lovnmy66

I recently picked up a 1966 f-85. It runs ok but it starts to shake when I go over 45mph. Also when it idles it makes a clacking noise in the engine. it has a 400cid 6.6L in it. I am new to v8's does anyone have any ideas on what could be wrong?

jaunty75

The shaking could be many things. Shaking is a vague term. Does the whole car shake, or do you just feel it primarily in the steering wheel? Front of the car, rear, or all over? Shake left and right or up and down like you're going over bumps?

Shaking could be due to worn or loose suspension parts, out of balance wheels, misaligned front wheels, unevenly worn tires, and probably a half-dozen other things.

You say you recently got the car. Have you done any investigating of the problem? If you don't know what to look for, you might want to have the car looked at by a mechanic to make sure you don't have a problem that could compromise the car's safety. You'd hate to have a wheel fall off at 50 mph.

lovnmy66

Ok it shakes like the motot is loose but the motor mounts look ok. Then that clacking noise in the engine worries me too but I guess its best if I do take it to a mechanic.

F-85 4-4-2

Is it an F-85 4-4-2, or did someone replace the 231/330 with a 400?

Rickman48

6.6 liter is a Pontiac term - Pontiac engine??

F-85 4-4-2

61 cubic inches per liter. 6.6 covers B-O-P.

MDchanic

How do you know what a loose motor feels like?

We can do the math, but nobody says "6.6."

- Eric

Tony72Cutlass'S'

I had a friend that used to say 6.6, he claims it's because we're all metric up here.

He's not my friend anymore.. and besides, it was a Trans Am.

oldcutlass

Has the car been sitting? Are the tires old? Bent wheel or tire balance?

Since the car is new to you, was there any history passed down from the previous owner on what was done to the car before you got it? The usual stuff, like brakes, suspension, front end, engine, trans, rear end, etc...?

The noise from your engine is most likely valve train, but can also be other things.

How are your mechanical skills?

Tony72Cutlass'S'

Could it also be possible that this is a drivetrain/driveaxle issue?

I know that when something reaches a reasonant frequency (like if your driveshaft is unbalanced) it can make the whole unit shake.

I could be also completely wrong, but it's worth a thought.

Rickman48

9 responses, and he vanishes - - - - ?????????

Maybe he took it to a mechanic!!!

Tony72Cutlass'S'

Clearly he is actually busy at work.. unlike myself

I sure hope my boss isint on CO, or is he

joe_padavano

The OP never said where he was from, plus he had never owned a V8 before, hence the use of the metric system. By the way, if you go to RockAuto.com and look up a 1966 442, the engine is listed as "6.6L 400cid V8".

Tony72Cutlass'S'

Joe has a point,

But up here in Canada, we still call it the quarter mile, not the 402.3meter..

oldcutlass

It's listed as a 6.6 at a number of sites! Not everyone is as old as.... Oh never mind!

MDchanic

Not to be an annoyingly pedantic nitpicker (oh what the heck, I'll be one, just this once), but...

The 400 engine was never called a 6.6 by Oldsmobile in any of its US literature. Period.
It is true that it is mathematically a 6.6 (actually 5.554), but so what?

The point is that "400" is a name used by Olds to designate a particular engine.
There are plenty of engines out there that are assigned displacement numbers that are different from their actual displacements (like the Chev. 396 that's actually a 402). We don't refer to them by their actual displacements, but rather by their commonly understood names. Calling a '68 Olds 400 a "6.6," when it was never known as such, is just as absurd as calling a '68 Porsche 2.0L a "134."
There are other cases in which using the metric designation would be appropriate, such as in referring to the F-rd 428 of 1965 to '68, which F-rd did, in fact, call the "7 Litre."

If you are describing an engine's displacement in a technical discussion, then, fine, use those darned liter things, but the actual name of the engine is the 400.

Using "6.6" to describe the 1968 and '69 400 engine is like using "2-door notchback" to describe a '70 Cutlass Supreme or "2-door fastback" to describe a '70 Cutlass S - both terms are technically accurate, but they tend to cause confusion when there are other commonly used terms that could be chosen instead.

And as far as parts sellers using liters, their computers generate numeric equivalents to displacements, regardless of whether anyone ever actually used those numbers in referring to those engines. You'll notice that all of the European cars have CID numbers, too - as in my example above, have you ever heard anyone refer to a BMW 318i as a "110," or a Mercedes 4.5 as a "275?"

- Eric

lovnmy66

Ok sorry for the delay. But yes I am new to v8 and I said 6.6 because thats what comes up when I search for parts on this engine. Its the original engine with 37,000 miles on it. Im the 3rd owner one guy had it for 40 years and the last owner had it till about 2Weeks ago. It has been sitting for about a year according to the guy I bought it from. He replaced the carb and battery and the tires are pretty new too. Its factory red with the v8 logos .ive drivin it around a bit today and got up to 65mph with out the shaking it seems to have stopped. My guess is it was just sitting to long. I plan on doing all the routine maintenance this weekend (spark plugs ,oil,fuel filter) and then take it to a mechanich because I also notice that when I accelerate I hear some kind of air blowing out some maybe the carb isn't properly hooked up. My mechanical skills are limited I pretty much learn as I go. Im transitioning from a 73 dodge Dart 225 to this new project. Thanks for all your input it helped me with some ideas.

w31man

I had this problem a few years back, ended up to be a U joint issue. Did the same thing at about 45 mph.

Greg

jaunty75

You could be right. The shaking could have been nothing more than flat spots in the tires that finally got themselves worked out once you had driven the car for a bit.

Do you know how old the tires themselves are? Anything more than about 10 years old, regardless of how much tread is left, should probably be replaced.

Rickman48

Now sounds more like a fouled plug that cleaned-up.

lovnmy66

I called the previous owner and he said the tires were about a year and 2 months old. I also just realized I should defiantly replace the valve cover gaskets because I noticed some oil leaking out of one.

Octania

OK, first off, what engine do you have? And I mean not by rumor or guesswork, but by casting number ID. Find your head casting number or letter, and engine casting number, and get back to us... because an F-85, which would have had "V-8" emblem on the fender, came only with a 330 V8 or perhaps an I6 Chevy or even a V6 back far enough like 1965... but only the 442 models came with a 400 cid engine in 1966. I'm a little rusty on the 1966 models, but doubt that the 442 pkg was available on an F-85 model.

Sure, ck the u-joints and driveshaft, but far and away most speed-specific vibration I have seen has been a BAD TIRE... and make no mistake about it, NEW does NOT equal "perfect". New things can be bad just like old things. Tires included. Tire places with verify balance and rotaional stability of the wheel/tire assemblies for you.

bigin1978

I believe that in 1966 the 442 was a cutlass/f85 option like 1972. It does sound like it is a 330 car with the v-8 emblem.