hey there!
I have an 89RS/305TBI/auto. Its already equipped with headers and manifold, and cam(non-roller), [all from Edelbrock], Holley TBI, Flowmaster exhaust with intermidiate pipe replaced, ADS chip, 160 thermo, fuzzy dice and other stuff but is not related to the swap.
I would like to swap in a 383 and try and use TBI. The longblock will be a pre 87. I going to switch to a bigger TBI (I have a 454 unit w/68#'s), get a custom chip, and go with a Crane Compucam 2040 or 50. An external 400 damper and Flexplate is also needed. I will also go with Holley's 2" TBI manifold. And i obviously have to get new valvecovers and oilpan/pickup/pump(HV). I'm not sure what else is needed for the swap. So here are some questions

1) What knock sensor do I need?
2) Do I need to replace my fuel pump?
3) Who is a respectable chip burner in Los Angeles/San Diego area?
4) Will my cooling system handle this?
5) For those that have done this already: Does it run efficiently with a TBI?
6) Is there a how-to on this board about the swap. (couldn't find one)
7) Did i forget something?

Thanx for you're help in advance.
BTW in regards to the chip...I'm not ready to do it myself. I want to see how the car runs before i go studying this stuff.

 

get a carb manifold, with an adapter, not holleys 2" tbi intake.

cant help much besides that.

 

In terms of doing the physical drop in swap, everything should bolt right in, because a 305 and a 383 are externally identical. I can't really coment on the knock sensor, but 68# injectors are a nice jump over stock and I would probably update the fuel pump incase you wanted to run NOS or boost later on. In terms of your cooling system, it's hard to guess. If your headers are coated, you run a low compression ratio and have a decent fan/radiator you should be fine. If your cooling system isn't performing, try a lower temp stat and "water wetter." Hope this helps, Tony

 

I am curious at to what a 454 TBI cfm rating is?
Won't he need something like 750cfm of 850cfm to flow that modified 383???

[This message has been edited by 91Bird305 (edited February 07, 2001).]

 

I was checking out some truck posting forum and read some threads... its looks like the TBI is still on the small side (even the injectors) for the engine. But there is no way i can go carb since i live in Cali. Hopefully it wont be too much of a restriction.
About the manifold....Will the hood still shut close or will the setup sit too high with that intake?

Thanks for the help guys.

 

Well I wouldn't use the 454 TB or the 670cfm TB on that 383. It needs something with more cfm. If you want to stay with TBI check Holley's website for higher cfm TB units. I think they have some.

 

I think the 454 TBI unit is 670cfm as well. That shouldn't be too restrictive with a 383 depending on the level on modifications. As we all know TBI takes more tuning than carb, that is the down side.

------------------
1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
*****Possible summer '01 mods*****
Open Element, Auburn Posi, Keyless Entry, wonder Bar off the IROC, 4th gen seats, T/A tail lights

1985 Camaro IROC-Z LB9 Auto
http://www.geocities.com/krt80/

 

go here and play around with some formulas.

http://www.prestage.com/carmath/calc_CarbSize.asp

 

Whats your plans on how you will be using your engine, in other words what rpm range do you want to run. If this is to be a mostly street driven car then I personaly would keep the rpm under 5500 and build the engine for what their best known for, torque. In this configuration I think the 670cfm would be adequate. I just did a quick check on a dyno program and 670cfm seems to be good to about 375hp and 425tq mabe more. Keep the rpms down below the stratusphere and you should be fine, and keep your foot out of the gas so you won't be buying tires every month. Just my opinion.

Steve

 

steve8586iroc - you pretty much got my operating range down... 5500MAX. The car will be a daily driver... thats why the cam isn't very wild. So just keep it below 5500 and the 670 will feed it?? gotcha. Thanks for the help.

Anybody have any comments on the other questions...Knock sensor...chip burner..etc.

 

1. Since a 383 uses a 350 block I would get the TBI 350 Knock sensor and ESC module.

2. You might. Especially if you have to raise the fuel pressure. If it has high miles on it, I would just replace the pump. The Walbro can be purchased from APE for a good price. http://members.home.com/syclone/APE/fuelpump.html

3. Might look up Intech, he's on the boards.

 

I just checked and the 350 knock sensor is what you need. As far as chip burning, it's almost a must with a 383, you're nearly 50 more cubes over the 305. The cool part is that you are keeping everything for emissions and so you won't have to disable anything like EGR and the spark chart should be fine, I don't think the engine will knock as long as you have a mild intake lobe and keep the EGR. So in reality you could just put on a 670cfm holley with the larger injectors and the stock chip should operate fine. I'd post in the EPROM board if you want to be extra sure. I also second the boasting fuel pressure, tune it. Drive around and keep a table for mpg and figure the best setting. Good luck with Cali emissions, I'm on the other side with NJ tests, boy do they SUCK. Just my opinion but I don't give any respect to people that are running no cat on a daily driver, the hp they gain isn't as good as they think and it's just messing up the air for no good reason. Also the AIR system helps the cat and doesn't steal as much hp as most think. I wish I could get some dyno numbers to prove it, oh well. To each his own.

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, Jon (91 RS too many mods to list), getting new engine in summer