305/350 crank

Lyn Smith · 12-30-2013, 08:03 PM

Got a street 305 Chevy im rebuilding.It had a bad crank,so I came across a 350 crank which is the same stroke.Can I use the 350 crank ,or will it have a balance problem?Dont really want to spend the money to balance it. thanks

BillK · 12-30-2013, 08:33 PM

Lyn,
The 350 and 305 cranks that I have done have been quite a bit different in balance. If you are replacing pistons it seems like they are making even the stock replacement pistons a lot lighter so that will make the problem even worse.

I would say it would be worth having it at least checked. You probably don't have to do the entire balance job, making all of the rods and pistons the same weight etc. Just use one of the 305 assemblies as a reference to make the bobweight.

Hope this helps,

Rob Petrie E395 · 12-30-2013, 08:51 PM

I cant say for sure what a 350 crank in a 305 will do. But I know for a fact that a 305 crank in a 350 will vibrate at around 2500-3000 RPM. Bad enough that you will take it back apart.

Steve Williams · 12-30-2013, 09:23 PM

The 305 crank with 350 rod-piston is a problem. The 350 crank with a 305 rod-piston is not a problem. No balancing required for a stock piston or cast replacement. The 305 crank is the nastiest piece of junk that is associated with Small Blocks IMHO.

Tim H · 12-30-2013, 10:02 PM

Quote:

Originally Posted by Steve Williams

The 305 crank with 350 rod-piston is a problem. The 350 crank with a 305 rod-piston is not a problem. No balancing required for a stock piston or cast replacement. The 305 crank is the nastiest piece of junk that is associated with Small Blocks IMHO.

Dont forget the 262 and 267 ci motors as candidate for piece of junk award

Rich Biebel · 12-30-2013, 10:26 PM

305-350 cast cranks were the same casting number and the only difference was the factory balancing. If I recall correct the casting number was 448...last 3 and if you look at the depth of the holes on cranks from a 305 vs a 350 you wll see a big difference in hole depth....the 305 bobweight was lighter so the crank had deeper balance holes drilled.

You could use either crank in either engine but needed to address the balance issue......

There is no difference in the counterweight overall diameter that I can ever recall....

BillK · 12-31-2013, 08:51 AM

Quote:

Originally Posted by Steve Williams

The 305 crank is the nastiest piece of junk that is associated with Small Blocks IMHO.

Steve,
Other than the balancing there is absolutely no difference between the two crankshafts.

I just looked through some old balance cards and found a 305. The piston and pin was about 60 grams lighter than most of the stock type 350's I have done. 622 grams compared to 682 for the 350 If that is not enough to make you believe that the 350 crank needs to be rebalanced to use in a 305, then I don't know what is

Mike Taylor 3601 · 12-31-2013, 10:17 AM

267,305,350 all are same crank, EXCEPT for balance,you can identify them by comparing counterweights,267 will have deepest holes,305 a little less, some 267/305 cranks have notches cut in counterweights to remove weight.

I would at least try to find 305 crank, or balance the 350 crank,I balance everything,be surprised how good a 3.5 briggs will cut grass when balanced,took 2- 3/4X3/4 pieces of heavy metal.
Might get someone to balance w/bobweight made up from 1 piston/rod.

Mike Taylor 3601

Dwight Southerland · 12-31-2013, 10:22 AM

Some of the rebuilder manufacturers make 305 pistons that are purposefully heavy for use with a 350 crank in a 305 block.

carl hinkson · 12-31-2013, 12:21 PM

I have balanced a few cranks for other shops and the F/M 345 pistons are now appox.72 grams lighter then the older ones.

12-30-2013, 08:03 PM	#1
Lyn Smith VIP Member Join Date: Dec 2001 Location: Pontiac,il. Posts: 1,183 Likes: 269 Liked 935 Times in 185 Posts	305/350 crank Got a street 305 Chevy im rebuilding.It had a bad crank,so I came across a 350 crank which is the same stroke.Can I use the 350 crank ,or will it have a balance problem?Dont really want to spend the money to balance it. thanks

12-30-2013, 08:33 PM	#2
BillK Member Join Date: Nov 2005 Location: Waldorf Md Posts: 230 Likes: 12 Liked 30 Times in 17 Posts	Re: 305/350 crank Lyn, The 350 and 305 cranks that I have done have been quite a bit different in balance. If you are replacing pistons it seems like they are making even the stock replacement pistons a lot lighter so that will make the problem even worse. I would say it would be worth having it at least checked. You probably don't have to do the entire balance job, making all of the rods and pistons the same weight etc. Just use one of the 305 assemblies as a reference to make the bobweight. Hope this helps, __________________ Bill Koustenis

12-30-2013, 08:51 PM	#3
Rob Petrie E395 VIP Member Join Date: Dec 2007 Location: Woodlawn IL Posts: 1,092 Likes: 162 Liked 216 Times in 77 Posts	Re: 305/350 crank I cant say for sure what a 350 crank in a 305 will do. But I know for a fact that a 305 crank in a 350 will vibrate at around 2500-3000 RPM. Bad enough that you will take it back apart.

12-30-2013, 09:23 PM	#4
Steve Williams Member Join Date: Aug 2007 Location: Detroit, Michigan Posts: 352 Likes: 0 Liked 1 Time in 1 Post	Re: 305/350 crank The 305 crank with 350 rod-piston is a problem. The 350 crank with a 305 rod-piston is not a problem. No balancing required for a stock piston or cast replacement. The 305 crank is the nastiest piece of junk that is associated with Small Blocks IMHO.

12-30-2013, 10:26 PM	#6
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,312 Likes: 25 Liked 543 Times in 212 Posts	Re: 305/350 crank 305-350 cast cranks were the same casting number and the only difference was the factory balancing. If I recall correct the casting number was 448...last 3 and if you look at the depth of the holes on cranks from a 305 vs a 350 you wll see a big difference in hole depth....the 305 bobweight was lighter so the crank had deeper balance holes drilled. You could use either crank in either engine but needed to address the balance issue...... There is no difference in the counterweight overall diameter that I can ever recall.... __________________ Rich Biebel S/C 1479 Stock 147R

12-31-2013, 10:17 AM	#8
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,350 Likes: 301 Liked 248 Times in 87 Posts	Re: 305/350 crank 267,305,350 all are same crank, EXCEPT for balance,you can identify them by comparing counterweights,267 will have deepest holes,305 a little less, some 267/305 cranks have notches cut in counterweights to remove weight. I would at least try to find 305 crank, or balance the 350 crank,I balance everything,be surprised how good a 3.5 briggs will cut grass when balanced,took 2- 3/4X3/4 pieces of heavy metal. Might get someone to balance w/bobweight made up from 1 piston/rod. Mike Taylor 3601

12-31-2013, 10:22 AM	#9
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,996 Likes: 63 Liked 756 Times in 189 Posts	Re: 305/350 crank Some of the rebuilder manufacturers make 305 pistons that are purposefully heavy for use with a 350 crank in a 305 block.

12-31-2013, 12:21 PM	#10
carl hinkson Member Join Date: Feb 2007 Location: NORTHEAST Posts: 287 Likes: 1 Liked 18 Times in 10 Posts	Re: 305/350 crank I have balanced a few cranks for other shops and the F/M 345 pistons are now appox.72 grams lighter then the older ones.