1967 383 issues

[GJS]

Hi all, I was recently looking at some running videos of my 67 Monaco 500 which is still down in Texas and I thought I'd try and get a jump on some of the issues I noticed.

In the footage taken at the rear of the car near the exhaust you can clearly hear a backfire/pop at random intervals. At first I thought it might be a toast valve but I'd think that the pop would occurr regularly in the cycle of that were the case.

Being that there is no backfire trough the carb, is it possible that the timing chain has enough slop that exhaust valves are opening before the fuel in the chamber has completely burnt off?

The motor has a tad over 100,000 on it and to my knowledge has never had anything done other than hardened valve seats and valves. .. I suppose that this could be a result of crappy work right there but again, it's the irregularity of the backfire that gets me.

Anyway, here's a link to the running video. Join my obsessive preparedness if that's your thing and thanks in advance.

Round back shot starts around 1:59 for the impatient.

 

[tracktor]

I see the power steering cover off is it leaking possibly soaking the plug wire causing a misfire?

 

[traintech55]

With well over 100,000 miles on the engine you could have a stretched timing chain. Most auto makers used a plastic coated cam gear back then. I would do a compression test on it first when you get it home and take it from there.

 

[69monaco]

I see the power steering cover off is it leaking possibly soaking the plug wire causing a misfire?

No , in the beginning it was on......
It runs very hard stationar ..!?
And it could use a new air cleaner filter.........

 

[GJS]

No , in the beginning it was on......
It runs very hard stationar ..!?
And it could use a new air cleaner filter.........

Indeed!

 

[GJS]

With well over 100,000 miles on the engine you could have a stretched timing chain. Most auto makers used a plastic coated cam gear back then. I would do a compression test on it first when you get it home and take it from there.

There was a similar issue with my 440 when I did it, tho far less pronounced. I never ran a test on it as I was tearing it down anyway... kinda wish I'd looked into it now!
Anyway, I'm hoping to get the summer and next out of the drivetrain in its current form. After that, I'll pull everything and overhaul.
Thanks for the tip!

 

[Mopars & Missiles]

Could be a lean fuel mixture causing the backfire, pop condition.

 

[GJS]

Could be a lean fuel mixture causing the backfire, pop condition.

Also pretty sure the fuel was bad...

 

[Welder guy]

I would start with fresh gas then new distributor cap and rotor there cheap. If you still have a problem new plugs and wires. Then a fresh case of beer.

 

[GJS]

I would start with fresh gas then new distributor cap and rotor there cheap. If you still have a problem new plugs and wires. Then a fresh case of beer.

Agreed. I can't even get a timing light on it so it could be retarded to hell for all I know.
I already have everything for an ignition overhaul, coil to plugs ... bring on the car and the libations.

 

[Welder guy]

#7 spark plug and wire was the problem child on my 383. It's the hardest plug and wire to change. Drivers side farthest back on the motor. I had to lift the car on my hoist and get it from underneath the car. That's where the beer comes into play.

 

[GJS]

#7 spark plug and wire was the problem child on my 383. It's the hardest plug and wire to change. Drivers side farthest back on the motor. I had to lift the car on my hoist and get it from underneath the car. That's where the beer comes into play.

No lift in my garage. In fact, no garage.

What was #7's issue? Heat?

 

[Polara_500]

#7 is just to the rear of the exhaust outlet and pretty close to it with the heat shield, then you have to maneuver around the brake booster and steering column/coupler, so it's just a wee bit challenging.

 

[GJS]

#7 is just to the rear of the exhaust outlet and pretty close to it with the heat shield, then you have to maneuver around the brake booster and steering column/coupler, so it's just a wee bit challenging.

I remember spouting quite a few expletives to #7 back in the day.

 

[commando1]

Looooooove removing and reinstalling the left manifold.
And with the heat shields.
And with a dual diaphragm brake booster.
Cruise control digging into your chest.




In the snow..,

 

[Welder guy]

No lift in my garage. In fact, no garage.

What was #7's issue? Heat?

Well I'm gonna say bad luck. I changed plugs and that plug was bad. Installed another one then the plug boot started to act up on the plug. Installed a new boot on the wire and it was all good. It's the hardest plug on my car to get to on my car. I have to get at it from under the car.

 

[traintech55]

Well I'm gonna say bad luck. I changed plugs and that plug was bad. Installed another one then the plug boot started to act up on the plug. Installed a new boot on the wire and it was all good. It's the hardest plug on my car to get to on my car. I have to get at it from under the car.

Welcome to the world of big block "C" bodies.