ozconnection Posted March 25, 2009 Share Posted March 25, 2009 Hey Oz, thats a pretty nice looking set up. Whats up with the three guages on the right fender well? Also what size carb are you running? Looks like a double pumper? Just kinda wondering because mine is a 625 tuned pretty lean, it sounds good idling and raps up pretty good, no hesitation or anything. Im gonna change the oil and filter today, then it should be ready for a test drive. Thanks man, its a big looking mutha but its only a 450 vacuum operated secondary. The guages are oil pressure, fuel pressure and manifold vacuum. I keep them under there so I can leave my interior stock looking. I also figure that if I have to lift the hood for any reason, its then I need to look at the guages under there. When I shut the hood, then all is well (hopefully!). Cheers. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 26, 2009 Share Posted March 26, 2009 Did either of you have to change out the secondary spring to something lighter to get rid of the dead spot between 2200-2700 rpm? Oz you probably have enough power not to have to worry about it, but it was the only thing that helped with my L24. I'm hoping that I can go back up to the heavier spring when I get my L28 built as it doesn't allow the secondary to come in until about 3200 in my current configuration. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 27, 2009 Author Share Posted March 27, 2009 Im running a Carter AFB, completley diffrent set up. Im in the middle of buying a house, so I still havent had mine on the road. I will update when i get it out. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 27, 2009 Share Posted March 27, 2009 Did either of you have to change out the secondary spring to something lighter to get rid of the dead spot between 2200-2700 rpm? Oz you probably have enough power not to have to worry about it, but it was the only thing that helped with my L24. I'm hoping that I can go back up to the heavier spring when I get my L28 built as it doesn't allow the secondary to come in until about 3200 in my current configuration. The stiffness of the seconary spring will change the character and response of your engine, either good or bad. The first thing you need to do is realise that the secondaries may not even be opening at 2.2K rpm on an L24. That flat spot you mention may be over enrichment from the power valve, lean or rich main jets or even from the accelerator pump! OR it could be too lean at WOT in that 500 rpm range! Manual or auto trans? Ignition timing, stock curve or modified? Vacuum advance? Stock camshaft profile or aftermarket? Stock head and ports? As you can see, there are quite a few things other than the opening point and speed of opening that can affect your powerband. Oh, and what do you plug electrodes look like? Take a photo of one and post it if you like. I don't want to start writing a tune up regime for you as you would probably have done some reading/research for yourself. All I'm saying is there are a number of other important variables you need to consider. I find that when I tune my combos, I tune the carb first, then play with the ignition timing. Remove the vacuum advance hose and plug it for tuning purposes. As a suggestion, if you're running stock timing, bump it up a couple of degrees to see if the engine becomes more responsive. Listen hard for 'pinging' and back it back down it it does. Cheers. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 27, 2009 Share Posted March 27, 2009 OZ, Thanks for the info, I'll see if I get all the info here: Manual 5-speed Stock timing on EI from D6F5-02 Dizzy-Vacuum Advance & E12-27 Control From PO: Some head work & mid lift street cam The engine ran smoothly, but never could get rid of the flat spot. If you pushed through it you could feel the secondary "kick in" and would run fine after 3000 rpm or so through the rest of the power band. BTW when the car was not under load this was never a problem it would free rev through this spot with no problem. I had done some research and found that some people with the L24 were having a similar situation caused by the secondary coming in too soon before the engine had enough air flow to support the extra fuel flow. This caused a dead spot in that RPM range and once the engine was around 2800-3000 would create enough flow and continue to run on through. When I changed the secondary spring out to the next lighter one (the lightest one they have) it did make a significant difference in the flat spot. It is now almost non-existent, but I'm sure I probably am giving up some power that I could have down low. I think that this is a lot of carb for the L24 and I'm hoping that my L28 build will support it much better. Having said all that I am now going to change all of the vacuum routing, the fuel rail, and air filter setup on the carb. I am going to clean up the dizzy and check the vacuum pot then reset the timing per Dave and your recommendations. I'll try and get a picture of a plug electrode for you tonight, they look pretty good (slightly rich) and I'm sure I need to go through and dial the carb in as I believe the PO just installed it out of the box. I will be searching for tune up procedures for the Holley as I am not familiar with this carb...YET. