Idle RPM

[VTHealey]

Hi, Anyone know what should the idle rpm be set at for cold and warm idle SU HD8? New to forum, appreciate the work of BCF for hosting and wealth of info on threads. I was unsuccessful in finding decent replacement parts for choke cable assy. and don't like the hard pull of the cables and locking mechanism doesn't work so on cold start driving with one hand on choke, one hand on steering wheel and the 3rd hand on shifter. I measured 6 lbs force for each SU carb to lift the choke 0.375" through the cables. The mechanical cables have 4 90 turns, just not a good setup. I am replacing my manual chokes with solenoids (I don't make any changes that I can revert). As part of this exercise I want to set the idle rpm as it seems a bit high. Thanks!

 

[tahoe healey]

Idle should be 600 to 800 rpm. Something is wrong if you need to pull hard on the choke. The knob turns 45 degrees, you pull to desired choke and turn back to set till warmed up. Chokes are available at Moss,VB,AH Spares and British Car Specialist and others. I'm not aware of any 90 turns. It should just glide. Which Healey do you have?
TH

 

[RAC68]

I see others stating the idle for a BJ8 should be between 600 and 800 RPM and have always wondered how they achieved such a low idle. Since new, I have never come close to 600 RPM and find that 900 – 1000 is what my car seems to stabilize upon when warm. Yes, my compression is a little higher then spec and I do like to run a little rich, however, the BJ8 has a more aggressive cam and will never settle down to a steady low RPM as do pre-BJ8 models.

As far as the choke, a rather strong spring has been centered between the HD8s to pull on both choke arms through a “Y” wire. This translates to a hard pull on the choke knob. Some have replaced their spring and “Y” wire with 3 click-pen compression springs mounted on the choke cable between the choke arm and mounting fixture. This setup substantially reduces the amount of force required to activate the choke.

Hope this helps,
Ray (64BJ8P1)

 

[Keoke]

Hi, Anyone know what should the idle rpm be set at for cold and warm idle SU HD8? New to forum, appreciate the work of BCF for hosting and wealth of info on threads. I was unsuccessful in finding decent replacement parts for choke cable assy.

That is because you did not go to a bicycle shop and purchase replacement brake cable.



and don't like the hard pull of the cables and locking mechanism doesn't work.

Maybe locking mechanism is worn out and needs a new choke.


so on cold start driving with one hand on choke, one hand on steering wheel and the 3rd hand on shifter. I measured 6 lbs force for each SU carb to lift the choke 0.375" through the cables.

The mechanical cables have 4 90 turns


If you have 90 degree turns cable will not move

just not a good setup.


OH it is fine if the routing is correct which is just one large gentel curve to the balance block and a bit of lubrication.

I am replacing my manual chokes with solenoids (I don't make any changes that I can revert). As part of this exercise

I want to set the idle rpm as it seems a bit high. Thanks!

ON the car Tach cold idle with choke shrould be set so that the tach reads 1000 RPM [ no choke ] HOT!!--Fwiw--Keoke

 

[VTHealey]

Thanks for the info. When I said 90s, they are curves, but turns nevertheless. I will put in the solenoids and let you know how they work. Thanks for info on the idle.

 

[Bob_Spidell]

... I am replacing my manual chokes with solenoids ...

I'd be interested in seeing how you do this. Do you mean you're adding the 'automatic' choke like some models had? It takes quite a bit of force to pull an HD8's choke lever; there's a couple springs to overcome and the mechanism typically isn't very smooth. The choke lever basically acts like a cam against the jet diaphragm, and there's a lot of friction there (so much that the choke sometimes doesn't want to return).

FWIW, when I put a Pertronix Ignitor on my BJ8 the idle improved and I was able to idle the car down below 400rpm (it was lumpy, but didn't stall). The car idles solid at 750RPM, just fast enough so it runs on the generator and not on the battery.

 

[Johnny]

Thanks for the info. When I said 90s, they are curves, but turns nevertheless. I will put in the solenoids and let you know how they work. Thanks for info on the idle.

I went to Walmart and bought a cheap set of bike cables, they even have the black sleeving needed. They also come with some extra barrel type ferrules to place around the stranded steel cables. The ferrules make it easier to insert in the holes where the cables go through. I used a dremel tool with a little circular cutting wheel that slices through the cables easily without fraying them. Oh, before cutting the cables put a drop of "super glue" on the cables where you're going to cut them. After drying they'll help hold the ends together.

As for as the choke cable on the dash, I removed it and cut about 2" to 2 1/2" off the metal sleeving and then cut the cable, works much better now. This eliminates all the "turns" in the cable.

Good Luck.