TC's vs Altitude

[Bud Bradford]

Hello anyone, Anyone have experience with the TC at altitude? We live here in NC mountains at approx. 3400 ft, the TC runs fine but when we start up into the higher peaks the trouble begins. At approx. 4700 ft. the power begins to tail off and then at about 5000 ft. the engine starts cutting out (missing). The cutting out is almost to the point of the engine stalling. Turning around and starting down everything comes back to life and is fine. Any suggestions?

Bud Bradford TC6761

[Dean Jensen]

Morning Bub I would look for a problems with the fuel, the gas vaporizing, the fuel pump not working, right, or the engine over heating. You may be getting fuel to the rear carb only.

Cheers
Dean

[Skip Kelsey]

Bud:

Try running EM needles. This is a classic problem as you go higher in altitude. The problem is further exacerbated if you are running without the stock air cleaner, or no air cleaner.

Cheers:
Skip Kelsey............................

[CFritz7001@aol.com]

Skip,
Don't you mean AP (lean) needles??? EMs ar the RICH ones, and the problem would seem to be that he's alredy running too rich because of the lower air density at altitude.
Regards,
Carl Frits

[Skip Kelsey]

Carl:

You are absolutely correct. The leaner needles are called for. I cant think of what went thru my mind. Thanks for catching that. You should also go much farther advanced on your timing. The higher you go, the more advance it will tolerate.

Skip...........................

[DickShaler@aol.com]

Bud, When both I and the TC were younger I would often drive it to Lake Tahoe and found that a change to *leaner* needles made driving more pleasant for the time I was up there. That being said I have also found that in carburated cars todays gasoline makes the altitude problem even worse.

Dick

[Dean Jensen]

Just thought of another thing, if you have a fuel filter on the inlet of the fuel pump, get rid of it, okay to put a filter on the output, the pump will have a hard time sucking the gas thru the filter when you are up high.

Dean

[Austin R. Baer]

We live at 7200 feet... I wonder what experience anyone's has had with 1-3/4" SU's on a TC(I've got an old pair from my Austin Healey that I - God help me - dropped a Corvette engine into in 1960). Machining some adapters is no problem. Any thoughts about better breathing? Change in fuel/air ratio curve with the bigger carburetor pistons? Thanks for any inputs (and I promise to keep the old ones strapped to the firewall for the next owner).

Austin

[Skip Kelsey]

Austin:

I run one and a half SUs, and have for about thirty years. If you do nothing else to the engine it is a waste of time. I am bored .100 oversize,head clipped to about 9.5-l compression,a crane cam, lightened flywheel, balanced engine etc. Now it does run very strong with the bigger carbs. I also run a derrington tuned int/ex. manifold. The result is that if I run even GJ Needles (TF) it runs too lean at speed. By doing a lot of experimenting,I came up with EL needles. THese work great. Max power and smoothness.

Cheers:
Skip Kelsey.............................

[Bud Bradford]

I want to thank everyone for their replies to my request for help with my altitude problem.

Bud Bradford
TC6761