I Can't Drive -- 65

[johnnyzoom]

Getting my 64 Comet back to daily driver status, was out of commission for almost a year due to brake trouble, moving to new house, life stuff.

I can barely get up to 65mph, not that I have much opportunity to drive faster than that where I'm at in Florida. I don't think I've ever had her going faster than 70 with a tailwind before. But I've been going through the shop manual and posts here to troubleshoot.

It's a 200 i6, with the wonderfully named Mercomatic 2 speed automatic transmission. I'm using an Autolite 1100 with the automatic choke disengaged, and what I believe to be a stock 64 distributor. Timing is advanced to 14 BTDC. I don't have a tachometer so I can't map out the advance, but I know that timing advances when I pull the throttle gradually and watch with a timing light. New fuel filter, don't appear to have any fuel flow problems (mechanical pump). Brakes aren't dragging, they're cool to the touch after 20 mile highway trip. Just repacked wheel bearings with grease and believe them to be adjusted right.

I've tightened the vacuum connections from the SCV to the distributor. Throttle linkage is set correctly for WOT. Transmission fluid is clean, at the right level, and I have an aux cooler in line for it. Shifts in and out of 2nd gear
smoothly. There is a very small leak at the manifold, I think broken bolt at the end.

Is this about what I can expect with this setup? If so I'm fine with that, but it'd be nice to have a little more speed for passing. Any ideas or things I've missed would be greatly appreciated.

 

[fordconvert]

Make sure the throttle is physically able to open all the way. Lots of things in all the linkage could be bent or out of wack over the years. Things like new carpet or floor mats under the pedal can also prevent it from opening all the way. I have wasted a few bucks and lots of time due to a floor mat under the pedal.

 

[rbohm]

8) i agree with fordconvert. my old 66 falcon had new carpeting installed, and it was poorly done. the carpet was pulled so tight that it prevented me from getting full throttle operation.

 

[170-3tree]

what rear gearing do you have? I would imagine that your top gear is at !:1 ratio. unless the engine is goin crazy at such high speeds. my car has a 3.5 gear and runs about 4000rpm at 70mph. which would have been 81mph from the factory, but i cannot find the correct size tires for this car with a 13inch wheel.

 

[BIGREDRASA]

What size tires are you running? Are they anywhere near, +/- a 25" diameter?

 

[SoCar72]

My '63 was much the same way with it's 2sp Ford-O-Matic. I think the fastest I ever got it up to was about 70 going downhill and (barely) 65 on flat land. After I swapped in a T5, 80 on flat land is sustainable with no other changes to the car other than lowering the idle speed. :mrgreen:

This led me to believe that either my 170 was running out of steam at that rpm (about 2750 @ 65 then, about 2250 @ 80 now), or the AT was just so parasitic at hwy speeds that it just couldn't go any faster. I haven't driven her any faster than 3000rpm in any gear (still the original build, I'm hesitant to push it), so the jury is still out...

If it is parasitic loss, perhaps an overhaul will help. Or swap for another trans : C4, AOD (if that's even possible), or a 4/5sp manual. I swapped mine because I wanted a MT, and I had a T5 lying around. Gas mileage doubled by the way.

What size tires are you running? Are they anywhere near, +/- a 25" diameter?

Here's a basic formula that I use for decoding tire sizes and choosing the size that I want (depending on which way you run the formula) :

section x .0394 / (aspect/100) x 2 + wheel size = overall diameter

sample : 195/70 r14
195 (section width in mm) x .0394 (mm to inch conversion) = 7.683" (tire width - NOT tread width)
7.683 x .7 (aspect ratio, sidewall is a percentage of the section) = 5.3781" (side wall height)
5.3781 x 2 (2 sidewalls, above and below the wheel) = 10.7562" (total rubber beyond wheel diameter)
10.7562 + 14 (wheel diameter) = 24.7562" overall diameter

The manufacturers vary their construction so reality tends to vary +/- 2%. You can run the formula different ways with any target value(s) to find your desired tire size. This is particularly helpful if your changing wheel sizes and want to maintain your overall diameter, hence speedometer accuracy.

