LilJayV10

iTrader: (5)

I have been reading the TBI boards now for almost a month. Until I get my 406 back together I have to mod something. It's making me nuts. I have done lots of searches and have read more tech articles than I can remember. I don't want to do anything crazy to my 305 TBI(heads/cam) just a few little things. I have a few questions. The car runs great now, I just don't want to mess it up. I have been guilty of that in the past. Can't leave well enough alone.

I have a 89 305 TBI. Bone stock except for the K&N filter, cat delete(it was clogged)and flowmaster muff. I just did a tune up on the car last week.

AC delco plugs, I went with the 44 heat range instead of the 45's that it called for? Was that a mistake?

Bosch wires. My friend works at autozone and we ohmed several different brands of wires and found the boschs have the same resistance as taylors. less than 1 ohm.

Accel cap/rotor w/ brass terminals.

The things I am wanting to do are the open element air cleaner, AutoZone had a edelbock 1722 or 1702, I think it was, open element air cleaner but it was a drop base. Whats the part number for the flat base. I read it's better and you don't have to use the factory spacer ring.

Fuel pressure regulator. I read the tech article on how to make your own. I also saw the adjustable GM unit. I don't which one would be more beneficial for the small amount of mods I am doing. I am also thinking about putting a TPI pump in the tank to make sure I have enough fuel volume, everything I have read says the stock TBI pump bearly keeps up. I have read that 13psi is a good place to start.

Timing. I run 93 octane in the car all the time, it runs a lot smoother. I was going to bump the timing up to 4 degrees.

The intake is leaking coolant so I have to replace the gaskets. A friend of mine has the edelbrock TBI intake that he isn't using. He bored the holes in the intake to accept the bigger 670 unit. Will that have a bad effect on my using a stock TB?

Also, is it going to hurt mileage if I remove the A.I.R. system? As I mentioned the cat is gone.

Do any of the injector pod spacers or TB spacers do anything? What about the ultimate TBI mods?

I am trying to keep it simple with the intake/open element/fuel pressure/timing mods.

Sorry this was so long. I appreciate the help.

Jason

dwillis

iTrader: (6)

number one the ultimate tbi mods are well worth it...the stock tbis are soooo restrictive....unless you have had your computer tuned the fpr won't help a whole lot...timing advance will help a little.....the tbi intake you speak of will be fine to use cause your throttle blades are smaller than the 670 unit...and it will flow better than the stock...but Remember you can put all the air and fuel into an engine but if it cant get out from restrictions like a stock pipe or stock manifolds<junk.....open element definatly a plus....the open element ti mods and the intake themselves will actually increase your gas mileage....the L03 was built to be an efficient long lasting engine that you canimprove on easily....mine has about 230,000 miles on it and it will still run high nines at the track.....1/8 mile track that is...hope this helped..
I did my tbi mods in about 3 Hours one saturday..a dremel tool is a must as is patience....That is where I would start...and it doesn't have to look perfect...mine dont...also you can remove the egr valve,AIR tubes and plug the holes and delete the smog pump with no trouble also...its all on the board here...just take time and you will find it......Dave
I have attached a couple of pics of my quickie job...I also did a cheap pod spacer and tbi spacer...dont invest a lot of money in them....for the pod spacer just add another pod gasket on top of the original one...

Fast355

iTrader: (2)

Here are my TBI lesson from playing around with my 305/350 TBI's.

The stock Rochestor 220 TBI unit is good for 300 FWHP, untouched. Above 300 FWHP it becomes a noticeable restriction. Below 275 FWHP NO noticeable power can be gained from "TBI mods". With all TBI mods on a small block TBI the smallish TB bores become a restriction around 325-340 FWHP. At this power level, either bore the TBI to 50MM or get a 454 unit. This will increase the capability to around 400-425 FWHP. Once you get above that, 454 TBI units can be pushed to 2.2", which is good for about 500 HP. At that stage, you might as well have the EBL and multiple TBIs or a 4 bbl TBI, as fuel will become the limiting commodity.

