1 Piece Seal Crank

brian schuetta · 10-15-2013, 09:50 AM

Is there a disadvantage or advantage to using a 1 piece rear seal crank? Found a 1 piece core 305 and wanted to use it in my car which was originally a 2 piece. Would an older 74 - 80 305 core be better?

richie 2 · 10-15-2013, 11:23 AM

whats the application?

brian schuetta · 10-15-2013, 04:22 PM

83' 305, 416 head, ft piston, Camaro

Lew Silverman · 10-15-2013, 06:19 PM

As I understand it, the way the rules are now written for Stock, you have to use the original OEM crankshaft for the year and horsepower claimed for your vehicle. There are a few aftermarket blocks that are acceptable, at least for the SBC, but the original crankshaft has to fit.

I may be misinformed, but as it stands now, no late-model blocks and cranks in early-model chassis.

Mike Taylor 3601 · 10-16-2013, 10:14 AM

As far as I know could use 1pc or 2 pc seal block and be legal.
1 pc. uses different flex/flywheel is external balance on rear and has different bolt pattern.
I have converted several to internal balance takes about 1'' heavy metal usaully depending on bobweight.
the reason they are external balance on the rear is when flywheel flange is made round it loses that extra flange that is counterweight
Mike Taylor 3601

brian schuetta · 10-16-2013, 12:06 PM

Any comments on strength of the newer block and 1 piece seal crank? The engine is tore down to the short block, it had 187 heads on it. It's layin there and the price is right.

Steve Williams · 10-16-2013, 07:39 PM

One piece rear main production blocks are junk if they have lots of miles on them. I have thrown away a few dozen blocks that would not clean up at .060 over. I have also found ones that would clean up at .060, but the wall was too thin on the thrust side. I am not trying to discourage the use these blocks, but a thorough inspection of the block is a must before even considering purchasing any parts. Two piece parts are easy to find, cheap and it is internally balanced. Whats not to like about that?

Tim H · 10-16-2013, 07:51 PM

Also have seen 1 pc style blocks with cracks in the lifter valley. Never really seen that in any of the mid 1970's or older blocks ? Castings were thinner in that area I believe.

Mike Taylor 3601 · 10-17-2013, 08:27 AM

The first versions of the one piece block 86,cracked like crazy in lifter valley, GM then made changes to correct,after that 1 pc blocks don't seem to crack any worse than the 2 pc blocks. Most of blocks you find cracked in lifter valley have been frozen,that is first place they bust when they freeze,then if froze more bust right below deck on outside.

Whatever block you use you need to check throughly,there are good and bad in all of them old or new.
Mike Taylor 3601

brian schuetta · 10-17-2013, 09:24 AM

Will check any block I use but I think we will try to trade this thing or go find a 2 piece. I have had trouble finding a 305 core already out of a car. 10 years ago you could trip over these things, now none of the local shops are keeping or taking them in. Found some in the junkyard last week attached to transmissions both L and H codes.

10-15-2013, 09:50 AM	#1
brian schuetta Member Join Date: Apr 2005 Location: san antonio tx Posts: 259 Likes: 5 Liked 28 Times in 15 Posts	1 Piece Seal Crank Is there a disadvantage or advantage to using a 1 piece rear seal crank? Found a 1 piece core 305 and wanted to use it in my car which was originally a 2 piece. Would an older 74 - 80 305 core be better?

10-15-2013, 11:23 AM	#2
richie 2 Senior Member Join Date: Feb 2009 Posts: 967 Likes: 419 Liked 200 Times in 91 Posts	Re: 1 Piece Seal Crank whats the application?

10-15-2013, 04:22 PM	#3
brian schuetta Member Join Date: Apr 2005 Location: san antonio tx Posts: 259 Likes: 5 Liked 28 Times in 15 Posts	Re: 1 Piece Seal Crank 83' 305, 416 head, ft piston, Camaro

10-15-2013, 06:19 PM	#4
Lew Silverman VIP Member Join Date: Mar 2010 Location: Newport News, VA Posts: 1,435 Likes: 371 Liked 129 Times in 59 Posts	Re: 1 Piece Seal Crank As I understand it, the way the rules are now written for Stock, you have to use the original OEM crankshaft for the year and horsepower claimed for your vehicle. There are a few aftermarket blocks that are acceptable, at least for the SBC, but the original crankshaft has to fit. I may be misinformed, but as it stands now, no late-model blocks and cranks in early-model chassis. __________________ Lew Silverman #2070 "The Wagon Master" N/SA

10-16-2013, 10:14 AM	#5
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,365 Likes: 342 Liked 286 Times in 99 Posts	Re: 1 Piece Seal Crank As far as I know could use 1pc or 2 pc seal block and be legal. 1 pc. uses different flex/flywheel is external balance on rear and has different bolt pattern. I have converted several to internal balance takes about 1'' heavy metal usaully depending on bobweight. the reason they are external balance on the rear is when flywheel flange is made round it loses that extra flange that is counterweight Mike Taylor 3601

10-16-2013, 12:06 PM	#6
brian schuetta Member Join Date: Apr 2005 Location: san antonio tx Posts: 259 Likes: 5 Liked 28 Times in 15 Posts	Re: 1 Piece Seal Crank Any comments on strength of the newer block and 1 piece seal crank? The engine is tore down to the short block, it had 187 heads on it. It's layin there and the price is right.

10-16-2013, 07:39 PM	#7
Steve Williams Member Join Date: Aug 2007 Location: Detroit, Michigan Posts: 352 Likes: 0 Liked 1 Time in 1 Post	Re: 1 Piece Seal Crank One piece rear main production blocks are junk if they have lots of miles on them. I have thrown away a few dozen blocks that would not clean up at .060 over. I have also found ones that would clean up at .060, but the wall was too thin on the thrust side. I am not trying to discourage the use these blocks, but a thorough inspection of the block is a must before even considering purchasing any parts. Two piece parts are easy to find, cheap and it is internally balanced. Whats not to like about that?

10-16-2013, 07:51 PM	#8
Tim H VIP Member Join Date: Jan 2007 Posts: 1,040 Likes: 1,066 Liked 481 Times in 158 Posts	Re: 1 Piece Seal Crank Also have seen 1 pc style blocks with cracks in the lifter valley. Never really seen that in any of the mid 1970's or older blocks ? Castings were thinner in that area I believe.

10-17-2013, 08:27 AM	#9
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,365 Likes: 342 Liked 286 Times in 99 Posts	Re: 1 Piece Seal Crank The first versions of the one piece block 86,cracked like crazy in lifter valley, GM then made changes to correct,after that 1 pc blocks don't seem to crack any worse than the 2 pc blocks. Most of blocks you find cracked in lifter valley have been frozen,that is first place they bust when they freeze,then if froze more bust right below deck on outside. Whatever block you use you need to check throughly,there are good and bad in all of them old or new. Mike Taylor 3601

10-17-2013, 09:24 AM	#10
brian schuetta Member Join Date: Apr 2005 Location: san antonio tx Posts: 259 Likes: 5 Liked 28 Times in 15 Posts	Re: 1 Piece Seal Crank Will check any block I use but I think we will try to trade this thing or go find a 2 piece. I have had trouble finding a 305 core already out of a car. 10 years ago you could trip over these things, now none of the local shops are keeping or taking them in. Found some in the junkyard last week attached to transmissions both L and H codes.