- Thread starter
- #21
That's just about the same rpm I have my first dead spot.
Hesitation upon acceleration issue
- Thread starter HKforte
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
That's just about the same rpm I have my first dead spot.
rsbcruiser
SILVER Star
Money is on entry 10, the bulldog called it a while ago, good thread though. Let us know when you get it figured HKForte
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
Nope.
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
No, if the valves were off far enough to cause running issues, it would be present at all speeds.
You should start a new thread about this, since your truck is a '67 w/ vac advance and 1-bbl, very different from HK's vac retard and 2bbl combo.
You should start a new thread about this, since your truck is a '67 w/ vac advance and 1-bbl, very different from HK's vac retard and 2bbl combo.
JohnnyC
Long ago TLCA# 2231
any progress?
i dont know if it was covered or not....but...
1)have you adjusted the mixture screws? when the carb is rebuilt it still needs to be fine tuned.
2)have you also checked the gaskets and vac lines with carb cleaner...spray around all the areas slowly and see if the rpm's change?
3) have you checked the weights inside the dissy to see if they are froozen up? EDIT....just read you had a different dissy and still did it...
just throwing things out there
were do you have the vac retard hooked up to the carb? is it ported vac or vac at idle?
i dont know if it was covered or not....but...
1)have you adjusted the mixture screws? when the carb is rebuilt it still needs to be fine tuned.
2)have you also checked the gaskets and vac lines with carb cleaner...spray around all the areas slowly and see if the rpm's change?
3) have you checked the weights inside the dissy to see if they are froozen up? EDIT....just read you had a different dissy and still did it...
just throwing things out there
were do you have the vac retard hooked up to the carb? is it ported vac or vac at idle?
- Thread starter
- #29
problem identified
Hey guys,
I've made some good progress on this issue.....
I closed the mixture screw on the carb as much as possible, without losing smooth idle and vacuum, and reduced the hesitation. I also proceeded to hold down the weight that opens the secondary on the carb, which eliminated the hesitation completely, no matter how hard I pushed the gas pedal on the FJ. (my terminology & description may be incorrect, so here's a picture marking the weight I held down)
I believe there was too much air going through to my carburetor under hard acceleration, due to the this weight flipping open the secondary too fast. I zip tied the weight so it does not move and went for a drive..... On straight roads the car drove very smoothly with no hesitation. On steep hills, it seemed like the car was losing some power due to the lack of air.
I discussed the issue with Mark (65swb45), and we agreed that I should make the weight heavier, until it opens at the proper rate.
For now, the weight is zip tied and the vehicle does not hesitate whatsoever on straight roads. Has any one experienced a similar issue? Any additional input?
Thanks.
Hey guys,
I've made some good progress on this issue.....
I closed the mixture screw on the carb as much as possible, without losing smooth idle and vacuum, and reduced the hesitation. I also proceeded to hold down the weight that opens the secondary on the carb, which eliminated the hesitation completely, no matter how hard I pushed the gas pedal on the FJ. (my terminology & description may be incorrect, so here's a picture marking the weight I held down)
I believe there was too much air going through to my carburetor under hard acceleration, due to the this weight flipping open the secondary too fast. I zip tied the weight so it does not move and went for a drive..... On straight roads the car drove very smoothly with no hesitation. On steep hills, it seemed like the car was losing some power due to the lack of air.
I discussed the issue with Mark (65swb45), and we agreed that I should make the weight heavier, until it opens at the proper rate.
For now, the weight is zip tied and the vehicle does not hesitate whatsoever on straight roads. Has any one experienced a similar issue? Any additional input?
Thanks.
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
A couple minor things:
Adjust the secondary link rod so it hits the secondary later.
Move the secondary air valve butterfly toward the outside of the carb to make it open later.
Increase the size of the secondary slow jet (it's hard to make that one too large).
Ultimately, this is one of the minor design flaws of the carb that was corrected with the introduction of the vacuum secondary in 1975.
Adjust the secondary link rod so it hits the secondary later.
Move the secondary air valve butterfly toward the outside of the carb to make it open later.
Increase the size of the secondary slow jet (it's hard to make that one too large).
Ultimately, this is one of the minor design flaws of the carb that was corrected with the introduction of the vacuum secondary in 1975.
I have a very similar problem with my 1972. I know nothing about carburator so I read your post with a lot of interest. When I look at the weight you show I am not sure what is suppose to make it move. I don't see nothing link to it externally or something that will come and push it.
If this is not to much ask can you show me a picture of your carburator I want to understand what you mean by zip tide the weight. thanks for your help
If this is not to much ask can you show me a picture of your carburator I want to understand what you mean by zip tide the weight. thanks for your help
Too many carbs, need more fiber
wait, so who's the dysfunctional retard?
wait, so who's the dysfunctional retard?
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
The weight is moved by airflow down the 2nd barrel of the carburetor.
If the air valve (weight) opens too quickly, the second barrel will be lean, causing a hesitation.
If the air valve (weight) opens too quickly, the second barrel will be lean, causing a hesitation.
