hey i was bored and was reading all the post on injector and stuff and the 670 i bought came with 57# injectors but they were not listed on the injector post??? i bought the 502-5 and according to the holley site the 502-5 injectors are 57 pph???
also how much pressure should i crank them to before they go static. i think they are set at 12 psi right now, also should i put the distribution ring back on? i noticed no difference with it on or off??
i have got all the stuff to make the aldl cable i just havent got around to it yet, but so i can have it running as good as its gonna get without chip tuning should i bump the fp up to 15-20 psi?
check the sig for my mods
also don't forget i have the open spacer in between the tb unit and the performer rpm manifold so it is drawing in a little more air.

 

Fuel pressure doesn't make your injectors go static, it keeps them from going static when your tuning your chip.

When your ecm injects the needed fuel i does so twice per engine revolution. So you only have so much time to inject all the needed fuel. This available PW goes down with rpm. At 6000 rpm you only have 5 MS to inject all your fuel. In order to get your duty cycle you divide your actual PW by your available PW. Say your need 4 MS at 6000 rpm. Thats 80% duty cycle wich is about has high as you would want to push it. If you get much higher than this your injectors go "STATIC" which means they are statically open all the time, so you have no control over your fueling. In order to feed any more HP you need to get more fuel into the engine. Two ways to do this, one is to hold the injectors open loger, which we decided isn't a good idea. Two move more fuel while the injector is open. You do this by getting bigger injectors or by making your existing injectors act bigger by cranking the FP. The only way to change your WOT PW or AFR is in the chip.

All this is great stuff IF you can change things in your chip. If you can't it doesn't mean squat. If you crank up your FP without telling the ecm about it your just going to be universally richening up everything. Which will make you way too rich at lower loads and rpm's and probably still won't get you enough of the needed fuel up top. With your cam and intake swap your going to need some chip tuning. The big TB does funny things to fueling at lower speeds. Getting your pump shot right is crucial to avoiding that dreaded big TB bog.

Your best bet is to use the stock injectors with the big base until you get into prom burning. That way the ecm will at least know how much fuel it's injecting and most of your part throttle stuff will still be close or as close as it was before you swaped TBs. Dataloging will show you alot of what I just told you, and help you get started in understanding what needs changed in the chip.

 

thanks for the input but i don't have the stock injectors... i sold them about 2 years ago with the modified stock unit, i was carb fo a while. it doesn't seem to bog down low at all though.

i already have a somewhat modified chip but it needs more work especialy around 4-5000 rpms.

 

YOur ecm will correct itself under normal driving conditions. I'm sure you've heard of people talking about BLM's and the likes. Problem is once you go WOT or above the point you normally cruise at that routine is shut off and your ecm basis your fueling off of your VE curves that are set up for the smaller injectors. I'd say thats why if feels funny at higher revs. I suggest you look into WINALDL and builing or buying you a cable. It's like haveing a snap on scanner for 10 bucks only you'll have more features. Then you can see for yourself just how far off your tune is and then you can decide whether or not you want to tune it right or go for another guess from whats his name.

 

not trying to be rude but i am not new to the board i painted my car and changed my screen name a while ago... i origionally got on board oct 02 and had about 1000 or so posts...
i posted b4 that i already have the stuff to make the cable i just need to sauder it together... i am a medic so i am not too great with the saudering iron... i bought that little cold heat thing at home depot and i used it to sauder wires for a car stereo and it works great... the only problem with the cable is the connecter i got to put the stuff in is small so i have to practice making all the joinings small.
i downloaded winaldl about 2 years ago and i have messed around with it a little but just to see how it works.
also what has been decided about the air distribution ring? to keep or not to keep???

 

Sorry bout the baby step posts, when I see some one with less than 50 post asking about doing a major mod I try to make sure they completely understand what their doing. You should definately get that cable put together it's really handy. As for the air ring, I don't run one, I don't think they would do anything good for your motor, but I'm not sure what the concensus is.

 

I also don't run the 'ring' (mine came off due to hood clearance issues with a 4bbl manifold, nitrous plate and adaptor plate, and stacked up.

As for the injectors, I would guess 12psi would be fine in your instance, my cam is a bit larger than the LT1, and I am doing just fine with the stock injectors, and the fuel pressure at about 15psi. In theory my motor should require more injector than yours. At 12psi you have much more injector that in do.

But you should get the cable built, you can output the PW into the ALDL stream, by changing the output address of the output for the PROMID fields. That will be what will really determine if you need more fuel pressure or not.

 

hey i just read what you were saying agin and i caught something...??? what ring are you talking about? i am refering to the ring that goes infromt of the 2 injectors and has nothing to do with hood clearance? its flat and goes around the base of the throttle body and has 2 metal flaps that stick up in the front and sit on the two injectors.supposedly it helps the fuel stabalize at high speeds or something like that? i tried it both was and noticed no diffrence

 

Those are the topmost ridges that are supposed to mimic the effect of a veturi since the stock setup doesnt have the tbi open around the sides. You can grind them off or leave it as is. Probably wont make much difference either way.

The idea with adjusting the fuel pressure is to find a balance between the demands of WOT and the needs at idle. You dont want the injectors static at high load, but on the same note you also would like to have the pulsewidth at idle be at least around 1 millisecond or greater if possible. These things you can find out through datalogs, but if you cant burn proms or see what your actual AFRs are then there isnt much reason to mess with the fuel pressure yet. The only real indicator youd have is if the motor was giving obvious signs of being lean. You can also do plug cuts but I gave up on doing that after I rounded off all the spark plugs and couldnt get them back off without removing the headers.

 

the holley does not have ridges??? i don't know what you are speaking of??? the thing i am talking about is a little gold ring that you have to screw down onto the tb it wraps around the top of the throttle bores and has little tabs that stick up. the pic is not in all the holley pics but you can see it if you look up the spare parts. its called a distribution ring its gold and unscrews off there... i'll try and find a pic.
also i am running bosch platinum 4's so i don't think i can cut them...

 

air distribution ring

 

Thats the ring that dewey was referring to. Stock tbis have something similar. Its a waste of time.

As for the platinum 4's, or any bosch product, get rid of them. Those bosch sparkplugs are a nightmare. I had nothing but terrible luck with their standard platinum plugs. They use those screw on terminals that have a habit of unscrewing themselves. At the very least the terminals suck HUGE ammounts of power and cause the car to misfire under high loads. Reason being is that deposits form at the threads of the screw off terminals and add lots of current blocking resistance.

Those bosch plugs cost me 100's in gas and nuked my ignition system when one of the terminals came off completly and caused that wire to carbon track internally. The spark ate the wire up untill the dist. cap. At that point it arced to everything nearby.

Get A/C Delco plugs.

 

i have had no problems with the bosch plugs! and i have been running bosch plugs for the last 15 years or so. not one problem...