Buccaneer

Ok, last post I'll be making on this only because you sound like the guy from the CFI vault named CFI400 or something like that and we've already gone over this subject before. If you're going to quote me, then at least quote me correctly ok. here's what I said...again. The KEY word in that whole thing was "UNDER 12psi" and you said... Mmmmm...there seems to be a difference on what was said, but ok.

I don't agree with the GM Service Manual on the pressures required which is 9-13psi. Hey, set your pressure @9psi if you want, I don't care. I'm sure your car will run just ducky at the setting. According to you and GM your motor will love 9psi because it's within the spec. Its your car and you can do anything you want with it. You have your idea on how a CFI runs and needs to be feed and I have mine. We can agree that we disagree on this subject and thats it. Sorry if I ruffled your feathers a bit.

One more thing. does your avatar of 13 second club pertain to your Stock 84? just wondering.

CFI-EFI

I am not that guy, but that comment indicates that I am not the only one that knows how this works.


I quoted you verbatim. Maybe you wish you had said something else.


Although it wasn't a quote, it is YOU that has misstated what I said. I said that I run my car at 14 psi, fuel pressure. I only mentioned 9 psi as part of the GM spec. I did not say or imply that I was running 9 psi.

Now that you have confused the issue by attributing statements and thoughts to me that I never stated, lets get back to the point. Installing an '85 or higher capacity/pressure fuel pump will provide NO gain in performance over an '84 pump that is operating properly. If the stock pump can maintain full regulated pressure and volume under the severest of demands, then no other pump can provide greater performance from the engine. PERIOD! Once you have all the fuel you can use, at the pressure the regulator is set at, what could possibly be gained.


My feathers DO get ruffled when someone touts spending money for nothing. Granted, if an '84 NEEDS a fuel pump, then a later model pump for a similar cost is a good idea. Because it will be operating at a lower percentage of capacity, it will likely last longer. However, a later pump will provide nothing over a properly operating '84 pump.


Wonder, no more. That avatar absolutely applies to the "Stock 84" as pictured in my sig.

RACE ON!!!

Grease Monkey

Im doing the same thing now... 350 to 383.

bogus

A quick thought... the pump will run at it's designed rate and pressure regardless what the regulator is set at. Is it possible that the 1985 pump would really last any longer?

billybonesmusic

i bought my 84 for $1000.00 and a guitar!

it had crossfire injection and it was faster than my buddies stock 85, dont know why, they both ran good, i did recently pull out the engine and am installing a small 400, gonna use the rpm air gap and demon 750
i am in the process of reinventing the cold air and a custom scoop (like corvette summer movie LOL) the Lord has been good to me with that car, wouldnt hesitate to buy another 84!! just my 2 cents.

CFI-EFI

The pump is designed to, and does, turn within a given rpm range. This creates flow. Pressure is the result of resistance to flow. The regulator, with it's spring keeps the resistance constant to keep the pressure constant. The later pumps were designed to overcome the resistance necessary to produce pressures in the 35 psi - 45 psi range. If you only require 1/3 the pressure (less resistance) from the fuel system as the pump was designed to produce, it should run cooler and last longer. In response to the statement, "the pump will run at it's designed rate and pressure regardless what the regulator is set at." is false. If that were the case, why have a regulator? The pressure, and therefore, the effort the pump must exert is determined by the regulator and the resistance to flow it creates and not by the pump.

RACE ON!!!

billybonesmusic

i think the gentleman was right on as far as the pump pressure, the regulator is what controls the pressure to the carbs, and the excess is piped back to the tank, the newer holly type elect pumps shut off when the regulator tells it, the tank pump just keeps on a pumpin'!

bogus

I see where you are coming from...

However... if the pump is designed to flow at 67 GPH, it will run at that rate, this is established by it's electrical design. The regulator will restrict it from sending more to the rails/TBs than is needed. Agreed.

But if it's restricted to X rate on the L98, and Y rate on the L83, wouldn't the lower rate (Y, in this case) add more resistance to the equation?

