Ok, first post but have been learning from this forum for years. thank you all!

issue: very original 1970 L46 manual engine died and failed to start 300 miles into a road trip.

trouble shooting thus far: Fuel: fresh full gas tank, new carb filter, good gas squirt in carb, tried starting fluid with no luck. It’s doesn’t seem to be fuel related. Ignition: I am getting spark to the plug but it does seem week. coil looked suspicious (oil leak), replaced it once with no improvement but was so convinced that was the problem tried 3 more coils with various price points. All ohmed correct, none fixed the issue. Replaced points, condenser, cap, rotor, and set proper gap and retimed it all. Ran great for 10 minutes, then died with no restart. Voltage going to coil is slightly low, 6.4 volts with key on, 11.9 volts while cranking. Tried jumping a wire from battery strait to positive coil but that actually made it worse. No spark at plug when doing that. New spark plugs. Old ones not terrible but showed blow by, engine is original with 150k miles. Tried to start it after it sat for a month. Started great, ran for 1 min then died with no restart. New coil to distributor wire, no improvement. Checked grounds engine to chassis, chassis to battery. All good.

recent work prior to roadtrip: replaced wiper motor. Installed a relay on the bright headlight circuit because the amp draw was overwhelming the cheap (but expensive) replacement headlight switch.

any advice would be appreciated.

 

Hmmm.... I would have suspected the coil also. It is curious that it does not start with starter fluid? What does that mean? Does it start and die? Or not even start? Depending on that response----
What I would check next is the "sock" inside the tank. Since it ran for a minute this could be plugging up? If it is a 1970 then I suspect it's like my 68 with a big hole on top.... and the top section is removable so you should be able to look in there and see the sock.... and change it if necessary.
Other than that, not that I can even imagine how, I would disconnect that recently installed/modified headlight relay..... just for ***** and grins....

 

The car currently cranks strong with a small (very small) moment every 5 seconds or so where it’s appears to be trying to catch and run. Spraying starting fluid into the carb during this does not change anything. It does not catch or run any more. I can also see fuel squirting when I rotate the throttle as well. I will disconnect the new headlight relay just to eliminate that possibility but I agree with your assessment that it’s probably not the culprit. I also don’t suspect the sock because I checked fuel flow from the pump when I disconnected the fuel line to replace the carb filter. It was strong but I know things can change and debris can clog things during operation.

 

Has the timing slipped because the bolt holding the distributer is not tight. Is it possible that the timing chain has slipped because the top nylon gear stripped? One hundred and fifty K is a lot of miles. Jerry

 

Well crap. Just researched nylon timing gears. Had no idea. It acts 100% like a timing slip. And that would explain why it ran briefly after I retimed it. I will dig into tonight and report back. Also, bolt on the distributor is tight.

 

150k is a good run. Good idea about the plastic timing gears. Consider it a good thing and a positive to replace the timing gears.... and while you're at it since you'll probably drop the oil pan replace that distributor drive shaft with agood steel one also. Fairly inexpensive too......

 

This is an easy test: pull the distributor cap so you can see the rotor, then pull all of the spark plugs. Using a long arm on a socket (11/16"?) rotate the engine clockwise from the front until the rotor moves. Now rotate counterclockwise while watching the rotor. If the timing chain is OK, it should move within a couple degrees of rotation. If more than that the chain/gear slop is excessive. To appease the data driven, you can align the timing mark at the furthest tab mark on CW rotation and then note where the mark ends up once the rotor begins turning on the CCW rotation.

My '67's timing mark showed something on the order of 16° slop with its original chain.

I believe you are referring to the plastic coupler, yes?

 

I added a picture to my post above.... replaces the "OE plastic sleeve"

 

I opened her up and found the nylon gear in a sorry state. Multiple missing teeth and the rest very rough. Obviously this needs fixed but I’m still confused as to how the dang thing would run for a minute after setting for a while. But we’ll get this fixed right and see how it goes. Thank you all for your advice and help!

 

martyg55
I pondered that also and I figure that it just happened to slip into the "appropriate" position to let it start...... then it once it started then it started slipping again until it got out of whack.... and then died.

 

Take a picture of the timing chain and gears with the crank dot in the 12 o'clock position and see if it did indeed jump time......this is a good catch, but I don't believe this is your problem.....

Jebby

 

Based on the picture you provided and the current location of the crankshaft timing gear mark and the camshaft timing gear dowel pin your engine has jumped timing. Appears to almost 180 degrees out of timing.

 

Now I see it....the cam dowel pin is on the wrong side........yes, way out....bottom dot on gear just visible on bottom left of photo.....

Jebby

 

With that much out of whack, isn't there some potential for valve train damage?

 

I would like to see head-on pic of the the top and bottom gear.
Bottom gear dot must be at 12 oclock.
Top gear could either be at 12 or 6 oclock, depending if BDC or TDC.
Could still be OK in that bad pic.

Try pulling on the chain and verify that you can slip it to the next gear tooth.

I had a Pontiac that ran weird but ran, was off by several teeth. Nylon gears.

 

At work now but searching my phone this is the most likely one to give you the view you requested. Bottom gear dot is at 12 o’clock. I’m not sure what the mark is for the top gear, but if it’s the reverse notch part it’s pretty close to 12 o’clock. Maybe one or two teeth off. FYI, the #1 piston is TDC on compression.

Apologies for the angle and quality of photo

 

A little hard to say, but that looks lined up to me. For TDC.

With the cam gear at 12 oclock, and the crank gear at 12 oclock, and the cam dowel at 9 oclock, you are at #1 TDC firing stroke and lined up.

The Dot to Dot version is just for ease of cam installation and actually happens at TDC #1 exhaust open. #6 Is actually at TDC firing stroke.

When you line up the dots on the timing gears12 oclock crank gear and 6 oclock cam gear, this puts the cam dowel at 3 oclock and #6 TDC firing stroke.

 

1 or 2 ? You are about 25 teeth off

My brain was stuck on the #6 dot to dot position.

 

Nope...that is on the money......I had the cam dowel pin position flip flopped in my head......
Anyway....it needs one so .....

Jebby