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 28, 2009 Share Posted March 28, 2009 The thing I found about using the Arizona manifold is that you can use a surprisingly large carburetor on them and get away with it. I'm talking L28's here but I still think that on an L24 you can get away with a 390 or 465 vac Holley no problems. The smaller the main venturi, the sharper the throttle response will be, so it makes sense that the 390 will be sharper than a 600, for example. This is also due to the nature/design of the manifold itself. That divider that's cast into the plenum separates the induction into two halves, so what we have is essentially, by definition, a dual plane manifold. These types of manifolds are popular with the V8 boys because they improve low engine speed torque. Compared to the Clifford 6=8 manifold which has a massive open plenum under the carb, the Arizona is superior for street driving IMO. The issue with the opening of the secondaries is that when they do actually crack open, there is a momentary change of gas velocity (reduction) through the primary venturis as the engine balances the airflow dilema out and shares the demand with the secondaries. This is where the base fuel curve (determined by the high speed air bleeds and emulsion circuits) changes a little and changes the air/fuel balance that the engine sees when the seconaries open. Reversion of the air/fuel mix also changes the air/fuel ratio that the engine sees. This issue is very prominant in my engine, so much so that just bolting on a Holley four barrel outa the box onto my engine results in a filthy rich top end mixture. I had to pull out heaps of fuel via smaller secondary jet to offset this, the proper fix is to play around with the emulsion tubes and/or bleeds to get the fuel curve 'right'. This isn't easily done on standard Holley carbs, especially the generic ones we all seem to start off with. Their calibration is for V8's and therefore when we bolt them to our engines, they'll run but not be optimal. That's why so many guys who get Holley's soon ditch them. They don't know why they can't quite get the tuning right and after mucking around with jets and power valves forever, call them junk. Dual plane manifolds do this, the Clifford wasn't anywhere this bad. So far apart are the tuning requirements of these two manifolds, I can't just change over the manifolds anymore and use the same carb calibration. I'm not suggesting you get out your drill bits and start opening out the holes, as it stands many of them need to be made smaller anyway! I spoke to a carb guru down here and he suggested that if I want to go so far as to getting my carb setup spot on, taking into account all of the L28's issues, he could modify the stock primary metering block to allow for custom tuning of these fuel circuits. I got him to do it for me and armed with a wideband o2 meter, tuning has become fun and vastly more accurate. I'm almost there, and I've learnt a lot along the way. The Innovate website has a forum just like this one and that site has very valuable information for anyone who decides to run a Holley carb on their engine. I'm looking forward to seeing your plugs, until then.... Cheers. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 28, 2009 Share Posted March 28, 2009 OZ, Here are a couple of photos of the plugs as removed. They are not the best pictures as I had to use my phone, I'll pick up my camera and get some better ones this afternoon. The are lined up in order with #1 far left in the picture. Interesting about modifying the metering block, I will look into this for the L28 when I finally have enough money to finish it. For now I'm just trying to keep the L24 running good enough to have fun with and carry me to work. As I don't have access to a wideband O2 setup, would colortune be the best way to dial in the carb? Thanks for all your help with this. Daniel Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 29, 2009 Author Share Posted March 29, 2009 Can anyone tell me how you upload your pictures to this site? Do you have to save them in photobucket or something first? I want to post the pics of my engine, but don’t know how. Citijet, Im gonna be using a narrow band to help tune as soon as my friend welds my bung in for me. I think that will be pretty close, at least let me know how I am at idle, through the transition from primary into secondary’s and at WOT. Since my adventure with my Carter I have helped my friend go through the Holley 600 he has on his Dodge, and man do I like the Carter! All the stuff you have to go through to get it dialed in is pretty bad. The Carter uses springs and a rod that rides in the primary port as the power valve, the accelerator pump is adjustable from the outside of the carb, and the primary and secondary’s are controlled by changeable ports in the bottom of the carb. You can completely change everything about your carb without spilling fuel or pulling the carb. I think I will just go with an Edelbrock 500CFM if I decide that the 625 is too much. