Thread: Car is up and running but have a few problems!!

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ok i just put the heads on my 454. i also just purchased a Demon carb and have that on my motor as well. ok so the motor cranks just fine....initial timing is at 10....total timing i have no idea because i dont understand that whole thing.....anyway the car runs fine except she runs really really rich....the carb i have has a 4 corner adjustment.....so i break out the ole vaccumm gauge to set her mmixture and the motors vaccum IS ALL OVER THE PLACE and still blowing out black smoke. now this is where i need help.....
1. do i reset timing....i know some 454's need timing set to 8....(My 454 is basically stock...mild cam and no insane compression)
2. seeing that my motors vacumm is all over the place tha leads me to believe that i have a leak....i have looked and dont see anything that might cause this....but you have any ideas i will look into it.
3. off idol does the advance of the dist. (yes i have hei...vacumm advance) have anything to do with how rich she runs

PLEASE HELP THESE ARE THE ONLY THINGS I CAN THINK OF.....I AM SO CLOSE AND I JUST WWANT SOLID VACUMM AND A CLEAN EXHAUST
thanx guys

STREETS I HOPE YOU STUMBLE ON THIS THREAD......YOU ARE THE ONE THAT HAS BEEN WALKING ME THROUGH SINCE THE BEGINNING...AND YOU HAVENT BEEN WRONG YET....WISH I KNEW WHERE YOU WERE AT SO I COULD BUY YOU A CASE OF BEER AND BURN SOME MAMMAL FLESH IN THE YARD....I OWE YOU MAN.

When you put the Demon on did you check the float settings? If the floats are letting too much fuel into the bowl, it will flood itself and run erratically, which in turn will cause the vacuum to go nuts. Check all the carb settings, not just the idle mixture. Also, by any chance did the engine back fire through the carb when you were getting it going? If you so, you may have popped a power valve which could also cause some of your symptoms. A timing change from 10 to 8 BTDC should not affect a rich condition.
Hope this helps, good luck with it.

Pat

ok the bowl levels are fine....half way on the sight classes....i have played with the position of the butterflies and nothing really happened.....checked the power valves and they are fine.....the Demon i have has the blow out proyection already installed...
so now i am back to square one.....the car runs good just really rich
but now it has a really bad miss.....so i guess i will yank all the plugs and clean them up.....i was thinking maybe something as simple as the gap on the plugs might be off....maybe i should open it up to allow more spark to burn the fuel.....or maybe even index the plugs.....i have jad mixed results in the past doing this though....the nitrous likes it....but stock motors just dont seem to run as well.....
any ideas are appretiated.

How about this? Have you tried tech support at Barry Grant?

http://www.barrygrant.com/demon/defa...ge=techsupport

That demon is designed for cars with big cams and therefore little vacuum. Maybe, you have too much vacuum and are drawing in excessive fuel as a result.

ok i have been playing with this damn car all week.....i have tested the to much fuel because of low vaccumm....well at idol i was watching the venturi and no gas is flowing into the carb....she doesnt detonate, does backfire a little bit...not loud at all and it is through the exhaust....but this is because she is drowning in fuel, no vaccumm leaks, i have no idea where the fuel is coming from...i have a stock 454 fuel pump....so i am not flowing to much.....i need some more ideas....i was thinking that since it is a mechanical secondary carb maybe the secondaries are stuck open at idol?.....how would i check this?....or is that not a possibility?

thanx guys

This is what I have found on my brand new sb400. It was doing basically the same thing. I advanced the timing to 12 degrees initial and it cured the backfiring thru the exhaust and the rich condition. And to check total advance you need either timing tape (which I found doesn't work very well) or a dial back timing light. It's simple to do.

I also agree with 76GMC1500. It could be an overly rich carb. The jets could be too big for you application.

Well i tore apart the demon and found debris all i the needle valves and fuel bowl......then i played with timing and advanced to 12...cleaned up instantly and no bog....thank god

thanx for all the help guys

Originally posted by 4speedTerror
....well at idol i was watching the venturi and no gas is flowing into the carb....she doesnt detonate, does backfire a little bit...
thanx guys

Bad idea. Never look down the carburetor of a running engine, especially one that isn't running quite right. That is, unless you don't like your eyebrows. Anyways, you should't be able to see fuel as the particles are too small to be seen by the naked eye.

yeah i did that with a small block i was firing up and cought a face full of fire...lol....and yeah the eyebrows and a little hair were gone....lol
i was looking to see if mt secondaries we pouring gas down the carb...it was and it ignited....i am a little more care full now...i use a mechanics mirror

This tech article is for Holley's but I would think that the BG's would be the same. The author is a very knowledgible guy who has helped me out on a lot of my projects. Hope this helps.

Wade
http://corvetteforum.com/techtips/viewsubtopic.php?SubTopicID=108&TopicID=3