[countymounty]

I was typing a post in another thread and decided to post my idea of what I am considering doing to my 1966 coupe.

I want a car that looks original so my idea is one that looks (on the outside) stock.

I want disk breaks and power steering and air but the real thing I’m considering is I want my 66 to be a daily driver (except for winter of course). I want a car I can jump in and drive cross country.

I have went back and forth on putting back the inline 6 or a jumping to a v-8. I have come to the conclusion that my 88 vert has all the power I need so I am considering another route.

This is what may want some of you to burn me at the steak. I am thinking of getting a modern 3.8 v-6 and making it a flex fuel vehicle. Ethanol gets slightly less fuel economy but one big reason is it’s being run in these low compression vehicles, I’m considering shaving the heads and bumping the compression up to 10:1 which would burn the ethanol much better, I would be stuck with premium gas when ethanol wasn’t around but what the heck.

What gave me this idea is a lot of guys running the 3.8 are getting 35 miles per gallon on gas mileage , I think with the lighter weight (plus the cheaper ethanol) I could get 40mpg in a daily driven mustang.

What do you guys (and gals) think?

[Veronica]

Hello. The 2.9 in my Bronco II gets nearly forty mpg on the highway, and that's while dragging a Bronco II down the road instead of a 66 mustang which is about a thousand pounds lighter. I could go out in the morning and take a look at it and my 64 1/2 and figure out what would be involved in swapping out the motors if you like. And who knows? It might be not a big deal to swap out the transfer case and everything. I know the Bronco II has a much shorter wheel base, so that shouldn't be a problem. I would hate to see someone hack up a rare mustang like a K code or something doing that, but the 6 cyl. cars it might actually help preserve some of them, so that people can restore them in forty years or so.

[Veronica]

Hi again. The motor mount attaching points on the 2.9 and a 260/289 are almost exactly the same distance apart from p/s to d/s. The attaching points on the 2.9 are a bit farther forward on the block than a 260, but not enough to where you would have a problem with the motor hitting the firewall. If anything, it would probably help you out on clearance for accessories up front. The only potential problem that I can see at a glance is that the top of the intake on the 2.9 ( throttle body) sits about an inch and a half higher from the motor mount attaching points than the top of the breather on the 260, which could possibly cause some hood clearance problems. Not a big deal if one is aware of that up front, but that's something that would be very easy to overlook until you actually hit the motor closing the hood the first time. Overall, it looks as if the swap could be very easily done. Good luck.

[systronic]

highway mileage (as i'm sure you know) has so much to do with gearing. i have a 96 cadillac with a 320hp 4.6L V8 in it that gets 32mpg highway. It's ridiculous.

I think if you went with a 5speed tranny in front of either a stock compression 302 (like 9:1) or even the Inline 6, you would be just as good off as a 3.8L.

If you're looking for an I6, i have one.... it's a 65 sprint 200 motor. don't know if it runs, but it cranks real easy by hand, and comes with a C4 (shameless plug)

[countymounty]

Actually I have the original inline 6 it was rebuilt before I bought the car (less then 100 miles put on it) when I parked it, it was smoking (blue? Cant remember) but that could have been because it was not broke in, but really it wasent safe to drive barely had breaks…….

I have considered using it, easy to work on and those inline 6 will run forever……………..

Which brings up what are people getting for gas mileage in there inline 6s?

[Veronica]

Hi again. My first car was a 66 model 6cyl coupe and it got something in the 21 mpg range around town. Not great, but certainly better than a lot of cars.

[Spraguepsycho1]

I would look for a rear diff with the 2.80 gearing, then add a mild 289/302 to it with a newer transmission that had over-drive. I have the 2.80 gearing with a C4 automatic transmision in my 1965 coupe, and was getting right around 22-25mpg on the highway as long as I kept the engine running on the 4 barrel carb's primary's. With overdrive I think 28 to possibly even 30mpg would be possible with reasonable driving habits, and a fairly stock V-8 since the cars are so light.

[Cobra6]

I think (like a couple of others) that the AOD would be the way to go.
There are plenty of websites that show an auto tranny conversion.
You might even want to go with a lower gear than a 2.80 rearend for some acceleration.

My personal opinion is that you would get mileage approaching high 20's or 30 mpg on the highway for minimal cost.

I don't know that you would ever recover the cost from converting to E-85. Everything I have read shows worse mileage from an E-85 carb, plus they cost big $$$$.

[countymounty]

I know you can buy kits to change over the newer vehicles to be flex fuel and the cost is not that must. Mainly Teflon coated fuel lines and the ethanol can touch any rubber gaskets. I have nerve even looked into converting the inline over so don’t know if/how it could be done but I expect it wouldn’t be too difficult.

One of the main reasons people get fewer miles to the gallon with ethanol is because in reality the flex fuel vehicles are gas vehicles that can happen to run ethanol. The ethanol really needs to be run in a high compression engine to benefit from its very high octane rating. I think I could get = mpg in a high compression engine, and at 50 cents a gallon cheaper I believe it would pay for itself but what really matters is my money would be supporting farmers and not terrorist and crazy south American dictators.

My idea I was going for was a classic that could get equal or better gas mileage then a modern Honda….and I already have a c-4 sitting in storage I was going to try to swap out for the 3 speed.

[ajusaf]

How hard is converting the C4 with a overdrive? My highway gas mileage sucks since I have a C4 speed and running 3.73 "9", and a stroked 351W to a 383 with a 750-850 CFM carb. My carb is a 750CFM with a Proform body which I heard might be upping it to a 800-850 CFM

[andrewmp6]

Id swap to a aod or aode it has a overdrive.