Login    Forum    Search    FAQ

Board index » Racing Forum » Fuel Systems




Post new topic Reply to topic  [ 111 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8  Next
Author Message
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 10:50 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
Milan.. wrote:
I feel that should work fine , maybe try the old BG fuel flow test with your pumps??


These pumps will fill a gallon super fast! When I first got the car i went thru the fuel system flushing it out and it was like a firehose man! lol

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 6:24 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
Your thinking seem to be that the jetting is lean. IT IS'NT. The plugs show rich. You look under the outside appearance of the plug, the outside is just idling stuff, the Dark Tan underneath on the porcelain is typical of a mixture thats around high 11's and thats what the jetting will give you too. The thing to solve for development of the engine is why does it have to be that rich to make so far its max power. The reasons for that could be in the exhaust, or the valve motion. Both of which have been changed. The carby apparently gave clean plugs in the past but it hasn't done it in this car, but you have started overfueling the engine and its going faster, that means it could possibly have done that in the other car if you had tried it.
Some things that respond to over rich mixtures are;
Ignition timing is too retarded.
Ignition energy is low.
Not enough exhaust heat retention
valve motion is too aggressive, causing lack of vacuum in valve curtain area at beginning of intake.
Cam advanced too far
Exhaust opening too early
Intake closing too early for high RPM , thus reducing cylinder fill and dynamic compression
Carby has poor atomization
Carby too big so fuel droplets not staying in the stream within the plenum, basically they fall on the floor and dribble into the cylinders.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 7:10 pm 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
My original log showed that with the 86/94 jetting it was 14, and power was way down, My thoughts are it had something to do with that screen I was using on top if the carb possibly choking off, like when you get a really restrictive air filter or even fuel filter, it doesn't allow the air to flow thru it. I agree with the plugs above it is way rich and that was with the 89/96 jetting , Before that big jet increase these plugs always looked clean etc, again i am thinking it may have to do with that setup on top of my pan? I dunno I put the carb back how I had it, other than the rear bleeds are now 21.5, compared to 18-20. Everything else is the same including the jetting 86/94, I also got rid of those screw in jet ext , and got some stainless ones that push over the jet, had to notch the float a little more as it would hit them and not allow float to drop all the way down, but i took it out today and stepped it down a couple of times granted not for very long, cause it's illegal, but the meter immediately went right to 12.5-12.7. I am going to make a pass saturday exactly as i have it and see what it runs etc, then i will add more jet to see if it picks up. will also be trying a tad more timing closer to 31-32 instead of 29 where i am at. The car felt very strong tonight and its cooled down, before when it was cool that morning the car didn't feel like it does right now. So lets hope it was that screen choking out!.. The cam is not too far advanced, its where the card said to put it. 108.5,That is also where the guy that builds motor's and does these heads see it make the most power on the dyno etc. fwiw He is a pontiac guy not just a engine builder so he knows these engines and setup's very well.
I also do have those skirted banjo's coming and more than likely will install them, can't hurt especially if the booster signal is a tad weak now. I won't do that til racing is over on the 7th then we only have non points stuff.

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 9:06 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
If you increase the HSAB to like I said and even go to the emulsion settings I said, you will atomize the fuel much better than the setup in the carby from the guy. Then the WB meter will read correct. The WB at the moment is reading wrong because the combustion is poor caused by poor vaporization caused primarily by poor atomization.
It is better to remove the sensor from the pipe to calibrate it, you dont have to calibrate it all the time just do it once a year or do it when you go to a high altitude track. You can tell when the sensor has been calibrated in a contaminated environment, it swings from full rich to full lean all the time. but your is not doing that so you have had clean enough when you calibrated.
I constantly say to people you have to have vaporization, which comes from atomization, Atomization in a carby comes from correct emulsion air flow rates. The emulsion air flow is responsible for LOWERING the fuel head in the main well, that creates a greater pressure differential from the bowl to the well, that enables a smaller main jet and smaller well drilling and angle channel etc, then you get faster exiting fuel from the booster, BUT annular boosters stuff it all up, straight down leg ones are better in that department.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 9:35 pm 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
I will drill out some extra bleeds tomorrow and some set screws for the emulsions, and if the car doesn't run well saturday i will pull carb and put your setup in and see how it runs from there .

