I'm really thinking hard about buying a 670 holley projection unit, sense there relitivly inexpencive secondhand even if they've never been used . What would i have to do to modify it for a 6? Would it be too much? It's going a motor with headers, clifford intake and 260"cam.

I know there are a few of us running these out there, (dart270)? I'm mainly looking for improved gas milage,throttle responce and torque. Is this realistic ? I also want the unit to be able to handle a more agressive motor that I'm planning on building .

Thanks in advance for any imput.

Andyman

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Never under estimate the power of stupid people!

You'll need an adaptor to the stock manifold or a new manifold. It comes with a fuel pump so your good there. I don't see an oxygen sensor and no mention of it on the website. Not sure how they get away without it. Looks like it would work. It says it's made for a V8 but I see no reason why it wouldn't work on a /6. 670 CFM is huge for this engine but if your planning on huge performance I see no reason it wouldn't work.

Where can you find one used? I would expect there aren't that many in the JY's. Summit has them for under 800. Not bad for 670 fuel injected CFM's.

The O2 sensor is the only thing that bugs me. If you have to install one then you will have to drill a hole the exhaust manifold or output pipe for it. Not that big a deal I guess. The only other thing is with a stock 2 barrel intake the long 1 and 6 runners might be an issue but I dought it. Go for it.

Oh one other thing is the MAP sensor must be integral to the throttle body. Looks cool.

Just a general efi suggestion.. Whatever you end up doing, make sure the computer you will be using is fully programable. I know some of the cheaper holley kits come with a computer that has a few knobs on it for adjustment and that is it... I have heard many stories that those style systems don't work well at all.

What intake do you have? Adapting a holley/gm throttle body to a clifford/offy intake isn't much of a challenge. You can make your own aluminum plate from scratch and drill 8 holes, or buy a plate from howell for ~$50 and drill 4 holes. Then modify your harness as needed so that everything reaches where it is supposed to.

I don't think it would be too much as long as you can program the computer running it. After adjusting fuel pressure (and/or using different injectors) you should be good to go.

How much can you get a complete kit for and what does it include? If you want to do this project frugally, I would suggest using a megasquirt computer and the rest junkyard parts. You can go this route and end up spending approx $500 and get a well running system. Oh, I just thought of it, you will need some sort of ignition upgrade as well to trigger the computer. The stock ignition will likely be too noisy (either points or electronic), as it was in my car when I upgraded to a GM based system. Plan on either an HEI module, or an aftermarket box with tach output.

I am assuming this is a throttle body injection unit.... Depending on how your carb is tuned, you may or may not see a difference in mileage/throttle response/torque. You will notice your engine will have much better driveability characteristics, especially when in cold weather. An efi system with programable computer will be easier to tune well then any carb, and will be much more consistent. So if your carb is running on its last leg, or just isn't tuned quite optimally then you will deffinately see an improvment in performance. If you want an even bigger improvment you must go to port style injection, which eliminates the fuel distribution problems on our slants and help squeeze out every last hp.

I am running a complete gm computer based kit I orderd. It came with everything needed to get up and running except for fuel line. It is a gm based computer, with a preprogrammed chip that was "tailored" to my engine, which means the only way to alter its calibrations is to take out the chip, reprogram it, put it back in, testdrive, then start all over. After the 5th or 6th chip from the place, it runs decently. A PITA.... Soon enough I will be upgrading to a megasquirt system ( http://www.bgsoflex.com/megasquirt.html ) and tune to my hearts desire with a laptop. If I were to do it all over again, I would deffinately go the junkyard parts + megasquirt route because in the end it will be cheaper and better performing. Also, with the megasquirt and a gm throttle body, you have the option of later upgradign to batch fired port style injection.

