C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Cross fire to carb

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Old 06-16-2017, 08:41 AM
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Jdog91
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A little rusty but still working
Green wires are from vacuum advance distributor

New used distributor how do I wire up to delete the ecu and just use the vacuum.
Old 06-16-2017, 08:42 AM
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Jdog91
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Originally Posted by ex-x-fire
If you want to keep it EFI, you could do this. Your stock wiring & ecm will hook up & run it. The junkyards are full of tbi units, crossfire is basically the thing as a 2 barrel tbi.
Nice very impressive wish I knew about this before
Old 06-16-2017, 10:15 AM
  #23  
Tom400CFI
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This project could have definitely used a little more prior planning.
Originally Posted by Jdog91
New used distributor how do I wire up to delete the ecu and just use the vacuum.
Nothing special needed; keyed power to the pink wire on the distributor, vacuum line run to ported vacuum port on the carb. That should get it running.



Originally Posted by Jdog91
Nice very impressive wish I knew about this before
Why? For way less money you could have replaced your CFI injectors and had the same performance.
Old 06-16-2017, 10:00 PM
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pologreen1
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So first off.. the cfi can work if it works at all. The intake you mention can be seen here and they manufacturer also gives a cam recommendation etc.

http://www.edelbrock.com/automotive/...orker-sb.shtml

I'm not a cfi guy and don't care to be. I can tell you it was built with a purpose. that purpose was not to give you a muscle car.

You now have an intake that will flow decent if you get a cam to match it and either work the heads or change them and add headers. If it goes 6k+ like it claims and a cam and heads to support it you'll be waiting for a cfi car to catch up to you, so you can drag them again.

You can port all you want and play with the cfi, a few guys made it their goal to make it "perform" now you have what is called bolt on parts, the more you bolt on the more power you'll be able to make.

I don't know the flow rate comparisons between the 2 intakes and in the last 30+ years surely somebody did one and wrote it down somewhere, but Edelbrock did the research, all you have to do is buy the parts. Don't feel bad you changed the car.

Feel bad you put that stuff on in that condition and considered doing that air cleaner set up.
Old 06-16-2017, 11:54 PM
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Tom400CFI
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Originally Posted by pologreen1

I'm not a cfi guy and don't care to be. I can tell you it was built with a purpose. that purpose was not to give you a muscle car.

You now have an intake that will flow decent if you get a cam to match it and either work the heads or change them and add headers. If it goes 6k+ like it claims and a cam and heads to support it you'll be waiting for a cfi car to catch up to you, so you can drag them again.

I don't know the flow rate comparisons between the 2 intakes and in the last 30+ years surely somebody did one and wrote it down somewhere, but Edelbrock did the research, all you have to do is buy the parts. Don't feel bad you changed the car.
Well that was a lot of rhetoric. "Edelbrock did the research..." Well there you have it folks....PROOF! (of who knows what). Edelbrock may have done some research (probably mostly packaging modeling) but the research that they did likely wasn't a Torker II on a 200 hp long block.
What he has, is a single plane intake on a smogger long block. What that equals is a terrible combo; the intake ensures no low end torque...the cam heads and exhaust ensure no top end hp. Maybe it will make "OK power" from like 3500-4502 rpm? Maybe. He'd have had a faster, better running car if he'd kept the CFI intake.

But you're right Polo; "all he needs" now, since he already invested in that big dollar intake and carb, is a cheap set of heads, a good cam, headers and full exhaust and he'll have a screamer. Yep...he's well on his way.
Old 06-17-2017, 04:24 PM
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Jdog91
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Update : got distributor setup too dead center go to start the car and exactly the same is happening . No combustion in even cylinders. About to bring to shop does not make any sense at all why if it has spark and fuel and compression and air why it will only run on half the cylinders.
Old 06-17-2017, 04:41 PM
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confab
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Originally Posted by Jdog91
Update : got distributor setup too dead center go to start the car and exactly the same is happening . No combustion in even cylinders. About to bring to shop does not make any sense at all why if it has spark and fuel and compression and air why it will only run on half the cylinders.
You out 180 degrees? They'll sputter and pop if you do that.
Old 06-17-2017, 05:08 PM
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pologreen1
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Originally Posted by Tom400CFI
Well that was a lot of rhetoric. "Edelbrock did the research..." Well there you have it folks....PROOF! (of who knows what). Edelbrock may have done some research (probably mostly packaging modeling) but the research that they did likely wasn't a Torker II on a 200 hp long block.
What he has, is a single plane intake on a smogger long block. What that equals is a terrible combo; the intake ensures no low end torque...the cam heads and exhaust ensure no top end hp. Maybe it will make "OK power" from like 3500-4502 rpm? Maybe. He'd have had a faster, better running car if he'd kept the CFI intake.

But you're right Polo; "all he needs" now, since he already invested in that big dollar intake and carb, is a cheap set of heads, a good cam, headers and full exhaust and he'll have a screamer. Yep...he's well on his way.
You are right.

