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Sorry, the mixture screw will affect the idle when setting the mixture, it just doesn't stop the problem no matter if it's lean or slightly rich. The idle speed screw is less than maxed out. If I set the idle speed up to 1500 it does not die but I can't stand that high of an idle. The crazy thing is that small adjustments of the idle speed screw have no effect on idle speed. The more I ponder the situation I am beginning to think something is wrong with the butterfly valves, possibly loose or binding on the spacer. I have had nothing but problems with this new Weber. First, the float valve was shot right out of the box and I had to replace it. The choke butterflies were sticking and would not close when cold and flooring the gas pedal. I found that if I loosened the butterfly screws a bit they worked fine. I may pull the carb tomorrow and inspect the primary butterfly for some malfunction.
This is my first experience with Weber and so far I am not a fan.
Just an FYI, I was a Volvo Master Tech for 30+ years so I am not a newbie. Thanks for the advice!
Wow ARCH, I think you may have just answered your own question!!
Meaning if you had that many problems out of the box with that weber I'd lean towards you have a defective carb.
 
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Discussion Starter · #22 ·
Wow ARCH, I think you may have just answered your own question!!
Meaning if you had that many problems out of the box with that weber I'd lean towards you have a defective carb.
I am thinking so. I was playing with it earlier and found the idle speed screw is actually past the 1 1/2 turn max. I pulled the primary idle jet and found a speck of crud. Cleaned it out and reset the mixture but it still needs a full 1 1/2 turn on the idle speed screw to idle at 1200 rpm. I'm going to pull the secondary idle jet just for grins and try another reset of the adjustments. I may just need a new carb. The frustration grows!!! I bought it through OGTS and it was from Redline so maybe I can return it if all else fails.
I wonder if Holley makes a carb that fits.
 

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Discussion Starter · #23 ·
Put a fuel pressure gauge on it. I know you say the fuel pump is "stock mechanical" and is new. But, in the Chevy world, you almost cannot get a "new" fuel pump with the correct spring. The spring determines the pressure. The morons designing the new pumps use "more's law"; Just in case you never heard of it, "more's law" says: if some is good, more is better. It is usually relegated to camshafts, but can worm its way into everything (but I digress).
When they use too stiff of a spring, it increases the fuel pressure. I would not be surprised to see this philosophy creep into manufacturing for other makes.

I had a "stock mechanical, new" fuel pump on an El Camino a few years ago. It behaved exactly as you describe. I put a fuel pressure gauge on it, and it was over 11 psi. It just overwhelmed the needle and seat. I swapped to a low pressure (4 psi) electric pump and have had no issues since.

Not saying it is fuel pressure. Just saying check it.
Since it runs so well off idle I highly doubt it is a pressure problem but thanks, I will keep that in mind if all else fails.
 

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Discussion Starter · #25 ·
Just a question here, But why 1200 rpm's at idle I think most keep there's at 850-950.
I'm sure they will chime in If I'm wrong or missed something with your set up
Just a question here, But why 1200 rpm's at idle I think most keep there's at 850-950.
I'm sure they will chime in If I'm wrong or missed something with your set up
OK, I have spent the morning trying to figure this thing out. I pulled the idle mix screw and both idle jets and sprayed all the jets and passages with carb cleaner. Reset the mixture screw and while trying to set the idle speed it will adjust up to 950-1000 and stay as I turn the screw until I get past 1 1/2 turns then will jump to 1300+. I have come to the conclusion that there is something wrong with the idle circuit and am going to have to replace/return the carb.
I would like to have it idle at about 1000-1100 to keep the oil pressure up. I'm not really sure how accurate the gauge is but below 950 it dips too low for my taste.
 

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FWIW, I have the same issue with my GT.
I've had the issue with my 32/36 and my 38/38.
Luckily I have an identical engine to my sons GT so I can use that as a benchmark. His runs good on the 38/38.
Since I built both engines I know they are identical.
I also won't be able to start the engine if it's warm and dies. Might need a more powerful battery. I also bought an OGTS starter to install for that issue.

The only two things I haven't replaced were the MC Booster and the distributor. Technically I've replaced the booster, I haven't given it a good test drive after that, though.

I'm hoping to see an answer here.
 