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 29, 2009 Share Posted March 29, 2009 thrustnut, If you want to download pictures off of your computer like the ones in my last post than you can use the "Manage Attachments" button below the window that you type your text into. When the box comes up push the "Choose File" button and navigate to the location of the picture on your computer. If you use an outside server (photobucket, etc.) than push the small yellow button above the text box that looks like a mountain with a sun above it and put the URL Address for the picture that you want to display. If you use this method than your picture will be embedded into the post. I hope that this helps. Daniel Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 29, 2009 Share Posted March 29, 2009 OZ, Here are a couple of photos of the plugs as removed. They are not the best pictures as I had to use my phone, I'll pick up my camera and get some better ones this afternoon. The are lined up in order with #1 far left in the picture. Interesting about modifying the metering block, I will look into this for the L28 when I finally have enough money to finish it. For now I'm just trying to keep the L24 running good enough to have fun with and carry me to work. As I don't have access to a wideband O2 setup, would colortune be the best way to dial in the carb? Thanks for all your help with this. Daniel No problem Daniel, I'm glad I am of some help to you. Your plugs look good from what I can see. You know your carb is working reasonably well then. I have never used colourtune myself, but I've heard they can be useful. I guess the best place to use one is on the dyno to test various rpm's and loads. However, at the dyno there should be a wideband exhaust sniffer that gets shoved into the tailpipe and that kinda makes the colourtune somewhat redundant. Still, at home setting up the idle, it would be a useful little tool. The best tool I ever bought was my Innovate Wide band. The second best tool was my Innova Equus 5568 Timing light. Within 5 minutes of testing my ignition with that, I found my distributor had advance problems. The degeneration was so gradual, that after I corrected the ignition, the engine response and top end increases were noteable. Quote Link to comment Share on other sites More sharing options...
citjet Posted March 29, 2009 Share Posted March 29, 2009 OZ, I do have a local shop that has a dyno with all of the bells and whistles, but the price they want per pull is pretty high. I was hoping to try to get my L24 dialed in "close enough" for a couple of months worth of driving until I can finish my other engine. The colortune may be a cheap option for me at home until then. I will definitely be putting the new engine on the dyno to get it dialed in perfect. I am interested in how your buddy modified the Holley you are using, sounds like it really opened up some tuning possibilities. I have also been looking for a good timing light and will look up the Innova light you mentioned. When I started reworking my vacuum routing I took off the vacuum advance from my dizzy and noticed that it was not moving. After moving the mechanism back and forth several times it loosened up and was working fine with no leaks. The mechanical side was very stiff as well, after taking it out and cleaning it and re-lubricating the vacuum would move the internals with no problem. God knows what my timing curve looked like, but I'm sure I was getting no vacuum advance. I will be setting the timing again tomorrow and will see how far off it is. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 29, 2009 Share Posted March 29, 2009 OZ, I am interested in how your buddy modified the Holley you are using, sounds like it really opened up some tuning possibilities. Maybe you could locate a primary metering block for your 390 (list 8007 for the carb) and get it modified by a local carb specialist. They need to drill and tap the PVCR and the idle feed restrictions for small 6/32 emulsion jets. I use blank jets that I drill myself with one of those micro drill sets. That way I have whatever size I need, not what the shop has to sell me. The standard metering block will not let you decide how much fuel to add when the power valve opens. Also the lack of tunability of the transition circuit means tuning the idle/transition circuit is always a compromise, where the idle can be adjusted via the idle mixture srews but the transition may be off, necessitating readjustment of the idle mixture screws, upsetting the idle mixtures....again. A dog and tail scenario. A real FPITA. I have also been looking for a good timing light and will look up the Innova light you mentioned. Unreal. Money well spent. Will be your friend forever and you're in control of your ignition with absolutely no surprises anymore. When I started reworking my vacuum routing I took off the vacuum advance from my dizzy and noticed that it was not moving. After moving the mechanism back and forth several times it loosened up and was working fine with no leaks. The mechanical side was very stiff as well, after taking it out and cleaning it and re-lubricating the vacuum would move the internals with no problem. God knows what my timing curve looked like, but I'm sure I was getting no vacuum advance. I will be setting the timing again tomorrow and will see how far off it is. This is what I love...its a form of blueprinting....and the results will be there. Excellent work. Good luck Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 29, 2009 Author Share Posted March 29, 2009 Heres some pics of the finshed engine, a few random wires have been tied up before the drive. No more vacuum advance on the carb, ran to the intake now. Still a little flat in the power, but this is the first driveable tune, so im sure theres more on the table. -Thanks for the info citjet Quote Link to comment Share on other sites More sharing options...
jt1 Posted March 30, 2009 Share Posted March 30, 2009 Looks great. I'm glad you got a handle on the vac leak. jt Quote Link to comment Share on other sites More sharing options...
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