950 Proform running Rich

[cordodge]

Guess I should place this here instead of my resto thread.

My motor is up and running but does seem to be running really rich, Tim had said he didn't have to touch the carb out of the box and it was bang on but he was running it with a 7AL box and I have a 6AL box, not sure if that would cause the rich condition or not. Timing is set at 32 all in but while the car is idling it will burn your eyes out and has a light smoking from the exhaust. Im not the best with carb so just looking for ideas, the jetting is 78 primary and 86 secondary its a 950 preform.

Thanks Bruce.

[Cuda Cody]

Sorry if you already told us, but could you remind me what the details on your engine are? The cam will dictate how much vacuum and that will determine how much feel it can atomized and burn cleanly.  So each engine is going to be slightly different.  @Chryco Psycho is driving back from Carlisle to GA and should be able to chime in later today or tomorrow, but I would think a jetting adjustment is all that is needed to get it running good. 

Have you driven it on the roads yet?  How's the carb respond under load?  Are you getting a lot of black soot from the exaust?

[cordodge]

Sorry if you already told us, but could you remind me what the details on your engine are? The cam will dictate how much vacuum and that will determine how much feel it can atomized and burn cleanly.  So each engine is going to be slightly different.  @Chryco Psycho is driving back from Carlisle to GA and should be able to chime in later today or tomorrow, but I would think a jetting adjustment is all that is needed to get it running good. 

Have you driven it on the roads yet?  How's the carb respond under load?  Are you getting a lot of black soot from the exaust?

Thanks Cody for responding looks like you guys had a great time this weekend. Tim hasn't sent me the details on the motor yet but I know its a very small solid. the funny thing is when he did the dyno and tuned it he said the carb was bang on but he was using a 7ALbox and im running a 6AL box not sure if that would cause an issue but the timing is set at 32 all in. Havent had it out yet but responds well off idle and it will puff out a light smoke that reeks of gas and very hard on the eyes lol. I have only had it to temperature a couple times and I remember when I originally tried to get it going before tim rebuilt it the headers had quite a bit of oil in them so im not sure the smoke I see is from that aswell.

Im thinking your right about the jetting primaries are 78  so I was thinking of dropping to 76/74?.chryco will know for sure.

Bruce

[HP_Cuda]

Another thing to know to help figure this out is vacuum at idle?

You could bump down the primary jet down but in the end it may be the wrong power valve setup for your motor or you may just need to do the ole CP trick of putting wire down the air bleeder holes. Alternately you could pin drill out an air bleeder to lean out your mixture as well.

Ideally AFR is what's needed to really figure out how to tune your carb.

[Chryco Psycho]

Jet have nothing to do with idle , so if the mixture screws are responding ok you can leak it out that way but you can also increase the size of the air bleed to lean it out

[torredcuda]

Another trick is to crack open the secondary blades which leans out the idle mixture. That way you can see if it helps before drilling anything out. You have to take of the carb to do it as the screw is underneath IIRC.

[Shane Kelley]

Jet have nothing to do with idle , so if the mixture screws are responding ok you can leak it out that way but you can also increase the size of the air bleed to lean it out

Main and secondary jets have nothing to do with idle mixture. First thing to do is check vacuum at idle. If your power valve is to big for the amount of vacuum you have it won't hold shut and cause a rich idle condition.  Your power valve should be the inches of vacuum divided by 2. Example: 10 inches of vacuum would require a 5.0 power valve. After that has been confirmed and your still rich and idle mixture screws don't correct it. Time to up the size of your air idle bleed jets. They are the on top the air horn. The 4 outer ones looking at the top (see pic circled in red). Looks like your comes with 70's. If you head this direction and I'm pretty sure you will. Try 80's and see what happens. Still rich go up to 85's. That's where I ended up at on my 750QF. It came with 70's also. If you go to high it will develop a stumble off idle. That's when you know you have gone to big.

[Shane Kelley]

cordodge: READ THIS BEFORE CHANGING ANYTHING.

Also another important point torredcuda mentioned are the slots in the throttle plate that control the idle circuit. Different things effect where your idle adjustment happens to be. Vacuum, timing etc. I circled the slots I'm referring to below. The carb needs to come off to verify this. If your primary throttle blades are opened to much it will bypass the idle circuit. The primary blade should be almost perfectly centered in the slot. This pic the blades are opened to much. The slot should end up looking like a square when your looking at it from the bottom. Set that and leave it alone. If you need to bring the idle up use the rear idle adjustment screws.

[cordodge]

Thanks for the info guys, I just talked with Tim and he said the carb was bang on when he tuned it.There is a regulator on it and set to 5.5 lbs. I did however fail to tell everyone that when I originally tried to start the motor and failed when I removed the motor to bring it to Tim there was oil coming out of the headers so I'm sure the exhaust would have a quite a bit of oil in it so maybe that's why I think it's running rich, could it be the oil that is burning off making me think it's running rich ? Not sure how long it would take to burn that off as I only brought the car to temp 3/4 times.Just a thought.

Bruce

[Cuda Cody]

Take it for a test drive and see how it drives.  When you get done park somewhere safe (lots of room in front of you) and have someone watch the exhaust while you apply the gas (while in D or in first gear) and keep your foot on the brake.  If it's running rich you should see a bit of black exhaust smoke.

[Shane Kelley]

Oil just usually stinks. Fuel is what causes your eyes to burn.

[HP_Cuda]

Btw CP, Holley says explicitly not to put wires down the idle or high speed bleeds as they could cause damage.

Shane - regardless AFR is what is needed to get to the correct solution. Everything else is just guessing as is pulling plugs and staring at them. 

[Shane Kelley]

Shane - regardless AFR is what is needed to get to the correct solution. Everything else is just guessing as is pulling plugs and staring at them. 

My nose is my AFR meter for idling. If your eyes are burning at idle. It's to rich!
A person can get close without one using known combinations. AFR meter will tell you if your running rich at idle but won't tell you how to solve it. I simply listed ways to check for possible problems and the resolution. AFR meter would really be beneficial for primary and secondary main jets.

By the way if you look at plugs with your naked eye it's a waste of time. A hand held microscope is needed. But that's for another thread. This one is for rich idling condition. 

[cordodge]

Thanks again guys, Well everyone's got some great info so I think I will wait and put a couple miles on it and see how it is hopefully the oil will dissipate and take that out of the equation, Tim was adamant the carb was dialed in when he tuned it and suggested like you guys to try and turn the air/fuel screws in an see what happens? who knows with the oil burned off all may be good. Just nervous as I don't want to wash the walls down with fuel as I haven't had the best of luck with this thing lol.

bruce 

[1 Wild R/T]

Holley says explicitly not to put wires down the idle or high speed bleeds as they could cause damage.

It's been done as long as guys have been tweaking carbs..... I've never seen any harm.... You use wires to learn, after you know where your going you replace parts.....