TBI Mods.

[CKTA]

Yes, cold air is the best....however, more air hot or cold is 10X's better then the stock set-up.

[kevinwebster1]

DJ-
ok sweet man. im not mad at you or anything. i was just thinking maybe you thought up a way that was better than the lid flip. no worries.

[oldred95]

So what TBI mod will produce the most mid and top end power for the least amount of money?

[heavychevy454ss]

The first thing you should do is to remove the restrictive duct that is inside the inner fender. First remove the air tube that goes to the fender. You will see the duct inside the fender hole. Then remove one small screw that is located behind the battery. Then pull like hell on the plastic ducting. It may be hard to get out, just keep trying. Once it is out you will see how restrictive it is. It is way more restictive than anything else in the intake tract.

[oldred95]

I've done that already and it helped a little. I've found a TB spacer on ebay for 29.95 but I have heard that they work and that they don't work so I'm not sure if I want to waist 30 bucks on something that may do nothing.

[heavychevy454ss]

Have you installed an adjustable fuel pressure regulator & tuned it for best power? That would be the next step.
FWIW if you want to flip the breather lid, remove the gasket that runs along the rear of the hood. That will allow some cold air to enter from the low pressure zone at hte base of the windshield. Not as good as a cowl hood but better than nothing.

[oldred95]

Just exactly how does a fuel pressure regulator work? How much more power would it make?

[heavychevy454ss]

The fuel pump operates at a pressure that is higher than the TBI requires. The fuel pressure regulator is located in the throttle body where there fuel line entrance is. Its purpose is to regulate the fuel pressure entering the throttle body. The programming in the ECM is designed around the factory fuel pressure level. As an engine is modified there are several ways to tune the system. First, the chip can be altered change the electrical signal to the injectors. In doing this you can increase the amount of time (duty cycle) that the injectors are spraying fuel. Next, by changing the fuel pressure you can also change the fuel mixture.
By increasing the pressure, more fuel is sprayed from the injector during the same duty cycle. A decrease in pressure will spray less fuel. One thing you have to keep in mind is that increasing the fuel pressure richens the mixture at all operating conditions.
A good tune involves optimizing the fuel pressure & the chip.
Here is a link to an article that has some basic TBI fuel mods.
454SS fuel pressure mods
Although the article is based on a 454 the basics are the same for a small block TBI.

[oldred95]

Wouldn't the extra fuel make it get worse gas mileage? I think my truck flows plenty of fuel considering the lack of performance I get from it. Thanks for the info.

[Silverback]

Those pumps work best when at full flow, so the regulator at the TB is a bypass regulator. All it does is keeps the pressure in the line in front of it at whatever it's set bypass pressure is, so the injectors always see the same pressure. Anything that the engine doesn't use gets returned to the tank through the return line.

[lowdown]

Another thing you can do that I done on mine...
The Baffle that goes between your fender and your air cleaner tube is actually 2 pieces.
It's a bit tricky but you can take the restrictive tube out of the center of it and it will flow much better.

[taz104]

Originally posted by chevyforu
That doesn't look near as bad as I thought it would but I'm still goin with the one on ebay for $10.95 because I'm ordering a TBI spacer and injector spacer from the same place. Thanks anyway.

I know this post is a month old...but if you haven't bought that p.o.s. tube and you REALLY want to try it, I'll sell you a used one for $5 +SH... It has a 1/4" crack on the end, but if you buy the new one, it will happen eventually anyway...
Or...you could do the wise thing and build a better Home Depot mod for about $10, like I eventually did anyway.
Couple of Fernco clamps, some dryer duct and some black paint is what I used. The only tools you need is: metal snips, screwdriver(or 1/4" nut driver), and sandpaper.

If you'd like, I'll post pics tonight when I get home...

[kevinwebster1]

yes do post pics please

[oldred95]

Another easy mod is to take out the "thermostatic air cleaner" as GM calls it. Its a butterfly valve located in the air cleaner housing that sucks hot air off of the headers. I used a hack saw and cut one end off and pulled the pin out and the whole thing comes out. Then I plugged the hole and did away with the flexible hose that goes from the headers shield to the air cleaner housing.

[taz104]

Originally posted by chevyforu
Another easy mod is to take out the "thermostatic air cleaner" as GM calls it. I used a hack saw and cut one end off and pulled the pin out and the whole thing comes out. Then I plugged the hole and did away with the flexible hose that goes from the headers shield to the air cleaner housing.

Not if you live in CA and have a visual inspection with your smogtest...

You don't notice...or doesn't it run rough until it warms up?
Mine broke in 1/2 and the truck shuddered alot until it was nice and warm. That's why it's called a "Preheater" hose...

kw1...Since you requested, I'll post pics tonight.

[oldred95]

My truck ran rough when cold even before I took out the thermostatic air cleaner butterfly. Low fuel pressure and an inaccurate fuel to air mixture will cause it to run rough when the engine is cold. Once the O2 sensor gets heated up the mixture is changed and it runs smooth. To answer your question, no I didn't notice any difference in idle quality once the butterfly was removed. My next mod is an adjustable fuel pressure regulator. Judging by the way my truck runs now I'm thinking its going to make a BIG improvement.

[taz104]

Yeah, I agree with that mod...
Been researching and apparently the suggested one is the Actron CP-7817. It measures 0-60 psi.

I've seen a mod where you modify the stock one, but I'm not too keen on that one...hate to f#@$ it up.

I bought the JET Performance one, but after 2 hours on hold with their customer service, was told that it had to be adjusted by a speed shop...so I returned it...

I have other problems right now, so I'm working on those before I order the Actron regulator.

[oldred95]

I ordered the Jet regulator too. Its been on backorder for about two or three weeks now so I don't know if I'll ever get it. What do you mean it has to be adjusted by a speed shop? Whats the point of making it adjustable if the average Joe can't adjust it himself? Did you get a fuel pressure gauge? Maybe they meant it can't be adjust correctly without some sort of fuel pressure gauge.

[taz104]

After install, the adjustment pot isn't accessible without removing it. Then adjust it, install it, remove it...etc.

I think that a speedshop might be able to run some sort of test on it to set it prior to install...maybe?

Originally posted by kevinwebster1
yes do post pics please

Posted them on my imagestation account.

Follow:
http://www.imagestation.com/album/?id=4287931931

Goto the index....to skip the rest....they're on page 3.

Just need 2 Fernco Clamps...that's what they're called and a length of ducting to fit the size of clamp you get.
After you cut the ducting, make sure to use sandpaper and smooth the edges to insure you don't get metal chips in the carb/intake. If you want to paint it...I'm sure you do...use the sandpaper to rough the ducting up a bit.
Then paint, dry, and install!

I think it ran less than $10 for everything.

[oldred95]

If you install an injector pod spacer the extra 1/4 inch may make enough room to adjust the regulator.