The Ford Barn

russcc · 09-18-2014, 07:04 PM

The 8Ba 94 on the 8RT in the roadster is, I believe running much to rich. The plugs are a sooty black, the exhaust smells of unburned hydrocarbons, and the car bogs starting out, and then clears out and runs a little better.
The carb is very clean inside,. I put a Daytona Parts kit in it with their float valve seat, and set the float low at 1.500 vs the recommended 1.375.
I am running their 5.5 power valve and the stock 51 jets. Got a rebuilt base with oversize, nice fitting throttle shafts from Charlie S in it. Suggestions on where to start trouble shooting. Thank you.

Charlie ny · 09-18-2014, 07:16 PM

Russ,
I answered your personal email to me regarding the above in the last hour.
The 1.500 will never cut it....by all means find a stainless steel needle and seat
and loose the 'flapper' seat, along with other thoughts, yada yada yada.
Charlie ny

Binx · 09-18-2014, 07:31 PM

This is one of my favorite Charley ny quotes:

"When they leak like that it's usually due to an internal leak most times
caused by incorrect float setting or a vacuum leak which allows the power
valve to not be 'pulled' shut which in turn allows uncontrolled fuel into the action.
A quick way to determine if you have a PV situation at hand is to slowly close
each idle mixture screw until the motor stumbles. When it stumbles back that screw
out 1/2 turn and the motor should smooth out. Now try the other mixture screw. If the motor keeps on idling with one
or both screws closed that is your signal that the carb is leaking internally".

Lonnie

Mart · 09-19-2014, 01:57 AM

94's can be made to run nice but as mentioned in may previous threads there are a few things that can make them run rich, all of which I can say I have personally experienced.

1, Needle valve not holding back the fuel. Caused by inferior needle valve (flap type as Charlie says) Or too high fuel pressure. I use the springs from old fuel pumps and older type needle valves to overcome these problems.
2, Punctured float. this tends to lead to a chronic overfuelling and makes it very hard to start when hot. (have to floor the pedal). Fix with a new or better float.
3, Damaged power valve. A perforated power valve will allow fuel to leak from mthe float bowl into the manifold. hard starts from hot as above. I also had one that had cracked at the root of the threads, probablly from overtightening. wrong shape and wrong gasket can also caise problems.
4, Warped castings. A new one for me, but mentioned by barners recently. I reworked both my 94's a few days ago and they were warped. As charlie says, the power valve can't pull closed properly so is over enriching the mixture all the time the engine is running. This warpage can also introduce a vacuum leak so is a bad situation all round.

There are probably other things, but the above are all ones I have experienced myself.

Once you address all the above points they should run like a top.

Mart.

russcc · 09-19-2014, 05:15 AM

Thank you all Binx, Charlie & Mart. Will replace the flapper with a needle & seat to start, and reset the float to Charlie's recommended 1.350. All the sealing surface have been lapped and are dead flat. The engine quits when you crank in the idle screws, so does that still mean the power valve is not leaking ?

Mart · 09-19-2014, 05:49 AM

Sponsored Links (Register now to hide all advertisements)

Yes, that is a good indicator.

Mart.

supereal · 09-19-2014, 11:51 AM

Warping is not unusual. It is commonly caused by overtightening the screws that hold the carb together. When we rebuild a carb, we place a sheet of fine emery paper on a piece of window glass and rub the gasket surface on it. It will quickly reveal any problems. Continue rubbing the part until the surface shows an even contact. When assembling, use only enough force on the screws to secure the part. Too tight will deform the gasket. That's why so many carbs have evidence of fuel leakage on the outside, and in places you can't see.

transbytip · 09-19-2014, 12:48 PM

If none of the above help I know this sounds strange but I once bought a rebuilt carb and it did as you describe finally took it apart to find the problem guess what, some one forgot to screw the main jets in no jets at all&it still ran but not good might give that a check.Cliff.

