A
Anonymous
Guest
cfmustang":2jg8rm8m said:
If it is running good, I would leave the gaps alone! One variable at a time....
SOLVED: Still running poorly, still having vacuum issues
- Thread starter cfmustang
- Start date
If it is running good, I would leave the gaps alone! One variable at a time....
In my humble opinion.
Fouled spark plugs
It runs better with a vacunm leak
It runs bad at idle and is hard to adjust and intermitent
You absolutely have a gas leak into your manifold most probably from your carb . You will never get this car to run correctely till you solve this problem. I'll bet your gas mileage is bad as well.
I would get a known good carb and put it on. Rebuilt one barrels are cheap and easy to adjust even if they don't perform as well. Once you get the car to run rite with the one barrel then that will eliminate a lot of other questions that have been plaging you. Then you can concetrate on the carb and its problems.
You've got enough compression and youre timing has been beat to death. The only thing left is youre carb.
Good luck
ps Ive seen engines run fairly good with a lot wrong with them ie broken rings, blown head gaskets and lots more. Youre engine can not be this finiky.
Fouled spark plugs
It runs better with a vacunm leak
It runs bad at idle and is hard to adjust and intermitent
You absolutely have a gas leak into your manifold most probably from your carb . You will never get this car to run correctely till you solve this problem. I'll bet your gas mileage is bad as well.
I would get a known good carb and put it on. Rebuilt one barrels are cheap and easy to adjust even if they don't perform as well. Once you get the car to run rite with the one barrel then that will eliminate a lot of other questions that have been plaging you. Then you can concetrate on the carb and its problems.
You've got enough compression and youre timing has been beat to death. The only thing left is youre carb.
Good luck
ps Ive seen engines run fairly good with a lot wrong with them ie broken rings, blown head gaskets and lots more. Youre engine can not be this finiky.
A
Anonymous
Guest
69.5 Mav, you have alot of good points.
My 440 cu. in. Satellite had all eight exhaust valves burnt, highest compression was maybe 60 psi and it still ran like a swiss watch and got 20 MPG (2.73 gears) (but very low on power)
There are only *so many* variables either way on the ignition....it either works or it doesn't. I am also thinking a different carb will make a lot of difference. Even if you have to change to a 1 bbl (temporarily) that will at least make it drivable?? Or swap on a good "american" 2 bbl until you get some jets and stuff to tune that Weber properly.
My 440 cu. in. Satellite had all eight exhaust valves burnt, highest compression was maybe 60 psi and it still ran like a swiss watch and got 20 MPG (2.73 gears) (but very low on power)
There are only *so many* variables either way on the ignition....it either works or it doesn't. I am also thinking a different carb will make a lot of difference. Even if you have to change to a 1 bbl (temporarily) that will at least make it drivable?? Or swap on a good "american" 2 bbl until you get some jets and stuff to tune that Weber properly.
Okay.
I didn't swap the carb today because it does not appear to be the exact same carb (it is a progressive two barrel, but it just looks different - in some ways) and I wanted to have more time when I swapped it and unfortunatly, life kicked in again and prevented me from having more than about an hour to work on the car.
However, I did map my dizzy curve. Interesting stuff. My engine analyzer is only marked up to 2500 rpm but i could estimate up to about 3000. Also, it is not so easly to do it myself (pull the trottle, watch the rpm and time at the same time), but I think I got it close enough for our purposes.
By the way, tape just was not working for me so I ended up using chalk and marked it using the timing tab to mark off the 10's on the damper.
Note: Vacuum adavance was disconnected.
900 RPM - 14*
1000 RPM - 14*
1500 RPM - 20*
2000 RPM - 29*
2500 RPM - 35*
3000 RPM - 36*
Above 3000, I could not tell the RPM but the advance pretty much stopped at 3000 rpm.
When driving, 14* seems good at idle. However, at this setting there is some pinging at WOT.
Honestly, the car is still running pretty darn good since I put the points back in. The difference is I got the dwell about dead on this time at 38* as opposed to around 35* before and left the plug gap at .045.
I still have to keep the idle pretty high (900 to a 1000 as opposed to the 600 that many seem to run with a automatic) so that I can idle in reverse and at lights with the brake engaged. I guess that is just a characterisic of the big cam that I will just have to live with.
Heck, I could even almost tune it following Webers instructions now (the intial settings of idle and mixture). At their suggested idle, if I have the mixture screw out enough, it will run..poorly, but run. I am still having to turn out the idle mixture screw way more than I should have to though.