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Thu Sep 27, 2012 10:27 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
I dont think you have been complaining that the car doesn't run well, your just complaining that you think it shouldn't need the amount of jet its using. The main concern is to establish if there is a discrepancy from plug reading to the WB. There definitely is with the information presented at this stage. You did some changes and the WB now reads much closer to truth so thats a good thing. What I think is going on is there used to be (prior to your latest changes) substantial O2 left over in the exhaust. If there is O2 left over and the jetting is flowing fuel to actually run heaps rich then there needs to be concern towards engine wear. The unused O2 is the key, its telling you there is unused fuel as well. I have a lot of experience with WB's and gas benches with exactly this style of engine problems. If the burn was using all the O2 there would be a tremendous amount of CO in the stream and thats a good thing because it tells you the vaporization and homogenization are good. I can tell thats not the case with your setup because the WB is reading lean not rich so there has to bore washing over fueling going on. When you changed to the larger HSAB you promoted more atomization thus sending the combustion more efficient.
You haven't seen the best of this engine yet.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Fri Sep 28, 2012 6:08 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
Yea I was very pleased when i kicked her down and held for a bit and to see it read basically perfect was nice to see! I also want to find a small piece of wire or something to measure that air bleed to see how small it is actually that i ran my .0215 drill thru it to open it up. I also changed out that plywood spacer too to a phenolic one, as well as those extensions, So maybe all three had a play in this along with that screen? Dunno for sure.Thinking if it shows rich yet at the track, would it be easier or better to just open that back bleed a couple more thous, then to lean out the jetting? I can tell you know what your talking about when it comes to this stuff! Don't think for a minute i don't appreciate it :)
I would have to agree with you I believe there is alot more E.T yet! \:D/

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Fri Sep 28, 2012 7:21 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
I found a place that sells those air bleeds and the stock size pilot hole is .020, so that is what was in the back, now its .0215. Not much bigger, how much does .001-.002 on air bleed make on jet size? If u have a 94 jet and u change air bleed .001. Does that equate to a 95 jet?

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Fri Sep 28, 2012 7:42 am 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
There is no relationship of HSAB size to the main jet. The HSAB is there for atomization and AFR correction across the CFM range. With zero HSAB air the mixture will get richer as the CFM increases and the atomization will be poor and the engine will require an overly rich mixture for maximum power. The mixture requirement of an engine is a function of homogenization and vaporization. Any wasted fuel is a symptom of these factors being executed poorly.

It doesnt take much of a change to alter the chemistry of the burn. The chemistry is like a switch, its either right or extremely wrong. A simple thing like the HSAB change you did is enough to switch the chemistry however you should not stop there and just accept the results. Experimentation leads to perfection.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Fri Sep 28, 2012 8:51 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
I plan on drilling another set of bleeds to match the fronts .024, and will try those in the back just to see if it helps it more even ,and still doesn't lean out WOT too Much.

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Fri Sep 28, 2012 5:17 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
I would go with the skirted booster and then you will need the emulsion setup I said. that would get you a safe fueling once you find the right main jet for it and allow you to experiment with timing etc.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Sat Sep 29, 2012 6:49 pm 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
Welll Did not get to do much tesing way too many cars today! Alot of street cars too. But I started out with jetting at 86/94 .024 Primary bleeds and 21.5 in back. car ran 10.85@123.95, 10.84@123.81, MY meter after launch and about half way down track it was back in warm up mode did that for a few passes, but finally started working and staying on and with above settings it showed 12.5-12.7 on meter and the graph shows that, I tried some higher timing like 31 car fell off 1 mph, so I put it back to 27-28, and changed rear bleeds to .024's and car ran 10.86@123.44 Meter now showed it was leaner with bleed change closer to 13.2-13.4. I know u shouldn't make two changes at once, but i already knew it doesn't like the timing, so i put it back where i knew itliked it, and i wanted to see the difference on the rear bleeds. Without the air filter today it picked up .05 in E.T. Best E.T for the day was 10.81@123.51 about 2200 DA. I never got to try square jetting today either. Just too much time in between rounds to get accurate information. It does appear tho that changes to the carb does show or did show on meter today so I think were headed in the right direction. It is suppse to be 60 next sunday so I will be changing the rear bleeds back to 21.5 so i will be in that 12.5-12.7 range. I have some logs I saved will post. The first graph is the smaller rear bleeds and the second is the 24's in that leaned it out. Whichj I am guessing that is why it picked up in the hotter weather it wanted to be leaned out which they did.

Image

Image

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Tue Oct 02, 2012 6:34 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
Any comments on my last time out?

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Tue Oct 02, 2012 7:31 am 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
It went all right didnt it? And it managed to use smaller jets and it read correct on the WB so its all good.


Top 
 Profile  
 
 Post subject: Re: 1050 Dominator
 Post Posted: Tue Oct 02, 2012 8:11 am 
Offline

Joined: Mon Sep 17, 2012 12:30 pm
Posts: 139
shrinker wrote:
It went all right didnt it? And it managed to use smaller jets and it read correct on the WB so its all good.



Yea I think so? lol.. I just wanted to make sure i didn't miss something, or there was something in the LOG that I missed etc. This sunday looks to be the same weather wise,except not sure on the Barometer yet, but temp wise and dew points, and humidity look close, even a tailwind :) I will be putting that smaller rear Air bleed back in cause that is the one that showeda nice 12.5-12.7 on the AFR at WOT with my 86/94 jetting.

_________________
74 Firebird 3580 lbs
10.56 @126.67 1.49 60 ft Image


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 111 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8  Next

Board index » Racing Forum » Fuel Systems


Who is online

Users browsing this forum: No registered users and 3 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron