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  #46 (permalink)  
Old 09-17-2010, 09:26 AM
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Quote:
Originally Posted by bubbahotep
What size power valve are you using?

The idle-eze or secondaries opened a bit should give instant results. Either should make your rpm go up at least 500-1000rpm and cause you to close your primary side.
I am running a 6.5 pv that came with the carb.

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  #47 (permalink)  
Old 09-17-2010, 09:40 AM
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Might be an issue, should be 1/2 your idle vacuum in gear (if it's an automatic).

4.5 if youre at 9hg idle vacuum. Maybe lower might even be better

Idle vacuum keeps it closed, low idle vacuum because of the cam might make it open and dump fuel...run rich.

6.5 is assumed for cars with 12hg or higher at idle, most stock motors are 15-20hg at idle.
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  #48 (permalink)  
Old 09-17-2010, 09:51 AM
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This is where the confusion began w/the dyno op saying to plug the PV and jet up.

Instead of that, use a 45 PV and that will keep extra fuel from being drawn into the engine from the PV opening at idle w/the transfer slot overexposed. If the idle slot wasn't overexposed, the PV being open at idle would be far less of a problem. But as it now stands, the PV needs to go down to a 45. As was said, this is idle vacuum IN GEAR if it's an AT, neutral if a stick.
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  #49 (permalink)  
Old 09-17-2010, 09:55 AM
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I will see if I can locate a 45 and see how it works.
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  #50 (permalink)  
Old 09-17-2010, 10:00 AM
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I found a 35 new in the pkg in my shop, will this do?
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  #51 (permalink)  
Old 09-17-2010, 10:24 AM
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For the time being- YES. It's better than the 65, for sure!
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  #52 (permalink)  
Old 09-17-2010, 10:32 AM
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Ok I will put it in a little later and see what happens.
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  #53 (permalink)  
Old 09-17-2010, 10:52 AM
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I installed a 4.5 PV months ago and it didnt do squat.. Even if it doesnt do anything, you should still have a 4.5 in it with your vacuum reading of 9hg (as cobalt327 said, a 3.5 will work for now)..
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  #54 (permalink)  
Old 09-17-2010, 11:15 AM
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Quote:
Originally Posted by My68Vette
I installed a 4.5 PV months ago and it didnt do squat.. Even if it doesnt do anything, you should still have a 4.5 in it with your vacuum reading of 9hg (as cobalt327 said, a 3.5 will work for now)..
LOL Sounds like you have the same kind of luck that I have.
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  #55 (permalink)  
Old 09-17-2010, 12:31 PM
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Originally Posted by redride
LOL Sounds like you have the same kind of luck that I have.
Below is a link to about 5 pages of the same thing your going through.. As you will see, I have already done and/or tried everything that your being advised to do.. In the end everyone thought it was an ignition issue but I can assure you it wasnt.. I ran my car 2 weeks ago and turned 6700rpm and ran 11.40's at the track and a weak ignition wouldnt let me do that.. I instaled new plugs at the track and by the 3rd pass, my plugs were toast just from the ideling I did in the pits and staging lanes. I thought I had another carb here but I gave it away so I never had the chance to try that or reducing the IFR's yet.. My wife and son are leaving town tomorrow so that gives me all day to install the .034 IFR's and see what happens..

Idle Restrictors on 750DP Mighty Demon?
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  #56 (permalink)  
Old 09-17-2010, 07:02 PM
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Just put the 35 power valve in and it seems to make a big difference. I am now able to close the front butterflys to their correct position and still able to get an idle of 1000 by only opening the back butterflys a small amount. I could not do any more tuning due to a problem with my oil pressure acting funny, I think it is in the line that I jacked up. I will replace the line tomorrow, hook up the vacuum guage and do some addition adjusting on the air fuel and see what happens.
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  #57 (permalink)  
Old 09-17-2010, 07:25 PM
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Quote:
Originally Posted by redride
Just put the 35 power valve in and it seems to make a big difference. I am now able to close the front butterflys to their correct position and still able to get an idle of 1000 by only opening the back butterflys a small amount. I could not do any more tuning due to a problem with my oil pressure acting funny, I think it is in the line that I jacked up. I will replace the line tomorrow, hook up the vacuum guage and do some addition adjusting on the air fuel and see what happens.
The 35 power valve will, or should, have the same effect for you at idle as the 45....both should be closed and doing nothing(the 35 will be even less likely to screw up the idle). Once you start to accelerate, the valves will open and having the correct one will give you better output.

Id use the idle-eze instead of the secondary plates. Leave the plates where you have em and do the rest with the idle-eze. And now thats assuming the idle-eze screw is also close to factory? You have to use one or the other only, that idle-eze was designed to avoid using the secondary adjustments I think.

A little trick I use for keeping the primary plates close to factory: Score a line mark on the baseplate where the primary throttle arm comes out on the driver side and another line on the actual primary arm itself. The 2 lines are lined up at whatever you choose as the "factory" setting. Then, over time, as you might adjust the idle speed screw you can see if you drifted too far off the original settings. Saves removing the carb and looking at the hole.
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  #58 (permalink)  
Old 09-17-2010, 07:28 PM
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After putting the 35 in I again attempted to use the Idle-Eze to adjust the idle but it will only lower the idle, not raise it to where the car will stay running.
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  #59 (permalink)  
Old 09-18-2010, 11:15 AM
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Ok, I changed my IFR's out to .033's and it seems I'm heading in the right direction but still need to go more... I had to open the idle-eze all the way to get any increase in idle speed, which did allow me to back down the main curb idle slightly. The idle didnt increase until the last full revolution on the idle-eze and only by maybe 100-200rpm. I tried re-adjusting the idle mixture screws again but they still run best about 3/4 out on all 4 corners.. Its still very rich but does seem a little better/smoother and I can dial the idle down a little more than before, without it wanting to stall..

I'm really confused about my carb though.. I have the 750 5402020GC and thought it was the same as the 5402010GC but with annular discharge but after taking it apart I noticed the jets are 70/77 where-as the 5402010GC is listed as having 77/83.. So nw my question to BG is are the IFR's the same size or are they smaller than the 5402010GC? The only other BG carb I can find with the 70/77 jets is the 650 and that carb has .029 IFR's in it so I'm wondering if maybe thats what I need.. Either way I'm going to try some .029 or .030's to see if that works even better, if not I'll bump up to 32's....



FYI, double check any new IFR's you buy to ensure they are the correct size.. I ordered .032's from Jegs BUT with a magnifying glass I can clearly see they are stamped 33, even though the part # on the bag says they are .032.. I also ordered some .034's and those were correct but I dont think I will be using them..
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  #60 (permalink)  
Old 09-18-2010, 01:08 PM
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Quote:
Originally Posted by redride
After putting the 35 in I again attempted to use the Idle-Eze to adjust the idle but it will only lower the idle, not raise it to where the car will stay running.
The 45 or 35 power valve will have the same effect at idle, even a 25 would be the same at idle. Thats a good thing though. The valves are closed at idle and are NOT part of the idle adjustments. The 35 or 45 will have different affects on acceleration.

As far as the idle-eze screw, is it maxed out in 1 direction? If it starts to lower the rpm its likely you're closing it up, taking away air. Also, whatever amount you have open on the secondaries will also affect the idle-eze adjustment (because you have 2 areas letting in more air).

Looking down the secondaries, how far open do they look? Typically they almost appear CLOSED even though they were adjusted to crack in more air.
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