Am I missing something??? Is the pump smart enough to back off when the loads increase?

Tom400CFI

No Bucaneer, that was ME. See the screen name? Same as on the CFI vault, FYI.

...and CFI-EFI is right; changing pumps for the sake of changing pumps is money foolishly spent. The FP gauge and WOT tells the story, cut and dry.

-Tom

CFI-EFI

No! Not agreed. The regulator will not "restrict it from sending more to the rails/TBs than is needed." As you said just above that statement, "the pump is designed to flow at 67 GPH, it will run at that rate" The pump and the regulator can, and do, send more fuel to the "rails/TBs than is needed". The regulator bypasses the excess fuel to the fuel return line back to the tank.

The running pump creates the flow. Pressure is caused by resistance to flow. The the spring loaded diaphragm in the regulator causes the resistance to flow. The amount of resistance is based in the spring pressure. As the restriction and pressure increases, the pump may slow down to reduces the rate of flow (GPH). For the sake of this discussion, well say that the flow rate remains constant.


There is less restriction necessary to develop the lower pressure for the L83 than necessary to develop the greater pressure required for the L98. Less restriction produces less pressure and takes less work to make.


The pump isn't smart. It just keeps on churning. If the pump is pushing 67 GPH at 14 psi, it is doing less work (and developing less heat and wear and tear on itself) than if it is forcing 67 GPH through the fuel lines at 35 psi. You have yourself confused and you are thinking it backward.

RACE ON!!!

bogus

duh. I see what you mean... I had totally vapour locked (bad pun) on the return part of this equation.

CFI-EFI

Hey Tom,

It's been a while. I was wondering if you weren't the "the guy from the CFI vault named CFI400 or something like that" The old wives tales are hard to squelch. Once the, "monkey see, monkey doers", get a hold of a falsehood, they like to spread it around. I think it makes them feel like they know something. Common sense takes too much effort.

RACE ON!!!

CFI-EFI

Your post came between two of mine, yesterday, and I didn't see your response until just now.
No, that is a good pun. Very appropriate. I am glad if I could help to "see the light".

RACE ON!!!

Tom400CFI

Indeed.

coupeguy2001

um fellas,
the original intent of this thread is how do you make a '84 last longer.
Bragging on it only makes it last longer cause right now all your driving is your home computer.
Give the guy some tips besides no octane booster and some throttle bushings

W89

do you guys know where you could buy new throttle bodies ? are they made still ? my 84 has 142000 miles and just thinking that might be cool if I could get hold of them or maybe get someone who knows something to rebuild them.

Tom400CFI

You used to be able to buy 1 bbl TBI's from Holley that were a direct bolt on. Not sure if you still can though.

Go to a Pull A Part junk yard. Look for old GM FWD cars w/the "Tech 4" 2.5 liter four cylinder engine. Later ones ('84 and up?) came w/a single 1 bbl TBI that is the same unit as those used on the CFI engine. Shouldn't be hard to find a bunch. Grab a couple that have little to no wear in the throttle shaft and your set. Better yet, grab a few and get two that you can get new bronze bushings pushed into, while you're still driving your car as is.

All this is based on if you actually HAVE an issue w/bushing wear on your TB's. My car had 150,000 + miles when I sold it, on the original (but bored) TB's, and I had no ill effects related to throttle shaft wear.

69427

I agree that it certainly would have been nice if Chevrolet had put the D44 in C4s from the start, but unless you do a lot of quarter mile stuff you can live with the D36. I've run hundreds of track miles (road course stuff is my thing) with my turbo 355, and the only casualty was the 4+3 transmission (replaced by an ROD6). As long as you keep the shock loads reasonable, the D36 will provide a long life.
Regarding CFI system reliability, I'm still using the original ecm and sensors. I did swap out the single barrel TBIs for a larger two barrel off a 454, and am using a (free) LT1 fuel pump, with a boost modified pressure regulator. Most of the CFI harness plugged right back in.

k9kohl

What coupeguy said lol

bogus