89 Vette motor in my 84 with crossfire

[Racer86y]

:W Would i be better off just to put carb on it.I have new cam in it also,more compression with aluminum heads.I have replaced a bunch of sensors,rebuilt injectors and still will die in a minute or so.Also makes labor knocking noise before it dies.What would you do?Replace with Quadrajet?:confused

 

[BADDUCK]

Exactly what is your question?

 

[Racer86y]

84 Vette

Should I or is there a chance of making it run right with CrossFire F.I.?I am trying everything but ready to go old school if its not really possiible.

 

[vetteboy86]

So you have taken an 89 corvette motor and dropped it into your 84?

 

[Racer86y]

84 Vette

Yes,and changed cam also.Not real big and wild.Just enough to have a good sound

 

[BADDUCK]

Did you move the 1989 ECM and all the wiring harness over? Also what are the specs on the cam you installed?

 

[philbillyvette]

Did you move the 1989 ECM and all the wiring harness over? Also what are the specs on the cam you installed?

Sounds like he is trying to get the 89 engine to run with the 84 CFI setup, so no need to swap the computer and harness over (if that is the case).

Not sure of the cam difference between an 84 and and 89, but you said you upgraded the cam anyway, so may be something with your computer/computer chip. May need to have a custom chip made for the car now.

 

[Buccaneer]

There shouldn't really be a big deal about what year motor you used, but it will make a huge difference on what cam you used with a stock 84 ECM. Post the cam spec's you are now using.

 

[BADDUCK]

Sounds like he is trying to get the 89 engine to run with the 84 CFI setup, so no need to swap the computer and harness over (if that is the case).

Not sure of the cam difference between an 84 and and 89, but you said you upgraded the cam anyway, so may be something with your computer/computer chip. May need to have a custom chip made for the car now.

I can't tell what he has done, but if he installed a more aggressive cam it will run like crap without a tune.

 

[Racer86y]

Cam

Ok.Cam is 480 lift 106 intake,110 exhaust lobe center 232 duration at 50

 

[BADDUCK]

Ok.Cam is 480 lift 106 intake,110 exhaust lobe center 232 duration at 50

That is probably the main reason the car runs like crap. The stock 1989 cam is .415/.430 lift 207/213 duration at .50 with a lobe sep of 117"

YOU WILL HAVE TO GET A COMPUTER TUNE FOR THE CAR TO RUN RIGHT

 

[ex-x-fire]

Put a vacuum gauge on it, it should have at least 17'' or more at idle. Is the needle smooth or bouncy? Those heads do not have the typical exhaust crossover ports to feed your CFI egr valve.

 

[Racer86y]

84 Vette

I unplugged knock sensor and it idles ok and runs a lot better.Still not good enough.:bash

 

[Buccaneer]

Ok.Cam is 480 lift 106 intake,110 exhaust lobe center 232 duration at 50

The lift isn't killing you, it's the LSA and Dur. 114 is ECM friendly and dur is a bit much for a stock 84 computer.

 

[Racer86y]

84 vette

Ok,now with knock sensor unplugged it will stay running,but does not accelerate very good.Who flashes computers?Is it expensive?hnoes

 

[BADDUCK]

It depends on how much you need done. There are several do a google search. One I know of is PCMforless.com

 

[Racer86y]

Flashers

Thanks,i will do exactly that.I hope it runs good after that or else its quadrajet time.Thanks guys

 

[vetteboy86]

Mail order tunes are fine if you have bolt on modifications. Unless they have experienced tuning a setup like yours, there only going to be in the ball park maybe. The mail order tune may get your car running, be aware, in my experience extensive data logging and tuning is required.

 

[vetteoz]

Ok,now with knock sensor unplugged it will stay running,but does not accelerate very good.

With KS disconnected you have no spark advance

'84 computer you are very much on your own regarding tuning.
Not aware of any major tuner doing those cars, most don't even do the '85 ECM , only '86+

Should ask the C3 guys about tuning because more CFI cars over there
http://www.corvetteactioncenter.com/forums/c3-technical-performance/

 

[Buccaneer]

With KS disconnected you have no spark advance

'84 computer you are very much on your own regarding tuning.
Not aware of any major tuner doing those cars, most don't even do the '85 ECM , only '86+

Should ask the C3 guys about tuning because more CFI cars over there
C3 Technical and Performance

He will have spark advance, just no spark retard (safety net) if it detonates.

As far as tuning a stock 84 ECM goes, your out of luck really. There are a few places that offer a remapped chip, but that really doesn't work well after you start doing mods like you made to a CF motor and would be total hit and miss for your application. I'd just put another cam in it more closer to stock LSA/DUR unless you want to go to a totally different ECM and start tuning yourself.