I noticed in some archived posts that Pablo and Fast Broker said a bone stock GM throttle body is sufficient for up to 300 horses. This set my mind at a little more ease. I've been having extreme difficulty with my TPI swap and decided to weigh my options. I've decided to stick with TBI, but I need some questions answered before I begin buying. First of all, here are my cam specs:

GRIND NUMBER: CS 264HR12
ENGINE: CHEVY SM BLK 305-350
INTAKE EXHAUST
VALVE ADJUSTMENT HYD HYD
GROSS VALVE LIFT .480 .480
.006 TAPPET LIFT 264 274
VALVE TIMING OPEN CLOSE
AT .050 INT 3-BTDC 33 ABDC
EXH 46 BBDC 6-ATDC
THESE SPECS ARE FOR CAM INSTALLED
AT 108 INTAKE CENTER LINE
INTAKE EXHAUST
DURATION AT .050 210 220
LOBE LIFT .3200 .3200
LOBE SEPARATION 112

This is a compcam by the way (Sorry it didn't paste very well). My engine is a fully balanced 350 engine, w/ a forged crank and pistons, basically stock heads w/ 2.02/ 1.60 valves. I will also be running headers, and most likely either a dual exhaust, or a cat-back. I'm really not sure what i'm getting into and feel lost at this point. Here are the questions I have:

1) Is the stock TBI unit sufficient?
2) What size injectors should I use?
3) What fuel pressure should I run?
4) Most importantly, who should I got to to get a PROM burned?

Thank you very much for any help you can give me. I'm sorry this is so long, but I'm anxious to get my 91 ragtop running again. She's been in the garage for almost 6 months!

 

I guess I'm the frist to take a stab at this. It's true that the stock TB can make 300hp. I went with the holley unit because I'm going to doing stuff to the engine this summer. I have lots of options now with the 350 that I didn't have with the 305. You have a forged bottom end so I'm hope you plan on using a power adder in the future. When you do go with a power adder you'll probably want the 2" bore. You should use 65 or larger injectors or 55 GM injectors with a high volume fuel pump and increase FP. There are some calculations that can give you a good idea of what kind of fuel pressure you're going to need for a 350 ___hp w/6000rpm redline. With that said I'd go with 65 injectors and run them at say 13 and watch the injectors and run the car to WOT and turn off engine, coast to side of road, pull the plugs and look at them. If they're white then your fuel pump isn't providing enough to support that kind of hp.
Program your own chip . That's what I'm getting into. I'm going to order the programmer this week. I still have a lot of reading to do but I have a good gist on things. There is always www.fastchip.com, they'll charge you $350 for a custom chip but they won't leave you hanging. I've heard nothing but good things about them. I just figure that for $200, I'll have the ability to change things around. If you don't plan on doing anything to the engine then give them a call. If you plan on doing bolt ons later on like a cam swap or roller cam, different intake, larger TB, etc then think about programming your own chips.
You sound just like me, 6 months and my car was sitting in a barn. Spring break came around and I did the engine swap, HUGE difference. I'm not saying my 305 was bad but this engine makes you feel like you went from a 4 banger to a miata with a big block.
Good luck with the swap and give us some more details. I'd like to know if you're going with a roller rockers, what intake, what heads exactly (L98?), any porting?, valve job?, what are your rear gears posi..trans...give us the good stuff.

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, Jon (350 TBI! getting 23mpg highway)
91 Red RS w/grey int, sq stereo (Alpine v12, kicker solo, MB quart premium etc)AIM: JPrevost

• Holley 670 TB unit w/ 1/2" spacer/adapter
• Edelbrock RPM vortec intake
• 350ho 330hp vortec crate motor
• 8" harm. balancer
• Stewart stage 2 water pump w/160 thermo
• SLP tri-y headers to full 3"
• Rebuilt trans w/ SLP shift kit
• Centerline 16x8's all around
• 36/24 mm sway bars
• Full poly bushings, even motor mounts
• SLP LCA and panhard
• Alston SFCs
• Edelbrock 3 point STB
• Global west steering brace aka wonderbar
• Eibach pro kit springs
• Bilstien high perf. struts and shocks
• All this and I still have AC

My websiteAny questions?

