Carbureted 305 to 350 with swap with knock sensor

[Savageftr]

Hi there, looking for an engine guy that might have some experience with this.

I just swapped out my stock 1986 305 for a 300hp ish 350.

Engine is:

74 block .030 over
Sealed power .125 domed pistons
882 heads ported to match edlebrock performer intake
Melling 22200 cam "327 - 350hp" copy
Headers with super 44s

I used the stock HEI distributor with the 5 pin Ignition control module and knock sensor.

It's my understanding that that knock sensor can retard the timing up tp 10 degrees if it senses detonation also unplugging it will default to "normal" timing.


1. Should I disconnect the 305 knock sensor? will it register "knock" from my high compression 350 (9.5+) and retard my timing? or replace it with a 350 knock sensor (rock auto lists a different sensor for a 350)

2. Should I replace my ignition control module with a performance one?


thanks any advice or lived experience on this would be helpful.

Engine seems to run good but I don't want to leave any horsepower on the table for nothing.

 

[BillK]

I did the same basic swap in my 85 K-5 Blazer years ago. The engine I built was a later model hydraulic roller cam with about 9.5 to 1 compression. I used everything of the 305 including the carb and I never felt it was not running properly. Had all the power I needed or wanted. I put at least 50K miles on it after the swap including a fair amount of towing.

 

[Savageftr]

I did the same basic swap in my 85 K-5 Blazer years ago. The engine I built was a later model hydraulic roller cam with about 9.5 to 1 compression. I used everything of the 305 including the carb and I never felt it was not running properly. Had all the power I needed or wanted. I put at least 50K miles on it after the swap including a fair amount of towing.

Thanks good to know.

I see people (on you tube) talking about deleting the knock sensor circuit going to the ICM or swapping for a 4 pin ICM but I think if I have a working knock sensor I should be able to run at optimum advance and not have to worry about detonation issues. It's just hard to know what it's doing.

I might advance the timing a bit more and see how it runs. I need to get it all tuned up before camping season so I can have trouble free vacation hopefully.

So far power isn't an issue...will smoke the tires off.