[black66]

I have set my initial to 18 degress with a total advance of 36. Below is a chart of how my advance is set.....

11.7 compression
245 duration, 600 lift comp roller cam (640 lift with roller rockers)
Mighty Demon 750 ( just put on and love it...!!!)
110 VP Race gas 100% all the time....!!! (It's free so why not......!!!!)


Here are all of the advance settings for my distributor. Being that I have a 3200 stall. The advance setting I used has full advance right around my stall speed. Any thoughts would be appreciated....





I took my car out and it seems to be running a little flat. I also just put on a Mighty Demon 750 Carb with mechanical secondaries. It has a slight hesitation when I take off at a normal speed. And at around 2800 RPMS and 60 mph it seems to be surging a little....

Back to the advance setting..... My car actually seemed to run better when the intial timing was set at 14 degrees and total of 36. But maybe I need to just get it dialed in. So do I want single stage or dual stage advance. I have the dual stage at first. But Demon says to bump the timing up to 18 initial so I decided to try the single stage. And help with this would be great.. Thanks.....

Dave

[lluciano77]

Use the orange and pink springs. You want your timing in as quick as possible. Use as much initial advance as you can without the engine detonating or kicking back on start up.

Don not use a dual curve spring combo. Like I said you want it all in as early as possible.

18 initial and 36o total sound about right. Check your carb tuning. you may need to jet up. Surging is usually caused by a lean cruise circuit. Jets are for cruising.

[black66]

Ok lluciano77 I put the orange and pink springs in. The car runs great. A lot more bottom end. The acceleration is incrediable. And the car has the best throttle response it has ever had......!!!!! I notice that there is actually another spring combination that would give me a quicker total advance than Orange/Pink.... Pink/Grey spring setup... Maybe I should do some more experimenting.....

Also about the carb running lean/rich. My tail pipes have more black exhaust residue than normal. It almost seems as though my car is to rich?

And my motor only has 1300 miles on it...... What is the average break in time for a small block chevy.....??

Thanks......

Dave

[lluciano77]

I'm sorry, I was reading the chart wrong. I meant the pink and grey spring combo would be best.

Your engine could be running rich. You could lean the jets down two sizes at a time. See if there is any surging at various engine speeds. As soon as you feel the slightest surging, go up two jet sizes and try running it there for a while.

The best place to tell if you are running to rich or lean is actually at the headers. Take off a header and look on the inside just before the head surface.

[black66]

I put the grey sping in. Car seems to run great. But I still have the surging during in-town cruising and freeway speeds. Also on my Demon Carb I am not getting any noticeable change when I adjust the four corner idle screw? My car is running on a average 12 degrees cooler. So all of this leads me to think it is running to rich? Any thoughts? Can the air/fuel screws lean it out enough to run the stock jets? This is my first true "double pumper" carb. So I am not up on the tunning quite yet....

Thanks.....

Dave

[lluciano77]

You have your ignition timing nailed. Now it is time to focus on the carb

It sounds like you either have a fuel leak, or your float levels are too high.

Do the metering blocks feel really cold to the touch as the engine is warmed up and running?

Did you follow the instructions from BG on setting the throttle postion?

[black66]

I did follow the BG instructions to a "T". But because my four corner idle screw adjustment did not give me any noticable change. I had to adjust the primary butterflys to obtain the proper idle. Now my car runs great at WOT. It is just when i am crusing in town of the freeway I have the surging. BG Tech support said it is either floats or jets. But I have also noticed my car smells more "gas-ee" than normal..... I am going to take the carb off tonight and put it back at the specified setting as called for by BG instuction sheet....

Now as for the floats. What is the proper way to adjust them? And if the floats are to high or low what type of issues will I notice...??

And what can you tell from the temperature of the metering blocks?

Thanks.

Dave

[black66]

I took the carb to check the butterfly settings in comparison with the transfers slots. I put them back to BG specs for ideling under 1000 rpms. Now my car likes to idle around 780-820. But with the carb set to BG specs. The best I can get is around 550. And that was with turning the air/fuel screws almost all the way in. And messing the four corner idle screw The manual says I need to run the air/fuel screws 1 to 2.5 turns out.. The float levels are:

front float is a little under half. The rear float is at half....

Right now I turned the screw in on the front butterfly's to get the car to idle.

Also when I had the Edlebrock carb on before the Demon. I was running my pcv valve connected the carb. I had it also hooked to the demon's rear vacumm port. I am assuming I do not need this at all? I only had it before so I was venting the block. But I have a valve cover air cleaner so the motor can breath. But back to the pcv valve. The hose was did not really have a good seal at the pvc valve. So I might have had a small vacumm leak. Could the vacumm leak cause the surging at cruising speeds..... The more I mess with this I seem to lean towards re jetting...

Thanks a bunch....

Dave

[lluciano77]

Run the PCV again. Venting the block using breathers isn't enough. You will get better ring seal and reduce oil leaks. A PCV is a must on a street driven vehicle.

I have never run a BG carb. I don't know what the correct fuel level is. Just go with what they say.

If you have everything tuned to their specs, you can try working out the jets. Cruise at steady speeds in 10 mph increments. Lean the jets down until you feel surging. Then go back up two jet sizes.

[black66]

Thanks for the help.....

[black66]

I lowered the floats. The car runs even better when I stomp on the gas. But cruising speeds and highway speeds still surges.... So jetting will be the next step.....

Dave

[black66]

Well I found my problem..... I went to Summit tonight and purchased new primary jets. Took the carb off and went to change the primary jets and noticed the primary jets in the carb where # 84. I thought that is funny..... That is the same jet size as the secondaries.... So off came the secondaries bowl. And wouldn't you know it..... The jets where backwards from the factory. Switched those bad boyz around and bingo... Car seems to be running 100% better. Cruising speed has no surging. And WOT is right on the money....

Thanks for the quality control BG......!!!

Dave

[lluciano77]

That is awesome!

Someone must have assembled that one first thing in the morning, (before the coffee had time to work its magic).

Either that or at the end of the day. "WOOHOO its FRIDAY! I'll just slap this last carb together and its off to the local watering hole!".