Boosters and squirters (unless those flat head screws are hiding the squiters in the pic)

There are squirters, just hard to see, there isnt conventionsl boosters, heres the 3rd picture i took, if you zoom in you will see a stepped machined area with slots and tiny holes

Smitty, thats weird looking not sure how that would work with no venturies to help draw fuel in ?

His idea is air will pull fuel thru the slots/feeds he built into the venturis. Before ever building the first complete main body he experimented with the design and adjusted things to get proper signal/fuel curve or draw. The design works when we tested it on dyno, it doesnt, however, out perform or keep up 100% with his modded 4150 that does so well, still in the experiment stage.

Pretty cool stuff!!!

Just a hunch but I wouldn't be surprised if the carb makes a little bit more torque and HP.

Biggest complaint I have with EFI engines is the lack or torque feeling at higher rpm where their carved brethren seem to be better IMHO.

I like EFI for the safety factor the most and I'm learning more and more about tuning every day!

I been bolting and fitting efi stuff on dyno a hour or two a day, using mefi, was going to use a mefi 4 harness and ecu as its already hacked up BUT i have a virgin mefi3 harness that seems to reach everything with very little mods, flowed and checked new injectors, they match well and are good to go, luckily a gm tps and iac bolt to the 2200 cfm throttle body, after looking at rons holley and seeing a extra wire on tps i started thinking i was fukked as far as tps but as long as it sweeps from .5 volts to 5 volts when i test it im goid to go. I expect to pick up some tq with ability to set timing tables vs the mechanical distributer we were running that had all timing in by 4000 but dont have high hopes of outperforming the good 4150 numbers as far as hp. Perf trends software shows a 20 hp increase over the 4150 and i wouldnt be surprised if it DOES make 20 more hp than the QF and both dominators as they didnt really break 660 hp with mufflers on but am not expecting to miraculously make 700 hp.

*Ahem*

My carbs are headed back, Huge shout out to Smitty and Norm, when Norm said noway they will flow enough fuel to support my cause Smitty made em work, big thanks my friend.

It's very cool how much time and work Norm and Smitty put into your carbs! Very cool stuff

That's for sure, anyone else would of probably just sent em back, Smitty knew I had some coin invested in these carbs and was bound and determined to make them work and did.

Efi up and running, sorting out initial problems, just called performance trends and ordered EVERYTHING they sell to convert the dyno to modern software WITH extra inputs and USB /windows capability. Norms depac is pretty consistent and fairly accurate, what it doesnt do however is allow me to input data from my 10 o2 sensors, only 2, I used AEM conversion boxes to change 0-5 volt analog 02 readings to data, the flaw is this backwards ass **** uses serial data to usb convertors and 9 out of 10 times refuses to connect to the lap top, tired of it, done, ****s going in the trash (aem). Mounting the new software side by side with the depac, will be able to make pulls and see both results! Nothing more frustrating then having nice data acquisition and NOT being able to completely use it trouble free!!

Those 2 black aem boxes in the above pictures are EVIL, done with them!

Remember the old saying. KISS "keep it simple stupid". We have all this cool technology but seems like chit is always failing. Makes you think about HEI and Carb. Btw I continue to tell myself kiss so it wasn't directly meant for you. I've been keeping up with your thread and glad your sharing everything. I give you a lot of credit...

This is an amazing window into some deep work that hackberries as myself just don't get to see. My hat is off to ya.

hackberries,that,s funny chit baja chicken.

makes me think of EFI !!! works great till it dosen't ...sorry smitty

Havent even touched on the efi teething problems. After motors wsrmed up it drops 1 batch of 4 injectors above 2500 rpms on green/black side of mefi harness. IF i was able to quickly and efficiently connect the 02 data everytime from all 10 sensors would have took me a hour to get done what took me 8 over past couple days. Im fairly knowledgable about efi and programming, i have no idea how someone w no experience could get past these problems. 1st order of business is getting new software connected after it comes so i can see the afrs perfect on all 10. Today going to trigger ign module w msd tester while i watch batches fire w motor off, try to get to bottom of it. Oh yeah, two ecus and two harness, same problem so thats why im scratching my head

are you running the stock distributor and coil ? are all the grounds tied together

Yep, motor has ran out to 6400 with current set up, just after a few minutes of run time same bank quits on 4 of the 8 injectors. Hooking msd signal generator to gm 7 pin module w oscilloscope and vom on injector leads right now, every efi i ever played w seems to have initial problems. Once thry are sorted out stuffs fine. Evertime i learn something else i didnt know before. Last motor w mpi intake had imbalanced afrs from 3000 to 4000 something, turning on double fire injectors straightened it out. With this open plenum intake it didnt like that , when i turned it back to single fire stuff straightened out BEFORE this batch problem started

didnt you or someone else perhaps have near this same issue a few months back? Great thread and hope you get it sorted out.

