Rayzer999

Can anyone give me some REAL specifics on what I will need for this conversion?? I know that I will need a new PROM knock sensor, and larger injectors with a Ajustable FPR...can anyone offer more??

TPI Guy

You will need what is commonly referred to as a "New Engine". This "New Engine" will have a substantial amount of machine work performed to it. Not only will it need to be rebuilt, but the 350 block will need to be clearanced for a stroker crank. This crank will have to be purchased from an aftermarket vendor. You will also need to buy an externally balanced flywheel and harmonic balancer.

Your "New Engine" will also require "new heads". Your 305 heads won't flow enough to do a 383 justice. I'd reccomend Dart 200's. Not too expensive, excellent flow. Make sure the springs can handle the lift of the cam. Full roller rockers would look pretty trick. Try Harland Sharp's ... 1.5 ratio.

Of course to match your "new heads" you will need to take care of the intake system. SuperRam base, runners, and plenum. Whatever base you get, make sure it is drilled for both before and after 1986 bolt angles.

You will also need to pick a cam matched to the intake system. Why not the LPE 219/219?! John Lingenfelter like the SuperRam, and so does his cam.

Don't forget the new fuel requirements. Depending on how hyper the cam is, you may be alright with SVO #24 injectors. Let's assume that with your new engine, your fuel pump is able to keep up with your fuel requirements, otherwise you will also have to buy a new fuel pump.

A high powered coil won't do you wrong.

Then there are the ECM issues. You actually don't need to buy a new knock sensor unless you can find one calibrated to the knock frequency of a 383 (GM never made one). So that means you will need to get Diacom Software or some other such program that allows you to monitor engine performance. You will then have to force your engine to knock and reprogram a chip to detect knock at this new frequency. This means you will need to use chip burning software such as TunerCat and the Pocket Programmer. You will also need some sort of laptop to make it all come together. A craig-moates adapter would be a good idea.

Whatever you do, don't forget the adjustable fuel pressure regulator or the throttle body airfoil, or your car may implode.

Headers are a must for this car, as is a free-flowing exhaust. It is critical that you check the condition of your muffler bearings at this point. A broken muffler bearing will stop your car dead in it's tracks.

You will also need teflon paste, engine coolant, gasket sealant, and silicon sealant, some oil for the run-in.

Ed Maher

A few addendums to the above.

The LPE 219/219 is a tiny cam for a 383. Maybe if you're trying to build a tow truck it'd work OK.

And the frequency of knock varies with bore size, not engine size, so a 350 knock sensor is fine (or at least so goes all tests to date) Even if it wasn't, there is nothing you can do in the chip to fix it. The frequency a knock sensor is calibrated for is built into the KS, it's a solid state piezo-electric microphone. There is nothing you can do about that in the chip.

And lastly. When i'm doing an engine swap, i often find myself needing a "new beer", sometimes quite often. Usually helps if you pick up a "new woman" to hand you "new beers" while you invent "new swear words" while installing the "new engine". If you happen to have a buddy over during the swap, and he drinks the last beer, you might also be in the market for a "new friend", unless of course he brought his sister over to be your "new woman", in which case go ahead and get him drunk until he passes out, then you can invent some "new positions" with his sis....ahhhh, you get the picture, lol

tpi_roc

My 383 Isn't externally balanced

TPI Guy

Yes, you can have you "New Crank" internally balanced.

Can you explain how knock is a function of bore size. What causes the 305 to differ in the frequency it knocks relative to that of a 350. More Grey cast Iron dampening, different flame front propogation, what?

What signal does it send the ECM when it detects knock? Is it just on or off, or is it discerning. Also, does tunercat give you the ability to completely ignore the knock sensor, and if not, how are the 406 guys monitoring knock?

Rayzer999

Good stuff guys, thanks for the help.

I plan on an internal balanced crank since it could complicate things like starter mounting and all..

Headers are on the way...and BTW, the 305 will not be really used for much other than small things....the heads and all other componets will be sold!

Moreover, Im looking to purchase a long block..heads..my selection of a cam...etc.

As for the computer, anyone know the difficulty of burning...Im really not that into buying all kinds of software and hardware just to burn one PROM...that would be good, but would out sourcing for that be better?? More $$?

350 knock sensor is what I was told was alright...

Question: the stock intake manifold...too little for the large 383 StelathRam?? I know that I can reuse the wiring and fuel rails...

Thanks again and keep the help comming! also I agree with the beer...it's a must!

ViciousZ

iTrader: (1)

I could be wrong, but I was under the impression that the difference between a 305 and a 350 knock sensor was the actual sensativity of the sensor. The 305 sensor is more sensative, because it's farther from the cylinders. A 350 sensor is less sensative because the 350 has a bigger bore and therefore it is closer to the cylinders. Since the 383 has the same bore as the 350, I dont see why there'd be a problem using the 350 sensor.

Ed Maher

I'm not sure on all the finer technical aspects of the difference between a 305 and 350 knock sensor. I know the knock sensor itself is a solid state piezo-electric microphone, and as such it can/is designed top pick up certain frequencies better than others.
The knock signal itself is not a simple on/off signal, it's a full AC signal as the output of a microphone usually is. Thus, not only does the KS itself need to be tuned to the frequency of the knock signals it will see, but also the ESC circuitry also must 'know' what to expect on the KS signal line as for what is knock.
As to why knock varies with bore diameter, it just does. I've read this fact so many times over the years that i've never bothered to try to form my own reason for why, but it makes perfect sense to me that the frequency of the sound of a knock event bouncing off the walls would have to do with the surface area exposed as well as the curvature of the wall as it hits.

As to what 400 guys do, beats me. I guess they're all running the 'wrong' KS and ESC circuitry and getting by. Or simply not running a KS at all (which in itself isn't all bad, i've never had a working KS on any of my computer controlled cars, thats what my ears are for.)

As for tunercat, you can adjuts how the ECM reacts to knock events (things like how much knock retard you can have, how aggressibely it retards the timing, how aggressively it restores full timing, etc)

cort351w

:lala: :lala:

89 Iroc Z

If you are putting a 383 in you might want to consider beefing up the drive train. Stock rears are pretty weak unless you have a 9-bolt (which I managed to brake with a stock 350).