WOT the heck?

Avout

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So I have this weird problem. From one day to the next, without anything touched or changed, my car likes to go WOT when I pull out of a standstill. This is quite scary if you're gently attempting to drive out of a parking stall or at a crosswalk, not to mention the looks of dismay as the 383 is getting to work full blast with squealing tires. It seems to stay in WOT until 2nd gear, where it drops back down by itself to whatever the accelerator pedal is at. I checked all the linkages, pedal and springs. Nothing seems stuck, loose, broken, binding, sticking or what have you. I disconnected the kickdown linkage to see if maybe something was affecting the throttle linkage, but it made no difference.

This only happens if I come from a standstill. As soon as I go 10-20mph, I can't replicate it.

It's not doing it in reverse either.

For years it was fine, until from one day to the next, it decided to act up this way

Chrysler '66 300. Engine is a 383, pretty much stock, aside from edelbrock 383 intake and Edelbrock 1406 carburetor, with the factory transmission.

Maybe someone has a few pointers for me to look at?

All help is greatly appreciated
 

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Check the engine mount on the drivers side. It may be broken causing this.
 

thethee

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Okay consensus seems to be a broken mount, but please, educate me on how does a broken mount cause this?
 

Avout

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Thanks for the quick reply guys. I'm by no means a motor mount guru, but I stepped out and checked the mounts, and they appear to be fine. I revved the engine a few times in Park while looking at the driver's side mount. While the engine does move slightly when I rev it, nothing seems to really move more than normal. Bolt in mount doesn't move, bracket stays in place and mount is attached to engine. These mounts were replaced about 10 years ago, and maybe have 10k on them. Could you recommend any other areas to check, or did I miss something else?

Thanks again
 

57fury440

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Make sure the shaft on the carb. is not sticking. Look again at the linkage and try moving it with the engine off to see if anything is getting caught. Try raising the idle a little and put it in drive without touching the pedal and see what it does.
 

Justin Plant

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The engine raises up as its tries to get the car moving, in turn pulling the throttle shaft or cable and opening the throttle up along with it. With the car moving down the road the engine doesn't work as hard so it doesn't come up as far, no WOT. Cars with mechanical linkage vs cables tend to suffer this more.
 

Justin Plant

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Have some one hold the brake pedal and tap the gas with the car in gear ( do not stand in front of the car ) if the mount is broke that engine will look like it's trying to jump out of the engine bay.
 

57fury440

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The engine raises up as its tries to get the car moving, in turn pulling the throttle shaft or cable and opening the throttle up along with it. With the car moving down the road the engine doesn't work as hard so it doesn't come up as far, no WOT. Cars with mechanical linkage vs cables tend to suffer this more.
That's why I suggested just raising the idle enough to get the car moving. If it works that way, then it is most likely the mount.
 

Big_John

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Okay consensus seems to be a broken mount, but please, educate me on how does a broken mount cause this?
The throttle linkage is mechanical on the '66, not a cable like later years. With a mechanical connection going directly to, and pivoting at the firewall, the engine moving will effectively change the length of that linkage and open the butterflies on the carb.

Later cars, with a cable throttle, won't experience this problem because the cable is mounted to the engine. When the engine moves, the cable moves with it.
 

413

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1964 was the last year for mechanical linkage. Yes, I just asked this question of Bob Merit because I didn’t know what 63 and 64 used. Car completely changed and first C-body in 1965 and that started a cable throttle.

I’ve owned a couple 66’s and they have a cable.

66 carbs have the same stud mounted above the throttle shaft.
 
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Big_John

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1964 was the last year for mechanical linkage. Yes, I just asked this question of Bob Merit because I didn’t know what 63 and 64 used. Car completely changed and first C-body in 1965 and that started a cable throttle.

I’ve owned a couple 66’s and they have a cable.

66 carbs have the same stud mounted above the throttle shaft.
I checked (not that I doubt Bob) and you are correct. I was off a couple years on that.

That kind of negates the theory about the bad motor mount though. The cable, being mounted solidly to the manifold, isn't going to move if the engine moves... Unless the engine moves so far that it yanks the cable out of the mount, I don't think it would matter if the mount is broken or not.
 

1970FuryConv

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I had an Edelbrock carb do the same thing years ago.
I think I had to remove the linkage rod between the choke valve at the top left side of the carb and the throttle linkage below in order for it to stop. Never figured out why the car did that.
Edelbrock 1406
1662154629529.png
 

Avout

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Thanks. Since removing that little rod takes 2 minutes, I'm going to try that first before trying to crawl underneath the car with my old carcass. When you say "left side", you are referring to the driver's side or left side of the carb when you are looking at it under the hood?

This car indeed has cable linkage, not rods and levers on the firewall.

I forgot to mention that this cable has the nasty habit of shifting in the mount, no matter how tight I screw it down. The cable moves freely in the sleeve, like a hot knife in butter. However, after fixing it, it will shift in the mount again on the next drive around town resulting in higher idle rpm. Maybe these 2 issues are related?
 

57fury440

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The cable sleeve is not securing properly? Try putting something under it to try and get it not to move. That may be the whole problem. Make some sort of shim to take up the slack so it clamps down tight.
 

1970FuryConv

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Thanks. Since removing that little rod takes 2 minutes, I'm going to try that first before trying to crawl underneath the car with my old carcass. When you say "left side", you are referring to the driver's side or left side of the carb when you are looking at it under the hood?

This car indeed has cable linkage, not rods and levers on the firewall.

I forgot to mention that this cable has the nasty habit of shifting in the mount, no matter how tight I screw it down. The cable moves freely in the sleeve, like a hot knife in butter. However, after fixing it, it will shift in the mount again on the next drive around town resulting in higher idle rpm. Maybe these 2 issues are related?
Left side is driver side. I'm trying to remember something from 20 years ago. It was either that choke pull-off rod that caused the problem or I had to disconnect the fast idle linkage. Does your car have a fast idle screw?

If the accelerator cable sheath is shifting forward and backward, I think it is contributing to the problem. Side to side may not be a concern as far as fixing the high rev issue.
 

Trace 300 Hurst

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Why would you crawl under the car? Don't DO that!

1. Have someone responsible behind the wheel. Car in D, foot brake firmly applied. Don't rely on useless parking brake. At all.
2. Have responsible person briefly gun the gas. Hard and very brief.
3. You are standing alongside the driver's side (left side of the car) and looking at the driver's side valve cover area.
4. If the engine leaps up on the driver's side an inch or two, that's a broken mount. The passenger side never wears out (never say never!) because it doesn't have to resist the torque of the accelerating engine. Instead, that torque actually compresses the passenger side mount vs. trying to tear the rubber apart on the driver's side. Unless you do burnouts in reverse....that'll break that one.
 

CBODY67

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When the lh motor mount on our '66 Newport 383 2bbl "delaminated", the way I checked it was to have the hood up, trans in "D", left foot firmly on the brake, and slowly raise the engine speed with the accel pedal. You can SEE the motor rotate upward clockwise. Then after it raises, quickly release the throttle input and the motor will return to its normal position with a "quiet thud", which you can feel. ALSO, the engine will only raise up so far as the front line out of the a/c compressor will contact the hood inner structure right above it.

Make sure the throttle return springs are in place and correct for the vehicle!!! NO way should the throttle go past idle when they are working. Yes, there are springs on the carb throttle shafts, but those should be considered auxilary to the springs that attach to the bracket in front of the carb, which pull the carb cable and kickdown rods FORWARD.

While you're at it, might as well change the two engine mounts and the rear trans mount, too.

Just some thoughts,
CBODY67
 
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