Sorta, when i dynoed 502 mpi i was making 540 hp, motor would be two to 3 points lean from 3000 to 4200 or so on 1 bank of injectors, match up from about 4200/4400 to about 5000 then would invert to opposite batch of cylinders/injectors. When i un-set the flag in programming like a 500 efi has to staggered injection/skip double fire problem went away, had to add about 1 ms to most injection tables to pw to acct for the double dead bands. Ended up making over 560 hp once tune was right. This motor has more even afrs with it ON, go figure!!
The problem i have NOW is quite different, after motor warmed up the green black batch of 4 injector leads would lose all power and motor would drop down to 4 cylinders and refuse to fire those injectors. just solved it after alot of pissing around. Hooked up msd tester to spare 7 pin ign module, made a heat sink so it wouldnt go up in smoke. Plugged it all in, fired all 8 injectors at 4000 rpms with a vom in each batch, ***** sat there firing all 8 injectors and dummy coil plug flawlessesly for 2 hours. Heated air intake temp sensor up to 60c, no affect. Heated ect sensor up to 65 c, no effect.
Meanwhile i scoured thru tune on lap top the whole time, comparing bins from stock 500efi, stock 502 mpi, previous blower motor tunes, etc. FINALLY found it.
1. One injector bank for rpm reduction turned ON
2. ECT OVER TEMP CAUSE RPM REDUCTION TURNED ON
3. Over temp threshold in constants and scalars was set to 69.9c (we only heated it to 65c but it runs about 68/69 on dyno)
4. Overtemp clear was set to 66c
Turned them down to 20 c, uploaded the file and bam, green black batch of injector leads quit firing!

Adjust tune and upload, plug everything back in right on motor andvremove all test equipment,go get another 10gallons 89 octane, warm her up and im back in business!!

Smitty, this is all in MEFI 3 correct? I had a conversation with you regarding this (Well kinda - regarding fuel vs spark rev limit rpm reduction) on facebook few days ago. Can you simply crank up the rpm reduction temperature vs ECT, or turn off? And where is the one injector bank rpm reduction located? Excuse me if its obvious, I do not have my laptop with me today to see. Thanks -Chris

[QUOTE=articfriends;4540223]Sorta, when i dynoed 502 mpi i was making 540 hp, motor would be two to 3 points lean from 3000 to 4200 or so on 1 bank of injectors, match up from about 4200/4400 to about 5000 then would invert to opposite batch of cylinders/injectors. When i un

Yes, definately set yours to spark only and now that im aware of this ect overtemp set it to 95 c, i went ahead and turned it off too but just in case there is a hidden table turn temp up. All the other causes rpm reduction i always leave turned off on my own stuff anyways. I just missed this one!

Please forgive a stupid question, but why use the mefi when there are aftermarket options?

I have 6 or 7 mefi harnesses and 10 mefi3/4 ecus laying around, no reason to spend another 5000$ on two aftermarket ecus/harnesses. If you read the whole thread too i sm movi g forward to extensive testing of two different 500efi intakes and various modified 500 efi parts, some of my harnesses are drop ons for them. Keep in mind too, a aftermarket efi isnt magic either, you still have to set targets, sort out glitches, etc plus im a glutton for punishment! Gimme fuel had a magic holley efi on his 548, it auto tuned a hole in one of his pistons!!

AUTO TUNE.... Works great for EDM. Electronic dance music. Lol! Under the hood of a car or hatch of a boat I'm not sold on it. I'm sure it may work flawlessly for several but I can't even do an AUTO download on my laptop or iPhone without something failing. I forgot about gimme fuels piston. That sucks!

Ok, I found overtemp clear and also overtemp set. Both set to 68*C which is only 154.4*F. I will turn this up. Where is the enable/disable for this??

