I have a 1977 ford 361fe engine with a 4 barrel holley carb that has a built in governor. It is the OE carb. Upon starting a cold engine the truck runs great. After 5 to 10 min of run time the primary flaps do not open upon pressing the throttle. Fuel squirts but the flaps do not open. This is only on a hot engine. I can manually push them open with a screw driver and the engine will run great.They will stay open with the throttle once assisted. There must be some kind of vacuum problem in the carb when warm. Any ideas?
Holley carb only works on cold engine
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I assume you are talking about the choke flap that's supposed to retract once sufficient heat is achieved? There should be an actuator for it on the side of the carb, it may have pooped the bed or the linkage for it is binding up/corroded.
Yes, sounds like a choke issue. Is it electric or mechanical?
In a few more years, all the people who know how to work on automotive carburetors will be dead. There were never that many who were good at it.
I'm not familiar with the particular carb you're talking about. By "primary flaps" I will assume you mean choke plate(s).
So you have a choke malfunction where it is sticking on. Generally, chokes are either manual (work with a dash knob, check the cable operation), work from a bimetal strip heated by the engine (check and make sure it isn't broken or unlinked) or electric (also bimetal but heated electrically instead of by the engine, make sure power is getting to it and it is not internally broken).
I'm not familiar with the particular carb you're talking about. By "primary flaps" I will assume you mean choke plate(s).
So you have a choke malfunction where it is sticking on. Generally, chokes are either manual (work with a dash knob, check the cable operation), work from a bimetal strip heated by the engine (check and make sure it isn't broken or unlinked) or electric (also bimetal but heated electrically instead of by the engine, make sure power is getting to it and it is not internally broken).
No electric choke. Manual only. It has a governor and I just spoke with a Holley tech and he believes it is in there. The primary plates are not directly attached to the throttle linkage like on a normal carb. That is why they are acting up on a warm engine.
The choke cable is actually frozen and it starts without the choke. Th truck also came with a manual choke from the factory.
The choke cable is actually frozen and it starts without the choke. Th truck also came with a manual choke from the factory.
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Get us a picture. If there's a governor, there's a linkage coming out of the engine, and a funky one that translates pedal input to throttle opening.
My mercedes turbodiesel of all things had an amazing "mechanical computer" that did all this. Linkages galore. It was a primitive smog thing to make sure it wouldn't over-fuel before the revs caught up.
My mercedes turbodiesel of all things had an amazing "mechanical computer" that did all this. Linkages galore. It was a primitive smog thing to make sure it wouldn't over-fuel before the revs caught up.
An important note for those responding - governed holleys do not have a mechanical linkage to the throttle plate. It's connected by a vacuum can instead. I'm not terribly informed on them, but I think they can have temp switches for the throttle and timing too.
Does it rev when cold?
Does it rev when cold?
More wild guesses. Take a couple samples of the vacuum line to a parts store and buy 2x as much as you think you need.I'd replace every bit of the vacuum hose. in the emissions system. EGR???? Get as big a copy of the Vacuum circuit off the inter-web as you can find good luck, please post a follow up.
Have you opened the vacuum servo? On something that old, the diaphragm is suspect.
To add, vacuum secondaries are very common. Sounds like this one has vacuum primaries.
To add, vacuum secondaries are very common. Sounds like this one has vacuum primaries.
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Originally Posted by The_Eric
An important note for those responding - governed holleys do not have a mechanical linkage to the throttle plate. It's connected by a vacuum can instead. I'm not terribly informed on them, but I think they can have temp switches for the throttle and timing too.
Does it rev when cold?
Works fine cold. I think it is internal on the carb gov vacuum system. Even the Holley tech did not know much about this style. That shows how old it is. I am going to remove the carb and see if I can somehow eliminate the vacuum gov and make it a mechanical linkage.
An important note for those responding - governed holleys do not have a mechanical linkage to the throttle plate. It's connected by a vacuum can instead. I'm not terribly informed on them, but I think they can have temp switches for the throttle and timing too.
Does it rev when cold?
Works fine cold. I think it is internal on the carb gov vacuum system. Even the Holley tech did not know much about this style. That shows how old it is. I am going to remove the carb and see if I can somehow eliminate the vacuum gov and make it a mechanical linkage.
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Are you sure the problem is the throttle plate not opening? According to this http://www.tocmp.com/manuals/Carbs/Holley/H4V-4150-60-80/HolleyB150_html/MCarbHollB150_0018.htm
there is mechanical link from the gas pedal to the throttle through a spring. In case of over-revving, the governor acts to pull against this spring and close the throttle even if the driver is holding the gas down.
