1961 305A vs 305D what is the difference?
 

So unless I am wrong, the later version of the 305A that came in some 1/2 ton 1961 GMC's had the same WW 2bbl carb as the optional 305D offered in 1961. The 1960 version of the 305A had the Holly 1904 carb so we all know that, but what is different between the later 305A w/ WW 2bbl vs the 305D w/ same carb?

Need to know because it doesn't appear any of you have a good running 305D to sell and I do have a good running later 305A w/ same WW 2 bbl on it as the D, so maybe its the same **** thing?

Re: 1961 305A vs 305D what is the difference?
 

I was not aware that there were 305A's with a two barrel. I thought the 305D was just the upgrade to the two barrel and all else was the same.

Anyway I found this in the Archives so maybe Lewis will chime in.

from the Archives by Lewis Matkin.

"LEWIS ELLIS MATKIN JR" wrote: > > These are the differences with the 305 engines. > 305A: 1bbl carburation 1904 series Holley, series 1000-3000 1960-61
> 305B: 1bbl carburation Zenith-Stromburg, series 3500-4000 1960-61
> both of these are gross 150 hp engines. > 305C: 2 bbl carburation WW Stromburg, series 3500-6500 1960-1974
> 305D: 2 bbl carburation WW Stromburg, series 1000-3000 1961-63
> both of these are gross 170 hp engines. All of the engines above are 4
ring piston engines. > 305E: 2bbl carburation WW Stromburg, series 1000-2500 1963-69
> this engine is 170 hp gross, and is equipped with 3 ring pistons.

Re: 1961 305A vs 305D what is the difference?
 

those listings from the archives are correct.

Re: 1961 305A vs 305D what is the difference?
 

I bought what appeared to be an untouched 61 GMC K1000 suburban and it had the A motor with 2bbl. Was a late 61 truck based on production number so thinking somewhere mid-year the A's might have got upfitted. Don't know

Re: 1961 305A vs 305D what is the difference?
 

Many of the "A" engines were changed over to the "D" configuration for various reasons, some for drivability issues, some for power, some for fuel mileage, and others simply because the owners wanted a larger carb.

Re: 1961 305A vs 305D what is the difference?
 

What’s the date stamped on the intake manifold?

Re: 1961 305A vs 305D what is the difference?
 

probably what happened to that 61 K1000 burb I wish I had back. No way to know now and didnt think to check the intake date code.

Re: 1961 305A vs 305D what is the difference?
 

When I had had my '60 3/4T step-side with a 305A for about five years in 1975, I met a guy with a the same setup in a fleet-side.
I had a one barrel and he had a two and it always ticked me off that I got 10 MPG and he got 15+.
On the bright side, mine still runs fine and regularly and his was junked 35 years ago.