61 305 HP 348

[oldskydog]

From my notes. Tommy Nolen (real61ss) had the only documented 305 hp engine I;ve ever seen.

61 305 HP RPO 572

-RPO 575 Initially, until about Feb 61, the 305 was only available as the RPO 575 305 hp engine which had a solid lifter cam, 11:1 compression pistons and the smaller 379 heads. Suffix code GD and was only availble with the HD powerglide.

-RPO 572 The short block was the same as 250 and 380 hp engines. Suffix code GE for powerglide and FL for 4 spd.
Heads were 1147's (part #3785085) but without the stronger springs....used the same springs as the 379 heads.
HD Powerglide was the same as Corvette PG.....had welded torque converter housing instead of bolt together like regular PG. Other differences were nternal parts and governor.
Intake was cast iron and I believe the one on Tommys car was cast 3769937.
Book says carb should be AFB 3221S, but Tommy's car had a 3012S.
I believe air cleaner was single snorkel.
Distributor 110948
Coil 115083
Starter 1107891
Generator 1102173, optional 1102174, both 35 amp
-119235 V/R
--Gen pulley 3.62 "PD (pulley diameter?)
-Fan 18" diameter 5 bladed, staggered
-Not sure about balancer, but I would think it would be the same as 250 hp since the bottom end and pistons are the same.
_Pulleys I would think would be deep groove to match up with the high performance generator and pulley which is the same as 340 and 350hp.
-Standard rear axle ratio with PG was 3:55

This is all info I have derived from the documentation in the factory manuals, service bulletins, assembly manual and Tommy's car. It's the only real 305hp car I have seen.
Don't take all my word for it, do your own research as mine may well be wrong.

Cecil

 

[Floyd Horton]

I have an incomplete GE engine. Didn't realize how rare it was. Sold the intake to Tom Kochtanek.

 

[Floyd Horton]

Casting date on rear of block is H3160.

 

[Tom Kochtanek]

Floyd I suspect that 305 horse block might be a "GD" suffix?

I bet I still have that intake. Didn't it have a carb on it?

I bought a 305 horse 348 thru Paul Stensland many years ago. It was of the second variety (FL suffix) and had the 1147 heads and a 540 intake (which I think was incorrect). Never used it and sold it to John (JED) to use in a 30s hotrod build. I think he's selling that as a package? I recall it was a proper "1961" casting (late 1960).

 

[Black 1961 Convertib]

I am the newbie here. I know a little about 61 348's as I owned a brand new 61 convertible. It was delivered in July 1961 so it was real late. Regarding 305 hp engines: Having two 305 HP RPO's make sense. So.............It sounds like the second RPO, 572? had the 250 or 280 short block. Yet it had the bigger heads yet again with the 250/280 hp springs? Going from there, this RPO 572 had the bigger exhaust manifolds' and pipes?
With the bigger heads, do we know what intake was used? and of course, the AFB? Was it the 340HP intake or yet another design? Was this second generation 305, RPO 572, available with a three speed?

Bill H.

 

[oldskydog]

I am the newbie here. I know a little about 61 348's as I owned a brand new 61 convertible. It was delivered in July 1961 so it was real late. Regarding 305 hp engines: Having two 305 HP RPO's make sense. So.............It sounds like the second RPO, 572? had the 250 or 280 short block. Yet it had the bigger heads yet again with the 250/280 hp springs? Going from there, this RPO 572 had the bigger exhaust manifolds' and pipes?
With the bigger heads, do we know what intake was used? and of course, the AFB? Was it the 340HP intake or yet another design? Was this second generation 305, RPO 572, available with a three speed?

Bill H.

Intake casting number 3769937.
As stated above RPO 572 was available with 3 spd, 4 spd, or HD powerglide.
The intake ports on the 1147 heads were no bigger than the 379 heads but had bigger/better intake runners.

 

[Carmine]

Some good info here. Thanks. I was always amazed at how many different hp 348's were offered. Seems like not a whole lot separated them, Carmine.

 

[Black 1961 Convertib]

So.........................OLDSKYDOG!!!!!! 7-11-24

RPO 572 used head # 1147. Were the valves bigger? Was the larger exhaust manifold and pipes used or the standard ones?
Was the four-barrel intake different than the 250 HP. 348? And that the AFB was used with this combination. So I am clear, is this what RPO 572 was?

1. Basic 250 hp 348 short-block.
2. Different head. 1147. Not necessity bigger valves? and Springs?
3. Perhaps the standard exhaust manifolds and pipes?
4. Different 4-barrel intake that the 250hp engine?
5. AFB Carb.

Thaanks.

Bill H.

 

[Floyd Horton]

Definitely GE Tom.

 

[Floyd Horton]

Engine has 1147 heads.

 

[JED]

Floyd I suspect that 305 horse block might be a "GD" suffix?

I bet I still have that intake. Didn't it have a carb on it?

I bought a 305 horse 348 thru Paul Stensland many years ago. It was of the second variety (FL suffix) and had the 1147 heads and a 540 intake (which I think was incorrect). Never used it and sold it to John (JED) to use in a 30s hotrod build. I think he's selling that as a package? I recall it was a proper "1961" casting (late 1960).

I do still have the engine, although I took it all apart to "mic" everything. The engine block is an "FL" suffix block, casting number 3755011 & date code B2661. The heads are casting number 3781147 with date codes B1661 and additional markings as "GM3" and "GM4". It also has an intake with casting number 3769957, and date code B2260.

The bare block, heads & intake are currently mocked up in my '33 Ford Roadster project, which is for sale with or without the engine. I would still like to put it in one of my hot rods, so that's why the car is offered with or without the 348 & the 700R4, both of which need to be rebuilt.

 

[oldskydog]

So.........................OLDSKYDOG!!!!!! 7-11-24

RPO 572 used head # 1147. Were the valves bigger? Was the larger exhaust manifold and pipes used or the standard ones?
Was the four-barrel intake different than the 250 HP. 348? And that the AFB was used with this combination. So I am clear, is this what RPO 572 was?

1. Basic 250 hp 348 short-block. YES, same pistons, cam
2. Different head. 1147. Not necessity bigger valves? and Springs? 1147 heads had 2.06 intake valves
3. Perhaps the standard exhaust manifolds and pipes? 2.5"exhust manifolds
4. Different 4-barrel intake that the 250hp engine? Yes, the AFB required a different intake to mount the carb.
5. AFB Carb. YES

Thaanks.

Bill H.