The "spinner" vacuum valve is normally open. The hose from the top of the carb merely supplies filtered air. The spinner is a vacuum leak that keeps vacuum from building up in the other hose, which is connected to the governor diaphragm. When the governed rpm is exceeded, the spinner closes and allows vacuum to build up and the diaphragm pulls the throttle closed.
there is mechanical link from the gas pedal to the throttle through a spring. In case of over-revving, the governor acts to pull against this spring and close the throttle even if the driver is holding the gas down.
The "spinner" vacuum valve is normally open. The hose from the top of the carb merely supplies filtered air. The spinner is a vacuum leak that keeps vacuum from building up in the other hose, which is connected to the governor diaphragm. When the governed rpm is exceeded, the spinner closes and allows vacuum to build up and the diaphragm pulls the throttle closed.
These might help. They a bit long but informative.
https://www.youtube.com/watch?v=1bYVWJul3z8
https://www.youtube.com/watch?v=RvlmJoeIcpw
https://www.youtube.com/watch?v=1bYVWJul3z8
https://www.youtube.com/watch?v=RvlmJoeIcpw
Originally Posted by mk378
Are you sure the problem is the throttle plate not opening? According to this http://www.tocmp.com/manuals/Carbs/Holley/H4V-4150-60-80/HolleyB150_html/MCarbHollB150_0018.htm
there is mechanical link from the gas pedal to the throttle through a spring. In case of over-revving, the governor acts to pull against this spring and close the throttle even if the driver is holding the gas down.
The "spinner" vacuum valve is normally open. The hose from the top of the carb merely supplies filtered air. The spinner is a vacuum leak that keeps vacuum from building up in the other hose, which is connected to the governor diaphragm. When the governed rpm is exceeded, the spinner closes and allows vacuum to build up and the diaphragm pulls the throttle closed.
The plate is clearly not opening when hot. If I manuallly open it with a screwdriver driver through the top it will then operate with the throttle until I release the throttle. It is that initial opening which is the problem. I am going to take apart the governor. There is no external vacuum source.
Are you sure the problem is the throttle plate not opening? According to this http://www.tocmp.com/manuals/Carbs/Holley/H4V-4150-60-80/HolleyB150_html/MCarbHollB150_0018.htm
there is mechanical link from the gas pedal to the throttle through a spring. In case of over-revving, the governor acts to pull against this spring and close the throttle even if the driver is holding the gas down.
The "spinner" vacuum valve is normally open. The hose from the top of the carb merely supplies filtered air. The spinner is a vacuum leak that keeps vacuum from building up in the other hose, which is connected to the governor diaphragm. When the governed rpm is exceeded, the spinner closes and allows vacuum to build up and the diaphragm pulls the throttle closed.
The plate is clearly not opening when hot. If I manuallly open it with a screwdriver driver through the top it will then operate with the throttle until I release the throttle. It is that initial opening which is the problem. I am going to take apart the governor. There is no external vacuum source.
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If you disconnect the bottom hose from the spinner to the governor diaphragm and leave it open, that should disable any vacuum governor action so then you can concentrate on the mechanical linkage.
Which looks at the least, really rusty. Was this truck left out in the rain with the hood open?
Which looks at the least, really rusty. Was this truck left out in the rain with the hood open?
Originally Posted by mk378
If you disconnect the bottom hose from the spinner to the governor diaphragm and leave it open, that should disable any vacuum governor action so then you can concentrate on the mechanical linkage.
Which looks at the least, really rusty. Was this truck left out in the rain with the hood open?
I fixed it. I took part the linkage for the governor and disconnected it from the primary plates. The plates now open and return freely. For some reason when the throttle retracted it was caming over and locking. It is a all light surface rust. A nice patina. Remember it is a 42 year old dump truck with the original carb. Thanks for all the advice.
If you disconnect the bottom hose from the spinner to the governor diaphragm and leave it open, that should disable any vacuum governor action so then you can concentrate on the mechanical linkage.
Which looks at the least, really rusty. Was this truck left out in the rain with the hood open?
I fixed it. I took part the linkage for the governor and disconnected it from the primary plates. The plates now open and return freely. For some reason when the throttle retracted it was caming over and locking. It is a all light surface rust. A nice patina. Remember it is a 42 year old dump truck with the original carb. Thanks for all the advice.
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