 

The TBI unit itself is sufficient enough, its the same unit that is in the 350 pickup trucks, the only difference are the injectors. I would recommend 65# injectors and you can get them from the dealer or from the junkyard (I forgot what the color codes are, but they are archived somewhere. Pablo--This should be a tech article by the way).
About the fuel pressure, I don't see why you can't leave it stock, I did and I haven't noticed any problems with it. And about getting the prom burned, thats another thing that I can't help you out with. I'm actually still trying to get my own burner so I can make my own chips.

Everything else is a simple bolt up, so that isn't too bad, but since you are keeping the computer remember that you need a 350 knock sensor and a 350 Electronic Spark Control Module...

Good luck,
Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch.

 

Hey JP, who are you getting the computer programming stuff from? what are they charging you?

thanks, Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch.

 

Wow! Thanks guys for the help. I'm just going to go with a straight Edelbrock TBI manifold for now, since I'm sticking with the stock Throttle Body. I want some serious low-end. Tranny is just the stock 700R4 with stock converter (I know, I know, I'm saving up for a rebuild to include a new converter). My rearend is, well, I'm not sure. It's whatever the stock rear came with the 91RS convertible 700R4.

I never thought about the ESC. What is that exactly? Is that like the ignition box? Where is it?

Already got new knock sensor. I'm going to use the fuel pump left over from the failed TPI swap, so pressure won't be a problem (or will it? As in too much?), since I plan on modding my regulator (great tech article on the AFPR by the way). Heads are in my future, so is a power adder, way, way, in the future, but not until I pay off the credit card bills from this current project . Thanks again guys. You TBI'ers never let me down. Keep the advice coming!

 

Actually, the Edelbrock tbi intake is not as good as the stock GM piece. The stock GM piece will also take a 2" bore (don't try for 2 1/8" however). If you need a bigger
throttle body, the early style 454 throttle body will line up and bolt on to the 350 manifold perfectly.

 

I don't think that you should experience any problems using the TPI pump. The regulator should restrict the flow either way (I could be wrong, but it seems logical)

The ESC is the Electronic Spark Control Unit. You might also hear people call it the Knock Module. Its located on the drivers side firewall between the brake booster and the wheel well. Here is what my little blue book says about the ESC, "It sends a voltage signal to the ECM. As the knock sensor detects engine knock, the voltage from the ESC module to ECM is shut off and this signals the ECM to retard the timing, if engine rpm is above 900. So its that dealy (technical term ) is what messes up your timing if your trying to adjust it without unplugging the wire by the heater housing....

later,
Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch, 3 angle valve job.

 

when i put my crate engine in last year i had the stock throttle ody on at first, tehn i switched to the holley after i got everything running right. low end i didnt feel that much of a difference, but DAMN dos the bigger throttle body work better in the upper rpms.

-brian

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1991 Camaro RS - ultra blue metallic, t-tops
GMPP 350 HO crate engine - 454 TBI, MSD ignition, SLP exhaust, everything is new
700R4 - 2,400 stall converter, vette servo, shift kit
10 bolt - SLP zexel torsen differential, GM 3.42s
z28boy.fbody.com
z28boy@twcny.rr.com
AIM - "Z28 Boy"

1998 Pontiac Grand Prix GT - 2 door, black

 

The TPI fuel pump should be okay for about 300hp from what I've been told.
Burntblues, I just ordered all my equipment today. www.tunercat.com for the software and definition file. I'm going to be using the pocket programmer from http://www.xtronics.com/memory/EPROM.htm
I got the DataRase II EPROM eraser PN: ER2-ND for $40 from http://www.digikey.com/. Then I just went ahead and bought 3 "EPROM(2732A-2F1)4KX8 21VPPG 24CERDIP" from <a href="http://www.jdr.com/interact/item.asp?itemno=gr-epromcircuits">2732A EPROMS</a>. You can find pull outs for like $2 a pop but I don't know exactly. When I do get all the stuff I'll put it up on my website. It'll be TBI specific so you don't have to go through the whole long tech article figuring what you need to get started.
About the ESC, I haven't changed mine for a 350 specific and I haven't had a problem with it yet. I'm almost positive you don't have to change it, just the knock sensor.
Russ-So Cal, I'm confused with your post. You say the edelbrock tbi intake isn't as good as the stock piece. I don't think you ment to day that. The edelbrock piece is better but it can't use a 2" bore TB so you're limited. It is true that the stock intake can be bored out to 2" but I don't think it'll be much better than an edelbrock performer piece. My advice is to just get a carb intake and an adaptor plate. Check for hood clearance first if you go for something other than the performer. Let my problem be an example of poor planning. Even though I don't give a %$^& that the RPM is tall, some might. It's an excuse to get a cowl hood .
I'm also confused about the early style 454 TB bolting onto a 350 manifold. Won't the TBs still hit since the intake bore is for a 1 11/16" bore TB!!??!?!
One thing that I'd like to stress about low end grunt. I just did a bunch of reading about engine build ups and even the wild horsepower setups had great low end because of all the new technology. The only time you want low end grunt is if you ***** foot it ALL the time OR you have a heavy truck and tow. A car like ours chould go for horsepower. The torque follows very nicely until you get really crazy like huge roller cam setups and 800+cfm intakes w/tunnel ram setups. I used to think the same way about torque being the best thing for a street car until I saw some of the builds. They were making 490hp with a CHEVY 350 with roller cam, single plane intake, pump gas, and AFR heads. The torque was still great for the street which was suprising. The Chevy 350 torque setups made the best torque in the normal operating range and it wasn't much of a difference between the horsepower setup. If you don't already have a subscription to Hot Rod mag and Chevy High Performance...GET ONE.
I hope to have a roller cam setup with roller rockers and be making just over 400hp by this summer. I have to do some more research but I think it's possible with the vortec heads and today's technology. The trick will be to get a streetable idle with the TBI setup .

