305 blocks- whats the best one to use ?

FED 387 · 08-19-2007, 10:34 AM

Kenny--GM did offer 2 blocks for the 305CI------A stock version of the block part#-10066098 & a Bowtie block part# -10051181(casting # 10051182)--The Bowtie block is machined for a 1 piece rear main seal and if you need a 2 piece seal you will need cshaft seal adapter #10051118 -- I do not know if these numbers have been changed or are up to date or if either of these blocks are still available from GM..Also remember that a stock production SBC block weighs approx. 152 pounds and a Bowtie SBC block will weigh approx 183 pounds . Good luck---Comp 387

Kenny Wigington · 08-19-2007, 01:17 PM

Thanks Reggie, and Dick. I'll check into that block. Mine has hardblock in it.

greg fulk · 08-19-2007, 02:28 PM

steve is right...take a 350 4 bolt block & sleeve it down to 305....my machinest dose it..about $620.oo though.

JRyan · 08-19-2007, 03:30 PM

Kenny,

Better not use a 4-bolt 350 block as a core to sleeve, as they aren't a legal replacement for a 305 (based on a call to NHRA). The 305's were all 2-bolt and that's what NHRA wants to see IF the pan ever comes off. The best block to use if you can find one is the '68, '69 307 block. Many were cored as 350's so you end up with the very thick walls of a 350 but can use a more generally available sleeve.

Jerry

Jim Cassels · 08-19-2007, 08:59 PM

Kenny,
Jerry is giving you the correct info, they will not accept the 4 bolt block, I learned the hard way. Some run them but they are not legal.

Don quinn · 08-19-2007, 09:21 PM

The 80 corvette had a 305 4 bolt block

Kenny Wigington · 08-19-2007, 10:50 PM

Thanks guys. I do appreciate the info.

Just for the sake of asking, how much extra would a block weigh , with all sleeved ? Is it lighter than that Bowtie block, Dick and Reggie mentioned ?

Steve Williams · 08-24-2007, 03:51 PM

Kenny,

The best block to use is the block that you have. This would be most cost effective considering the total cost to machine another block to duplicate what you already have. Sleeve that block. Knowing the history of the engine and the head issue-this crack was caused by water in the cylinder. Just my two cents.

Respectfully submitted,

Steve Williams

Jim Cassels · 08-24-2007, 10:14 PM

Kenny,Don & all
I finnaly got back on line. About 6 yrs ago I did the sleeved 350 4 bolt deal. When we began to assemble we were told what Jerry told you. I called Calif. and they said no way. I guess we need to ask Travis about that 80 vett. They should be ok if that is correct. I think I got 2 cases of beer for my $800.00 block.
Jim

John Leichtamer Jr · 08-25-2007, 05:04 PM

Mortec shows 2 different castings # for 305 4bolt blocks. They say there for hd trucks of course there Canadian.

John

08-19-2007, 01:17 PM	#2
Kenny Wigington Senior Member Join Date: Sep 2004 Location: Cumming,Ga. USA Posts: 967 Likes: 36 Liked 60 Times in 12 Posts	Re: 305 blocks- whats the best one to use ? Thanks Reggie, and Dick. I'll check into that block. Mine has hardblock in it. __________________ 2894 STK

08-19-2007, 02:28 PM	#3
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: 305 blocks- whats the best one to use ? steve is right...take a 350 4 bolt block & sleeve it down to 305....my machinest dose it..about $620.oo though. __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

08-19-2007, 03:30 PM	#4
JRyan Senior Member Join Date: Apr 2003 Location: Aberdeen SD Posts: 645 Likes: 30 Liked 112 Times in 31 Posts	Re: 305 blocks- whats the best one to use ? Kenny, Better not use a 4-bolt 350 block as a core to sleeve, as they aren't a legal replacement for a 305 (based on a call to NHRA). The 305's were all 2-bolt and that's what NHRA wants to see IF the pan ever comes off. The best block to use if you can find one is the '68, '69 307 block. Many were cored as 350's so you end up with the very thick walls of a 350 but can use a more generally available sleeve. Jerry

08-19-2007, 08:59 PM	#5
Jim Cassels Junior Member Join Date: Nov 2002 Location: Cairo, Ga. Posts: 90 Likes: 2 Liked 0 Times in 0 Posts	Re: 305 blocks- whats the best one to use ? Kenny, Jerry is giving you the correct info, they will not accept the 4 bolt block, I learned the hard way. Some run them but they are not legal.

08-19-2007, 09:21 PM	#6
Don quinn Junior Member Join Date: Dec 2002 Posts: 2 Likes: 0 Liked 0 Times in 0 Posts	Re: 305 blocks- whats the best one to use ? The 80 corvette had a 305 4 bolt block

08-19-2007, 10:34 AM	#1
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,410 Likes: 507 Liked 329 Times in 177 Posts	Re: 305 blocks- whats the best one to use ? Kenny--GM did offer 2 blocks for the 305CI------A stock version of the block part#-10066098 & a Bowtie block part# -10051181(casting # 10051182)--The Bowtie block is machined for a 1 piece rear main seal and if you need a 2 piece seal you will need cshaft seal adapter #10051118 -- I do not know if these numbers have been changed or are up to date or if either of these blocks are still available from GM..Also remember that a stock production SBC block weighs approx. 152 pounds and a Bowtie SBC block will weigh approx 183 pounds . Good luck---Comp 387

08-19-2007, 10:50 PM	#7
Kenny Wigington Senior Member Join Date: Sep 2004 Location: Cumming,Ga. USA Posts: 967 Likes: 36 Liked 60 Times in 12 Posts	Re: 305 blocks- whats the best one to use ? Thanks guys. I do appreciate the info. Just for the sake of asking, how much extra would a block weigh , with all sleeved ? Is it lighter than that Bowtie block, Dick and Reggie mentioned ? __________________ 2894 STK Last edited by Kenny Wigington; 08-19-2007 at 10:52 PM.

08-24-2007, 03:51 PM	#8
Steve Williams Member Join Date: Aug 2007 Location: Detroit, Michigan Posts: 352 Likes: 0 Liked 1 Time in 1 Post	Re: 305 blocks- whats the best one to use ? Kenny, The best block to use is the block that you have. This would be most cost effective considering the total cost to machine another block to duplicate what you already have. Sleeve that block. Knowing the history of the engine and the head issue-this crack was caused by water in the cylinder. Just my two cents. Respectfully submitted, Steve Williams

08-24-2007, 10:14 PM	#9
Jim Cassels Junior Member Join Date: Nov 2002 Location: Cairo, Ga. Posts: 90 Likes: 2 Liked 0 Times in 0 Posts	Re: 305 blocks- whats the best one to use ? Kenny,Don & all I finnaly got back on line. About 6 yrs ago I did the sleeved 350 4 bolt deal. When we began to assemble we were told what Jerry told you. I called Calif. and they said no way. I guess we need to ask Travis about that 80 vett. They should be ok if that is correct. I think I got 2 cases of beer for my $800.00 block. Jim

08-25-2007, 05:04 PM	#10
John Leichtamer Jr Senior Member Join Date: Sep 2006 Location: Orange City Fl Posts: 764 Likes: 0 Liked 0 Times in 0 Posts	Re: 305 blocks- whats the best one to use ? Mortec shows 2 different castings # for 305 4bolt blocks. They say there for hd trucks of course there Canadian. John