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Re: Tuning a Holley 750
[Re: Magnum]
#911898
01/31/11 11:53 AM
01/31/11 11:53 AM
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Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
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Will Work For Mopars
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OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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Quote:
When you snap the throttle open. Can you see the spring compressing?
I will have to look next time I am messing with it. The accel pump has a red spring. I know when I move the throttle at all (without the engine on) I can hear it squirt fuel.
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Re: Tuning a Holley 750
[Re: Magnum]
#911899
01/31/11 12:50 PM
01/31/11 12:50 PM
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Joined: Jan 2003
Posts: 5,186
Wherever I am.
Junky
master
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master
Joined: Jan 2003
Posts: 5,186
Wherever I am.
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Quote:
I was able to cure my bog with a 35 shooter...
Same here.
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Re: Tuning a Holley 750
[Re: Chilort]
#911901
02/01/11 07:53 PM
02/01/11 07:53 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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The shooter (squirter)should have a two digit stamping on it. The stamping would be on the side that is facing the middle of the carb.
(28=.028", etc.)
I have a carb that both squirters came from QF with no stamping which means .031" to them.
Note: the larger the squirter the "quicker" it will deliver the fuel and visa-versa.
Do you have any extra squirters to try?
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Tuning a Holley 750
[Re: YO7_A66]
#911902
02/01/11 10:06 PM
02/01/11 10:06 PM
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Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
OP
Will Work For Mopars
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OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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Quote:
The shooter (squirter)should have a two digit stamping on it. The stamping would be on the side that is facing the middle of the carb.
(28=.028", etc.)
I have a carb that both squirters came from QF with no stamping which means .031" to them.
Note: the larger the squirter the "quicker" it will deliver the fuel and visa-versa.
Do you have any extra squirters to try?
Nope. But, it is raining here and is supposed to rain through Saturday so I couldn't try anything out even if I wanted to.
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Re: Tuning a Holley 750
[Re: DOUGG]
#911904
02/03/11 03:53 PM
02/03/11 03:53 PM
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Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
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Will Work For Mopars
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OP
Will Work For Mopars
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Cookeville
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Is there any advantage to this kind of squirter: http://www.holley.com/121-135.aspversus this kind of squirter: http://www.holley.com/121-35.aspI currently have the style similar to the 121-135. What kind of jetting on the primary and secondary is just so high that it would indicate that I need to start looking for other sources for problems? My highway ping is still there (though it seems better in some ways) and I'd like to fix it.
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Re: Tuning a Holley 750
[Re: Chilort]
#911905
02/03/11 05:12 PM
02/03/11 05:12 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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Did you confirm that the fuel is squirting as soon as the spring is depressed?
I had a vacuum secondary carb that I had to shim the primary side spring to get it to work properly too.
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""My highway ping is still there (though it seems better in some ways) and I'd like to fix it.""
If you are still getting the ping at highway cruise/WOT, and since you are running the orange pump cam, then a larger squirter would delivery that pump shot quicker. I would try a 035 or a 040 (with hollow screw) for your next testing. If one of these fixes the ping, then you can back down on your main jetting as long as your plugs are looking good. Your pump cam might get smaller too with the bigger squirter.
It appears that it wants more fuel but the guess is "when" it wants more fuel.
BUMP for the reference on the 440/750 (Holley #80508S) jetting.
---------------------------------------------
I found this info about the straight versus tube online:
The "straight" type are basically first design, and are for straight boosters. The "tube" type was developed to aim a straighter stream of fuel against the booster, usually a dropped booster venturi. As the fuel hits the booster venturi, it atomizes better than the straight type.
I have also read that most cases you can use the style that the carb came with.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Tuning a Holley 750
[Re: YO7_A66]
#911906
02/03/11 06:40 PM
02/03/11 06:40 PM
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Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
OP
Will Work For Mopars
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OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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Quote:
Did you confirm that the fuel is squirting as soon as the spring is depressed?
I had a vacuum secondary carb that I had to shim the primary side spring to get it to work properly too.