I hate to claim victory, but it is starting to seem like I am to the point where it is just going to be tuning the carb (jetting) now. The weird thing is there was no A-ha! point where it happened all at once. It has just sort of been getting better and better in little bits. Because of that, I can't seem to point to just one thing either.
I have been fighting it so long that I have forgotten everything that I was fighting... Or my expectations have lowered...
I didn't swap the carb today because it does not appear to be the exact same carb (it is a progressive two barrel, but it just looks different - in some ways) and I wanted to have more time when I swapped it and unfortunatly, life kicked in again and prevented me from having more than about an hour to work on the car.
However, I did map my dizzy curve. Interesting stuff. My engine analyzer is only marked up to 2500 rpm but i could estimate up to about 3000. Also, it is not so easly to do it myself (pull the trottle, watch the rpm and time at the same time), but I think I got it close enough for our purposes.
By the way, tape just was not working for me so I ended up using chalk and marked it using the timing tab to mark off the 10's on the damper.
Note: Vacuum adavance was disconnected.
900 RPM - 14*
1000 RPM - 14*
1500 RPM - 20*
2000 RPM - 29*
2500 RPM - 35*
3000 RPM - 36*
Above 3000, I could not tell the RPM but the advance pretty much stopped at 3000 rpm.
When driving, 14* seems good at idle. However, at this setting there is some pinging at WOT.
Honestly, the car is still running pretty darn good since I put the points back in. The difference is I got the dwell about dead on this time at 38* as opposed to around 35* before and left the plug gap at .045.
I still have to keep the idle pretty high (900 to a 1000 as opposed to the 600 that many seem to run with a automatic) so that I can idle in reverse and at lights with the brake engaged. I guess that is just a characterisic of the big cam that I will just have to live with.
Heck, I could even almost tune it following Webers instructions now (the intial settings of idle and mixture). At their suggested idle, if I have the mixture screw out enough, it will run..poorly, but run. I am still having to turn out the idle mixture screw way more than I should have to though.
I hate to claim victory, but it is starting to seem like I am to the point where it is just going to be tuning the carb (jetting) now. The weird thing is there was no A-ha! point where it happened all at once. It has just sort of been getting better and better in little bits. Because of that, I can't seem to point to just one thing either.
I have been fighting it so long that I have forgotten everything that I was fighting... Or my expectations have lowered...
A
Anonymous
Guest
From 14* to 36* is 22 degrees of mechanical advance.
1) At what degrees initial do you get your best idle at?
2) Do you know what exact RPM pinging occurs??
1) At what degrees initial do you get your best idle at?
2) Do you know what exact RPM pinging occurs??
Good work! You are making progress, albeit one step at a time 
I see nothing alarming in your timing curve. 22 degrees of actual crankshaft advance, all in by 3000 rpm is pretty standard. For absolute best performance you may want to re-curve the distributor but let's not get hasty just yet.
I still think that your engine combination is a perfect candidate for manifold vacuum advance at the distributor. First, you will need to retard the timing until the high speed pinging is eliminated. Try backing it off about four degrees, this will put it at 10 degrees initial and 32 degrees at high speed.
Once you have the timing set for best high-speed performance, you won't have enough advance for good idle with that big cam. This is where the manifold vacuum advance comes in. Just hook it up and your idle speed should increase a whole bunch. Then you can slow down the idle with the idle speed screw, and you should also have enough vacuum to adjust the mixture too.
I highly doubt that you will get it to idle well at 600 with that cam. Don't sweat it, just bring it down as best you can and still get decent throttle response.
Joe
I see nothing alarming in your timing curve. 22 degrees of actual crankshaft advance, all in by 3000 rpm is pretty standard. For absolute best performance you may want to re-curve the distributor but let's not get hasty just yet.
I still think that your engine combination is a perfect candidate for manifold vacuum advance at the distributor. First, you will need to retard the timing until the high speed pinging is eliminated. Try backing it off about four degrees, this will put it at 10 degrees initial and 32 degrees at high speed.
Once you have the timing set for best high-speed performance, you won't have enough advance for good idle with that big cam. This is where the manifold vacuum advance comes in. Just hook it up and your idle speed should increase a whole bunch. Then you can slow down the idle with the idle speed screw, and you should also have enough vacuum to adjust the mixture too.