The stock 55 lb/hr 305 injectors will support up to 300 HP without upgrades. You just have to change the regulator and fuel pump to allow for 32 PSI. The stock fuel pump will limit you to around 200 HP anyway and is a MANDITORY upgrade, IMO. Smaller injectors at higher fuel pressures work best for efficiency, therefore power AND mileage.

The stock intake manifold works fine for economy and performance use. I found that it offered nearly no loss in power over a performer RPM intake all the way to 5,500 rpm. In fact from idle-3,000 rpm it offers better torque than the 3704 peformer TBI, Holley Projection, and even performer RPM. At 5,500 rpm the performer RPM took the lead and had a commanding difference by 6,000. At 6,500 rpm the stock intake was about 15 RWHP down against the performer RPM/TBI adapter combo. The projection intake offered slight gains from 3,500 to 6,500. The 3704 gives a slight boost in torque around 3,200 rpm and a 10 RWHP advantage at 6,500 rpm.

I typically see 8-10 RWHP by going to 1.6:1 full roller rockers on the L03/L05 tbi engines.

A full exhaust from the head ports back is manditory for getting any kind of decent power from the TBI cars.

Even stock TBI cars can benifit from DIY chip tuning. I have seen gains of 15-20 FWHP and up to 40 ft/lbs on 4.3/305/350 TBI engines. Throttle response can become impressive and I have seen fuel mileage DOUBLE over poorly matched and running TBI combos with no tuning (383 w/ 454 injectors, 350 ECM, RV cam, full exhaust, etc)



I have seen 4-7 RWHP gains @ 4,500 rpm by adding a 1" open center TBI spacer on near stock TBI engines with the stock intake and stock TBI unit.





A good, complete tuneup with A/C plugs, quality wires, quality cap and rotor, PCV valve, ALL filters, reset timing to 0* BTDC (timing chains have almost always stretched enough to retard the timing 2-6*), check the fuel pressure (12 PSI is a good starting point), mimimum air rate screw on TBI set to spec, and a 3-wire O2 sensor conversion, will restore power and fuel mileage. An out of tune engine will run like crap, waste gas, and bog down on acceleration.

https://www.thirdgen.org/forums/tbi/...ck-basics.html

I know I am overlooking some stuff, but it is late and I've gotta work in the morning.



This is a dyno of a rich running 350 TBI with mild bolt-ons(1.6:1 rockers, 1" TBI spacer, headers, exhaust, a little bowl work on the heads, and a PEANUT roller cam). These numbers may seem low, but consider that this engine makes a miserable 180 HP @ 3,800 and 300 ft/lbs @ 2,400 in stock trim.

.

DM91RS

Jason

If replacing intake gaskets and you have the Performer TBI available try it. I would not buy one new but it "may" be an improvement over stock. Others with first hand experiance with it may be better suited to answer that question.

First off to 'keep you busy' with mods try some prom tuning as it is not that expensive and most of the things that you will do past the point that you are now with the car will benefit from it and will keep that 'good running' car that you want.

I mentioned tuning because you also asked about adjusting fuel pressure. You should only need to change your fuel pressure if data logs show that you need more fuel beyond what you can tune into it with the prom. I think one of the first 'tools' needed for efi cars is at least a basic way to datalog. Other wise you are guessing at what you have (as in what the engine is actually doing)

Removing the A.I.R. system will not hurt anything.

DM

And listen to Chris (Fast) full exhaust.....

LilJayV10

iTrader: (5)

Wow, guys I appreciate the repsonses. I can tell that several people in this thread have had real experiences with TBI mods and not just what they have read somewhere.

I am suprised that the stock intake yeilds better power than the edelbrock TBI, did I read that right?

I have considered the DYI prom burning but man I don't know jack about any of that stuff. I would be afraid I'd grenade my engine.