09-18-2014, 07:04 PM	#1
russcc Senior Member Join Date: May 2010 Posts: 2,871	Trouble shooting 94 running way to rich ? The 8Ba 94 on the 8RT in the roadster is, I believe running much to rich. The plugs are a sooty black, the exhaust smells of unburned hydrocarbons, and the car bogs starting out, and then clears out and runs a little better. The carb is very clean inside,. I put a Daytona Parts kit in it with their float valve seat, and set the float low at 1.500 vs the recommended 1.375. I am running their 5.5 power valve and the stock 51 jets. Got a rebuilt base with oversize, nice fitting throttle shafts from Charlie S in it. Suggestions on where to start trouble shooting. Thank you.

09-18-2014, 07:16 PM	#2
Charlie ny BANNED Join Date: May 2010 Posts: 3,019	Re: Trouble shooting 94 running way to rich ? Russ, I answered your personal email to me regarding the above in the last hour. The 1.500 will never cut it....by all means find a stainless steel needle and seat and loose the 'flapper' seat, along with other thoughts, yada yada yada. Charlie ny

09-18-2014, 07:31 PM	#3
Binx Senior Member Join Date: Oct 2011 Location: Gloucester VA Posts: 1,042	Re: Trouble shooting 94 running way to rich ? This is one of my favorite Charley ny quotes: "When they leak like that it's usually due to an internal leak most times caused by incorrect float setting or a vacuum leak which allows the power valve to not be 'pulled' shut which in turn allows uncontrolled fuel into the action. A quick way to determine if you have a PV situation at hand is to slowly close each idle mixture screw until the motor stumbles. When it stumbles back that screw out 1/2 turn and the motor should smooth out. Now try the other mixture screw. If the motor keeps on idling with one or both screws closed that is your signal that the carb is leaking internally". Lonnie

09-19-2014, 01:57 AM	#4
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,747	Re: Trouble shooting 94 running way to rich ? 94's can be made to run nice but as mentioned in may previous threads there are a few things that can make them run rich, all of which I can say I have personally experienced. 1, Needle valve not holding back the fuel. Caused by inferior needle valve (flap type as Charlie says) Or too high fuel pressure. I use the springs from old fuel pumps and older type needle valves to overcome these problems. 2, Punctured float. this tends to lead to a chronic overfuelling and makes it very hard to start when hot. (have to floor the pedal). Fix with a new or better float. 3, Damaged power valve. A perforated power valve will allow fuel to leak from mthe float bowl into the manifold. hard starts from hot as above. I also had one that had cracked at the root of the threads, probablly from overtightening. wrong shape and wrong gasket can also caise problems. 4, Warped castings. A new one for me, but mentioned by barners recently. I reworked both my 94's a few days ago and they were warped. As charlie says, the power valve can't pull closed properly so is over enriching the mixture all the time the engine is running. This warpage can also introduce a vacuum leak so is a bad situation all round. There are probably other things, but the above are all ones I have experienced myself. Once you address all the above points they should run like a top. Mart.

09-19-2014, 05:15 AM	#5
russcc Senior Member Join Date: May 2010 Posts: 2,871	Re: Trouble shooting 94 running way to rich ? Thank you all Binx, Charlie & Mart. Will replace the flapper with a needle & seat to start, and reset the float to Charlie's recommended 1.350. All the sealing surface have been lapped and are dead flat. The engine quits when you crank in the idle screws, so does that still mean the power valve is not leaking ?

09-19-2014, 05:49 AM	#6
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,747	Re: Trouble shooting 94 running way to rich ? Sponsored Links (Register now to hide all advertisements) Yes, that is a good indicator. Mart.

09-19-2014, 11:51 AM	#7
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Trouble shooting 94 running way to rich ? Warping is not unusual. It is commonly caused by overtightening the screws that hold the carb together. When we rebuild a carb, we place a sheet of fine emery paper on a piece of window glass and rub the gasket surface on it. It will quickly reveal any problems. Continue rubbing the part until the surface shows an even contact. When assembling, use only enough force on the screws to secure the part. Too tight will deform the gasket. That's why so many carbs have evidence of fuel leakage on the outside, and in places you can't see.

09-19-2014, 12:48 PM	#8
transbytip Senior Member Join Date: Dec 2011 Location: ottumwa Ia. Posts: 132	Re: Trouble shooting 94 running way to rich ? If none of the above help I know this sounds strange but I once bought a rebuilt carb and it did as you describe finally took it apart to find the problem guess what, some one forgot to screw the main jets in no jets at all&it still ran but not good might give that a check.Cliff.