I highly doubt that you will get it to idle well at 600 with that cam. Don't sweat it, just bring it down as best you can and still get decent throttle response.
Joe
A
Anonymous
Guest
Chris - do you keep a log of where all your settings are so you can come back to the same settings later, if need be?
JW has some great suggestions, I would try what he suggests and then report your findings. You can then always go back to where you were.
JW has some great suggestions, I would try what he suggests and then report your findings. You can then always go back to where you were.
No I haven't been keeping a log, but I probably should start with what I have as this is about the best it has run.
I thought the total advance looked okay (it probably is 20*, not 22*...I may have been a little off in my marking.) If I remember right, the weights in the dizzy are 10 and 20, so it should be on the 10 weight allowing for 20* total mechanical advance. Again, for a inital advance of around 14* that should be about right. My guess is I will need to get different (heavier) springs. Shouldn't I be getting full advance around 3500? That could also prevent some pinging by slowing down the curve.
I don't know at what RPM the pinging occurs because the tach went bad a while ago. It might be time to scour ebay for a cheap aftermarket tach.
It is hard to tell where the best idle is. With the lumpy cam, the higher initial setting doesn't necessarily smooth out the idle so much as raise the idle speed and up the vacuum. I know that at a certain point (I don't remember what), the engine gets hard to start.
A little later this week, I will try the manifold vacuum and see how it goes.
I thought the total advance looked okay (it probably is 20*, not 22*...I may have been a little off in my marking.) If I remember right, the weights in the dizzy are 10 and 20, so it should be on the 10 weight allowing for 20* total mechanical advance. Again, for a inital advance of around 14* that should be about right. My guess is I will need to get different (heavier) springs. Shouldn't I be getting full advance around 3500? That could also prevent some pinging by slowing down the curve.
I don't know at what RPM the pinging occurs because the tach went bad a while ago. It might be time to scour ebay for a cheap aftermarket tach.
It is hard to tell where the best idle is. With the lumpy cam, the higher initial setting doesn't necessarily smooth out the idle so much as raise the idle speed and up the vacuum. I know that at a certain point (I don't remember what), the engine gets hard to start.
A little later this week, I will try the manifold vacuum and see how it goes.
cfmustang":3f6cbexl said:
Full advance at 3000 is pretty normal, you can certainly play with it later on. I wouldn't mess with it yet.
Setting the timing back to 10 degrees should help it start easier and also reduce (or hopefully eliminate) pinging. The manifold vacuum advance should help with tuning the carb at idle.
That cam is not going to allow either a smooth idle or a slow idle, so you will just have to tune it as best you can.
I think we mentioned idle speed a long time ago. Expect that cam to ilde between 800-950 at best. It will never idle at 600 with any reaonable smoothness.
It doesn't get difficult to start till well after 14*. I am guessing it is closer to 20* initial and then the starter starts having trouble.
It isn't so much the smoothness of idle at lower idle RPM speeds as much as it is drivability. 900 to 950 is about as low as I can go and still idle in reverse or at a traffic light without stalling or shaking to death.
Once I get this sorted out, it is probably just tuning/jetting the carb. Then I relax and enjoy the car for a while. Honestly, at some point (this winter?) I will replace this cam. I just am not impressed with the ratio of smoothness : performance increase.
It isn't so much the smoothness of idle at lower idle RPM speeds as much as it is drivability. 900 to 950 is about as low as I can go and still idle in reverse or at a traffic light without stalling or shaking to death.
Once I get this sorted out, it is probably just tuning/jetting the carb. Then I relax and enjoy the car for a while. Honestly, at some point (this winter?) I will replace this cam. I just am not impressed with the ratio of smoothness : performance increase.
Agreed. This cam is right on the edge of what you could use with a stock converter. It really needs more stall.
A
Anonymous
Guest
"My problem is I have to turn my idle screw all the way in to get it to idle where it does not stall in the first place (around 900 rpm). The wierd thing is if I cause a vac leak at idle, the rpms go up and it smooths out. I was just wondering if that was caused by the inital timing being too low and if that was causing all of my problems"
It depends on your jetting! What do you run?
If you have 55-70 for a primary idle and 140-160 for the primary main jet you have to have a properly working “full power needle valve assy†or you can end up with an engine that fit to your description of increased idle speed with slightest air leak. (It riches up the mixture on the primary side) So check the “power valve†for dirt or sticking function. Also check that the membrane that operates it is not broken. It´s in your top cover near the float. If it is, the engine vacuum can´t pull up the power valve and that one should be closed at idle. A god way to check if that causes the problem is to remove the “full power needle valve assy†and plug it. Don’t forget to use some silicon sealer to block the air signal from the secondary throttle to avoid an air leak. My old carb suffered from all of these things. Good luck.
