Author Topic: Carb Tuning - yes again!!!!  (Read 863 times)

Offline CUDA JAS

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Carb Tuning - yes again!!!!
« on: June 03, 2011 - 09:41:38 AM »
I know this gets asked alot, and I have looked through a number of the posts, but I am still stumped.

My 360, with 750 vac secondary carb stalls out completly when I go from idle to WOT.  If I roll into the throtle not slowly but not stomping it, I accelerate quickly, even slipping the tires a bit.

I am currently running the orange pump cam, jets and shooter(31) are stock.

I think it is a rich condition when I stomp on ,killing the engine.  Would I be correct to move down on pump cams. Or is the stallign out a lean condition.  To be clear, it does not bog, it dies when I stomp on it.

I am also dealing with a rich idle conditon, and that may be contributing to the problem.

Any thoughts??

Jason
74 'cuda 360/727



Gearhead: car nut, automotive enthusiast, one who loves hot rods, muscle cars, hot trucks, burnin' rubber and neck snapping performance. 

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Offline mrob

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Re: Carb Tuning - yes again!!!!
« Reply #1 on: June 03, 2011 - 10:04:02 AM »
Jason,
You say you have a rich idle condition. Can you describe why? Does it smell rich, or is the motor puffing black smoke out of the exhaust at idle? If so, I'd first check the power valve and make sure that it isn't blown.
Another thing that could cause excessive richness at idle is if the float is set high enough that fuel drips out of the discharge nozzles (in the booster venturis). You can see that by looking into the carb venturis at idle. There should be no fuel dripping out of the boosters.
Get the idle system working first and then move on to the power enrichment system (i.e., pump cams, nozzles, accelerator pumps) and the secondaries.

Offline CUDA JAS

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Re: Carb Tuning - yes again!!!!
« Reply #2 on: June 03, 2011 - 01:36:48 PM »
Jason,
You say you have a rich idle condition. Can you describe why? Does it smell rich, or is the motor puffing black smoke out of the exhaust at idle? If so, I'd first check the power valve and make sure that it isn't blown.
Another thing that could cause excessive richness at idle is if the float is set high enough that fuel drips out of the discharge nozzles (in the booster venturis). You can see that by looking into the carb venturis at idle. There should be no fuel dripping out of the boosters.
Get the idle system working first and then move on to the power enrichment system (i.e., pump cams, nozzles, accelerator pumps) and the secondaries.
Yep very stinky at idle.  no decernable black smoke.

PV is good...when I run in one of the idle mixture screws the car dies.

Float level looks good, maybe enven a litlle low.

I think the problem is my single plane intake results in the carb getting a bad signal.

I will try an work out the idle issues first  :thumbsup:

Jason
74 'cuda 360/727



Gearhead: car nut, automotive enthusiast, one who loves hot rods, muscle cars, hot trucks, burnin' rubber and neck snapping performance. 

Just call me a gearhead!

Offline Strawdawg

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Re: Carb Tuning - yes again!!!!
« Reply #3 on: June 03, 2011 - 03:37:42 PM »
I would think more likely it is lean when it goes wot..but, without any real data, that is just a guess.

Make sure you don't have too soft a spring in the vacuum pot.

If you can get someone to drive behind you and watch the exhaust, if it goes black when you stand on it, then you are right, too rich.  If not, probably too lean and you need slower secondary opening, or a bigger pump shot.