Yes, it is squirting right away. The spring compresses and then slowly lets out.
Quote:
"My highway ping is still there (though it seems better in some ways) and I'd like to fix it."
If you are still getting the ping at highway cruise/WOT, and since you are running the orange pump cam, then a larger squirter would delivery that pump shot quicker. I would try a 035 or a 040 (with hollow screw) for your next testing. If one of these fixes the ping, then you can back down on your main jetting as long as your plugs are looking good. Your pump cam might get smaller too with the bigger squirter.
It appears that it wants more fuel but the guess is "when" it wants more fuel.
If it is pinging at WOT I cannot hear it. The ping starts when I am running around 75mph in 3rd and have to increase the throttle a tad to go up hill or pick up speed a little more. Then it rattles like a coffee can full of bolts. I would guess engine speed is about 2700rpm based on gear and tire size. Engine vacuum is still over 15inhg when this happens. If I get into the throttle more I can make the rattle go away. I'm guessing still to lean on the primary side. I'm currently still running the 78 jets on the primary and 84 on the secondary. I did drive the truck today and will check some plugs when I gethome.
Quote:
The "straight" type are basically first design, and are for straight boosters. The "tube" type was developed to aim a straighter stream of fuel against the booster, usually a dropped booster venturi. As the fuel hits the booster venturi, it atomizes better than the straight type.
I have also read that most cases you can use the style that the carb came with.
Mine came with the straight types, so I guess I'll go with that.
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Re: Tuning a Holley 750
[Re: RapidRobert]
#911908
02/03/11 06:53 PM
02/03/11 06:53 PM
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Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
OP
Will Work For Mopars
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OP
Will Work For Mopars
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Posts: 1,226
Cookeville
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Quote:
Quote:
The ping starts when I am running around 75mph in 3rd and have to increase the throttle. If I get into the throttle more I can make the rattle go away.
Try turning the vac can 3 turns CCW w a 3/32" allen wrench
Vac can is completely disconnected. I'm still trying to sort this out so I can then reconnect the vacuum advance and then go through all of this again.
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Re: Tuning a Holley 750
[Re: Chilort]
#911909
02/03/11 06:59 PM
02/03/11 06:59 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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The Q (to me) is is it a lean prob or timing. I'd suspect timing (if your octane is adequate). I'm wondering if a slightly stiffer spring combo would help (& I'm assuming your total (w vac adv unhooked/capped as it is now) is correct for the eng family 35-SB 36-38-BB.
live every 24 hour block of time like it's your last day on earth
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Re: Tuning a Holley 750
[Re: Chilort]
#911911
02/03/11 07:08 PM
02/03/11 07:08 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Yeah you are not overboard w timing. Holler how it turns out. Didn't read all the posts & dont know if more octane is a practical option for you but that's my guess
live every 24 hour block of time like it's your last day on earth
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Re: Tuning a Holley 750
[Re: Chilort]
#911914
02/03/11 10:26 PM
02/03/11 10:26 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
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master
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""The ping starts when I am running around 75mph in 3rd and have to increase the throttle a tad to go up hill or pick up speed a little more.""
Your running Champion RC12YC plugs,high pump octane (93), 9.2 compression, no vac advance, timing at 3500, orange pump cam/031 squirter, 78 primary jets, and you still have pinging at light accel at 2700rpms and 15hg vacuum. HMMMMMM.
This problem may get worse as the outside temps go up, unless you are lean. I still suggest that you try the 035 or 040 squirter.
My second thought is that the plugs are tooooo hot in the range.
----------------------------------------------
What heat range Champion spark plugs are other members running on the street? Are 12's too hot?
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Tuning a Holley 750
[Re: Chilort]
#911915
02/03/11 10:39 PM
02/03/11 10:39 PM
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Joined: Jan 2003
Posts: 1,996
s. e. pa.
calrobb2000
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,996
s. e. pa.
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hi what is your cranking compression psi ? per haps you have too much cyl psi ? may need to back off timing to 32-34 deg total . 
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