So you say, you want to convert your TBI to a TPI or carb. why? for what reason? First of all most of the TBI performance problems are in the heads and cam , next is the intake manifold. So most of the conversions are worthless if you dont replace these main performance restrictions. Heads cam and so forth. The way to go fast in a TBI f-body, and not spend alot of money is not to go overboard on your set up. dont go with a radical cam. lumpy idle and so on .
A mild cam with a duration in the area of 210 @ .050 and in the .450 lift , dont forget 110 to 112 LSA. WOULD WORK GREAT..
why, you ask? because ,you have to consider the flow of the stock throttle body. Its not to good, but it will work. Next is the intake manifold, From my experience, a performer or performer RPM, would work great with a tbi adapter , or just get the performer tbi.. The RPM is the way to go for power, but you have to check for clearance. Second thing is, the heads, a great replacement is either the vortec 350 heads , which need to be milled and tapped for the intake manifold ( not to expensive $125 ) or try to find used L98 corvette heads and just bolt them on. D ont forget these are all mods for your tired 305 and most with little installation modification. I will be right back to finish

 

Please finish, these are all mods I wanna do before the summer, I have been gathering all the info I can. I was going to switch to the 454 TBI too.

 

Im back . next , on building a great TBI is to consintrate on rocker adjustment, which is very important. Without adjusting the rockers right the car will run like sh---t.. VERY IMPORTANT.. Next is up on top baby..( a lttle humer) the TBI itself, now forget about porting this and that. it helps but you might as well get a 454 TBI unit and install the 305 injectors on it quick and simple. Now fuel pressure is about 7-9 #s , try that first, if the car tends to lean out on the top side then ad fuel pressure. dont forget some thing so very important. you want the car to start running a little leaner after the torque peak wich should be at 5250, once it reaches that point. then the car will want less fuel. to rev.. the exact amount will tepend on tuning and that is up to you and your skills..

P.S. all these mods will work with a stock chip and computer and wiring so like I said before and Ill say again why would you want to convert to something else when you have a great setup waiting to wake up.. good luck to all and dont go overboard, you have a graet slate to start with , and great luck on your prjct GODTI........

 

I though U had to mill vette heads too...
what year vette heads?85-91
do U know the casting number?
why dont u need to mill?

 

no the Vette L98 aluminum heads do not need to be milled because they have the same CR as 305 heads. They get away with smaller combustion chambers(compared to a truck 350) because vettes need 92 octane and the aluminium helps fight detonation.

------------------
-Tas
'89 Formula WS-6
[soon to be Torch Red with black hood and headlights =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

[This message has been edited by Tas (edited January 16, 2001).]

 

I have never really tuned a car before, so how do you know when a car is running lean??

 

These are all mods that I'm planning to do as well. I know there aren't any concrete numbers, but what can u expect from these mods? Also, if u can get a little deper in tuning and how to do it

Thanks

 

badbrd, I have read a lot of threads on this board that say you need to go to the 65# injectors. I know you got 55# injectors on your 2" TBI unit, but I wonder if the 65# would be better. i know the cop cars used them on 350's but they only used the 1 11/16 TBI.I wonder if 2" plus 55# is about the same as 1 11/16 and 65#? What the theory on using the smaller injectors. Thanks.......bob

------------------
91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

 

when i install the nest set of mods (cam,intake,TB unit, maybe heads) im going to 65# just because w/ all the air i will need the #, and if it runs rich ill just take some out of the chip.



------------------
1992 Camaro RS
Mods:
Custom chip, 14x3 Open element w/ K&N filter, MSD 6a, MSD GM blaster Coil ,MSD 8.5 SC wires, AFPR,Fuel Pressure gauge,A/F guage, 3-Row Al rad. , 180* t-stat,Proform 1.5 roller rockers, Hooker 1 5/8 headers, 3" Catco cat, 3" Hooker Aero Chamber cat-back, "Ultimate TBI" mods, Nitto 555R Drag Radials

Next

454 TB,intake,SLP Posi,3.42 gears
Al Driveshaft, Underdrive pulleys,
LT1 cam. 2400 stall Tq converter

Best Time: 15.279@89.02MPH
Underdog Racing

 

This should answer your question

Required fuel flow to support a given horse power:
lbs/hr = (HP × BSFC) ÷ (No. of Injectors × DC)
BSFC is .45 to .55 N/A... .55 - .65 with power adder, DC is % duty cycle


Fuel pressure effects on injector flow:
New Flow Rate = Rated Flow Rate x the square root of New Pressure / Rated Pressure

Do a search in yahoo for "fuel injector sizing" for more info.


