BT7 carburetor - choke - fuel questions

[blueskies]

While getting around to the restoration of the 100-6, we have a nice restored 1961 BT7 to drive.

The engine was completely rebuilt during the restoration. Once warmed up, the engine runs well and has good power. However, it does start hard when cold. It starts and then sputters and quits. Giving it gas with the foot pedal may help but also may cause it to stall; still working on developing the best cold start procedure. After repeated starts and stalls, it warms up enough to run on its own. Also, when slowing to a stop, the engine may stall if one does not pull out the choke a bit.

The previous owner (a pilot) told me that he preferred to run 100 octane low-lead aviation fuel in the car. When he used premium pump gas, he added octane booster to get it up to 100 octane.

It looks to me as if the choke cable only leads to one of the two carburetors. Should the choke only work on one of the two carburetors? Or should there be an (internal or external) linkage between the carburetors that activates a choke on the second carburetor?

Should I live with the hard cold starts and having to use the choke when slowing to a stop, or is this just a matter of carburetor adjustment? I don't recall having these issues with my first Healey, although that was a while ago.

How about the 100 octane fuel recommendation? I don't know what pistons or compression ratio the engine has, but it seems to me that it should run fine on premium pump gas. Or am I wrong?

 

[Brinkerhoff]

Its a choke issue. Check the shop manual for your specific carbs. Both should be choked.

 

[vette]

Yes you have a choke issue but also, maybe some carb adjustment to do as well. If your car is starting the way you describe then you need to get chokes to come on more and consistent on both carbs. You can also check the Moss cataloge to see the pictures for what choke cable arrangement you should have. Then the other issue you mentioned is that it wants to stall when coming to a stop unless you pull the choke out. That leads me to believe your carbs might be alittle lean. But that also depends on where your choke is set at. If when you pull the choke out it is merely pulling on the fast idle screw to increase the rpms to keep it from stalling that is one thing. But if your choke cable is adjusted closely enough to where it should be and with that it is enrichening the jet (as what a choke is suppose to do) then the enrichening which is keeping it running means it is too lean to begin with.
Read in the manual how to check the carbs for leaness and set the choke up properly and it will tick over and idle easily and not stall when you stop.

 

[blueskies]

Thanks for the helpful replies, Brinkerhoff and vette. vette, I assume by your handle that your interests extend beyond Healeys; that seems to be a common problem.

Any comments on what octane fuel the Healeys like best?

 

[Brinkerhoff]

I run 93 octane.

 

[vette]

If it has wheels (preferably 4) and a motor I like it. Attached are some pics of the things that keep the vital juices flowing. About the octane, I have never run anything less than 91 octane in my Healey. I think I have the high speed cam in my Healey from the previous owner. I runs well on 91.
Red Vette is an original 350/350 hp with 11:1 compression and it definately does not like 89 octane. It will ping alittle at high rpms, and then deisel when you shut it off. With 91 or higher it has none of those problems. Dave. Oh, I should mention, there are a couple of fishing rods over in the corner of the shop.