confusing carb issue
Safety Car
Joined: Nov 2004
Posts: 4,182
Likes: 94
From: going faster miles an hour...with the radio on in browns mills new jersey
Barry,
Yes,I did. Thanks for the compliment. With only 2 cars in my class
I think they just flipped a coin.
I had to retorque my manifold about 3 or 4 times [after a heat cycle] before all the bolts finally stayed torqued. I haven't had any creeping idle problems since.[IMG]smiley with crossed fingers[/IMG]
Yes,I did. Thanks for the compliment. With only 2 cars in my class
I think they just flipped a coin.I had to retorque my manifold about 3 or 4 times [after a heat cycle] before all the bolts finally stayed torqued. I haven't had any creeping idle problems since.[IMG]smiley with crossed fingers[/IMG]
Burning Brakes
Joined: Aug 2000
Posts: 883
Likes: 2
From: Hilton Head SC
Barry, If I understand you correctly, everytime you have this problem, you back out the idle speed screw. Taken to the extreme then, you will eventually have to remove the screw. Obviously, something else is changing. If the idle speed screw is on the stop each time it happens, that eliminates the throttle linkage and fast idle cam.There are only a couple of ways left to raise idle speed without touching the adjusting screw:
1- Increase in timing advance
2- Change in mixture (vacuum leak?)
These cover 99% of the possibilities. Find out which it is. My first guess would be the timing. I am suspicious of anyone who says there is a better advance can for an L76 than the 1810. Secondly, you chose to use a used part. My last guess woud be the carb. I just sold my extra 2818-1 to another forum member so I can't help with a loaner.
1- Increase in timing advance
2- Change in mixture (vacuum leak?)
These cover 99% of the possibilities. Find out which it is. My first guess would be the timing. I am suspicious of anyone who says there is a better advance can for an L76 than the 1810. Secondly, you chose to use a used part. My last guess woud be the carb. I just sold my extra 2818-1 to another forum member so I can't help with a loaner.
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
Barry, I'm guessing it's your choke. Have you loosened the choke and set the cap at full off? In other words, rotate the cap so that when the internal spring relaxes and expands when hot, the choke lever still can't move and interact with the throttle. Try this and see if this doesn't cure your problem. It may be that the choke needs to be set more lean to counteract the effect of the spring tension which tries to set the choke when the throttles are opended.
Another thing you might look at is an intermittent leak at the secondaries vacuum pulldown diaphragm. If the diaphragm is not installed properly between the two halves of the housing, it might have a pinhole leak at the perimeter that sucks in just enough air to allow the diaphragm to open the secondaries. This would cause the increase in your idle speed you experience. Good luck.
Another thing you might look at is an intermittent leak at the secondaries vacuum pulldown diaphragm. If the diaphragm is not installed properly between the two halves of the housing, it might have a pinhole leak at the perimeter that sucks in just enough air to allow the diaphragm to open the secondaries. This would cause the increase in your idle speed you experience. Good luck.
Thread Starter
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
JSB
I see what you are saying about the idle screw. I'll have to mark it so I can determine after the problem occours again if the screw is moving or not.
as for the 1810 can, you are right, not much better than the 1810, EXCEPT the original factory can which is what I have back on the car.
The only issue I have or doubt I have regarding a vacuum leak which has been suggested many times now although I understand why, is that it's an intermittent problem. If I had a vacuum leak wouldn't the problem ALWAYS be there? Plus, if there was a vacuum leak causing the idle to go up and once I readjusted the idle screw to back the idle down wouldn't it stay down simply because I've now compensated for the leak by the readjustment? Mine keeps wanting to go back up again after driving for a while. That to me is what's so confusing about it.
Coves, you may remember back in Jan/Feb when I had to deal with my choke on this carb. I can tell you that if there is ANY part of this carb that I've gotten somewhat familiar with it's the choke system. It's definitely working correctly. it comes on properly and is going off properly and not sticking on the fast idle cam. I actually set it back when I was working on it to the leanest condition I could and have it operate.
I'll go thru it again while I'm checking everything out just to double check but I don't think that's where the issue is coming from.
Well, this week sometime I have a lot of checking on this carb to do
I see what you are saying about the idle screw. I'll have to mark it so I can determine after the problem occours again if the screw is moving or not.
as for the 1810 can, you are right, not much better than the 1810, EXCEPT the original factory can which is what I have back on the car.
The only issue I have or doubt I have regarding a vacuum leak which has been suggested many times now although I understand why, is that it's an intermittent problem. If I had a vacuum leak wouldn't the problem ALWAYS be there? Plus, if there was a vacuum leak causing the idle to go up and once I readjusted the idle screw to back the idle down wouldn't it stay down simply because I've now compensated for the leak by the readjustment? Mine keeps wanting to go back up again after driving for a while. That to me is what's so confusing about it.
Coves, you may remember back in Jan/Feb when I had to deal with my choke on this carb. I can tell you that if there is ANY part of this carb that I've gotten somewhat familiar with it's the choke system. It's definitely working correctly. it comes on properly and is going off properly and not sticking on the fast idle cam. I actually set it back when I was working on it to the leanest condition I could and have it operate.
I'll go thru it again while I'm checking everything out just to double check but I don't think that's where the issue is coming from.
Well, this week sometime I have a lot of checking on this carb to do
Burning Brakes
Joined: Aug 2000
Posts: 883
Likes: 2
From: Hilton Head SC
Barry, Most vacuum leaks are not intermittant. That's why timing variation is my #1 choice. Next time the idle goes up, disconnect and reconnect the vacuum advance hose a couple of times. Maybe (if you are real lucky) if it's hanging up, moving it back and forth will help.
Thread Starter
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
JSB, that's my point, I can't see it being a vacuum leak issue since it's intermittent.
I drove the car about 120-150 miles on Sunday without a problem at all. Go figure!
Good idea on the idea to pull the hose off than reconnect it from the can next time it happens and see if it brings the idle back down. That very well may indicate the diaphram in the can may be sticking - I wouldn't have thought of that.
Of course with my luck it won't happen again for a while now that i WANT the problem to occur to track it down!
I drove the car about 120-150 miles on Sunday without a problem at all. Go figure!
Good idea on the idea to pull the hose off than reconnect it from the can next time it happens and see if it brings the idle back down. That very well may indicate the diaphram in the can may be sticking - I wouldn't have thought of that.
Of course with my luck it won't happen again for a while now that i WANT the problem to occur to track it down!
