Re: Tuning a Holley 750
[Re: Chilort]
#911918
02/04/11 01:42 AM
02/04/11 01:42 AM
|
Joined: Feb 2003
Posts: 10,205 Someplace you aren't
SomeCarGuy
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 10,205
Someplace you aren't
|
I did a quick scan of the thread, didn't see these things, forgive me if this was covered already.
-looks like you changed the vac spring before the engine was ran w/ this carb. Very easy to get the diaphram off center. Could have a huge vac leak at the pod.
-are you running a choke? I was having fits w/ my 3310 and another member pointed out that there is a hole that needs to be plugged if it is removed. Looks like a screw hole, I didn;t even think it was anythign until that was pointed out. I put a self tapping screw in and my carb now runs fine.
-I bet you have a vac leak someplace. If not at the above spots, someplace. Have you went over all of the intake areas with carb cleaner to check?
-how sure are you that the TDC mark is reliable? Maybe you have a bunch more timing than you think.
-have you tried different gas stations?
I really find it hard to believe that a 9.2 to 1 engine w/ aluminum heads pings on 93 octane w/o any vac advance at all. The jets you have in there just sound way too big. The plugs should be pretty dark, unless extra air is coming in somewhere. There has to be something missing in this picture.
I want my fair share
|
|
|
Re: Tuning a Holley 750
[Re: SomeCarGuy]
#911919
02/04/11 11:25 AM
02/04/11 11:25 AM
|
Joined: Sep 2004
Posts: 1,226 Cookeville
Chilort
OP
Will Work For Mopars
|
OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
|
Quote:
-looks like you changed the vac spring before the engine was ran w/ this carb. Very easy to get the diaphram off center. Could have a huge vac leak at the pod.
-- nope, changed it while it was on the engine.
Quote:
-are you running a choke?
-- running a choke.
Quote:
-I bet you have a vac leak someplace. If not at the above spots, someplace. Have you went over all of the intake areas with carb cleaner to check?
-- I have not done this.
Quote:
-how sure are you that the TDC mark is reliable? Maybe you have a bunch more timing than you think.
I am not sure. But the initial makes sense based on other's setups. I dialed it in with the max vac then pull back 1 inhg method. Total mechanical is then relative to the initial. Maybe it is still too much and I could try to take even more out.
Quote:
-have you tried different gas stations?
-- Yes
Quote:
I really find it hard to believe that a 9.2 to 1 engine w/ aluminum heads pings on 93 octane w/o any vac advance at all.
--- Me too. I didn't check any plugs after I finished up last night. I guess I'll start plugging off ports (not that this has many accessories) to see if maybe that's the issue.
|
|
|
Re: Tuning a Holley 750
[Re: Chilort]
#911920
02/04/11 11:29 AM
02/04/11 11:29 AM
|
Joined: Feb 2003
Posts: 8,020 Pangaea
B5 Bee
master
|
master
Joined: Feb 2003
Posts: 8,020
Pangaea
|
You need to find the problem. Lower rear gears and spark plugs won't fix a carb problem.
There are two things that will make it sneeze back when you punch it, slow timing and/or a lean condition.
10 sizes larger on the jets is crazy. It may eliminate the symptoms but the problem still exists. Seldom does any motor with a Holley perf carb need more than 4 jets sizes up. My first guess is you have a problem with the power valve circuit. A bad power valve, a power valve with too low of a rating, or a stopped up passage. My second guess is it's lean on the accelerator pump circuit. Nozzles should be big enough if it doesn't sneeze when you hit it from an idle. Make sure have a pump cam that still has travel from half to full throttle. If you want to eliminate the chance it's the secondaries opening too soon, disconnect them and try it on primaries only. BTW, the spring has only a small effect of when the secondaries open. The main control is something called a kill bleed. Although one will effect the other, basically, the kill bleed controls when the secondaries start to open, the spring controls how long it takes to get them fully open.
Remember that there are 5 fuel delivery circuits in a Holley. -idle ports, from the idle mix screws -transfer slot, near the idle ports -acclerator pump system, delivers fuel to squirt nozzles -power valve system, delivers fuel to boosters -main jets, delivers fuel to boosters
The goal is to find and fix the problem, not just eliminate the symptoms. You have understand how something works before you can fix it, GRASSHOPPER.
|
|
|
Re: Tuning a Holley 750
[Re: B5 Bee]
#911921
02/04/11 12:09 PM
02/04/11 12:09 PM
|
Joined: Jan 2003
Posts: 5,789 Hamilton, Ontario Canada
Magnum
master
|
master
Joined: Jan 2003
Posts: 5,789
Hamilton, Ontario Canada
|
If your spring is compressing, I'd aim your efforts there.
Let's assume the spring is weak or there is too much resistance in the squirter circuit. Switching to a hollow shooter screw AND/OR shimming the spring will help.
Unlike bigger jets and bigger shooters. This modification will not consume more fuel.
69 Super Bee, 93 Mustang LX, 04 Allure Super
|
|
|
Re: Tuning a Holley 750
[Re: Mr.Yuck]
#911928
02/05/11 10:18 PM
02/05/11 10:18 PM
|
Joined: Oct 2008
Posts: 1,894 Mira Loma, CA
69B3GT
top fuel
|
top fuel
Joined: Oct 2008
Posts: 1,894
Mira Loma, CA
|
Quote:
it won't get any better until you get some gear. Putting a 2.73 in a 440 car is like having a pretty girl friend that has bad breath. yeah you can get past it but it will take a second or 3.
Words cant describe how hard I just laughed
|
|
|
Re: Tuning a Holley 750
[Re: SomeCarGuy]
#911929
02/06/11 04:36 PM
02/06/11 04:36 PM
|
Joined: Sep 2004
Posts: 1,226 Cookeville
Chilort
OP
Will Work For Mopars
|
OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
|
Quote:
You need to check for leaks. Not about cleaning anything. You are about 99% sure to find that you have a vaccum leak.
I worked my way around the carb ... no problem. Went around the outside of the intake manifold ... no problem. Sprayed into the valley tray area ... problem.
Time to try to fix it.
|
|
|
Re: Tuning a Holley 750
[Re: Chilort]
#911931
02/06/11 05:45 PM
02/06/11 05:45 PM
|
Joined: Nov 2007
Posts: 21,822 Kirkland, Washington
Pacnorthcuda
Too Many Posts
|
Too Many Posts
Joined: Nov 2007
Posts: 21,822
Kirkland, Washington
|
Quote:
Nothing in the intake runners to indicate that it was sucking oil. I'd used a full set of intake minfold gaskets on both the top and bottom of the bath tub pan. I guess I need to figure out how that is going to work because what I had on clearly didn't. And I used Gasgacinch to seal it up even.
It could be the gaskets moved over time and led to the leak. Very common. I superglue the fiber gaskets to the valley pan before install so I KNOW they wont move.
|
|
|
|
|