Disregard, found a flag/switch "Engine over temp causes rpm reduction". It was set (checked)

Keep in mind, there IS a reason for these safetys, in my case though the dyno runs close enough in temp to trigger it, im going to have to go back and look at a stock 502 tune at THAT temp, a 500efi has it set at 98.7c or something. Personally on a single engine boat i would not want ANY saftey parameters that could reduce power to point you couldnt get off water and you watch temp/oil press resl close. On a twin engine boat having some of the ssfety oarameters turned on, at least oil pressure and temp would be a good idea, i will prob turn some of this stuff on when im almost done with this project , set thresholds pretty high, Smitty

Well, motor firing on all 8, new data aquisition showed up (not installed yet). 1st thing im seeing i do not like even with only 4 o2 sensors working is un-even afrs from cyl to cyl at different rpms, rons victor rpm also did this. We stagger jetted the carbs to help with it. We also thought perhaps once the flow was dry flow from tb that some of that would go away. No ability to tune cyl to cyl w mefi, if air flow is so uneven between long runners and short runners that afrs are 2 plus points apart at certain wot and part throttle settings would you really want too??. Again too, double firing the injectors on a mpi intake made the uneven afrs much better, doing it on this made it worse. As we move on i will be trying gimmefuels 105 mm tb on a 90 degree elbow, going to be interesting how IT affects un-even afrs. Not going to bother doing much more changes how ever till all the new data aquisition is up and running so we can capture afrs vs map vs rpms on all 10 02 sensors.

So now back to what everyone is really interested in, how does the 2200 cfm tb and efi compare to the carbs, right??
Well, results are NOT at all what I expected to see. There MIGHT be a tq or hp gain somewhere in the peaks with a little bit more tuning i am going to do as soon as the 2% correction factor air comes back (we were in the 4.5%range yesterday)
Anyways, 2200 cfm efi setup makes virtually same hp as norms magic 4150, what it DOESNT do is make torque. Tq peak shifted to 5400 from 4900/5000 and AFTER tayloring timing curve best tq was a dismal 608 ft lbs, we were in the 625/635 corrected range w the 4150. In the high 6 teens (616/618/620 ish ) with the dominators. Before changing timing in tq peak w efi we were making 597/599 peak. Now, does this GOOD carb magically make 22 more ft lbs but same hp, most likely NOT. I have always been under impression that a tb that flows too much wont really chsnge much at wot, the motor is basically "un-restricted" at that point, the ports/intake flow what they can flow but evidently that may be flawed. Next step is to try a couple more timing changes in tq peak and some slight fuel tuning but right now it looks like the high flow#s of the tb are hurting torque peak. Anyone have a 1200 or 1500 cfm 4 bbl tb i can borrow to test? Im about spent out on this project do really dont want to buy one to try!

I have a Holley 4150 1000cfm one you can have but it does not have an IAC provision, thus why I never used it.

What are throttle bore diameters on it? I dont need a iac to do dyno testing

there a lot of humidity in the air?

Theres more than their was and today its pouring rain, going to hold off on the final tweaking on this tb setup till we have those 2%cf days again, i dont trust the CF 100%, i feel its slightly flawed, when its damp, humid and warmer and cf goes from 2% to 4 or 5%, sometimes observed hp/tq drops 5% when it theoretically should have dropped 2 or 3% and have also seen the opposite. That's the main reason i tested all 4 carbs against each other in as short of time and w same air /cf to get accurate, comparitive data.
BUT, out of all of my testing these are bu far the lowest observed and corrected tq numbers and we have tested at 4.5% cf before

Whats going to be REAL interesting is how the cf on the depac with ITS weather station compares to the cf on the NEW dyno software with ITS auto correcting weather station! Like i mentioned, they will BOTH be up and running side by side!

Im the data NAZI, i refuse to use flawed numbers to impress anyone, if a combo doesnt work, ill be the first to ssy it!

Holley 9900-174 1000cfm w/o IAC

I measured throttle bores at 1.748. So they are probably 1.75.

[QUOTE=articfriends;4540724]Well, motor firing on all 8, new data aquisition showed up (not installed yet). 1st thing im seeing i do not like even with only 4 o2 sensors working is un-even afrs from cyl to cyl at different rpms, rons victor rpm also did this. We stagger jetted the carbs to help with it. We also thought perhaps once the flow was dry flow from tb that some of that would go away. No ability to tune cyl to cyl w mefi, if air flow is so uneven between long runners and short runners that afrs are 2 plus points apart at certain wot and part throttle settings would you really want too??. Again too, double firing the injectors on a mpi intake made the uneven afrs much better, doing it on this made it worse. As we move on i will be trying gimmefuels 105 mm tb on a 90 degree elbow, going to be interesting how IT affects un-even afrs. Not going to bother doing much more changes how ever till all the new data aquisition is up and running so we can capture afrs vs map vs rpms on all 10 02 senso