Happy New Year to Everone

I have a 1981 F150 / 302 / Automatic / Holley 2 barrel carb / California emissions

PROBLEM

After reinstalling my carb after a rebuild job I am unable to get it to run correctly. When I make adjustments to get it to idle correctly while in gear the RPM’s jump way too high when I put it in Park. When I make adjustments to get it to idle correctly in Park the RPMs drop way too low when I put it in gear. I cannot seem to close that gap.
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I have tried both what my Chiltons and Hanyes books suggest to get it dialed in as well as what is suggested on the Holley website. All with no luck.

The guy that rebuilt the carb for me use to own his own carb shop so I am going to assume he knows what he is doing. When I brought the carb in for him I asked him what model Holley he thought it was and he said and old Holley 500. While he was rebuilding it I called Holley to ask them about something else and while I was speaking to them I gave them the list number on the carb I was getting rebuilt and they told me that that carb was a Holley 2300 (230cfm) not a Holley 500. That got me worried thinking maybe my rebuild guy was not so good. When I mentioned to the Holley guy that the rebuild guy thought it was a 500 the Holley guy said it is easy to confuse the two as they appear the same. He said even he cannot tell the difference. That gave me a little more confidence in my carb guy. I would like to think that the carb guy realized the carb was a 2300 when he took it apart and as such rebuilt it with the correct kit and to the correct specs.

Now that I have the carb back and cannot get it dialed in before I go back to the rebuild guy I would like to know as much as I can if I am going to sell him on the idea that he may have made a mistake when he rebuilt it

QUESTIONS

1. Is the internal differences between a 500 and a 2300 such that an experienced carb guy should know what the carb is after taking it apart?
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2. Does anyone know if the kits and the rebuild settings for a 2300 and a 500 are different?
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3. Could someone rebuild a 2300 using kits and specs for a 500 and not know it.
4. Could that perhaps be the cause of my not being able to get this carb to run correctly?
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5. If I am way off base here any suggestions where I am going wrong or on what I should try next?

 

Internally about the same, the difference is in the barrel sizes.
Sounds like you have a vacuum leak somewhere or the timing is way off.

 

LXMan1,

Thanks much for your quick reply.

I considered vacuum leaks and have searched for them. Have not located any.

I have considered timing however I discounted that since the truck ran so good before the carb rebuild. Could it be that the timing was set just right for the condition of the carb before the rebuild and now with the rebuilt on needs to be adjusted?

Mike

 

It is possible. Also, make sure that the vacuum advance is hooked up to ported vacuum and not direct manifold vacuum.

 

Actually, if you hook the vacuum advance up to manifold vac, it will give it a more even idle between park and drive. Most Fords from the factory had this system starting in the early 70's, it also gives better fuel economy while cruising.

 

They had a thermo switch to advance it when cold, then back it off to ported when warmed up to keep detonation/emissions down.

 

Thanks to everyone for providing some input and your thoughts on my problem. My books have reference to vacuum advance at the distributor however part of what has made these books not much help for this problem is that my truck does not have what the books refer to and what I know to be vacuum advance. I am assuming that when you folks refer to vac advance you are also referring to what I know as vacuum advance which is usually on the outside of the distributor. Not sure in my truck what in the system compensates or acts as a distributor vacuum advance acts in other Ford truck systems. Is it the THERMO SWITCH THAT YOU REFER TO LxMan1. If so where is it. Is it one of those what I call solenoids mounted on the valve covers? If so, do you know which one or how I can find it?

Edit: After writing this I went and read some more. Seems with the DuraSpark III ignition or EEC III (which according to a sticker under the hood is what I have) spark advance is controlled in response to a crankshaft position sensor. Therfore no traditional distributor vacuum advance. And therefore no vacuum line connection between the distributor and carb (ported or manifold)

Your references to manifold and ported vacuum were great in that they made me do some research on what the difference is and how you know which is which. I now think I understand that better.

I will stick with it for a little longer tonight. Will let you know how it works out. Again, thanks to all for sticking with me and helping me learn as I go along. Please feel free to keep the thoughts and suggestions coming.

 

Ok, I thoguh you already changed out the distributor for the DSII unit-
The EEC/DSIII system uses a map sensor, oxygen sensor, throttle position sensor, and few others. Without all this, especially the TPS and MAP, the computer can't control the timing, so it stays at the base setting. Running an aftermarket carb, you need to replace the ignition system to get it to run right. Luckily, on this truck, that's cheap, just a distributo and an ignition module. Order both for a 78, and you'll be good to go.

 

Ford_Six

My statement regarding my truck having EEC/DSIII was based on the sticker under the hood and some info in my Chiltons book. I cannot say that I definatively have the EEC/DSIII. The truck ran great with this carb before the rebuild and with the existing ignition system, whatever it is. If the distributor that you suggest can be identified by having the vacuum advance then I can say for sure that is not what I have. If the distributor that you are suggesting does not have the vac advance then perhaps the distributor and ignition module that you suggest has already been done before I got it because as I said the truck ran great with the pre-rebuild carb and the existing ignition system.

How can I be sure what I have.

Again, thanks for continuing to help me. I really appreciate it.

 

Is the rotor button in the distributor round or kinda triangle shaped? If round, then you have the EEC III. The EEC III does not use a vacuum advance. Thye distributor is non adjustable and has a notch where the hold down bolt goes so that it will not move.