Distributor Swap

[Ricko1966]

The aftermarket ones usually limit centrifugal to 18degrees that comes in quicker so now you have to bump initial to get the same total.And yes that's going to be quicker off the light, and probably just fine for something that does not see much heavy work. I wouldn't recommend it on a 305 with ESC becausev they need a lazier curve the are ping monsters. They upped the compression which is why they went to ESC .

And yes they also changed the vacuum advance amount so they could run retarded at idle for better emissions.

 

[bucket]

The aftermarket ones usually limit centrifugal to 18degrees that comes in quicker so now you have to bump initial to get the same total.And yes that's going to be quicker off the light, and probably just fine for something that does not see much heavy work. I wouldn't recommend it on a 305 with ESC becausev they need a lazier curve the are ping monsters. They upped the compression which is why they went to ESC .

And yes they also changed the vacuum advance amount so they could run retarded at idle for better emissions.

I only remember installing one on a truck 305. It was my '84. The Street Fire went in when the factory esc dizzy started having major troubles. Base timing was set at 10*, I never had any pinging issues. That's not to say someone else may have different results though.

Edit
Oh, and on the gutless 305 in my old K2500 Suburban. But that one was a '79 engine, so may be apples/oranges.

 

[Ricko1966]

I only remember installing one on a truck 305. It was my '84. The Street Fire went in when the factory esc dizzy started having major troubles. Base timing was set at 10*, I never had any pinging issues. That's not to say someone else may have different results though.

Edit
Oh, and on the gutless 305 in my old K2500 Suburban. But that one was a '79 engine, so may be apples/oranges.

I'm betting the streetfire has 18 centrifugal and should have 18 initial to have proper total. You couldn't have run 18 initial on a high compression 305 or it would have pinged like crazy.

Well I guess streetfire is a fitting name I looked on the internet got 2 different hits but 1 says 21 degrees the other says 22 degrees, so the streetfire is real similiar to stock in that regard. That is great still should have 14 degrees initial but still a way better distributor than the 18 degree go fast distributors.

 

[bucket]

I don't know if I would consider an 8.5:1 engine as "high compression".

Anyway, I ran that gutless 305 in the '84 as hard as I could on a regular basis. Hot weather too. It never pinged and I never could blow it up. I eventually gave up and swapped the engine out.

 

[Ricko1966]

305 4bbl truck is 9.5 isn't it. Mine pinged like he'll when I swapped a junkyard HEI dizzy in because my esc box went bad. Researched and found lots of people with the same issue,trying to recurve gm HEI to work right in their trucks. I ended up swapping my esc distributor weights springs and vacuum can into the junkyard dizzy and its done pretty good. I do have a d1940 module I'm going to put in so I can raise my initial a little more.

 

[Ricko1966]

There's going to be a pic of a cat head with a piece of bread around it soon, if we keep going.Who had that pic?

 

[bucket]

I don't think any of the carbed 305's were over 8.5:1? In any of the trucks or cars? I'll have to go digging to check.

 

[Ricko1966]

You must be registered for see images attach

 

[bucket]

You must be registered for see images attach

Sure that's not a typo or misinformation? A basic low output 305 with more compression than the L69?

 

[Ricko1966]

I believe it's correct. Why would they go knock sensor and ESC if they didn't raise compression.

 

[Turbo4whl]

305 4bbl truck is 9.5 isn't it.

Yes, 9.5:1

I don't think any of the carbed 305's were over 8.5:1? In any of the trucks or cars? I'll have to go digging to check.

Here it is, LG4. Bought in my 1982


LG4
The LG4 produced 150–170 hp (112–127 kW) and 240–250 lb⋅ft (325–339 N⋅m). Introduced in 1978, the LG4 was essentially an LG3 with the addition of a 4-bbl carburetor and larger valves. The engine saw a series of gradual improvements, increasing reliability, mpg, and power output through its production run. In 1981 (1980 for California models) Chevrolet added GM's new "Computer Command Control" (CCC) engine management system to the LG4 engines (except Canadian models). The CCC system included the electronic Rochester 4-bbl E4ME Quadra-Jet, with computer-adjusted fuel metering on the primary venturis and a throttle position sensor allowing the CCC to calculate engine load. In the ignition system, CCC was fully responsible for the timing curve; mechanical and vacuum advances were eliminated from the distributor. The more precise spark timing provided by the CCC made possible a series of increases in compression ratio from a pre-CCC 8.4:1, to 8.6:1, to a knock-sensor-assisted 9.5:1, all while still only requiring 87 AKI regular unleaded fuel.

-From Wikipedia

Cars got the CCC system first. ESC was in trucks '81 and the fuel management CCC, was a couple years later for trucks.

Link: (halfway down the page)

https://en.wikipedia.org/wiki/Chevrolet_small-block_engine

 

[bucket]

Wow. I'm very familiar with the old LG4, somehow I never realized the compression was that high. Guess I just didn't care, lol.