Got the back firing solved...

[Brian N.]

Seems the carbs were set WAY too rich. When I finally got them dialed in, as best I could, the jet is actually about a quarte turn from its top, as view when the damper and piston are removed.

Also, the slow idle screws are all but a half turn from bottomed out.

Turns out this all means the throttle shafts are worn and leaking lots of air. This proved true. The test is to squirt some carb cleaner on the shafts at their point of exit from the carb body. If the engine RPM changes, air is otherwise getting in. The far front seal had LOTS of air getting in.

Seems I can dial in the carbs to compensate, and things apparently run OK. But the choice is either to a) do nothing else. b) get the premium rebuild kit and also service the shafts/bushings, c) send them to Joe Curtto or some other qualified rebuilder, or d) shell out the bucks for a new set of HD's.

Has anyone been down this road and can give advice?

 

[piman]

Hello Brian,

A quarter of a turn from the top is well off the standard setting. It should be two full turns down from flush with the bridge.
You may be setting the idle mixture correctly, compensating for the air leaks, but if the correct needles are fitted and installed as they should be in the piston then your mixture should be far too weak when the throttles are wide open.

I would suggest that a rebuild kit is the way to go, and not too difficult to fit. The kit contains a new throttle spindle, spindle bushes and seals for the HD6 and should restore the carburretor(s) to A1 condition. I went this way on a triple HD8 set up I once had.
I will repeat, because of it's importance, advice I have given before about not using any type of abrasive cleaner on the piston and inside the dashpot, just use a solvent to clean them.

regards,
Alec

[ 11-22-2003: Message edited by: piman ]</p>

 

[tahoe healey]

Have you checked the needle position? They may be up too high. Or they may be the wrong ones. Check that before you spend money.

 

[Brian N.]

Alec,

Thanks for the thoughts.

You point out exactly the problem with air leaks. The Idle mixture can be dialed in, but the running mixture becomes way off.

Settings can only compensate so much for other defects.


Also, as worn as these carbs seem to be, there is no telling how off spec the needles might be. They appear to be mounted correctly, and look OK, as do the jets, but there is really no way to tell for sure without comparing to correct needle profile. Just because there are no obvious worn areas or out of round orifices does not make it certain.

If I get the rebuild kit, which jets/needles should I get? Are there options you would suggest?

The rebuild kits seemed kind of expensive. About $200 for this car. Does that sound right?

Thanks for your adivce.

 

[piman]

Hello Brian,

yes I suppose that is right, I'm guessing (I am no Healey Specialist) that your car is a 3000, but all HD6 equipped Healey's use a CRK 217 rebuild kit, £35 each on my ten year out of date price list.
There is a lot of parts in a rebuild kit, gaskets, jet, jet spring, throttle spindle, bushes and seals, throttle disc and screws. It does not include the needle which should be a non wearing part anyway. The standard needle is a AUD 1112 (CV).

Alec

[ 11-26-2003: Message edited by: piman ]</p>

 

[Hangtown Healey]

I would get new carbs from Midel in Australia. With the exchange rate, they are cheap.

 

[piman]

Hello HH,

what do you call cheap?

Alec