------------------
, Jon (350 TBI! getting 23mpg highway)
91 Red RS w/grey int, sq stereo (Alpine v12, kicker solo, MB quart premium etc)AIM: JPrevost

• Holley 670 TB unit w/ 1/2" spacer/adapter
• Edelbrock RPM vortec intake
• 350ho 330hp vortec crate motor
• 8" harm. balancer
• Stewart stage 2 water pump w/160 thermo
• SLP tri-y headers to full 3"
• Rebuilt trans w/ SLP shift kit
• Centerline 16x8's all around
• 36/24 mm sway bars
• Full poly bushings, even motor mounts
• SLP LCA and panhard
• Alston SFCs
• Edelbrock 3 point STB
• Global west steering brace aka wonderbar
• Eibach pro kit springs
• Bilstien high perf. struts and shocks
• All this and I still have AC

My websiteAny questions?

 

I'm running the 255l/hr Walbro with my stock TBI setup and have had no problems with it.


Steve

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Steve's Trans Am Temple

 

JP,

I'm trying for 400hp with my Vortec heads, ported a bit, Hot Cam kit (cam, 1.6 roller rockers, springs, etc) RPM Air Gap intake and the 2" Rochester TBI (80pph), if/when I get the time to buy one...

Should happen... engine dyno tesing in Summer/Fall??? Still have not got my engine back in my Jeep, yet. Little worried about the fuel distribution in the rear, but I'll find a way to make it work...

I ran the Hot Cam for a bit and found that the engine would not idle at stoich. I need to fool the ECU into running OpenLoop at idle only, to get around this. Or, raise idle to 850+rpm or so... Not.

EDIT: Actually, I may just buy some Fast Burns and be done with the head work. Plus, I KNOW that you can get 400+hp on Fast Burns with the Hot cam, with a carb, anyway. Been there, done that.

[This message has been edited by FastBroker (edited April 17, 2001).]

 

Hmmm... I'm getting mixed reactions about the ESC. I might get a new one just to be safe. How are you guys running the throttle linkage to your TBI with the adaptor plate and where did you get the plate. I'm going to run the stock TBI unit, performer, and adaptor, if I can figure out linkage. I also plan on using caprice cop injectors and chip (until I can burn my own). Will this work? What PSI should I use? Are my stock rocker arms ok for now?

thanks

 

I've tripped my SES light a few times, and thats either because I haven't changed the knock sensor or the ESC. If JP changed the knock sensor and hasn't had problems with it, then I would say just spend the money on the new knock sensor and leave it at that. I don't think that you're going to damage anything. I was told to change this stuff by a magazine, so they may have been doing a few safety precautions with the ESC module...

JP, thanks for the help on the chip, email me when you get your site up, I'll put off ordering the stuff until you get the site up so I can learn some more about it first. Could you email me with the address when you get it worked out.

I just read an article about putting on carbs that are too big and how you can actually loose power. They said that the thing to do is use smaller bores and match the jets. In your case, a TBI unit is pretty much the same as a carb, I would say use the 305 TBI sense it is pretty much the same and then just make sure that your injectors match.

Good luck, Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch, 3 angle valve job.