Also. I asked in another thread but I will in this one too. Is the 3 wire o2 conversion a good thing? I was watching my 02 switch the other day on the scanner and man it's slow. Nothing like a LT1.

DM91RS

Fast or others would have to answer the stock vs Performer debate as I went from stock to Vortec style. I do believe that the stock and Performer TBI with the heated water jacket makes for a better running stock type engine and may help in the quest for MPG.

As far as tuning read the thread https://www.thirdgen.org/forums/tbi/...free-tune.html and that will give some insight for a beginner.

As far as the O2 what you are seeing is the data rate for the stock computer vs the later faster LT1 unit. I have the stock one wire O2 and it works well with the faster data rate of the EBL unit that I am using now. The three wire is good if you have long tube headers and the unit does not want to heat up as well as the sensor being closer the the exhaust ports as in the stock units.

DM

FreeLoader

you're gonna want to tune.

there's a hundred and fifty ways to get setup for it, i'm sure you could find one thats relatively cheap and easy enough to work with for you to start tuning, but you really are going to want to do that no matter what.

you can throw off the stock tune(which even now you're probably not sitting at) with your basic full exhaust change, hell even an open element can lean you out slightly overall.(although between the two, the oe is far less of a worry).

as far as tuning goes, you should also note that chip tuning practically negates having to buy or build a fuel pressure regulator, or adjusting the timing by hand(both of which less effective when done that way as they only change your base timing/fuel, wheras in chip tuning you can alter both at every...10 rpm's I believe? so's you never are running more rich in one place than another), which will save you from spending a little more money.

I'd personally say your best and easiest bet would be to get setup for tuning, buy your open element(or if you're the rebellious type, go for cai), get the injector pod spacer(or do the double gasket thing), get a FULL exhaust change, tbi spacer if you really want it, I'm still not convinced that they're worth **** until you're in the 250's..., you may want to change out your fan switch too(so it will be in compliance with the ecm changes you make), 170 deg thermostat, an aluminium 1-core or the copper 3-core radiators from autozone might even be a good idea if you're having cooling problems at any point...and then tune.

tune the hell out of it.

if you're still not satisfied, there are mounds of suspension and drivetrain mods you could do that make wonderful and beautiful things happen to the way your car will run and drive(only someone who's done at least some of them could use words like "wonderful" and "beautiful", and believe me they're great), the point of this being that you're not limited to engine mods, nor should you think as such.

as for the free intake manifold, I'd take it. it's free, and it WILL be useful later. not to mention one of the biggest things you want your engine to do is be able to pull up to 4500-5500 rpm's, 0-4k just isn't enough of a powerband in my opinion.

LilJayV10

iTrader: (5)

So it's not nessicary to get an AFPR when tuning with the ECM, but should use a bigger fuel pump?

FreeLoader

from what i've suggested, you don't need one.

I can say that i switched to a tpi fuel pump when mine died, and with no tuning whatsoever it made a world of difference for my car(although that may have been the pump dying over time).

my car runs to empty now, it doesn't starve almost at all in hard cornering, without tuning it doesn't bog as much anymore in general, throttle response improved.

basically, you don't need it. but it could do nothing but help.

also, if you intend to even go so far as changing the cam, or anything basically beyond your usual tuneup/exhaust/air intake setup, you're probably going to want to, as it won't take you too long before you reach the limits of that pump.

LilJayV10

iTrader: (5)

Well I put the open air cleaner element on today. It's a big zero on the butt dyno. I didn't put a k&n on it, just a regular paper filter.

I used the Mr. gasket air cleaner, part # 4340 I think it was. I can double check if someone needs it. It's a flat base air cleaner, it's tapered a little bit, it clears the throttle linkage and sits about 1/2 inch above the coil and I didn't use the factory spacer. I think I have read people have had problems with the coil shorting out and the linkage hitting the bottom of the air cleaner.

I used a uni bit to drill a hole for the IAT sensor and plugged the vacuum line. It almost looks factory.

