305C-305E Difference?
 

I am a new owner of a 64 1000 with a 305E,I am looking for a spare engine to keep for parts,I have a chance to buy a 305C but I am not sure of the differences between the 2 engines,does anyone know what the difference is between the 2 engines?Thanks

Re: 305C-305E Difference?
 

305C = 840 lbs dry weight 250 ft pounds of torque, takes 8 qts of oil
305E = 795 lbs dry weight 260 ft pounds of torque, takes 5 qts of oil

That is the main difference I have in my notes on the two. The club's information page for engines is here:

http://6066gmcguy.org/EngineData.htm

Re: 305C-305E Difference?
 

The biggest difference between the 305C vs 305E engine is the 305C has 4 ring pistons rather than 3 ring pistons, it will have the higher mount water pump/ timing cover housing for medium duty applications and valve rotators (which were also equipped in the optional HD305E)other than that it's really the same engine and will be good for parts. Pete Chronis Northern Cal.

Re: 305C-305E Difference?
 

Also forgot to mention the extra oil capacity of the 305C was due to a larger oil pan and canniter style filter, still not a problem to transfer the 305E oil pan and filter assembly. Pete Chronis Northern Cal.

Re: 305C-305E Difference?
 

Thanks for the quick response,I saw the weight difference and TQ,hp numbers but didn't know why.Valve rotators?what are they?I guess the early v6 had 4 ring pistons,wonder why they switched to a 3 ring

Re: 305C-305E Difference?
 

Valve rotators were used to keep valve seats clean, they're mounted on the bottom of each valve spring. Used in bigger truck applications, though in later years an HD305E was offered with this feature. 4 ring pistons were used on all 305C engines from 1960-74, again this was a big truck feature that had one extra compression ring, it also phased out the 3 ring pistons in 305E engines for replacement for the purpose of standardization around 1970-71. Pete Chronis Northern Cal.

Re: 305C-305E Difference?
 

my 305 A had 3 compression and 1 oiler ring, most people are surprised when I show them an old pistion.

Re: 305C-305E Difference?
 

All 305A,D and E engines all came with 3 ring pistons, while 305B & C came with 4 ring pistons

Re: 305C-305E Difference?
 

Thanks guys,I'm trying to get familiar with these engines,up until 2 weeks ago I had never seen or heard of them.

Re: 305C-305E Difference?
 

How do you determine the "abc's" of the engines?