hi,

this winter I will swap from a 305 to a 350. a lot of people say, that I will need another esc from a 350.

so, why is that so. what exactly is the esc doing, and what are the differences between a 305 and a 350 esc??
greetings

S!MON

 

I can't speak to the details of how it works but I can tell you that you don't need to change a thing. I've swapped out original 305s for 350s and 400s. Also, original 350s for 383s and 400s. I reused the original knock sensor and ESC module in every instance. Never a problem and the system still functioned just fine.

 

shouldn't have a problem at all

 

SO I don't have to change the knock sensor or the esc? I am going from a 305 to a 383, I was under the impression I would have to change both... so what's the deal?

 

Lotsa chatter about stuff like that on the internet. However, I was doing engine swaps on these cars before there was such a thing as an internet (well before it got popular in the private commercial sector, anyway) and it never occurred to me to change out the KS or ESC for different units, so I never did. And I never had a problem becuase of it. And the sensor continued to function, as near as I can tell from Diacom scans.

Now, in the last few years there are all kinds of posts about changing out the sensor and such. GM even recommended it for some of it's swap kits they used to sell to put a ZZ-4 in place of an old carbureted 305. I'm doubt GM would recommend something that wasn't necessary, but they are the mother ship and they have engineering resources that people like you and me don't. And the sensor/ESC they recommended were designed to work together and only with the ZZ-4 engine. See where I'm going with this?

Why don't you try this..... Put in the new engine with the original KS and ESC for starters, save your money for now. See how it works. If you start having problems with the knock sensor or the ESC THEN go get the replacements and try them out. They are parts that are easy to change even with the engine in the car.

 

If you have TBI you will need a 350 knock sensor. Your car will not work right. The ESC is not entirely necessary. The knock readouts that the ECM uses will not be the same with the larger displacement. I am unfamilair with any other type of knock sensor compatabilty but for TBI you will need the 350.

 

Shiftycapone,
I have a 350 TBI and it is throwing the esc code, so what exactly do you suggest? You were to vauge for me. So I need to buy a 350 ks to replace my 305 ks? The esc is good though? I tested both and tested fine. Any advice?

 

You need a 350 knock sensor or the ECM will not read the right knock counts. You can get away with a 305 ECS module but most go with a 350 module. You can get both at any parts store.

 

Thank you very much, I will have to do a parts run tommorow. Ill reply back and let you know how its going. Thanks!

 

On a 90-92 car, the ESC is built into the prom module. The main reason most folks change the 305 for a 350 version is for the LIMP HOME mode in case the prom goes bad. A 305 Limp Home would probably run your 350 (very poorly!), but maybe not. When I went from my 305 to the 383 I got the 350 module even though I'm doing my own proms. Just in case.... (I also carry a spare tuned prom)