It depends on your jetting! What do you run?
If you have 55-70 for a primary idle and 140-160 for the primary main jet you have to have a properly working “full power needle valve assy†or you can end up with an engine that fit to your description of increased idle speed with slightest air leak. (It riches up the mixture on the primary side) So check the “power valve†for dirt or sticking function. Also check that the membrane that operates it is not broken. It´s in your top cover near the float. If it is, the engine vacuum can´t pull up the power valve and that one should be closed at idle. A god way to check if that causes the problem is to remove the “full power needle valve assy†and plug it. Don’t forget to use some silicon sealer to block the air signal from the secondary throttle to avoid an air leak. My old carb suffered from all of these things. Good luck.
A
Anonymous
Guest
cfmustang":3zburxvu said:
Bringing advance in sooner with lighter springs quickens the curve, not slow it down.
Now I'm confused. If it is mechanically advancing in full at 3000 and is pinging, I would assume that it is advanceing too soon. That is why I thought I would need heavier springs. That would push the total advance out to closer to 3500 and spread the curve out. Right?
Conversely, wouldn't lighter springs cause the total advance to happen sooner than 3000 and shorten the curve causing even more pinging?
Also, as for the carb that GTM1086 sent me, I don't think I can use it. It is a progressive two barrel but it is oriented all different. I am assuming it is a Holly 5200. The throttle mechanism is on the wrong side of the carb so mounting it would put the choke and all adjusting screws toward the back of the engine. The fuel inlet is facing backwards so I would have to plumb new fuel line and the adjustment screws are completely different and there are what looks like multiple vacuum ports...I think. I am not even sure what screw is what. It doesn't look like it will be a simple bolt on...
Finally, I tried a new pvc valve last night. What a mistake that was. The second I put the new one in it started acting horrible (like it used to). I had to turn in the idle speed screw all the way to get it to about 800 RPM and it was really shaky and rough. It also appeared to be running real rich because opening up the vac tee to the manifold vac line sped up the idle and smoothed it out. Clearly running rich. Once I put the old pvc back in, it was back to normal.
I am assuming that the new valve was bad. The old one was a black plastic Motorcraft pvc valve. The new one the made the car run so bad was some generic aluminum valve from autozone. Is is common to get bad pvc valves out of the package?
Conversely, wouldn't lighter springs cause the total advance to happen sooner than 3000 and shorten the curve causing even more pinging?
Also, as for the carb that GTM1086 sent me, I don't think I can use it. It is a progressive two barrel but it is oriented all different. I am assuming it is a Holly 5200. The throttle mechanism is on the wrong side of the carb so mounting it would put the choke and all adjusting screws toward the back of the engine. The fuel inlet is facing backwards so I would have to plumb new fuel line and the adjustment screws are completely different and there are what looks like multiple vacuum ports...I think. I am not even sure what screw is what. It doesn't look like it will be a simple bolt on...
Finally, I tried a new pvc valve last night. What a mistake that was. The second I put the new one in it started acting horrible (like it used to). I had to turn in the idle speed screw all the way to get it to about 800 RPM and it was really shaky and rough. It also appeared to be running real rich because opening up the vac tee to the manifold vac line sped up the idle and smoothed it out. Clearly running rich. Once I put the old pvc back in, it was back to normal.
I am assuming that the new valve was bad. The old one was a black plastic Motorcraft pvc valve. The new one the made the car run so bad was some generic aluminum valve from autozone. Is is common to get bad pvc valves out of the package?
A
Anonymous
Guest
Your perception of the advance curve & springs is correct.
A
Anonymous
Guest
You are right, I don't have any idea what I was thinking when I wrote that.... 
it was long day, though.
it was long day, though.
cfmustang":1apj5i3p said:
I put a new pcv valve in a couple of weeks ago and it was really rough at the beginning, and the car was huffing and puffing. At one point I heard a "pop" from it and it settled a bit. I assume the carb was "tuned" for the old valve and it was worn out. (I've only had the car a short while)Maybe it needed "breaking" in. Had to readjust the carb. Really didn't have a choice since I had tossed the old valve. :roll: So maybe your old valve was shot.
It now runs OK.