4000 rpm @ 81 mph, 1:1 high gear, 3.50 rear gear and a 13" wheel would need a 175/80, 185/75, 205/70, 215/65, 235/60, 255/55, or 285/50. Most of these sizes probably don't exist, but would be of the geometry to suit your needs. Double check the tire manufacturer's specs for proper wheel width to see if yours will work. Step up a couple of wheel sizes and your search gets a lot easier.

 

[64falconsix]

Firestone makes a 185/80/13 in a blackwall which is 24.7" in diameter. this is suppose to be the equivilent of the original 7.00 x 13" I have a set on my falcon with 3.20 gears I am hitting 60 M.P.H. at around 2700 R.P.M.s

 

[170-3tree]

my tires are actually about 22" diameter fully inflated. i usually run them just a hair under the 35 i had it set at. the engine actually seems to love it around 60-70 but lacks dramatically too much above 72. at the time it was the only tire i could find that wasn't a trailer tire. I wanna keep the same wheels but need something a bit bigger. sad thing is that even with such small tires i usually pull around 22mpg actual. i set a gps up to have a trip odometer since mine is a wee bit off.

 

[BIGREDRASA]

I think you're going to need to switch to a 14" rim size, so you can get decent tires. A 22" diameter is waaay too small, and is like driving a 3 speed in 2nd all the time. 65 MPH in 2nd gear is too much for steady driving. Time to shift to 3rd. You need at least a 24.5" to 25" tire diameter, and that doesn't look like it's available online in a 13" rim size.

 

[170-3tree]

I actually found the right size tires. I was looking at the tires on there and they aren't rated for anything above like sixty mph which isn't where highway speeds. these are rated at 108 or something which in my opinion might cure a lot of the shaking the car does at 70mph and bring my speedo back into line with the gps. i just need to save the money for a set of those puppies.

 

[Lazy JW]

..... wanna keep the same wheels but need something a bit bigger. sad thing is that even with such small tires i usually pull around 22mpg actual.....

Are you absolutely certain you will make things better by going to larger tires? 22 mpg sounds like a success story, not a failure.
Joe

 

[JackFish]

What's the final gear in that tranny?
Maybe swap to C4 or ?

 

[170-3tree]

automatic tranny takes a lot out of the gas mileage. it has a 1:1 final gear in in the 2.77 tranny. today i filled up with the new ignitor 2 full set up and readjusted valves halfway through the tank and got a bit over 25mpg unless my math is off, but i imagine that 125+ (turned my gps on a mile or two into this tank to keep track) divided by the 4.7~ gallons of gas i put in is around 25+mpg. i just want a bit more and to not kill my freshly rebuilt engine doing highway speeds around 3500rpm figure if that dropped to 3000rpm or so then i would be getting around 27+mpg on top of matching the speedometer and needing my gps with me all the damn time.
remember this is in a fairlane sedan not the tiny little falcons. which i imagine are significantly lighterweight than my huge car. i think that this full set up in a falcon could have potential to see 30mpg or more with my mixed driving conditions. since on top of the larger size of the car i drive with passenger 75% of the time and at least 100lbs of tools in the trunk as well as three layers of sound deadening to the floor and one on the roof. just my train of though in all of this.

+edit+ how much could i gain with header. i keep thinking it over and then just beat the idea off with the fact that it's a 170 so the gains would be much less than with 200.

 

[johnnyzoom]

What size tires are you running? Are they anywhere near, +/- a 25" diameter?

I have a lot to learn about tire size, but just using a tape measure they're 25" diameter, and the wheel measures 15" across. According to my ID plate it's a Mercomatic 2 speed with 3.20:1 axle ratio.

Make sure the throttle is physically able to open all the way. Lots of things in all the linkage could be bent or out of wack over the years. Things like new carpet or floor mats under the pedal can also prevent it from opening all the way. I have wasted a few bucks and lots of time due to a floor mat under the pedal.

The carpet is a little iffy by the pedal, but I had someone depress the accelerator while I looked down the carb and it appeared to be WOT. I also sprayed down all the linkage with some WD-40. I'll investigate further.


There's a big article on these transmissions and swapping them in the new Nov. 2009 Rod and Custom. Don't think there's any info not already available here at fordsix.com, but still kind of cool to see it in print.

