305/350 crank

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.

Steve Williams · 12-31-2013, 10:31 PM

Quote:

Originally Posted by BillK

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

Bill,

The differences go further than just balance. The use of a 350 crank in a 305 has been done several times in our shop and with a cast replacement piston, I never sent one out for balance. The advice of my crankshaft guy was that 305 cranks rotating 350 rod-piston was a problem, but 350 crank in 305 with cast piston or cast replacement was not a problem provided it was a stock rebuild, stock intended RPM range. As far as the weight difference between the two engines, I don't recall what the exact number was, but it seemed it was much closer than 60. I want to say it was 46 or 48. I can tell you that the 305 crank, if used in a 350, will have a bunch of mallory in it. Built one for a customer who supplied this balanced assembly. He knew nothing of what the crank was until we looked it over closely and told him. The amount of mallory was a dead give away that something wasn't right.

BillK · 01-01-2014, 06:20 PM

Quote:

Originally Posted by Steve Williams

Bill,

The differences go further than just balance.

Steve,
Not sure what you mean by this ???? They are both the same exact castings. The 305 cranks have more metal machined out of the counterweights but other than that they start out as the same piece.

I tend not to take chances on balance. The first time I would put a 350 crank in a 305, I guarantee you the thing would vibrate ...

Why even take the chance anyway ?? Balance it and be done with it.

There are also too many variations in stock piston weights to take a chance. Some of the late model 350 pistons are really light compared to the early ones. If I don't know where a crank came from, I will recommend balancing it, period.

Just my opinion,

12-30-2013, 08:51 PM	#1
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	#2
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	#4
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 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	#6
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,371 Likes: 352 Liked 306 Times in 103 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	#7
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 780 Times in 194 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	#8
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.