I've seen a bunch of posts coming up on the Holley 670 TBI again. Hopefully I can answer some questions before they come up. I've been using it for about 4 months now, and here are my thoughts on how it works and what needs to be done.

(1) With my mods, it's worked great. There was a deffinent gain, especially up top. I pull 5,100 rpm outta 2nd, and 5,500 rpm outta 1st. I'm confident I could get more, but I have the stock cam in there and I'm pushing it as it is.
(2) It does take time for the ECM to catch up to the new hardware. It took mine almost a week of going through all the throttle positions and driving "techniques" before it was running where it should have.
(3) I am using the 502-5, the one advertised for the 305. It comes with 57 lb/hr injectors. Stock are 40 lb/hr I believe. I needed to turn the fuel pressure down. What I'm am saying is, don't go out and buy the one for the 350 unless your 305 is putting out monster power, or, you're going to install it on a 350.
(4) The fuel pressure regulator is adjustable. It is very simple to remove the cap that comes on it from the factory. Simply start a hole, either with a drill or nail, within the outling of the hex. Then screw a screw in. Then use plyers, pull on the screw, and viola...the cap is off. You'll need a 4mm hex to adjust it. Counter-clockwise to drop pressure, clockwise to increase.
(5) INJECTORS Holley has been using GM Delphi injectors for the last 2 years now. They are quality injectors. So if you hear bad things about Holley TBI injectors, forget about it, because they stopped using their brand. If you are buying one used and aren't sure which injectors are being used: The half sphere black caps over the injectors means they're the old holley injectors.
(6) The gasket included is a reducer made to fit the stock intake. If you're installing an intake with 2" bores, or adapter plate for a carb intake w/ 2" bores, you will need a new gasket.
(7) LINKAGE The throttle linkage bolt is on the reverse side and will work fine like that, however you will not be able to hook up cruise controll like that. Your best bet is to remove the throttle linkage bolt on the throttle lever of the TBI and simply turn it around so it faces in instead of out. Do this when the TBI is off!
(8) WIRES Wires are easy to connect. They are color coded. All you need to do is a little splicing.

These are all the things I can think of off the top of my head, but if there are any other questions out there, feel free to ask, and I will help to the best of my ability.

 

Well I guess I found my extra guaranteed 30 hp. a holley swap is next in my books. If it will allow a pull into the 5100 range on a 305 TBI, then based on my last dyno and RPM pull, that would send me into the 180 RWHP bracket. Not to mention the torque gain which more than likely be substantial. 200 RWHP may be a reality for me...

 

The MSD dual connector coil complements the TBI perfectly as well. It pulls much higher into the rpms than the stock one did. It's only $40, and probably the best numbers for dollars gain I've had. Just something to keep in mind.

 

the hypertech coil i had seemed to make a difference in my car also...for 2 months anyways then it went out and left me stranded...needless to say after pull the distributer, replacing the pickup, and module i installed my 14 year old stock pump and wala ran again....

 

My pump died the second monday after new year's this year. At least it brought me back home before dying lol

 

I have been wanting to put the 670 unit and msd coil on my truck. I have a vortec swap and know a guy with a 383 in a TBI van who runs the 670 and coil. He told me about the 900 cfm four barrel conversion for the TBI syock systems. I guess you patch in the second set of injectors to a w.o.t. switch and they operate on a set time scale and gradually open to w.o.t. I wonder what kind of HP they recommend to run that setup? I have tock injectors and TBI. my injectors have 160k on them so I figure it is time to update anyway. If the the 670 is worth it I will do it. Is anyone running the holley to stock size bore adapter plate the sell. I saw it online its aluminum.

 

My friend did full exhaust, open element, and hypertech chip, then did the holley 670 and Pro-Jection manifold and picked up nothing in the way of HP and didnt knock off any time in the qtr mile, but his trap speed went up about 1 mph.

I really wouldnt recommend the setup unless you're building for the future, but even at that, if you're going to have the intake manifold off you minus well go one step futher and chage the cam at the same time. With a better bump sitck you'll see nice gains from the 670.

 

I dont plan on having the manifold off or changing the cam, I already have a kickass cam and manifold, I even run an egr. I just plan on running the 670 because it only cost about $110.00 more for a whole new TBI than just buying gm injectors. That and the guy with the TBI van and the 383 said it was the single most noticeable improvement he has seen on his rig besides his motor. I already run vortec heads and the gm bowtie intake that converts to TBI on them. My motors is almost done except for the the TBI and ignition setup.

