Well,I'm at my wits end now. Yesterday I went to my local salvage yard and got an electric fan to try out before I get a clutch fan to try to quiet this car down a bit. I hooked it up and took it to the highway. Same old crap. 65 mph and It's screaming for a 5th gear....
At first I thought it was the diff, but it's 3:25. Then the aftermarket fan, nope.
The tranny #'s match, 4 speed toploader with traction lok, I don't think anyone before me would have altered the gearing???? I confirmed the RPM's with a tach, 2500 at 55mph and 2900 at 65 mph. What's next? I have the long style headers, Edelbrock intake and carb, 14" rims (stock) and 25.9" tires. If it was the cam the rpm's would be off.
Header leak?
Mufflers?
Any idea's what I can try next?

 

HAHA, That is normal for a 3.25. My 2.80 rear end runs me at 65 probably at 2300-2400 RPM's.

 

Keep in mind these things have no sound deadner under the hood, there is little there to keep engine noises in the engine compartment. Engine noise is a part of the old car life.

 

Yeah, I don't see what the problem is. That sounds about right for the RPM's with 325's and a top loader. Check into adding an AOD.

 

I understand the noise issue but this is like it's running at 5K RPM at 65 mph. I have to go to 4th gear at 40 mph. I just talked to my dad and he was wondering if maybe the clearance/backlash setting on the ring & pinion was too tight and the friction was holding it back, or too loose. Think it's worth pulling to find out? It dosn't make any clunking noises, maybe I'll pull it and have it checked out. If it checks out OK I'll have 3:00's or 2:83's dropped in. Thanks for the replies.

 

Have you ever ridden in another Mustang @ 3000 rpm down the highway? With the same setup you have?

Well, It is loud (some may say noisy) and it sounds like it screams for another gear. I`ve read your other posts on this subject, and from what you are describing, it sounds like your car is PERFECTLY NORMAL.
The Toploader will add some wining at high rpm, but your main source is the longtubes. Put on some exhaust tape. That will also cool down the engine compartement, which is always good. Also use sound deadning mats on the floor and behind every panel inside your car. (will add weight, not good)

You could also put back on the stock intake, carb, exhaust manifold and single exhaust and drop in a set of 2.80:1 ratio, or buy a friggin HONDA if you want to go quiet down the street

 

Another case of "Modern Overdrive Sedation". After driving my 97 F 150 I used to think my 70 Mach 1 was about to fly apart when I hit 65. It's the way it used to be!

 

normal, and i agree. Go buy a honda. if you want a quiet, smooth, nice ride.

 

You think the mustangs are loud, you should ride in my 1970 f100 at about 65 down the highway with no sound deadening whatsoever and 4:11 gears. You really can't talk to the person sitting with you comfortably. Lol....Its great!

 

just punch that pedal all the way down and realize that you have PLENTY more to go. Take that baby clear up to 100MPH if you have the *****! I also have a '75 F100 with a 460 and an 06 Charger R/T for modern/family car speed.