Ok decided now to keep crossfire system on my 84 vette
 

After reading alot of question about the crossfire induction compared to going with carb setup, I am going to keep my 84 vette with crossfire , I want to do some mods and this is where I am starting first, first fuel pressure adjustment and bumping initial timing, where exactly is fuel pressure adjustment made( where do I get this tool to make adjustment), also whats the correct way to adjust initial timing on my car and what should I set it at. And since I am Maryland( there is no emissions needed for my 84 Vette) so I am keeping the original headers, installing new pipe that includes oxygen sensor from that point new 2.5 custom dual exhaust to rear of car with Flowmaster muffs , then adding Renegade intake, so I hope doing all this will increase the hp & torque and I would feel a noticeable performance improvement, any help with this would be greatly appreciated

My dad has a 1984 vette that he bought new and it currently has about 50k miles on it. He's never had any issues with the Crossfire Injection but a lot of people seem to not like it.

Be careful with the renegade... read my thread on my missfire carefully and determine if it is worth the headache. Too many parts machined wrong for me.

Fuel pressure is on the drivers side throttle body. Remove the top pod and there is a cup. Knock out the cover on the bottom and loosen it a few turns. I adjusted mine by reusing the gasket and checking pressure until it was where I wanted it.

Timing simply disconnect the EST wire by the booster and set like a normal distributor. Mine liked 8 degrees according to the data logs.

adding exhaust from the stock manifolds back won't gain much. The factory manifolds aren't great.

Porting or swapping the stock intake along with optimizing the setup will gain roughly 25hp. You will feel that but you'll also feel you'll cleanly rev out to 5200 instead of 4600. Same curve but a better range.

Just doing the timing and fuel pressure will change the whole dynamic of the car if it is off. Start there.

These "mixers" are below the throttle bodies. Some recommend removing them, but GM wouldn't have put them there if there wasn't a reason for them:

Before:
https://cimg0.ibsrv.net/gimg/www.cor...20622e9a1d.jpg

After:
https://cimg6.ibsrv.net/gimg/www.cor...e27375f705.jpg

my 84 got 70k on it no trouble at all with crossfire ,replaced tps sensor and map sensor

Good man! :thumbs:


Fp is adjusted w/the rear/driver's side throttle body regulator. There MAY be a weld blob that needs to be ground off so you can access/turn the adjusting screw. CCW is more pressure, CW is less. Both timing and fuel pressure specs? 13-14 on fuel pressure, on a stock engine, IMO. Timing, feed it what it wants...but likely the most you can give it w/o pinging/detonation.


Timing and fuel pressure and your proposed exhaust changes will give you a tq increase that you can feel across the RPM range. An intake solution (either the Renegade or a ported stock intake) will increase tq (hp) that will extend the usable RPM range another 1000 or so.



I'm one who doesn't agree with keeping the mixers. MY take on them is this: GM wouldn't have put catalytic converters on there if there wasn't a reason. I'm sure GM had a reason; criteria that they had to meet. But I'd submit that is criteria that we don't care about (emissions/CAFE, COLD weather drivability etc.) I removed mine entirely, bored my TB's to 53mm, and radius'ed the outlet of the TB's and TB holes in the lid...kind of going the opposite direction GM went with the TB inlet to the plenum. My car ran mint, idled like stock and even got 24-25 mpg w/a SBC 400....so...I don't think the mixer fans do anything that we care about.


.

So, here is what I'd do in the order I'd do it assuming you engine is squared away. Also, hit up Buccaneer on the C3 forum. He invented the Renegade and knows what to do.

1. Put in a new fuel pump from a 85-89. About $100
2. Adjust the timing to 12 (yes, mine LOVED 12) FREE
3. Add the Renege intake. Prices vary... 650ISH?
4. Remove the factory cat and add a performance model cat... $200
5. Headers (you already have them?) $800

So... a totally kick ass TBI for under $2000

If you have time, tools and talent, porting the stock intake can get you some gains as well, rather than the Renegade intake manifold.

The Renegade seems to be hit or miss. Some have them and they are great. Others have had issues with fitment and quality. If you get one with no issues, it will flow more than even a ported stock intake manifold. There were a couple of other "performance" manifold options back in the day. You can't find them new any more, but once in a while, one turns up on FleaBay.

As for the order for the mods, I'd strongly recommend doing the intake manifold first. The ports on the stock manifold are very restrictive. The ports in the head are significantly taller than the ones in the manifold. The stock setup has a really big "step" at the manifold/head interface which follows the really restrictive part of the manifold passages. That's even worse than just the tiny passages in the stock manifold.

Mixers will help prevent puddling when cold and low speeds... that being said knowing how much of a mixer is needed for static mixing processes... that ain't doing much of anything. You want a 99.9% perfect mix you need one of these bad boys... besides, look at a pipe flow velocity diagram... where is the max speed? The middle. And look at that, the blades aren't in the middle. It's got an open circle. Cold an idle only. I noticed no appreciable difference between the renegade and stocker at idle except when it was roughly zero. The car would stall when it was that cold but only the first time...