- Thread starter
- #35
Below you will see that I used a hose clamp to add weight to the High Speed Arm that is connected to the High Speed Shaft. I noticed that if this arm opens too fast, it causes hesitation. At the same time, if it does not open at all, it boggs down the vehicle when it's under load (even though that eliminates the initial hesitation issue). I tried different sizes and weights of hose clamps until I found one that that was more acceptable to use than the others. Although my carb is now better off than before, the hesitation issue has not been resolved.
When I look at the High Speed Arm I see a little notch that may serve the purpose of coming into contact with another carburator arm piece in order to prevent the High Speed Arm from flinging up its full extent and causing the vehicle to hesitate. I believe that there maybe something assembled incorrectly on my carb, because with the way my carburator is assembled, that notch on the High Speed Arm does not serve any purpose at the moment.
From all the trial and error I've gone through, I believe that if the High Speed Arm operates with its own weight alone, but does not fling up higher than 75% of its full extent, then the hesitation symptom will be resolved. If someone could post a picture of the backside of their 1972 carburator, I'd really appreciate it. I would like to compare the way the linkage arms and High Speed Arm are assembled.
When I look at the High Speed Arm I see a little notch that may serve the purpose of coming into contact with another carburator arm piece in order to prevent the High Speed Arm from flinging up its full extent and causing the vehicle to hesitate. I believe that there maybe something assembled incorrectly on my carb, because with the way my carburator is assembled, that notch on the High Speed Arm does not serve any purpose at the moment.
From all the trial and error I've gone through, I believe that if the High Speed Arm operates with its own weight alone, but does not fling up higher than 75% of its full extent, then the hesitation symptom will be resolved. If someone could post a picture of the backside of their 1972 carburator, I'd really appreciate it. I would like to compare the way the linkage arms and High Speed Arm are assembled.
I have tried to take a picture with my cell phone but the result is not good. I wonder if your picture was taken with the engine running or not. If I look at your picture and my picture there is a lot of difference in the adjustment of the arms. My picture was taken with the engine off.
Sorry for the picture quality it was taken with my cell phone.
I have taken that other picture to show where I pull the vacuum for the little arm. When I use the one closer it was stalling my engine at a stop because it was pulling to fast and to far. If you know where the other large tube where there is a bolt to close it suppose to go please let me know.
I know I can not really help you but reading your post I was able to improve a lot the setting of my carburator. I am running 35 inch tire with a 3.70 gear ratio and I am able to follow traffic in town and highway now. The added weight since to have help my truck like you said. If I push the gaz when I am above 1500RPM I don't have much hesitation anymore. It is only if I am under 1500RPM and completly push the gas to maximum.
thanks
Sorry for the picture quality it was taken with my cell phone.
I have taken that other picture to show where I pull the vacuum for the little arm. When I use the one closer it was stalling my engine at a stop because it was pulling to fast and to far. If you know where the other large tube where there is a bolt to close it suppose to go please let me know.
I know I can not really help you but reading your post I was able to improve a lot the setting of my carburator. I am running 35 inch tire with a 3.70 gear ratio and I am able to follow traffic in town and highway now. The added weight since to have help my truck like you said. If I push the gaz when I am above 1500RPM I don't have much hesitation anymore. It is only if I am under 1500RPM and completly push the gas to maximum.
thanks
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
QC,
You are talking about the choke breaker (vacuum pot).
That is a completely different system from the secondary air valve.
You are talking about the choke breaker (vacuum pot).
That is a completely different system from the secondary air valve.
- Thread starter
- #38
QC72FJ40,
My pictures were taken with the engine off. I think with these rigs we should not start troubleshooting from the carb. The 1972 is my uncle's rig which I have been working on. I recently had a very similar problem with my rig which is a 1978. The hesitation ended up being caused by a few vacuum leaks connected to the intake manifold and the bottom baseplate of the carb. It's amazing how nice these engines work and sound when those leaks are all fixed!
My pictures were taken with the engine off. I think with these rigs we should not start troubleshooting from the carb. The 1972 is my uncle's rig which I have been working on. I recently had a very similar problem with my rig which is a 1978. The hesitation ended up being caused by a few vacuum leaks connected to the intake manifold and the bottom baseplate of the carb. It's amazing how nice these engines work and sound when those leaks are all fixed!
FJ40Jim,
Thanks for the information about the name. At first I had to run with some chock but since I change where I connect the vacuum I am fine. I notice his connecting rode is bented a lot more then mine. This is probably why mine is complety on the right side where his is more in the middle.
I don't want take to much of KHforte post I will continu to read that post with grant interest.
Thanks for the information about the name. At first I had to run with some chock but since I change where I connect the vacuum I am fine. I notice his connecting rode is bented a lot more then mine. This is probably why mine is complety on the right side where his is more in the middle.
I don't want take to much of KHforte post I will continu to read that post with grant interest.
- Thread starter
- #40
QC,
This thread is all yours. Feel free to post all your quesitons, troubleshooting and findings here. I'm curious to see how this issue gets resolved without abandoning the stock carburator.
Maybe if someone has a detailed picture of the linkages on a stock '72 carb, we can use it to compare to our carbs.
Thanks.
This thread is all yours. Feel free to post all your quesitons, troubleshooting and findings here. I'm curious to see how this issue gets resolved without abandoning the stock carburator.
Maybe if someone has a detailed picture of the linkages on a stock '72 carb, we can use it to compare to our carbs.
Thanks.
