How bad is your gas mileage?

[TLHanna]

IMO the range is the important thing. If you can't afford to put has in it then get something else but who wants to stop every 100 miles.... or less?

[S1965C]

Thank you, Mark. Surprised that with the two light springs your total timing is not all-in well before 4,000rpm. Agree that MSD caps and rotors are an annual maintenance item.

[Moritz55]

Originally Posted by S1965C

Thank you, Mark. Surprised that with the two light springs your total timing is not all-in well before 4,000rpm. Agree that MSD caps and rotors are an annual maintenance item.

Thanks... I think Roush says RPM should be above 3500 or 3700rpm .. so I just run it around 4000rpm .. to assure Full Advance ...

[patrickt]

Originally Posted by Moritz55

Thanks... I think Roush says RPM should be above 3500 or 3700rpm .. so I just run it around 4000rpm .. to assure Full Advance ...

You want all the timing in by 3000 rpm, but you should check the total timing at 3500 rpm. Often times magnetic trigger distributors back up a degree or two by 3500 rpm. I don't know why, but they do -- it's just one of those things in life that is hard to figure out. Kind of like why Superman could stop bullets with his chest but would still duck down when the bad guy threw the empty gun at him.

[renaissance man]

I'm late to the game here but, wanted to chime in and get some opinions:
I'm running a '65 K-code 289, 4-Speed Toploader and a 4.10 rearend. I'm getting about 10 mpg. My car is running 4000 rpm at 70 (peak torque @4500 rpm) and 4400 rpm at 80 mph. Isky Racing Cam. Super fun and loud! Anyone think I should drop to a 3.73 or even a 3.55 since my 4th gear is 1:1 ?

[HTM101]

Originally Posted by renaissance man

I'm late to the game here but, wanted to chime in and get some opinions:
I'm running a '65 K-code 289, 4-Speed Toploader and a 4.10 rearend. I'm getting about 10 mpg. My car is running 4000 rpm at 70 (peak torque @4500 rpm) and 4400 rpm at 80 mph. Isky Racing Cam. Super fun and loud! Anyone think I should drop to a 3.73 or even a 3.55 since my 4th gear is 1:1 ?

The answer to your question is another question. Do you think you want a different rear ratio?

A 3.73 will bring your 80 mph rpm to approx. 4,050, not a big reduction. However, the 3.55 may be a good option.

[renaissance man]

Originally Posted by HTM101

The answer to your question is another question. Do you think you want a different rear ratio?

A 3.73 will bring your 80 mph rpm to approx. 4,050, not a big reduction. However, the 3.55 may be a good option.

@HTM101 I will have to consider a 3.55. I love the sound of this engine at 4000-5000 rpm. I think I did enough due diligence with putting in the ISKY Racing Cam and other components to handle this. The 4-Speed Toploader was a must for me with it's 1:1 4th gear. I was mainly concerned with engine stress over mileage. Like I said, I hope I did enough to enjoy it at these higher rpms? The 4.10 rear, from what I've read about it is very desirable. I will just keep up maintenance and upgrades in the future. It's just too glorious sounding at 80mph!

[HTM101]

I have a big block with a wide ratio Toploader. My rear ratio is 3.70 and is adequate for where and how I drive. 60 mph is 3,000 rpm, 80 is 4,000.

I rarely drive on an interstate and took that into consideration when I installed the Toploader. However, if I were on an interstate a lot more, I'd keep the 3.70 rear and install a 5-speed.

I average 7 mpg.

[IMG][/IMG]

[RockBit]

I have a 482 cid FE, 3.54 rear, and TKO600 with .64 5th gear. In the city I get 8 mpg on 93 octane pump gas, and I get 12 mpg on the highway. It purrs along at 2,000 rpm at 70 mph.

[patrickt]

Originally Posted by RockBit

I have a 482 cid FE, 3.54 rear, and TKO600 with .64 5th gear. In the city I get 8 mpg on 93 octane pump gas, and I get 12 mpg on the highway. It purrs along at 2,000 rpm at 70 mph.

I'm 35 cubic inches smaller, but otherwise I'm exactly the same on all the other numbers. And I really enjoy when I'm out on a remote highway and have the road to myself and hit the "quiet spot" in my revs, at about 2200 RPM, and just cruise at 75 MPH. It actually restores mental health.

[RockBit]

Originally Posted by patrickt

I'm 35 cubic inches smaller, but otherwise I'm exactly the same on all the other numbers.

That’s very encouraging. It implies mine is tuned ok since I know yours is.