ddunmore81

So here is an overview of my issue. I had my 1970 350 cutlass motor rebuilt last fall and everything has been running great until this summer. Keep in mind I live in Houston and ITS SUPER HOT!..... So 2 weeks my idle was running high, I had a light vibration in the gas pedal and steering wheel also the timing seem off so I had my carb and timing adjusted for the summer but the issues did not get better.

Now to the rattling noise I have heard the rattling noise in the winter a few times but now it seems worse. Once the car gets warmed up to 190 and the oil gets hot I hear the rattle when throttling my mechanic said it is the gas and I should use premium. I have about a half of tank left too burn off before I can give that a go. So my 1st question is what kind of gas do you guys use?

The next issue is the vibrating pedal and steering wheel. Just to eliminate a exhaust leak I just replaced the the most of the exhaust pipe, muffler and tail pipe today. I feel the vibration when turning the most although it does vibrate when driving from stop to acceleration. Once I take my foot off the gas the vibration stops. Please take into account I don't drive the car hard at all. So even when I ease on the gas I feel the vibration. Question 2 is could the gas be cause the vibration? FYI while the car is cold the gas does not rattle.

I will add that I have 4 new tires and have had an alignment done when I bought them 2 months ago. The shop has pulled each spark plug, checked the distributor (which is new) adjusted the timing, checked the motor mounts as well, checked the oil pressure, Changed the oil to 10w30 , checked the drive shaft.

I'm out of ideas of what it could be.

Fun71

I run premium, which here in Phoenix is 91 octane (10% ethanol).

You can top off your tank with premium and it will mix with your current gas and raise the octane. Don't drive around trying to burn off the low octane gas before you fill up with premium.

Not likely. It may be something in the driveline, such as a bad u-joint. Does it happen only when you are accelerating? What happens if you put the transmission in neutral and coast?

Well, it's all relative. I grew up and lived on the Texas/Louisiana Gulf Coast for 30+ years and it never go this hot back there.

ddunmore81

[QUOTE=Fun71;1097554]I run premium, which here in Phoenix is 91 octane (10% ethanol).

You can top off your tank with premium and it will mix with your current gas and raise the octane. Don't drive around trying to burn off the low octane gas before you fill up with premium.

Not likely. It may be something in the driveline, such as a bad u-joint. Does it happen only when you are accelerating? What happens if you put the transmission in neutral and coast?

Well, it's all relative. I grew up and lived on the Texas/Louisiana Gulf Coast for 30+ years and it never go this hot back there.


Will do on the gas issue. I just went to check and my passenger side tie rod has some slight play. It always made a popping noise when reversing but I never investigated it until now. I'm supposed to take a ride with the mechanic tomorrow so they can actually see what I mean when I say it's vibrating on acceleration. Hopefully its just the damn tie rod.

lunaboy

"Once I take my foot off the gas the vibration stops"


Did you chk the motor and trans mounts?

ddunmore81

Brand new motor mounts and yes we checked those again. We'll take a look at the trans tomorrow.

oldolds88

. It always made a popping noise when reverse
Once I take my foot off the gas the vibration stops.


my guess is u joint or trans mount

oldcutlass

If you have a posi is there enough additive in the rear? For the pinging, are you running an HEI or points? What are your timing settings with and without vacuum advance?

ddunmore81

Not sure what you mean on the 1st question. The 2nd question is HEI.

oldcutlass

Posi additive, its a special lubricant you add to keep the clutches from sticking and chattering during turns.

Disconnect and plug the vacuum line to your vacuum advance on the distributor, drive it and see if the pinging goes away. With an HEI you cannot use the stock timing settings so if your running too much initial timing, then add the mechanical, and the vacuum advance it may be too much for the engine to tolerate. In addition you can compound the issue if your compression requires higher octane fuel.

BSiegPaint

I'm with everyone on the u-joint as a possibility on the vibration. I had a similar issue with my Corvette that turned out to be an unbalanced driveshaft. One of the little counterweights had broken/rusted off and it started vibrating out of nowhere. A dent from a thrown rock or road hazard can throw things off. Worth a look.

ddunmore81

It was the u-joints. They were the original ujoints from 1970 and had no grease in them. Thanks guys.