 

Sounds like he either miss matched the injectors, or didn't adjust the fuel pressure, or maybe he had the old unit with the Holley injectors as opposed to the GM Delphi. Mine ran like a$$ before I lowered the fuel pressure, and that was with the one for the 305 w/ 57 lb/hr injectors. When I adjusted it, there was a SOTP gain in both low end torque, and upper rpm hp. If he had a 305 and bought the 502-6 (for 350s), then he really over did it.

 

No, he put the stock GM injectors and pod back on it, then he did some fpr tuning. The engine just doesnt need the extra air/fuel with a stock setup. If you have heads and a cam, as mentioned above, then a 670 is a great great upgrade over the stock tbi. Im going to be running a stock tbi on top of my vortecs and Im sure that Ill pick up a lot of HP when I get the money to get a 670 or 454 SS tbi, but if you put it on a near stock engine it wont help much.

 

That's a round-about way of saying the ECM is having a $hit-fit and it needs some PROM tuning.

If the ECM needs to "catch up" to any mod then that mod prolly required tuning in the first place.

Just so ya know.

 

Hmmm...... Something doesn't seem to be right here.... I have stock heads, intake, and cam, and the Holley worked great for me-though I used the injectors that came with the unit. Your friend might have messed up by putting the stock injectors on it for the fact that the holley flows more air than the stock TBI, even with the stock manifold because the Holley TBI's base is already flat. Kinda like the stock TBI after it's been dremeled down per Ultimate TBI. More fuel is needed with more air flow. Thus, this is why the stock injectors may not have been flowing the fuel needed. I don't mean to argue, I'm simply trying to say that this unit worked well on my near stock set up. Holley's website has a chart comparing 0-60mph times on a 350 truck using the two different TBIs. With the 670 TBI ALONE-no engine mods at all, there's a gain of around .8 seconds. I don't know if I gained that much, but I can say there was a seat of the pants difference.

 

Not trying to argue here either, but his O2 readings are right between .850 and .900 at WOT, Im not sure on his pressure because he doesnt have a gague. The 350 truck could use the large TBI just because the LO5 didnt suck as bad as the LO3 did in stock form from the heads down. He has an LT1 cam and ported stocker heads that are going in soon, so when those are on Im sure he'll see additional gains from the 2" tbi, he just didnt see them now.

 

Is your buddy running a 2" manifold or did he run the adaptor, it makes a huge difference if the fuel charge is running into a 1 and 11/16" hole from a 2" bore. Your buddies o2 reading at w.o.t indicates a lean mixture, that can caus ejust as much trouble with performance as too rich of a mixture, he cant make power if he doesn't have the gas to burn. If I am thinking correctly the higher the oxygen content the higher the voltage on the o2s. Usually you want a steady reading somewhere around 1/2 volt. I am not to familar with OBD I.

 

I know for damn sure that the computers in these cars don't learn shiznit. Doesn't matter if you have the 670cfm throttle body or not. If you've got a set-up that's far from stock, the speed density computer system that's in our cars can't keep up. End of story. With custom PROM tuning, it's possible to run correctly, but the stock PROM can't do it.

 

Well I was going off Pablo's write up on how to adjust, which he says between .850 and .900 at wot. Should we be tuning higher? We had it about .950 and he was running rich, to the point where you could smell the extra gas. He's running the Holley 2" Pro-Jection manifold for TBIs.

 

V8Astro Captain said it best, custom prom tuning is the only way to go if you want to get the most outta your mods. You're right in a way when you say our computers don't learn shiznit in that it doesn't permanently save anything to our proms. However it DOES adjust to the best of it's ability to what it has to work with.

 

I will ask *** today at work and let you know about the fuel pressure.

 

I talked to *** and he said your 02s reading is way lean like either you have low fuel press. or a vac. leak. It should oscillate in voltage between .200 and .800 15 times in 10 seconds that is a well tuned engine, no wonder it doesn't run ok, he isn't feeding it enough fuel for the air he is using. It doesnt even sound like it is close to trying and compensating for the problem he is having.

 

If you guys disconnect the battery for 30 seconds on a TBI system it erases the fuel map and it will learn a lot faster after mods.

 

Learn what? The ECM can only compensate for PART THROTTLE fuel delivery.

In the PROMs I work with (7747 ECM stuff) the BLM can only be between 108 and 160. Anything out of that range will set the SES light.