I agree. Applying no throttle, mine would stall on the first start attempt when it was BELOW 10F. However, I had:
*blocked off my exhaust x-over under the plenum,
*eliminated THERMAC entirely,
*hard-wired my Cowl inducted hood so that it was open 100% of the time,
*plugged the air snorkel/inlet under the hood.

So...when it was below 10*F, my car was starting with a 10* or colder intake manifold...and then drawing 10* or colder air, 100%. If I gave it a little throttle for the first 10-15 seconds, it would start up, stay running and run normally thereafter.

Also, at "idle", your throttle blades are closed. So, they're already "stopping" the fuel and then spilling it off the edges....velocity through the fan blades at that point is nil.

Here is what my plenum lid looked like when I was done w/it:


https://cimg2.ibsrv.net/gimg/www.cor...61c89fefd.jpeg

Well I completly forgot about the throttle blades! :rofl: it's been a long two weeks and I've got mixed design still on my mind so I'm still thinking in open channel lol.

Anyway, they're only there more than likely for one particular scenario GM wanted to mitigate. In my expert (Ha, funny right?) Opinion they ain't doing crap.

Back on topic, do what they said. They all know more than I ever will. I wanted to light my car on fire at one point. :rofl:

Tom, you may have gotten away with all this stuff, but as you said, the mixers may have been needed for improved fuel atomization so the car could pass the tough pollution requirements. I need to pass the California requirements, so I didn't want to take a chance on that issue. As I said, my car passes the CA smog test with flying colors! And I don't have a stalling problem when I first start the car, either! The car must also pass a thorough visual pollution system inspection! My car would fail BIG TIME if I tried your tricks!

https://cimg6.ibsrv.net/gimg/www.cor...d252863c3d.jpg
:cool:

I never tested the stock unit below 32... never had a reason. (BTW, my car passed its last inspection with the cat core spun sideways... theres a lot of room left on the plate in the stock emissions...)CA emissions are a bitch I've been told. How cold does it get in CA anyway? I had no business starting that car that day. Then I drove it and it was like driving on ice. We had a week of sustained single digits and below zero nights... the 10w30 gave the starter a work out and that was the only time I could spin the tires in all 4... Stupid intake manifold. Luckily in the peoples republic of NJ the only thing I don't have to do is get the thing inspected. Guy cursed me out for bringing that "piece of s#!t" manual in there.

Anyway, you have an actual need for it because why take the chance. I really don't see it making a difference.

Edit: long story short, not trying to be a jerk, I am genuinely curious if cut vs uncut makes a difference. At that low of a temp I think it could still stall. Might have to get my hands on another lid and hack it up.

https://cimg8.ibsrv.net/gimg/www.cor...96fb82814a.jpg

We have it all, but I doubt that my car has ever seen 10*F. I live about 5 miles from the Pacific Ocean. (Photo is Lake Arrowhead, about 1 3/4 hrs. from my home.)

:cool:

In Cali, HRR you DO have to meet criteria most of us don't....and I certainly don't. So keeping your in may have helped in your situation. I speak strictly of the criteria most of us care about; driveability, performance and somewhat, fuel economy.

I shouldn't have been driving my car back then, when it was 10* out anyway, so really holding the throttle for a few seconds at start up under those conditions wasn't a big deal...or something that I cared about.

We have an interesting argument going here: "MY CROSSFIRE IS BETTER THAN YOUR CROSSFIRE!" I certainly agree with your criteria of driveability, performance, and economy, and I have all of those, so what benefit do you have that I'm missing? I'd like to know how your car is better than mine because of your modifications? Increased pollution? Who wants that? I wish we were closer! It would be interesting to compare our cars. I certainly surprise a few people by the good performance of this old Corvette!

One thing is for sure: There's nothing wrong with the CrossFire that a few mods can't fix! Carburetors are dead!

:cheers:

Oh. I'm not saying mine's better, that's for sure. First, my CFI was a collection of junk yard parts and home made stuff. But it worked good. Second, Yours and mine aren't comparable as mine was a 400. Finally, w/regard to the swirl plates, only a A-B test on a dyno would show the diff.

I just posted so the OP would know all of his options; I've seen it posted many-a-time that you "need" the swirl plates for atomization etc. I don't think you do -especially where emissions aren't critical. I'm not even convinced that they help emissions other than at or near WOT. Overall, I'd guess that they "help" (emissions, economy) as much as they Hurt (power)....not very much. Keep 'em, ditch 'em...I don't care. I was only pointing that you CAN eliminate them entirely and the car will still idle, throttle response, run, fuel economy, and everything else, just dandy. :thumbs:

I'm working on the dyno thing at the moment. In trying to locate a non screwed renegade and stock unit to do all the mods on. So it'll be stock unit, ported base, removed swirl plates and then renegade. I want to see what yields the best results... hopefully the renegade but who knows.

I have a renegade in my 84, i also have edlebrock aluminum heads, mild cam, 1.65 ratio roller rockers, long tube headers, and the exhaust system that came with them (melrose).
i upgraded to a the later fuel pump before the mods as well.

i ended up going with an ebl flash ecm in order to get it running right.

lots of work with the ebl flash, but worth it.

the car really screams now, and adding a 3200rpm stall converter makes it pretty easy to light up the tires.