80 SG, what jets at altitude?

[dbeardslee]

Normally you don't need to seal them - the rubber seal usually works pretty good. You can tell if they're leaking by spraying some starter fluid around the boots where they mate to the engine (while it's running, and with a fire extinguisher handy). If the rpm's rise when you spray, they're leaking. If they are leaking, ford 2.3 L thermostat gaskets can be cut down to fit, or permatex ultra copper works well - just make sure you let it cure fully. There's actually a little convex arc to the flange on the motor, so if you see a little light when holding the boot's flange to a flat surface it's to be expected.

[Bonz]

Thanks much, I'll get it up and running soon!

[TopCatGr58]

Hey Hbonser,

The screws on under the caps are NOT air screws, they are fuel/air mixture screws, CW is leaner, CCW is richer. There are very small washers and o-rings down on the ends of the screws. Their tips are not as sharply pointed as in the 78-79 series, and less likely to get stuck when you lightly seat them to count the # of turns out they are at.

The rubber on the intake boots ages with heat and time, and once you break the seal, you may even see some rubber come off with their removal. I would use some sealant when I put them back on, for insurance if nothing else.

ALso, if you headers are stock, they are double walled and so you would not see any color change if you were lean or rich, since the inner wall gets all the heat, the outer layer is the show layer!

Yeah, with a nice little black layer around the base ring of the plug, and white insulator, sounds like you are spot on. Does the throttle fade any in near redline??
T.C.

[trbig]

Seems to me that you came on here asking jetting suggestions, then shot down everyone's suggestions since you thought everything was currently good? I don't get it. Seems all you REALLY wanted was for someone to say, "Your setup should be just about right."

As TC stated, the stock pipes are double walled, but will still blue if the bike is running too lean. If you want to see if it's lean, go take a run up to 7-8k rpm and chop the throttle. As it's slowing down.. does it pop and backfire? No? Then leave it alone since the mileage is good.


Tod

[CatatonicBug]

I have to respectfully disagree with vacuum timing advance negating the need for re-jetting at altitude. Timing advance has nothing to do with how much air/fuel is mixed and sucked into the engine. As we know, timing is critical to the overall performance of the engine, and ours was ahead of it's time in this regard. But timing advance never was nor will be able to compensate for lack of oxygen in the air, and the subsequent surplus of fuel through the fixed jets in a carburetor at altitude.

I apologize. I coulda sworn I had read something about that last year, but I did a bunch of reading today and determined that I am totally wrong. High altitude causes a lean condition. Totally white plugs are too lean. They should be sightly tan.

[trbig]

High altitude causes a lean condition.

High altitude SHOULD cause a rich condition. Less oxygen in the same volume of "air".


Tod

[CatatonicBug]

High altitude SHOULD cause a rich condition. Less oxygen in the same volume of "air".


Tod

I'm battin' 1000 here today... Yeah, Altitude = rich.