Building a 10.5 cr 440, closed chamber aluminum heads and setup for quench. Planning on running on the pump 94 octane I can buy 5 minutes away from my house at the local gas station. However I am also setting the car up to be able to take some longer road trips with - overdrive trans, a/c, cruise. I'm concerned because it's quite likely I will end up needing fuel and be in a small town that only has 87 available, 91 if I'm very lucky.

What do you do? I would bring along some race fuel to mix but I run an o2 sensor and I hear lead's no good for them. And 100 octane unleaded race fuel won't get me that far with mixing. If not that, then bring along the timing light and back the timing down 10* or so and go easy on the throttle while you burn the 87?

Flat ground or hilly? Altitude? Cam specs?

O.K., a couple of ideas.They may not be the ultimate answer, but they're free/cheap.First: Run the coldest heat range plugs that don't foul.You can change them in only one cylinder at a time to save $$$ on plugs while determining which is the coldest it will tolerate without fouling. Second:Go to the aquarium supply section of your favorite retail outlet,and get one of those air distribution/gang valves for a fish tank air pump.{$3-$4}. "T" into your vacuum advance line going to the distributor and run the line inside the car to your remotely mounted valve. Bleed off enough vacuum from the advance to prevent detonation on cheap gas. Remember,you're not a"cheap a$$",you're innovative.

I don't know about 87 but 91 works. I drive every year with my buddy from Phoenix to Las Vegas to Mopars at the Strip. Our ride is his 64 Fury convertible. 440 w/eddy heads,10.7-1,234@.050",cross ram w/OE 3447 Carters,3.55,5 speed Tremac w/od. Runs fine even at low speed in high gear.
Doug

you could probably use 87 for farting around town but as soon as you get into it...it will ping. Then when you get to the track you will have to use 110. So I'd try 89 1st then 91. You should be ok w/ that. FWIW I was using 93 on the 10.70ish:1 440-6. I only had the timing at 36* no problems. I was going to add 3 gallons of 110 at the track and bump the timing to 38*

If you run .039 quench and pay attention to all the details like grinding and polishing all the sharp edges in the combustion chamber and valve reliefs to eliminate hot spots I think you could get by with it. Camshaft choice would be a big player as well. You would not want to get too aggressive with the timing curve and a cooling system that can keep the temp under 180 wouldn't hurt either. My 493 is set up the same way but only 9:1 and it works great on 87 all the time.

Kevin

Cam timing and cylinder pressure will determine if you can get away with it.Having some way to get cooler outside air into the carb will help as well.
Worst case you disconnect the vacuum advance and retard the timing 4-6 degrees.

another thing is if you can plan where your gas stops are going to be. Fill up at the last place that is known to have 93 even if it's only been a 100 miles since the last fill up, and if possible don't run the tank low on 93 when you put in 87. diconnecting the vacuum advance could help alot too.

"diconnecting the vacuum advance could help alot too"

who runs a vac advance anymore???

Cam would be a comp xe275hl, around here it's pretty flat and usually around 1000ft above sea level.

Main problem is, the last known place that has 94 is the place 5 minutes away from my house. It seems only a select few places in Manitoba sell anything higher than 91. 91 is the standard 'premium' most places sell, however I have been through some towns where even that is not available, just 87. I'm fairly confidant I'd be fine if I fueled up everywhere 91 or higher was available, but you just never know right...

10.5-1 on alum heads with proper quench and that cam will likely tolerate 87 while cruising.Worst case you back down the timing a little.
Having some kind of cool air intake to lower the temp of incoming air goes along way.
You could always swap in some heavy advance springs in the distributir to slow down the timing advance as well.

Retard the timing until it barely moves and only put in enough gas to get you to the next station with high octane.

Why not just keep a couple bottles of octane boost in the trunk when you are driving far from home. Be a lot easier then messing with tubes, hoses and such.

Mark

I go back to the cam choice. You do not want to build too much cylinder pressure. So, you can talk to a few on this board about that. It is critical to make sure that you adhere to the quench plan. After that you can push the envelope a little on cylinder pressure. I've heard about 180 is the max but I could be wrong. Your "normal" or average density altitude and cooler ambient temps come into play as well.

As others have already posted, cylinder pressure & cam overlap will dictate the CR teh engine's actually experiencing. Based on my fairly similar combo, I don't foresee much success with 87 unless you pull so much timing out of it that the MPG drops like a lead balloon. That said, I've been in that spot before, and I just "drive around it" as far as RPM/load/speed for the most part, but in some situations that's almost impossible to do.

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What do you do?

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I keep a bottle of octane boost in the trunk at all times.

Just people that want to get more than 8 mpg. Anybody that thinks a vacuum advance hinders performance doesn't know how it works.

Kevin