421 or 427 sbc rotating assembly in a 400 gm passenger block
08-03-2009, 12:38 PM
#11
Senior Member
RACING JUNKIE
Join Date: Jan 2006
Location: La.
Posts: 2,890
400 blks. are o'k if they are your only options, i've got 2 of them and have had 1/2 doz. in the past. If they are prepared correctly they will handle 600hp for a time. The bottom end and cylinder walls being the weakest points. I personally drill out the steam hole and put pipe plugs in them (keeps them from cracking to the bolt holes)also fill the block to the bottom of the water pump bolts. I've cracked cylinders, broke main webs but have never blown one to pieces. I've had friends that blew the cranks out the bottom and split the steam holes to the bolt holes. This has never happened too me. The best thing about a 400 blk. is that they are getting harder and harder to find, most have gone by the wayside due to racing mishaps.
bottom line is the Dart block is Sooo much better and safer build. I got one of those too.
The 377" in my malibu is a stock block and welded, but i would not recommend doing what i did to keep it alive.
JMO
Zip.
bottom line is the Dart block is Sooo much better and safer build. I got one of those too.
The 377" in my malibu is a stock block and welded, but i would not recommend doing what i did to keep it alive.
JMO
Zip.
08-03-2009, 01:12 PM
#12
Member
MASTER JOURNEYMAN
Join Date: Feb 2008
Posts: 45
Not this time
I know even after i had Howard's splayed caps installed in my 400 i still chickened out using it in a supercharged application. Where do i find these guy's that love these 400 blocks, i'll sell mine .030 over Howard's splayed caps plate hone 750.00. Never assy. after machine work.
08-03-2009, 03:56 PM
#13
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RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
Re: Not this time
Originally Posted by heshtesh
I know even after i had Howard's splayed caps installed in my 400 i still chickened out using it in a supercharged application. Where do i find these guy's that love these 400 blocks, i'll sell mine .030 over Howard's splayed caps plate hone 750.00. Never assy. after machine work.
08-04-2009, 06:16 AM
#15
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RACING JUNKIE
Join Date: Dec 2008
Location: Sugar Hill, GA
Posts: 1,365
Just another note on the GM400. I have some strange friends that drive in left hand circles. When they build a 400, they use the 2 bolt bottom end because the outer (straight pattern) bolt holes weakens the webbing.
Dave
Dave
08-04-2009, 10:44 AM
#16
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RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
Originally Posted by oldandtired
Just another note on the GM400. I have some strange friends that drive in left hand circles. When they build a 400, they use the 2 bolt bottom end because the outer (straight pattern) bolt holes weakens the webbing.
Dave
Dave
08-04-2009, 02:35 PM
#17
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RACING JUNKIE
Join Date: Jul 2009
Location: Clarksville, TN
Posts: 1,922
Ok you guys can call me slow.. But, I just realized that I have a SB 400 in my 4x4 that was just built. It was beefed up some but I dont know how much. So yeah it has power. Anyways, should I worry bout this motor trashing itself or no?
08-11-2009, 06:33 PM
#19
Member
JUNIOR BUILDER
Join Date: Oct 2003
Posts: 84
I think your ok Dirka, its only in high compression race engines have I seen the problem. Despite the weaknessess of the 400 block it is my favorite engine all around because it is so amazing. I built a 406 with ported Brodix heads and GM Block with a solid lift cam and 10.5 to 1 compression. In a 3200lbs car with a glide and 5000 stall converter it ran 10.60s with a best (in good air) of a 10:55. It ran for 3 seasons every weekend and no problems. Took it out and change compression to 14.5 to 1 and a roller cam, split the cylinder in the 1st pass!!!! Awesome engine tho.
Chris
Chris