OP what is your purpose here? Do you just want it to drive or be able to make power at some point?

I think what tom400cfi is trying to say is you should look for more of a lower rpm intake to stick on it, since the peak torque on the stock POS is like 290TQ @ 2800 and 205HP @4300 rpm. You could try to match that, many others used the performer series. Unless you for some reason don't have the stock parts on the motor anymore, then you might be able to run it up higher. Do you know your rear gears? I think some 84's can have a little lower gear than most of the TPI models.

If you want to build it, do all the other stuff and the intake is fine. Let us know how it goes, I doubt it but you might like it.
Old 06-17-2017, 05:25 PM
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Jdog91
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No I am not off 180 degrees and no popping either is the hei distributor computer controlled. I get spark when starter is moving engine but as soon as it gets to 500 rpm no spark from even cylinders.

Last edited by Jdog91; 06-17-2017 at 05:26 PM.
Old 06-17-2017, 05:31 PM
  #30  
confab
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Originally Posted by Jdog91
No I am not off 180 degrees and no popping either is the hei distributor computer controlled. I get spark when starter is moving engine but as soon as it gets to 500 rpm no spark from even cylinders.
I haven't seen one in years, But I remember the distributor you want isn't computer controlled. It gets 12V to the + pin in the cap, and that's it!

All there is to it. You run the vacuum line to ported spark and you're done. The one in your pic is the right one.

Could it be bad? Module or something?

Last edited by confab; 06-17-2017 at 05:32 PM.
Old 06-17-2017, 05:32 PM
  #31  
Jdog91
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This engine only has 70000 miles on it I plan on get it running right then eventually rebuild the engine at 100000 miles
Old 06-17-2017, 05:33 PM
  #32  
Jdog91
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But this god dang half engine not firing crap is really pissing me off
Old 06-17-2017, 07:48 PM
  #33  
ex-x-fire
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Tight rocker arms? Check compression.
Old 06-17-2017, 08:28 PM
  #34  
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This thread just makes me sad/cringe...

Brandonbeast bought an 84 where the previous owner did a total hack job of a carb conversion...

Good luck!

​​​​​​​I personally laid down some money and modified my existing CFI to be more fun...
Old 06-17-2017, 10:06 PM
  #35  
confab
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Originally Posted by Gibbles
This thread just makes me sad/cringe...

Brandonbeast bought an 84 where the previous owner did a total hack job of a carb conversion...

Good luck!

​​​​​​​I personally laid down some money and modified my existing CFI to be more fun...
That's a good point.. Can someone list an actual reason why a carb and dumb distributor would produce more power with a mild street motor than a computer controlled FI system?

Given the parameters here.. I can't think of one?
Old 06-19-2017, 10:59 AM
  #36  
Tom400CFI
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Originally Posted by Jdog91
I get spark when starter is moving engine but as soon as it gets to 500 rpm no spark from even cylinders.
HOW have you confirmed this?

Because earlier, you said:
Originally Posted by Jdog91
if it has spark and fuel and compression and air why it will only run on half the cylinders
So...what is really happening, here?


.

Last edited by Tom400CFI; 06-19-2017 at 11:02 AM.
Old 06-19-2017, 04:45 PM
  #37  
billschroeder5842
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Originally Posted by Tom400CFI
So...what is really happening, here?
I had an 82 with the exact engine so I have a crazy idea here (but isn't this what we are all about?)

If my old TBI memory comes back to me, there is a main and a secondary that feeds each side (odd and even) side of the engine. There are IACs that work independently for each of the TBI. The TPS is only on the main as is the MAP sensor with the EGR pulling from the secondary.

So... because engine is "morphed" could the computer still think that twin TBI are in place and when the rpms get above the idle, the computer looks for normal (escalating) TPS and IAC input values and effectively "shuts down" the secondary (the even number cylinders) as there is no signal and the computer becomes confused?

Sure its crazy (and I'm at work, so I can't blame it on alcohol) but I'm not coming up with anything else?

BTW... my '82 XFire was a rock solid performer. I'd get another in a heartbeat.

Last edited by billschroeder5842; 06-19-2017 at 04:47 PM.

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Old 06-19-2017, 05:09 PM
  #38  
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^Hard to know for sure in this thread, but I think that the ECM is totally out of the picture now. He has a carb, and a mechanical distributor. Computer couldn't shut down anything if it wanted to, at this point. It may not even have the ECM in the car.
Old 06-19-2017, 05:23 PM
  #39  
Jdog91
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Used vacuum advance distributor didn't work so I have the stock one controlled by the computer on there. How would I wire up the stock distributor to not use the computer ?
Old 06-19-2017, 05:30 PM
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Originally Posted by Jdog91
Used vacuum advance distributor didn't work so I have the stock one controlled by the computer on there. How would I wire up the stock distributor to not use the computer ?
I'm not sure you can. I think you'll need a good vac distributor, or go back with the FI and the computerized distributor.


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