spark control valve
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Fleet Owner
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From: Central PA
spark control valve
The continuing saga of my '54's carb problems...
I bought a an oversized Throttle plate shaft for my carb. It was something like .005" oversized. I took my carb and the new shaft to an older gentleman that rebuilds carbs. Although he said he does not rebuild Ford truck carbs he said if I can get a new shaft he would bore out the throttle body where the shaft goes and put in bushings. He has a small machine shop at his place. I dropped it off at his house Saturday. He said the shaft was loose like it was worn and this allowed the carb to suck air. He asked me if it started hard and I said it did. He said that is because the air/fuel mixture is not right. I then told him when I last drove the truck I had to have the choke out part way. He said that also seemed to confirm the poor air/fuel mixture idea.
He called me today to with some good news: the oversized shaft fit perfectly into the worn hole without him having to bore it out or use bushings...
Question: he asked what the valve thing is on the back of the carb. He was referring to the spark control valve.. I told him what it was called and that it had something to do with vacuum and the distributor. He asked me if they can be adjusted or can they go bad. I didn't know...
Can they be adjusted? Or do they go bad???
I bought a an oversized Throttle plate shaft for my carb. It was something like .005" oversized. I took my carb and the new shaft to an older gentleman that rebuilds carbs. Although he said he does not rebuild Ford truck carbs he said if I can get a new shaft he would bore out the throttle body where the shaft goes and put in bushings. He has a small machine shop at his place. I dropped it off at his house Saturday. He said the shaft was loose like it was worn and this allowed the carb to suck air. He asked me if it started hard and I said it did. He said that is because the air/fuel mixture is not right. I then told him when I last drove the truck I had to have the choke out part way. He said that also seemed to confirm the poor air/fuel mixture idea.
He called me today to with some good news: the oversized shaft fit perfectly into the worn hole without him having to bore it out or use bushings...
Question: he asked what the valve thing is on the back of the carb. He was referring to the spark control valve.. I told him what it was called and that it had something to do with vacuum and the distributor. He asked me if they can be adjusted or can they go bad. I didn't know...
Can they be adjusted? Or do they go bad???
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Joined: Sep 2012
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As far as I know, and I've read up on it quite a bit and built a few 94s in my time, they are not adjustable (one size only). They do go bad. So can the diaphragm in the distributor advance. As well, you need to make sure to use the flat sealing surface model on a 94. Some newer ones have a step in the sealing surface and that dog won't hunt. Good rebuild kits with the proper spark control valve may be found at Mike's Carburetors. Holley 94 info: http://www.carburetor-parts.com/Hole...10_ep_332.html
And: http://www.carburetor-parts.com/Spar...Valve_b_2.html
That being said, I modified my last one like Ted Eaton explains on his web site. http://www.eatonbalancing.com/blog/2...-distributors/
That will allow me to ditch that stinking loadomatic distributor and get far better performance.
And: http://www.carburetor-parts.com/Spar...Valve_b_2.html
That being said, I modified my last one like Ted Eaton explains on his web site. http://www.eatonbalancing.com/blog/2...-distributors/
That will allow me to ditch that stinking loadomatic distributor and get far better performance.
Last edited by The Horvaths; Aug 5, 2013 at 10:50 PM. Reason: Lynx.
Fleet Owner
Joined: Jul 2004
Posts: 27,299
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From: NM
Abe, I have at least three of them, if you want them. My carb has one but I don't use it. Basically it's function is to give a little advance on coastdown with closed throttle to prevent popping in the exhaust, which is considered unseemly by some.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
B5AZ-9B572-A .. Spark Control Valve ~ Use with 1954/55 Holley EBV 2V ~ 1948/56 Ford Truck Parts Catalog ~ Parts list T28
WESLEY OBSOLETE PARTS in Liberty KY has 8 = 606-787-5293.
GREEN SALES CO. in Cincinnati OH has 15 = 800-543-4959.
WESLEY OBSOLETE PARTS in Liberty KY has 8 = 606-787-5293.
GREEN SALES CO. in Cincinnati OH has 15 = 800-543-4959.
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Fleet Owner
Joined: Dec 2000
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From: Central PA
What do you mean by the flat sealing surface? Do you mean the gasket between the carb bottom and the manifold?
Fleet Owner
Joined: Jul 2004
Posts: 27,299
Likes: 1,059
From: NM
...That being said, I modified my last one like Ted Eaton explains on his web site. Eaton Balancing » Modifying the Holley 94 two barrel for late model distributors
That will allow me to ditch that stinking loadomatic distributor and get far better performance.
That will allow me to ditch that stinking loadomatic distributor and get far better performance.
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