So the ECM "learns" after some mods....great. That means it's either running too rich or too lean and it HAD to compensate. Then you stomp on the gas...the ECM goes into PE mode and disregards all it "learned" and looks back to the original fuel tables which are now WAY OFF because the engine combo is all out of wack. So it's STILL too lean or too rich in the exact place you don't want it to be.

Play with the base timing and the fuel pressure all you want but it's like putting a band aid on a severed head.

 

Now you've confused me. Are you tuning at idle or WOT? On my car when it was stock it didnt oscillate (according to WinALDL) at idle except ~+/- .100 and WOT it was nearly dead on at .870 the whole time. His car runs great running wise, it doesnt stumble at all which would be a sign of vacuum leak and it pulls hard during 1st and 2nd gear, but at the top of 2nd it just dies because there isnt enough cam and the heads are horrid. I'd go get some logs for you but my car doesnt have an engine in it. It would seem to me that at WOT if your readings are all over then you'd have problems, the spray should be constant.

Can someone else throw a hand in here?

Edit: also his plugs are look fine when we check them, and it idles fine

 

You always cjeck o2s by running the car at 2500 rpm at idle, the volts should do what I said. Try that and see what the car gives you. .850v is still lean at w.o.t! I deal with this stuff all the time and know that at least isn't right.

 

Ill tell him about it, my *** is goin to Florida tomorrow for some much needed R&R

 

I don't think 0.850V is that lean at WOT. And the switching O2 is NOT supposed to switch during WOT, because WOT is a rich mixture.

V8Astro, the ECM will richen the mixture during WOT partly based on the part throttle BLM, correct? So if you have a cruise BLM of 120, when you go to WOT, the engine will be getting more fuel (within the range of the injector duty cycles) than it would if the cruise BLM was 128 (near stock). Isn't this correct?

If the BLM is OVER 128 during cruise, and you floor it, I believe the computer does not lean out the WOT mixture, to be safe...which is why you always want to be under 128.

 

O2S voltages climb as oxygen is added to exhaust, they react to O2, therefore the higher the O2 content the higher the voltage. If wot is a richening procedure the voltage would hang at about .200-.500v, but technically it is supposed to oscillate where ever it is running. If it reads .850 volts, then it should go to .200v and then back to .800v and vice versa. That is a sign of a healthy and properly operating monitoring system.

 

The more fuel added=more HC's and CO's=lower oxygen content in exhaust!

 

If I'm not mistaken the richer the A/F mix is the higher the voltage. WOT should be around 850mv or so 900mv is kinda rich. If I'm mistaken plese enlighten me.

R

 

Should be less air in exhaust and more HC's(hydrocarbons, unburnt fuel) which is a lower voltage, The leaner the exhaust the more O2(oxygen) the higher the voltage.

 

um, richer=too much gas=higher voltage

leaner=less O2 voltage, but if u feel otherwise go on a WOT blast with your O2's around .200 and see what happens

 

Also, i don't know if SBC's are different but in the turbo buick world .850mV is pretty damn rich, we tune for around .780-.800

again not sure if you guys are different

 

Thanks fly89gta I wasn't sure if the crack I was smoking went bad or if it was Audiman's.

R

 

You guys running a zurconium filled negative coefficient O2S, I didn't thinks so, Bless you!

 

um, yeah..uh-huh don't pass off wrong information unless you want someone to blow up their car...

 

Dude I don't know what kind of whack A$$ technology the audi's run but in relation to the O2 sensors everyone else runs you don't know what you're talking about and I'd appreciate if you keep your misinformation to your self. And it's spelled Zirconium.

R

 

amen!

 

Sorry! Anyway, anyone else have feedback on the Holley TBI.

 

heys guys

First of all i have a stock lo3 with a gutted cat k/n filter and exhuast will the TBI mods help it. BTW where can i get info on the mods.

As for the o2 #'s the bigger the # the more fuel is in the exhaust.
so about 8.50-9.00 is kinda rich

like the guy said earlier in the post when at WOT or @ 4.20 or higher millivolts i think the computer looks at base maps( power enrichment) since it's a speed density ecm and instead of a mass air ecm.

i used to have a grandnational and when i run it @ 18 psi of boost my car like to run best @ about 8.30 millivolts. and pulled like a **** but i had a buddy who's car run better a tad leanner like 7.90

so each car i diffrent to how it reacts to fuel mixture. but it sounds like somebody needs to have the car dyno and look at when the ecm is too rich/lean during a pull.