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Since it runs so well off idle I highly doubt it is a pressure problem but thanks, I will keep that in mind if all else fails.
Putting a fuel pressure gauge on it is pretty easy compared to swapping the carb, or going inside the carb. Again, I am NOT saying it is a fuel pressure problem conclusively. I like to start with the easiest potential problem BEFORE heading down the rabbit hole.

As far as running fine off idle; IF it is a pressure problem, it is still possible to run fine in situations other than idle. Why? The excess fuel that is getting by the needle and seat is getting burned.
Your car; your time and money.
 

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Discussion Starter · #29 ·
This may or may not mean anything But does your fuel tank still have the sock in it?
I pulled the tank, removed the clogged up sock and cleaned it out. The outlet pipe is sticking up about an inch or so inside the tank to prevent leftover rust from getting out, or at least minimize it. The filter before the pump is clean.
 

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Discussion Starter · #30 ·
Putting a fuel pressure gauge on it is pretty easy compared to swapping the carb, or going inside the carb. Again, I am NOT saying it is a fuel pressure problem conclusively. I like to start with the easiest potential problem BEFORE heading down the rabbit hole.

As far as running fine off idle; IF it is a pressure problem, it is still possible to run fine in situations other than idle. Why? The excess fuel that is getting by the needle and seat is getting burned.
Your car; your time and money.
I have a Snap On pressure gauge but not the in-line adapter needed. My gas mileage and plugs show no signs of running rich.
 

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I understand you are a very experienced mechanic and I mean no criticism here, but even with the spacer gasket you can still overtighten the carb bolts causing the base plate to warp. This can also happen to the intake itself if you have filed out the sides to get more air flow. While this was more common on the stock carb, I have received GT's with Weber and China knock off Weber's that have a warped base plate. This caused idle issues as you described. However if you are having to mess with the butterflies straight out of the box, and have found debris inside the jets, then you either got a China knock off or a bad unit. Before banging your head much more, I would opt if possible for a replacement. If you get another Weber from OGTS, ask them for the correct jets and emulsion tubes for a better set up for your engine. Also a little concerned about your comment on oil pressure. If you need a higher rpm to maintain a suitable oil pressure, I have to ask if your cam bearings are worn. If you are running hydraulic lifters with worn cam bearings, this can be an issue as the engine warms and the oil thins as well. This us usually not a problem with solid lifters, but worn cam bearings are a pretty high cause for low oil pressure.
 

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Discussion Starter · #32 ·
I understand you are a very experienced mechanic and I mean no criticism here, but even with the spacer gasket you can still overtighten the carb bolts causing the base plate to warp. This can also happen to the intake itself if you have filed out the sides to get more air flow. While this was more common on the stock carb, I have received GT's with Weber and China knock off Weber's that have a warped base plate. This caused idle issues as you described. However if you are having to mess with the butterflies straight out of the box, and have found debris inside the jets, then you either got a China knock off or a bad unit. Before banging your head much more, I would opt if possible for a replacement. If you get another Weber from OGTS, ask them for the correct jets and emulsion tubes for a better set up for your engine. Also a little concerned about your comment on oil pressure. If you need a higher rpm to maintain a suitable oil pressure, I have to ask if your cam bearings are worn. If you are running hydraulic lifters with worn cam bearings, this can be an issue as the engine warms and the oil thins as well. This us usually not a problem with solid lifters, but worn cam bearings are a pretty high cause for low oil pressure.
Thanks for your concern my friend, your comments on a warped base plate is a possibility that I haven't considered. I will need to get it good and warm and check that out. The engine is a fresh rebuild with new everything except oil pump. I must admit that knowing I was going to change the oil after a 300-500 mile break in I used a cheap oil ( O-Reily's brand) and added the ZDDP. I think it gets too thin when hot. I did plastigauge the bearings when all was back from the machine shop and they were great. The machine shop I use is top notch. I am hoping when I change the oil and use good oil that the low pressure issue will be gone and is really only an issue below 800 rpm idle. The cam bearings are also new as is the cam and lifters. I have put over 300 miles on the new motor and will change the oil probably this weekend.
It would be great if I had a vacuum leak at the base plate as that would be an easy fix but I never get that lucky. Wish me luck and thanks again!
 

