Minimum octane for Windsor class engines?

With gas prices headed for the $3 mark for the summer, what's the lowest recommended octane rating for 289/351W engines? I know... the lowest I can use without knock, but would like to know what is actually recommended. Thanks. Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike
Loading thread data ...

I can retard the timing on my 8.75:1 302 4v to 5-6deg initial, using a curve that gives full advance by 3500, and cannot use regular unleaded without a ping somewhere in there (at 550 ft. elevation).

However, it is always set for 10-12 deg. initial, with full advance by about 2800. I run 89, and time it for 89 by ear. I get better mileage with a more aggressive timing curve. More vacuum, and better response. $30 for 200 miles sucks, but it could be worse..

Whaddyouwant for 8 carbed cylinders......

When gas prices spike, I drive the beater more, thassall

Reply to
Wound Up

Thanks for the info on the racing stripe, I'll try waxing it today!

When I bought my 02 GT it was in July so the weather was pretty warm here in Orlando, I was using regular grade 87-89 octane with no problems there. But when winter came and the weather started cooling off into mid 30-50 deg reange my engine started knocking. I brought it back to my dealer and they checked it out and "re-flashed" the computer since then I don't have much problem this winter using regular gas. I will here a knock if I lug the engine.

Reply to
Adrian Gruber

Thanks for the suggestion, but we cannot re-flash carburetors and distributors.

Reply to
Wound Up

There are a lot of factors involved, so there really is no simple answer. Compression ratio, valve timing and overlap, and ignition timing are major contributors. But cylinder head temp, ambient air temp, barometric pressure, humidity, and engine load all play a role. My dodge does really well on mid grade, especially in the winter. But if I'm towing a moderately heavy trailer I add a little premium or it will knock. My '74 302 (in my '66) never knocks on the cheap stuff - it has 9:1 compression and an RV cam. The 427W in my cobra needs premium.

Reply to
.boB

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Reply to
Wound Up

FWIW... the manual for my '67 recommends 99.8 octane for the A-code 289. ;)

This was before they started using the R+M/2 value, so subtract 10 points, as a rule of thumb.

Reply to
Wound Up

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Hey! Spikey Likes IT!

1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok Vintage Burgundy w/Black Standard Interior Vintage 40 Wheels 16X8" w/BF Goodrich Comp T/A Radial 225/50ZR16
Reply to
Spike

Prolly a good thing, you'd take it out and play with it.

| | Hey! Spikey Likes IT! | 1965 Ford Mustang fastback 2+2 A Code 289 C4 Trac-Lok | Vintage Burgundy w/Black Standard Interior | Vintage 40 Wheels 16X8" | w/BF Goodrich Comp T/A Radial 225/50ZR16

Reply to
SVTKate

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.