Gregor
Well-Known Member
Now that's the kind of mileage I'm looking for. Your right I need to learn about this machine and how to fine tune it.
What is a slanty?Yeah those tires are for slantys. But the height is close at about 26.4 high; which calculates to 83.4 in circumference. All my calculations were based on a 27.0 inch tire at 85.0 circumference.
Got it, thanks.slant 6
I had no problem getting 16 mpg with a 750 DP Holley on a 360 .030 over and 3.91's with a .484 lift / 284 advertised MP cam.Had similar builds with a 750dp and got 18+mg on the highway and mid teens around town.
I would be happy with 12 mpg. What is the largest size tires that would fit? Right now it has 215/70r14 up front and 225/70r14 on the rear.The OP is way too green to be tuning air bleeds and emulsion, and that's if his carb is adjustable.
Certainly he can drill and tap all that stuff and make it tuneable, but he's better off paying someone like Thumperdart on here and over at moparts to do it for him.
I'd leave the gears you have in there. A bit taller tire. And let it go. If it's not you daily driver, what's the difference between a well tuned 12-13 MPG with what you have, or 16-18 if you go to taller gears. You'll give up a butt load of performance with less gear.
BTW, higher numerically is a LOWER ratio. For example, a 4.10 is a LOWER gear than a 3.55. It is higher numerically but the ratio is lower. You are always better off specifying ratio than numeric value. Sometime in the 1990's the numeric value started getting tossed around and has become a bad habit.
In a 70 Dart, in the rear,nothing big enough to survive a stout 360.
I think it's been said here on FABO many times; 255/60-15. These are about 27 tall and 10inches across the sidewalls when mounted on 7 inch rims which are much to small; that's just how they rate them. That tire needs an 8 at the least. You will need a custom wheel with a custom backspace.You may need to move your springs inboard IDK.
I had one of these cars back in 1970. After killing the original E70-14s and several more sets of various tires, I finally bit the bullet an sprung for new wheels and get this Gs! Hyup G60-14s. G's are 8.25 inches across the tread. So they fit on an 8 inch rim. But those puppys were a different style of tire, a belted polyglass so the ratio of tread-width to sidewall-width was different than it is for radials. The sidewall was not much bigger than the treadwidth, perhaps an inch, on an 8 inch rim. So that makes the sidewall dimension maybe 9ish inches. As I remember it, it was still a very tight fit.But I did not have to move the springs. Those Gs still sucked for traction.
On the front on the 4" bc, you are limited to a couple of sizes.
The 235/60-14s being about the biggest on commonly available 7 inch rims.These are a tic over 25" tall.
Depending on your ride-height,you may have to trim the wheel opening for full-lock steering. The most common interference is at the front lower corner. The wheel will have to have an offset to move the rubber inboard , but not so far that it rubs on the frame on the backside. Most 7inch wheels come with a 3.375 bs. This is not enough. I found a set with 3.75" bs. These barely fit and I did have to trim the metal.
The other commonly used tire is I think,a 225/65-14. this tire is about 25.5" tall, but with it's slightly narrower section width is a little easier to fit. This will also fit on a 7"rim. Trimming may still be required, depending on your ride height.
If you look closely, your front 215s are currently probably just avoiding trouble. If your rear wheels are the same as the front, you can try those 225/70s up front and see where you are at. They are almost a full inch taller than the 225/65s. Before you get too excited,you will have to roll the car at least 6ft, (or 3ft in each direction), with all the car weight down,to settle the suspension.
The OP is way too green to be tuning air bleeds and emulsion, and that's if his carb is adjustable.
Certainly he can drill and tap all that stuff and make it tuneable, but he's better off paying someone like Thumperdart on here and over at moparts to do it for him.
I'd leave the gears you have in there. A bit taller tire. And let it go. If it's not you daily driver, what's the difference between a well tuned 12-13 MPG with what you have, or 16-18 if you go to taller gears. You'll give up a butt load of performance with less gear.
BTW, higher numerically is a LOWER ratio. For example, a 4.10 is a LOWER gear than a 3.55. It is higher numerically but the ratio is lower. You are always better off specifying ratio than numeric value. Sometime in the 1990's the numeric value started getting tossed around and has become a bad habit.
We looked at the carb today and my friend agreed that the 750 is too big for this motor. jets in it are 72 and 80. Pouring fuel in. I just ordered a new Holley 650 double pumper and gasket set. He's gonna help me set it up and dial it in. Also on your recommendation we are gonna change the timing. He's been racing for years and definitely know what he's doing. I'll let ya know how it shakes out. Later.I would try more Initial and less total.
Bump it to 16* initial and see how she likes it.
Limit total to 36 or less.
What heads? Is the distributor a MP part? Or a stock unit?
We looked at the carb today and my friend agreed that the 750 is too big for this motor. jets in it are 72 and 80. Pouring fuel in. I just ordered a new Holley 650 double pumper and gasket set. He's gonna help me set it up and dial it in. Also on your recommendation we are gonna change the timing. He's been racing for years and definitely know what he's doing. I'll let ya know how it shakes out. Later.
There is no way that carb is too big.
Good luck.
Hey, that formula works on Chebbies!
Agreed.
What happens when and if the 650 runs rich? If it's a DP carb, you can almost plan on it.
I know plenty of people that have been racing and into cars for a long time that can't tune a carb to save their life. Ignition timing is A number 1 on the list to get correct, then work on the carb.
NO WAY is a 750 too large for what you have. The tune up is a mile off.
Hey, that formula works on Chebbies! LOL, fixed itHey, that formula works on Chebbies!
Hey, that formula works on Chebbies! LOL, fixed it
It was supposed to be a poke at Chebbies not being able to use as much carb as Mopes, on account of our superior design.Purely posturing