Strange noise from car....

[Davea Lux]

Went out to check the distributor vacuum assist, pulled the hose off the carb and tried to create some suction by using my mouth... sorry no vacuum gun yet. There was no vacuum created. I can blow air straight through it, so I guess thats not working either.... But as I was taking off the distributor cap, I found 2 loose wires that fell off. I reconnected them as was hoping that was the problem. Nope, but it does have a lot more power now. Guess i was running on only 6 cylinders. This car is so low, its new to me by the way, I can't really get under it to see very well. Ill have to put it on jacks to be able to see anything underneath it. I took it out for a quick drive and recorded the sound. Definitely seems to be more in the rear of the car area, like under the back seat. trying to upload the video to youtube now...

There should not be much vacuum created at idle to the vacuum advance if you have the vacuum advance hooked to the proper port. You should should not be able to blow air thru the diaphragm for the vacuum advance. If it does not hold pressure, it needs to be replaced.

Dave

 

[rkrochen]

Sure sounds like engine ping. Noises do carry in cars so sometimes it is hard to diagnose.
Could also possibly be a u-joint rattling under load. Easy to check take the driveshaft off and check to see if they move freely and or are loose. Look for rust at the cup.
On the vacuum advance hook up your timing light lwith the vacuum advance disconnected. Run the engine at a higher idle and check the timing. Reconnect the vacuum advance and run at the same speed you should see a difference. Sounds like the mechanical advance is working though.

 

[Davea Lux]

Hearing the noise, it sounds like the timing is too far advanced. You should be running a premium grade of fuel in this engine as it is still a high compression engine. If you are already running premium fuel, try reducing the base timing by about 7 degrees and see how it sounds. If the noise goes away, you now know it was timing related. You can try re-advancing the timing in two degree increments to see at what point the engine starts to ping again and drop it back to where it stops pinging.

Dave

 

[Big_John]

Sounds like spark knock to me.

First question... What gas are you running?

Second question... Is car running hot?

 

[kenfyoozed]

Not running hot that i know of but i am having a heat soak issue with the carb, so I may just be on the edge of running hot.

I am not running premium fuel, Next tank I will try that and see.

The diagram on the distributer is not holding any pressure. I assume i can buy just that part?

 

[Matt Gallant]

As suggested though, it would still be an idea to check your u-joints. If there's no vibration under load or de-acceleration, then the u-joint might not be done, but if there is vibration, address that asap, I neglected to do so and snapped my extension housing open

 

[Big_John]

I am not running premium fuel, Next tank I will try that and see.

Yep, you have to run premium fuel in that car. That is your problem.

The diagram on the distributer is not holding any pressure. I assume i can buy just that part?

Yes, but it should hold a vacuum, not pressure. It can be replaced, but for now, just plug the line from the carb so you don't have a vacuum leak. Don't worry about it right now. We can circle back around... One problem at a time... It will run just fine without it for now.

 

[kenfyoozed]

Well I found 2 plug wires loose at the distributor. After hooking those up I could tell there was more power from the engine and the sound now is only about .25-50% of what it was. So could the rattle I heard could have been two pistons rattling, or dragging around? And if so and the noise is less now but still there could I have another? Should I do a compression test on each syslinder followed by a spark test to confirm spark at each cylinder?

 

[67Monaco]

could have been wristpin knock but it definitely sounded like pre-ignition (spark knock).

 

[kenfyoozed]

I also rebuilt the carb today. It was very dirty. I adjusted the IMS by using the best lean idle method from Edelbrock. Car seems to run better now. IMS are now set a little richer than they were before the cleaning.

 

[live4theking]

How's it drive?

 

[kenfyoozed]

Drives great otherwise....

 

[MarPar]

Just kidding. I agree with Big John, use premium fuel.