until yesterday that the high performance FE 427 425hp Fords came with nylon gears too.  

I forgot to mention that these chains can jump for a couple of reasons. One chain stretch and nylon gear coating breaking off. Sometimes you can't tell what happened because when a chain jumps it can break off parts of the nylon coating.

 Replacing a chain and sprocket is not the only remedy or fix to cars that have these nylon coated gears. There have been many mechanics or owner mechanics burned on these jobs because they never took the engine oil pan down to remove this plastic debris which gets stuck in the oil intake.

Another FYI, stick shift cars have a sooner failure rate than automatic's in both chain stretch and coated gear failure.

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OK, the old timey method is to use a VOM (I use a DMM now) and connect across the points. They should open just before TDC and can check the rotor to see which cyl the rotor is on (should be 1 or 6 - firing order of a 300 is 18436572).

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