Whew, hopefully that coverd everything

take the above advice and stay away from the early projections

they only had a low middle and high rpm adjument knob

these did not work very well at all

tried one on a small block and finally sold it just to be rid of it

bp

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pekingese parker all bark no bite and piddles on the carpet..... bad puppy

Talked to my machinist today about the 670. He had nothing good to say about it. He said he had a few buddies who tried it and no one could make it work right. He said there is no reason it should not work but Holley just couldn't get it right. Just his 2 cents. Take it with a grain of salt. BTW he said there IS an O2 sensor. Funny there is no mention of that on the Holley website. The key to fuel injection is that sensor.

Good luck.

Actually, if eveything was perfect an o2 sensor wouldn't be needed. I wouldn't say it is the key to an efi system. If engines never wore and all tolerances stayed perfect a o2 sensor wouldn't be needed.

You would be surprised how well an open loop (no o2 sensor for feedback, just temp/tps/map/maf sensors) will work if tuned. At a bare bones minimum to get an efi system to run you need a map (or maf) sensor, tps, and some form of rpm pickup (from the distributor, crank/cam sensor, ignition box tach output). The rest of the items are just luxuries of sorts to the efi computer to assist in more precise fuel metering.

Andy,

See my post over on ss.com.

I can also back up Pierre's statments about programmable being awesome. Also, he's right that running an O2 sensor is good for dialing in a fuel map, but once you've got it tuned up it doesn't help you that much unless something goes wrong. You can also weld an O2 sensor bung into the exh headpipe rather than the manifold.

Lou

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Home of Slant6-powered fun machines since 1988

I just got an idea...

How could you conceivably hook an unheated oxygen sensor to an exhaust pyrometer gauge to give you a gauge readout of oxygen content? Would installing a pyrometer and thermocouple work as well or better in helping you tune and monitor fuel delivery, on either EFI or carb?

I could imagine how hooking one to each exh runner could help you keep a three deuce setup in tune, thats for sure.

I think there are some of the newer efi computers that use a EGT sensor but I know the obd1 GM systems don't. I have seen several intake air temp sensors though in systems.

That would be nice, to be able to grab a thermocouple right off the shelf rather than source one thru an industrial supplier, thats for sure. What I want to do though, is hook it up to a gauge, so I can run out and make adjustments at a stoplight. Hehe! Or, synchronise a multi carb setup without that pesky airflow meter thing with the ball in it.

I put a projection 670 2D on my Duster with a 225 slant a few years ago. Make sure you know somebody with an emission computer that you can play with. This kit tends to run RICH (derr, it's meant for a small But I managed to get it running ok. Runs pretty well, a little glitchy on the start. Get the 2D system because you have the ability to adjust choke, idle, main, accel, low and high rpms. Just don't fiddle with it once you get it right, I messed with mine and now can't get it through emissions. Also, expect the fuel pump it comes with to go out on you after a while, bought a better one, but that may be my problem. There is an optional O2 sensor, I recommend if you're going to do it, get the O2 sensor, that will have it running way better than if you start fiddling with the knobs, a fraction of a turn in any direction and the settings are way off.

I used a 4bbl intake from clifford performance. It has built in bungs so you can do multi-point FI if you have the $$$. All said and done, I wish I woulda just stuck a Holley 390 on it and been done.

If you have to go Holley, and you have the throttle body or old 2D kit cheap, there is an upgrade kit for the Commander 950 Prom and harness (you will need a cheap laptop to program the fuel map, spark map too if you run a crank trigger), neither are really "cheap", you will need an oxygen sensor for it....

I'll be using the 950 MPFI on a clifford hyperpak intake, machining should be done by the end of the month...

good luck,

-D.Idiot

I tried a projection on a SB Chevy (in a 1980 Avanti II) and it was too rich at its leanest settings. It washed the oil off the rings and never ran right. I finally took it off and replaced it with a 500 cfm Eddy, and the car cranks and runs wonderfully. No way can I recommend the Holley projection, despite its high price. If you want mine, you can have it for $250, and I'll be glad to get the dough. Otherwise, it will stay in the box for the rest of my life.....

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Restored '62 Signet, 229 4bl, Offy intake, auto, Dual Dutra exhausts, shaved head and block, high stall converter, 1.6 roller rockers, etc.