High tick over

[427jlc]

Hi all, I’ve just swapped out a 770 street avenger for a 650 double pumper. I’ve upped the jets on the primary and secondaries as I took the 650 off initially as the Cleveland was running out of fuel at top revs!

Since then I’ve changed the carb to a bigger one but also has a fuel sump fitted to the fuel tank, I should have just done this first and stuck with the 650 maybe?? Hence why I’ve swapped back.

The problem I have is tickover is 1000 - 1100 but I’m wanting 800’ish.

So easy to say turn the idle screw off but I’ve set the carb so I can see a square transfer slot under the butterfly’s so I don’t get an off idle stumble hence why I don’t want to touch it yet

I’ve moved the carter fuel pump as it’s a push pump to the rear of the chassis, so I get the 7psi into the carb.

I’ve set the air mixture screws to 1 1/2 turns out as a start, gonna is a vacuum gauge when the timing is sorted. This engine pulls around 21hg of vacuum.

Timing is the next one but what should I be at static and at 3000 rpm for the 351c Cleveland??

What else can I do to get the revs down??

Lee

[RogerKnill]

The square transfer slot is on the primary only, right?

I’ve set the primary to square, and use the secondary to set the idle.

I’ve changed out the secondary stop screw for a Allen grub screw so you can adjust it without taking the carb off the engine.

[427jlc]

Thanks Roger, I’ve seen that screw but what size is it to replace with a grub screw?
Also I have set a square on the secondaries transfer slot, do I need to shut off the secondaries or do I keep opening it until the revs drop?
I was also wondering maybe stupidly, if I was to reduce the size of the primary jets think less fuel would reduce the revs?
Thanks
Lee

[RogerKnill]

Close down the secondaries to get you idle speed whilst keeping the primary transfer slot square. If you’re at 100/1100 it won’t take much to get it down. From memory the secondary throttle stop screw is a 10-32 unf.

reducing the primary mains won’t have an effect on idle fuel

[Eggbert]

As you were changing carbs, could a vacuum line become cracked or broken and is leaking air?

If everything else fails, you could check your timing. Too much advance at idle will cause the idle to be high. How your vacuum advance is connected can cause issues at idle, but after that, everything stays the same.

Just speculation on my part in the event you get nowhere, but it really should be an adjustment on the carb as the others have mentioned.

[jon1d]

You have a good vacuum so not a radical cam over lap in 14-15 hg so am surprise achieving 21 hg why you need to open up the secondary.
Check your choke is not in if manual.
PSI for pressure is 5 to 6 psi from Holley.
I would also remove your needle valves and clean and check for debris.

[427jlc]

Thanks Roger, for the record it’s running a 268 cam, with no advance or retard as it’s not an aggressive cam. Roller rockers and dual plane manifold.

I’ve ordered a grub screw.

A friend commented that my engine is running strong vacuum 21” was the number but may even be 24” of vacuum as it was so long ago!

Once the screw turns up I’ll update you, thanks

[427jlc]

Thanks John(Egbert) I have left the carb alone until the grub screw arrives, I did back of the timing just by feel and watching the revs drop, got it to 800 but acceleration at top felt lean, so I’ve move the dizzy back towards its original position but not quite there, I’m at 1000 rpm until me little grub screw arrives.

No air leaks but with the 770 running so rich I’m gonna throw a set of new plugs in as well.

Once I have the carb settled I’m going set the timing once I find out where I need to be
Cheers

[427jlc]

…..and Jon1d, thanks as well- I believe once I settle the carb the timing needs redoing, I’m going to get some time Tuesday morning to get the timing set and once done I can start to tune the carb.

Gives a couple more YouTube days!!

Thanks, Lee

[RogerKnill]

My static timing is 14-16 deg, 36 mechanical all in by about 3000, can’t remember exactly. I’m running an msd which has 22 deg of advance set in by the bushes ive used. Don’t know what the vacuum is set to but running from the ported source. These may need some mods dependant on the set up of your engine.

i would set timing first and then adjust the carb.

lets us know what you get to .