Please Help, Need info on High Alltitude Carb Settings!

[green73brc]

I plan on going on my first high alltitude run next monday. It will be a peak of 9500 feet. I have a stock 2bbl 302 c4 if any of that makes a difference. The trail will have minimal off camber situations if any at all. Will i have any trouble with my carb? Is there anything i need to do to it to get it working?

Thanks

Eric

 

[Skuzzlebutt]

Well...
Your carb will probably be OK. If you were permanently moving to 5000+ alt, you would probably benefit from rejetting it. But that's alot of trial and error work for just a visit.
What you can do is lean out the idle mixture a little, and advance your timing a bit to help throttle responce. The thinner air effectively lowers your compression, ergo reducing problems with detonation.
Make sure your air filter is very clean and that your choke is opening all the way when hot.

 

[green73brc]

cool i have a k&N so i will make sure it is really clean (was going to anyway but now have a really good reason)

and i ran a carb cleaner last night to make sure everything is nice and clean...


everything will run rich right? since the air is thinner meaning more gas less air....

i know how to advance the timing but i have not messed with my carbs ever for fear of messing them up... so how do i

"lean out the idle mixture a little"?


and how to i see if

"your choke is opening all the way when hot."?

 

[VBH289]

I live at 8000+ feet, and here is what I do when I go 4x4ing and get above 11,000. If I stop somewhere to take a break and my bronco has been a little doggy, I start it, idle it, and turn the adjuster screws to rich one turn, then turn back slowly just until it starts to die, then I turn it back slightly and it is happy to go!

 

[green73brc]

I live at 8000+ feet, and here is what I do when I go 4x4ing and get above 11,000. If I stop somewhere to take a break and my bronco has been a little doggy, I start it, idle it, and turn the adjuster screws to rich one turn, then turn back slowly just until it starts to die, then I turn it back slightly and it is happy to go!

thanks... any other pointers... i will be going alone so it is nice to have a little confidence under the belt

 

[Rustytruck]

If you had the time you could rejet the carb 2 sizes smaller or at worse you could induce a vacuum leak. Rejetting a carb on the trail is not my kind of fun just make sure you have the gaskits to put it back together. The old 289 engines in cars had a little valve on the pvc line you pop open at high altitude. Fords way of high altitude compsation. ( OLD School) The problem is it leaks unfiltered air. You could leak air from behind the air filter to a small valve and then to manifold vacuum but you would have to use a vacuum guage to adjust to the proper air leakage. Just adjust the valve to get the highest steady vacuum reading like you would adjusting the the carb needle screws. as soon as the vacuum needle gets a little squirrly close it back down a little. The best thing you could do for the engine is get a set of Autolite plugs as they have a very open porsalin area for anti fouling and that will really help at high altitude. Just remember to reset everything as soon as you get below 5,000 feet you dont want to burn a valve or cause excessive detonation.

 

[mtkawboy]

Mark the distributer base and the block at the present timing with a timing light then again +4-6 degrees then put it back stock before you leave. Bring a distributer wrench which you will need to get this far too. When you get up high just loosen the distributer hold down clamp & move to the +4-6 degree position, no timing light needed. Follow the above advise on the idle screws or if you have the ability which it doesnt sound like you do bring 1 or 2 sizes leaner jets & change them too. You can get by doing nothing, it will be just down on power a little which it will be no matter what you do. As far as the choke just take the air cleaner off and make sure the choke plate is wide open when hot, not partially opened. Give a shot of carb cleaner all around the choke assymbly before leaving. Nothing like the high country!