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Discussion Starter #1
Just got my '68 on the road this week after two years in the garage. I'm running a 350 4-speed (rebuilt Saginaw trans) with a 4 bbl and electric choke. The rear is the original 10-bolt 2.73. After warming up, the idle settles in at around 1,000 RMP. But at 55-60 MPH the tach is clocking 2,700 and it feels like I need a fifth gear. Maybe this is normal for the set-up I have but it just feels tight. I was told the engine is out of a '93 Chevy pick-up and has 37,000 miles on it.

Any thoughts? :confused:
 

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Taching 2700 at 55-60 sounds about right to me with 2.73, but the 1K idle rpm is too high for a 4spd. I have a 350 (with 5spd), 750cfm carb, mild cam, and my idle is good at 600-650.

Have you tried to adjust the idle down?
 

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Taching 2700 at 55-60 sounds about right to me with 2.73,
If you had a 20" tall rear tire. With a 25" tire you should be running about 73 mph at 2700 rpm.
 

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If you had a 20" tall rear tire. With a 25" tire you should be running about 73 mph at 2700 rpm.
Yes, you're right. I should have used the on-line calculator. By memory, it seemed right thinking back to the Saginaw I had before the TKO swap.
 

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Discussion Starter #6
Taching 2700 at 55-60 sounds about right to me with 2.73, but the 1K idle rpm is too high for a 4spd. I have a 350 (with 5spd), 750cfm carb, mild cam, and my idle is good at 600-650.

Have you tried to adjust the idle down?
Not yet, but that's the first thing I'll try this weekend. It's been 16 years since I owned my last '68 and I may just not be used to the feel of a muscle car. It just seemed really tight. My father thought maybe the choke was sticking or not set up right. Just looking for ideas to hunt for.
 

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We gotta know what your definition is for 'really tight'.
 

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Discussion Starter #8
We gotta know what your definition is for 'really tight'.
2700 RPM at 55 MPH and a slight bit of whining that leaves me feeling like I need to shift one more gear. That's the best I can describe it. Like I said, it may be fine. I've only put 10 miles on the car. Just looking to see if anyone could suggest where to start looking first or if that sounded right.
 

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55mph @ 2700 rpm in 4th gear with a 25.6" tire (ie, 225/60R15), you must have a 3.73 gear, not a 2.73. And/or your tach or speedo are reading incorrectly. Or you aren't in 4th gear. Or the clutch is slipping REALLY BAD.

Tip: most GPSes have a very accurate speedometer feature (on flat roads at least) to verify the speedometer reading.
 

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4th gear is all the way over toward the pass seat and down!

Sorry, I'm in a good mood and just being funny!:D
Unless you are using 3spd shift levers on a 4-speed saginaw... the only way to make it fit is to flip the 3-4 lever upside down which makes the pattern look like this:
1 4
2 3

My old 67 was like that when I got it...
 

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One mile covered in 60 seconds = 60 mph. Yes, with a 2.73 gear, cruise rpm s/b around 2100-2300 rpm. OE size tire (check glovebox door for decal), correct speedo gear, and 3.73 gear = 3000 rpm.

Match with a following vehicle, or as suggested a GPS unit.
 

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My vote is for the speedo being off. What's the rear tire size, and do you know what color driven speedo gear you have in the Sag?
 

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Discussion Starter #16
My vote is for the speedo being off. What's the rear tire size, and do you know what color driven speedo gear you have in the Sag?
Rear tire is 25 1/2 inches in diameter. Don't know the color driven speedo gear of the Sag? I am going to check the speedo against my wife's car this weekend, but I was sitting in traffice up on the 202 by-pass between 401 and Boot Road so I know 60 MPH can't be that far off.
 

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Yeah, depending on time of day, if you were keeping in traffic on that stretch I might be thinking the speedo is reading low ;) .

Running a calulation with 2,700 RPM, 2.73 gears, 4th gear (1:1), and a 25.5 inch tire, I show speed should be 75 MPH. Sounds right for 202 N without the morning backup... 55MPH should be turning 2,000 RPM.

You sure the rear is untouched? 3.55s would make the RPM and reported speed with the combo.

Seems like one local department or another always has the speedminder radar cart parked local here. I have been meaning to check mine the next nice day I see the cart in Downingtown or Upper Uwchlan.
 

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Discussion Starter #18
Yeah, depending on time of day, if you were keeping in traffic on that stretch I might be thinking the speedo is reading low ;) .

Running a calulation with 2,700 RPM, 2.73 gears, 4th gear (1:1), and a 25.5 inch tire, I show speed should be 75 MPH. Sounds right for 202 N without the morning backup... 55MPH should be turning 2,000 RPM.

You sure the rear is untouched? 3.55s would make the RPM and reported speed with the combo.

Seems like one local department or another always has the speedminder radar cart parked local here. I have been meaning to check mine the next nice day I see the cart in Downingtown or Upper Uwchlan.
I'll have my father pull the cover off and count the teeth this week before I get over to the shop. Then I'll check it against the wife's car up on the by-pass. At least I have a good idea from this thread about where I should be.

Funny story, we took it out this weekend and after the 202 run went up through the Great Valley High School parkinglot so she could drive it around a bit. She wanted to "get a feel for it" before taking it out on the road. So she pops it into first, slams the gas, and drops it into second all before I could scream "Look out for the speed bump!!!" We went over it like the Dukes of Hazzard with everything underneath getting banged around. All I got was "Oopsie."
 

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Discussion Starter #19
Yeah, depending on time of day, if you were keeping in traffic on that stretch I might be thinking the speedo is reading low ;) .

Running a calulation with 2,700 RPM, 2.73 gears, 4th gear (1:1), and a 25.5 inch tire, I show speed should be 75 MPH. Sounds right for 202 N without the morning backup... 55MPH should be turning 2,000 RPM.

You sure the rear is untouched? 3.55s would make the RPM and reported speed with the combo.

Seems like one local department or another always has the speedminder radar cart parked local here. I have been meaning to check mine the next nice day I see the cart in Downingtown or Upper Uwchlan.
I'll have my father pull the cover off and count the teeth this week before I get over to the shop. Then I'll check it against the wife's car up on the by-pass. At least I have a good idea from this thread about where I should be.

Funny story, we took it out this weekend and after the 202 run went up through the Great Valley High School parkinglot so she could drive it around a bit. She wanted to "get a feel for it" before taking it out on the road. So she pops it into first, slams the gas, and drops it into second all before I could scream "Look out for the speed bump!!!" We went over it like the Dukes of Hazzard with everything underneath getting banged around. All I got was "Oopsie." :sad:

**Sorry for the double post, I was just trying to add the smiley at the end**
 

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Those are some serious speed bumps! Did you have to clean the new seat covers?
 
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