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Hi,
I just bought my wife grandfathers 77. His son didn't know anything about the car and sold it to me. Driving it home i noticed while on the interstate going 65 that the cars rpm was at 5500. I've replaced the transmission modulator but that didn't help. I also check the line going back to the engine and couldn't find any air leaks. It seems like it's not going into 4th gear. Is it normal for it to be running that high? Any help is appreciated.
If it is a automatic then it doesn't have a 4th gear. That is presuming it is the original automatic transmission.
With that being said, 5500 RPM is high for 65 MPH.
Without knowing any details about the car you might have to do some digging.
Is the car all stock? Any mods?
When was the last time it was driven?
Fluid level in the trans?
Is the tach accurate?
Does it seem like the engine is really turning 5,500rpm when the tach is indicating 5,500rpm? That's pretty much at or past the redline for a stock engine in a 1977. Guessing the tach is not right but you need to better understand what's been done to the engine, transmission, and rear differential in your car. Photos of these mechanicals would help us see what you are working with.
If it is a automatic then it doesn't have a 4th gear. That is presuming it is the original automatic transmission.
With that being said, 5500 RPM is high for 65 MPH.
Without knowing any details about the car you might have to do some digging.
Is the car all stock? Any mods?
When was the last time it was driven?
Fluid level in the trans?
Is the tach accurate?
Everything is original. He told before he passed that had the rear-end rebuilt. My money is on that it's still stock gears. The car did sit for 2 years in a garage. But I've checked all the fluids and they are good. It does still have some old gas in it though could that be cause? At idle it's reading 1800 rpms. Im.unsure if the tach is accurate is there a way to calibrate it? Sorry for the noob questions. This is the oldest vehicle I've owned and I don't know a lot about it.
If it is a automatic then it doesn't have a 4th gear. That is presuming it is the original automatic transmission.
With that being said, 5500 RPM is high for 65 MPH.
Without knowing any details about the car you might have to do some digging.
Is the car all stock? Any mods?
When was the last time it was driven?
Fluid level in the trans?
Is the tach accurate?
Everything is original. He told before he passed that had the rear-end rebuilt. My money is on that it's still stock gears. The car did sit for 2 years in a garage. But I've checked all the fluids and they are good. It does still have some old gas in it though could that be cause? At idle it's reading 1800 rpms. Im.unsure if the tach is accurate is there a way to calibrate it? Sorry for the noob questions. This is the oldest vehicle I've owned and I don't know a lot about it.
You'll want a digital dial-back timing light anyway, so confirm the tachometer with the tach on the timing light. The Innova 5568 (linked) is what I use. And be sure to pick up a 1977 shop manual, and 1977 assembly instruction manual.
I had something similar happen to me recently. I had brought the selector down to second instead of drive. I was well over 3,000 RPMs once I got on the freeway. Once I noticed and shifted up once it all went back to normal.
5,500 sounds like you’re still stuck in first gear though, assuming your tach is correct. I would make sure you’re only going down Park>Reverse>Neutral>Drive, 3 clicks, and no further.
1,800 sounds very high for a warm idle RPM. If you confirm that with a timing light I would look at getting that lowered.
Oh yeah, and welcome to the forum! Post some pictures of your new purchase.
Here’s the speed the car would be going if you were stuck in 1st gear at 5,500, assuming you have a 3.08 rear end
2nd
My guess, assuming the tach is accurate, that he’s stuck in 1st
The car is shifting into third I can feel when the car shifts. However when it does go into 3rd the rpms don't seem to drop like they should. I just got home from work and started it up it idle at 1800 for a bit and I reved the engine and when I came back to idle it stopped at 2600. I let it set there for a bit and shut off the engine when I cranked it back up it is idling back at 1800. Could it be my carburetor is messed up? There is a hose that come out of the back then turns into the intake that I can completely remove.
The car is shifting into third I can feel when the car shifts. However when it does go into 3rd the rpms don't seem to drop like they should. I just got home from work and started it up it idle at 1800 for a bit and I reved the engine and when I came back to idle it stopped at 2600. I let it set there for a bit and shut off the engine when I cranked it back up it is idling back at 1800. Could it be my carburetor is messed up? There is a hose that come out of the back then turns into the intake that I can completely remove.
Take some closer and larger photos of that carburetor, all sides...
Not your hi rev problem but....
That vacuum line should be connected to the short pipe on the carburetor top plate (air horn).
Hot Air Choke Fresh Air Port:
Last edited by bmotojoe; Aug 27, 2024 at 12:57 AM.
Provide pics of the carburetor at idle, with the air cleaner off. Different sides. Do you think the engine is really idling at 1800 rpms or are you relying on the tach reading ? Putting it in gear at that rpm will give you a jolt.
There is an emission sticker in the engine compartment on the driver's side. It shows what the idle should be for that engine.
Normally for autos:
L-48- 500 rpms
L-82- 700 rpms
77 running at high rpms