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Discussion Starter · #34 ·
I'm thinking it's a vacuum leak ....
Ever use propane to check for leaks before??
OK guys, I got it figured out. No Sir, no vacuum leaks. It turns out to be the ign. timing! I had it set at factory spec but got to thinking that with the mods maybe it could use a little advancement. Bumped it up to 5 deg advance and it idles like a champ and runs somewhat stronger too. I am tempted to try a little more but I ran out of adjustment ( the vacuum advance is hitting the head) I may try pulling the distributor and reposition it so that there is more adjustment room but it is running fine so that will be another day.
Thanks for all the suggestions and advice!
 

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Depending on how the distributor is installed (ie at what position the teeth are engaged), the angle of the advance pot can vary a lot. As would the "X" that Gord describes.

These engines will certainly idle better at 10 degrees advance.

Without getting into a huge, unproductive discussion on CIH ignition timing, the most important aspect of timing these engines is the MAXIMUM ignition advance. For most 1.9 or 2.0 CIH engines, any ignition advance greater than 36 degrees BTDC at max mechanical advance (typically 3500 rpm) will cause a loss of top end power. My procedure is to set static (idle rpm, vacuum advance & retard disconnected and plugged) at ~5 degrees BTDC. Then, using a digital advance timing light), I increase the rpm to 3500 rpm. I then adjust the distributor to get 36 degrees ignition advance. Then I go back and check the static advance. But it is what it is, and I leave it there. If it is 12 degrees, perfect, but then the distributor is either a 1975 unit (max mech advance is ~24 degrees) or has been modified to limit advance. I always do that to older distributors.
 

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Depending on how the distributor is installed (ie ar what position the teeth are engaged), the angle of the advance pot can vary a lot. As would the "X" that Gord describes.

These engines will certainly idle better at 10 degrees advance.

Without getting into a huge, unproductive discussion on CIH ignition timing, the most important aspect of timing these engines is the MAXIMUM ignition advance. For most 1.9 or 2.0 CIH engines, any ignition advance greater than 36 degrees BTDC at max mechanical advance (typically 3500 rpm) will cause a loss of top end power. My procedure is to set static (idle rpm, vacuum advance & retard disconnected and plugged) at ~5 degrees BTDC. Then, using a digital advance timing light), I increase the rpm to 3500 rpm. I then adjust the distributor to get 36 degrees ignition advance. Then I go back and check the static advance. But it is what it is, and I leave it there. If it is 12 degrees, perfect, but then the distributor is either a 1975 unit (max mech advance is ~24 degrees) or has been modified to limit advance. I always do that to older distributors.
Does this hold true for both the high and low compression 1.9's or does the high compression motor like less total advance ?
 

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Discussion Starter · #39 ·
Depending on how the distributor is installed (ie ar what position the teeth are engaged), the angle of the advance pot can vary a lot. As would the "X" that Gord describes.

These engines will certainly idle better at 10 degrees advance.

Without getting into a huge, unproductive discussion on CIH ignition timing, the most important aspect of timing these engines is the MAXIMUM ignition advance. For most 1.9 or 2.0 CIH engines, any ignition advance greater than 36 degrees BTDC at max mechanical advance (typically 3500 rpm) will cause a loss of top end power. My procedure is to set static (idle rpm, vacuum advance & retard disconnected and plugged) at ~5 degrees BTDC. Then, using a digital advance timing light), I increase the rpm to 3500 rpm. I then adjust the distributor to get 36 degrees ignition advance. Then I go back and check the static advance. But it is what it is, and I leave it there. If it is 12 degrees, perfect, but then the distributor is either a 1975 unit (max mech advance is ~24 degrees) or has been modified to limit advance. I always do that to older distributors.
Interesting! Thanks for the info.
 

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Does this hold true for both the high and low compression 1.9's or does the high compression motor like less total advance ?
Notionally, both will "like" approximately 36 degrees total advance (static + mechanical + vacuum). Realistically, gas octane, engine temperature, fuel mixture, cam design and compression ratio, and others, will limit (or allow) a different maximum ignition advance, relating mainly to pre-detonation (aka "knock" or pinging). If the engine pings under load, retard the ignition a degree or two. Or use higher octane gas.
 
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