------------------
1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Lunati roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

 

Hello bob , about your question. the reason I recomend starting with the stock injectors, is to keep away from having to change the fuel map on the computer in other words reprograming, another reason is that when you raise fuel pressure you get a better burn. basically a better spray pattern from the injectors thats a deffinate plus... baout your Q on going to a 65# inj. from the 55#er , well , only do it if you detect the car leaning out to much in the higher rpm band . you can get a cheap air/fuel ratio meter from cyberdine for about 30$s or the autometer for about 49$s .
know DAN W has the right idea, about with what he wrote. and simply if you raise the pressure in your 55# inj. then its not 55#s anymore, thay are all rated at the same pressure , I think around 8# of fuel pressure, so youll have to work with it . Its all about the tuning . thats how you save money. now if you have all the money in the world , well , then programing is the way to go but personally I dont so I teach my self how to make what I have work and you could do the same.. Take your time and be patient and youll do fine. Anyway if you put the 65# injectors on your 305 then Expect the car to run alot richer from the get go and of course youll be runing stock fuel pressure. so In my book thats another negative. If you use DAN Ws calculations youll see the injector size will be close in relation to 65# inj. @ 8#s of pressure, and 55# inj. @ 15#s of pressure. By the way do you have a 305 or 350? later

 

Badbrd, I still have my 305 but am upgrading to 350 shortly. So that why i was asking about the 65# injectors. Seems like its worth it to stay with the 55# injectors and see how it goes.
Danw, thanks for the calcs. I will check out the site. What is BSFC? ya lost me there. thanks......bob

------------------
91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

 

FYI, the Vette heads have 58cc combustion chambers, and came on 86& up L98 vettes. The 85 L98 vette heads, are cast iron not aluminum.

I had a set,..still kicking my self in the *** for selling them.

------------------
305 TBI
700-R4
L98 cam, 1 5/8 headers, 2 1/2 y-pipe, 4bbl edelbrock performer, holley adapter, open element K&N, afpr, flowmaster catback, MSD coil, accel wires cap & rotor, vette servos, shift kit, 2000 stall converter, TC lockup switch, all the free mods and some I left out.

 

Bob, BSFC is Brake Specific Fuel Consumption (how much fuel the engine uses per power, I believe - Dan, correct me?)

Rock, I have a set of L98 heads on the way for my CrossFire. ('90 Vette!) They are excellent heads and can be ported to flow better.

Also, I do believe that the '84 Corvette used #65 injectors.

Ken

 

Exactomundo Ken.
To elaborate just a bit more, its used when dyno testing... gives an indication of how efficant the engine makes power. Gas mileage for the dyno... fuel / hp instead of mile / gallon. The lower the number the less fuel its using. To get an engines exact fuel requirement, it has to be run on a dyno. This is not nessicary to select an injector because we know a range of how fuel efficant our motors are at WOT. We can take up the slack with fuel pressure changes and ECM calibration.

 

http://phobos.spaceports.com/~roguez/transam/heads.htm

Ken, the above link is amazing flow #'s on the set of 1990 vette heads that I sold. My buddy that I sold them too had them ported and polished by Nickens Racing here in Houston. Check it out, they are wild.

/me kicks self in *** one more time.

------------------
305 TBI
700-R4
L98 cam, 1 5/8 headers, 2 1/2 y-pipe, 4bbl edelbrock performer, holley adapter, open element K&N, afpr, flowmaster catback, MSD coil, accel wires cap & rotor, vette servos, shift kit, 2000 stall converter, TC lockup switch, all the free mods and some I left out.



[This message has been edited by Rock90rs (edited January 19, 2001).]