Demon 750 Idle

[Geed_up_442]

I recently had to drill a bolt out on my intake which involved me having to remove distributor carb etc. Since then i've had to replace the coil. My carb is a Speed Demon 750 w/ vacuum secondaries. Well i've got everything back together timing is almost right but I've got a few hick-ups. After pumping the throttle linkage a few times after i finally do get the car running it idles pretty high 1500 is the lowest so far. When i give it gas it stumbles or hesitates then picks up speed and holds for a min before slowly reving back down. And The motor shakes excessively, so much to where it shakes the battery. its got 4 corner idle mixture screws all are set 1 turn out right now but i've played with it from all the way in to 2.5 turns out.

My cam is comp cam 284h so i expect it to be lopey. I've had the car running fine a few weeks ago so i dont want to change anything unless its absolutely neccessary. I'm removing the carb tomorrow to take a look at the power valve and set the butterfly blades to the transfer slots. I don't have a timing light but i'm working on getting one this week also so i can talk real numbers eventually. Spark plugs are new but i'm pulling them also to test. plug wires and distributor are new also.

I want to be sure i'm going about this the right way and that I'm not over looking something. Thanks

 

[mebe007]

I had a speed demon 650 vs carb and i had tons of idle problems. mine always seemed to be related to the electric choke. removed it and it was fine. now others have had many issues with flashing still in the metering blocks. it would be worthwhile imo to drop the bowls and have a look at the metering blocks. Also are the floats adjusted properly?

 

[Geed_up_442]

I've rebuilt the carb twice. Fuel bowls are right below the sight glass. metering blocks are all good. i dont have an electric choke on it.

 

[mebe007]

Thought with the demons there are 3 lines on the fuel bowl next to the sight glass and it is suggested to have it right at the middle line which is pretty much middle of the glass, not that that would really effect the idle honestly.

 

[Geed_up_442]

I thought exactly like you, And i did have it set on the middle line. I had a guy from my local performance shop come out and see if he could work some magic and he set it right below the sight plug. But reading tonight i found that right below is okay for street. I would think that could be the reason for the hesitation but when i give it gas i clearly see fuel squirted town the barrels.

 

[mebe007]

Does it have the idle eze base plate where you remove the air cleaner stud and use a screw driver yo adjust another needle valve like air bleed? Mine did

 

[Geed_up_442]

It does have it. But it didn't have any effectnon the idle speed

 

[mebe007]

Are you sure your not a tooth off on the dist?

 

[Geed_up_442]

I'd Be lying if I said no. Ive got to get a timing light this week.

 

[565bbchevy]

1500 idle is very high for your application it sounds more like a timing issue it is probably extremely advanced but I would physically check all your hoses and make sure none are causing a vacuum leak and make sure all your plug wires on correctly due to the excessive shaking. You definitely need a timing light.