I will probably swap out the intake sometime later this week. There's something rattling up front, I am afraid it's the timing chain, I might have to replace that too.

Probaby the extent of my mods for a while will be the air cleaner, intake, timing, and fuel pump.

I was reading about the tuning stuff. wow, I am going to have to go back over it. It's going to be a while before I am comfortable to do that.

DM91RS

Believe me once you start it's like a snowball going down hill.


DM

FreeLoader

you're not going to see a whole new dimension of speed by putting on an open element, your stock one allows plenty of air to your engine to 3000 or so rpms(i'm being vague here), from there you'll see a difference, and that difference, at least in my case, was that the car will continue to pull to 4500 rpms, as opposed to dropping off at around 3600.

as for the filter, I'd personally go with an amsoil foam filter if you want to step away from paper, they flow as well as k&n and filter as well as most paper filters (the research I'm basing this off of actually showed it to be almost exactly as good at filtering as fram, specficially, if i remember correctly), I wish i still had the link, but it was an annoyingly long read anyway.

the point being, it flows great, filters better than k&n, all thats required to clean it is compressed air (as opposed to that oil stuff), and it's only 30 bucks I think.


as for the chip tuning, I haven't done it, but i've got a pretty good grasp of it. the best way to start to understand it is to work with the basics. start figuring out everything you'd need to start chip burning, and everything you'd need to start datalogging, and make sure you keep them seperate.

then, learn why you need each of those parts.

then, start looking at pics of the programs, or download the program and look at it, so's you're comfortable with it.

then, if you don't already, learn about engines, so you know why you're doing it in the first place .

once you've got all those down, it should be a bit less overwhelming, and the actual programming/tuning should start seeping in if you start reading the various threads/stickiess.

LilJayV10

iTrader: (5)

I was a mechanic for 10 years. i have a good concept about them, just not the tuning part. But I think I will have to learn about that now.

LilJayV10

iTrader: (5)

well I put the different intake on my car. Now the car doesn't shift the same as it did. It shifts to soon and it's not firm like it was before. I tightend the cable up some but didn't really make a difference. does that intake change the geometry of the TV system? IT feels like it pulls harder from 2500-3500 but if I can't get it to shift like it did I am going to put the stock intake back on it.

FreeLoader

I'm shootin from the hip here...

first off, just so's it's clear, I'm going to assume you're referring to the intake manifold.

could it be that the engine is leaning out at the upper rpm range? if so, the engine could be pulling timing and you're shifts could be weaker.

again, I'm shooting from the hip, I could use some help, and we could use some more information.

what rpm does it shift at? what rpm did it shift at before? is there a difference in pull at those rpms? how is the shifting weaker? is it sitting at a certain rpm range longer than it should when at WOT?

LilJayV10

iTrader: (5)

Yeah I put the elderbrock intake on it. IT shifts to early and it's not a good positive shift like it was before. It feels like it drops out then shifts. The gas pedal doesn't feel the same.

I have readjusted the TV cable twice and it hasn't helped.

Looks like I will be putting the stock intake back on. I'd rather it shift right like it did than pick up a few horses.

FreeLoader

I'm stickin to what I said before, it sounds to me like you're starving for fuel at the upper rpm range.

I could be wrong, but I had problems very similar to that just before my pump died, once replaced it was firm as ever.

that's not necessarily a fix for you, I'm just using it as an example.

it may be a better idea for you to stick with the stock manifold until you start tuning, or you could buy the neccesary parts to start tuning, or simply change the fuel parts to bigger pieces(ie pump, injectors, vafpr would honestly be the easiest fix).

it's really up to you.

LilJayV10

iTrader: (5)

I am wondering if you are right about the fuel pump. I have to push down almost 1/2 throttle to really get the car to move. It feels mushy, if I drive it hard it will shift firm, but just driving around it's sloppy. I have a 255lph pump I can put in the car. The car has 88,xxx miles and never had a fuel pump.