 

[Lazy JW]

.....
remember this is in a fairlane sedan not the tiny little falcons. which i imagine are significantly lighterweight than my huge car. i think that this full set up in a falcon could have potential to see 30mpg or more with my mixed driving conditions. since on top of the larger size of the car i drive with passenger 75% of the time and at least 100lbs of tools in the trunk as well as.......

Yup. Which is why I am still doubtful; larger tires may indeed return a bit better mileage and then again perhaps not. This all depends upon so many variables that it is difficult to say for certain, but I have at times observed poorer mileage with taller gearing, and sometimes better mileage.

Your Fairlane is indeed heavier than a Falcon of similar vintage, and you have the smaller engine that loves to rev. It "may" be happier and last longer by revving faster but not having to pull as hard. I dunno, but this particular case doesn't seem cut-and-dried to me.

25 mpg still sounds like a success story to me You are already doing some things very RIGHT.
Joe

 

[170-3tree]

you are probably very right. in all reality driving at lower rpms the pedal must be depressed a bit more than at 65 or seventy. This to me means implies that for every rpm at 3500ish it uses less fuel than trying to maintain speeds of 45-55 at around 2700rpm where the pedal is halfway on the ground as apposed to about a quarter at 70.

I apologize for hijacking this thread.

It would be my opinion that the 2 speed is probably robbing your higher end power enough to knock your top speed down a bit. the engine is fresh and you have the right tire size and a gearing that isn't too over the top. also check things like engine restriction and possibly your timing chain. Is the car just running out of juice at speed higher than that or is it doing something weird?

 

[johnnyzoom]

I apologize for hijacking this thread.

It would be my opinion that the 2 speed is probably robbing your higher end power enough to knock your top speed down a bit. the engine is fresh and you have the right tire size and a gearing that isn't too over the top. also check things like engine restriction and possibly your timing chain. Is the car just running out of juice at speed higher than that or is it doing something weird?

I don't consider it a hijack, it's the way to learn.

Doesn't run out of juice, just tops out at 65, maintains power. I have a 60 Rambler with a 196 and 3 speed, very similar to the Ford setup, and it loves 65-75 mph. So I think I just need to fine tune the Comet, and look into an upgrade. I'd like to rebuild the 200 this winter at some point, and that would be a good time to swap for a c4, they're not too uncommon on c-list around here. I think that would make me happy. Until then, this is still the funnest 65 mph going for me.

I'm still new to a lot of this and wanted to see if my results were to be expected or if I was missing something. Thanks for the help.

 

[Lazy JW]

Johnny,
Try advancing the timing about five degrees and try it. Try more if that helps, if it hurts then back it down.
Joe

 

[Lazy JW]

you are probably very right. in all reality driving at lower rpms the pedal must be depressed a bit more than at 65 or seventy. This to me means implies that for every rpm at 3500ish it uses less fuel than trying to maintain speeds of 45-55 at around 2700rpm where the pedal is halfway on the ground as apposed to about a quarter at 70......

Please do not misunderstand, I am not positive that larger tires will hurt, just not certain they will help either (I'm pretty sure they will hurt in the town driving). One thing that is important is to do an honest evaluation of what TRULY is your primary type of driving. If it's only 20% freeway then keep the small tires and let 'er rev up on the highway. If ever there were an application for a auxiliary overdrive, this is it.
Joe

 

[66 Fastback]

You might want to verify that the balancer has not slipped and that your timing is set correctly. Take the plug out of the #1 cyl and stick a long screw driver in the cylinder. Turn the engine balancer to TDC and see if the piston / screwdriver is at the top of its stroke. Pop the cap off of the distributor noting where the #1 post is located and see if the rotor is pointing at/near the #1 wiring post.
If it is way off, rotate another 360 deg and see if things line up correctly.

My car was a dog and had no power. I had set the timing "correctly" using a timing light etc but it ran poorly. I timed it by ear and gained more power and the timing mark was way off the scale according to the timing light. When I finally checked the TDC of the timing mark, I discovered that my balancer ring had slipped. I eventually replaced the bad balancer and timed it correctly.
Doug