400 chevy block in C4?
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Motor was built 3 years ago, so far so good...Going to the drag strip today to rip it up
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by chriswtx
I have a forged crank, 350 mains with the 400 stroke. No bearing spacers required..
RACE ON!!!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by hooblyboobly
I never knew one could run a 400 without using steam holes. 
RACE ON!!!
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
So why did GM decide steam holes were necessary on 1970-1980 400s then, if they truly weren't needed? Are you saying you could use just a regular SBC head gasket vs. a head gasket required specifically for 400s? Inquiring minds want to know...
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
400's have a 4.125 bore, so the standard sbc gasket will not work for that reason.
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
The 400 SBC was the first production block with siamesed cylinders, and the engineers at the time "thought" that air would get trapped in those areas and therefore needed a place to escape, thus the steam holes (and it would be a "water" passage, not a "steam" passage). That has proven either not to be the case, or not a problem if that in fact does occurr. GM has since built siamesed cylinder blocks w/o steam holes, as has the aftermarket.
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
I have a forged crank, 350 mains with the 400 stroke. No bearing spacers required..
I have 400 mains with a 350 srtoke..I have a 1970's 2 bolt 400 block that I added splayed 4 bolt main caps to....
Last edited by chriswtx; Sep 16, 2007 at 05:34 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by hooblyboobly
So why did GM decide steam holes were necessary on 1970-1980 400s then, if they truly weren't needed?
Originally Posted by hooblyboobly
Are you saying you could use just a regular SBC head gasket vs. a head gasket required specifically for 400s? Inquiring minds want to know...
RACE ON!!!
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Intermediate
Joined: Feb 2008
Posts: 47
Likes: 0
Eveyone should take a breath... Whew this isn't politics. The best part of this forum is people like all of you. I have learned a lot reading your wealth of knowledge. And not having to wade through all the egos. There is often more than one correct answer.
can't we all just get along?
Sorry I couldn't resist that one.
can't we all just get along?
Sorry I couldn't resist that one.
Burning Brakes
Joined: Sep 2005
Posts: 993
Likes: 3
From: Iowa
For more of a hot rod type of car that doesn't get used much except for playing around I wouldn't build anything under a 400. My current power plant is a 355 and even with fully ported Brodix heads all my friends still love the old 406 it replaced better for seat of the pants feeling....
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
I made a major mistake in my build (actually it was the builder, but I share the blame). He built me a 383 with an externally-balanced rotating assembly. This gave me the WORST of both worlds. PITA rotating assembly, but not the 406 cubic inches to make up for it. Anyway, it's in my car, running, without modifying the corssmember or anything. I picked up a forged, 153 tooth, externally balanced flywheel from a place in LA for $100 (they said they sell a lot of 'em to people who do this by accident). I also got a 6.75" externally balanced balancer from the same place for $60. I'm running a stock LT1 small starter, and everything nestled quite nicely into my engine bay.
When I get tired of the 383 I may build a 406+ for the car and slap the same flywheel/balancer on that...
When I get tired of the 383 I may build a 406+ for the car and slap the same flywheel/balancer on that...
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
Oh yeah, lessons learned the hard way:
1.) A stock 400 flywheel DOES NOT FIT
2.) A 4+3 bellhousing CAN NOT BE CLEARANCED for a 400 flywheel
3.) A small internally balanced balancer CAN NOT BE BALANCED to a 400 crank
I think that's most of my personal issues on this one.
As for the 400 thing, a guy on the crossfire forum named Tom slapped a ported CFI intake on a bone-stock junkyard 400 and it ran fantastically well. Stock ECM, stock 400 engine, mildly ported CFI intake. Cubic inches are great...
1.) A stock 400 flywheel DOES NOT FIT
2.) A 4+3 bellhousing CAN NOT BE CLEARANCED for a 400 flywheel
3.) A small internally balanced balancer CAN NOT BE BALANCED to a 400 crank
I think that's most of my personal issues on this one.
As for the 400 thing, a guy on the crossfire forum named Tom slapped a ported CFI intake on a bone-stock junkyard 400 and it ran fantastically well. Stock ECM, stock 400 engine, mildly ported CFI intake. Cubic inches are great...
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
before you get it in and all screwed together, check that your 400 block is not missing one starter mounting tapping for the 153 wheel, many are only tapped for the two ''big wheel'' starter bolts, not three tapped holes for universal 153/168t fit.
with an lt1 intake conversion, you can ''space out'' the motor mounts enuf to clear the 400 front balancer over the vette crossmember...my 409 (400+.o40) only needed abt 1/4'' rise...tPi would probly hit the hood.
a 30 lb nodular iron 153t flywheel, neutral balanced for a 350 2-pc, can easily be rebalanced to 400 external balance and lightened additionally...some are bolting weights to the 350/L88 15lb wheel to get 400 balance but i like having two feet -no thanks.
GM power book sez steam holes are not req'd for operation over 3000 rpm, but lower speed use should have steam holes.
with an lt1 intake conversion, you can ''space out'' the motor mounts enuf to clear the 400 front balancer over the vette crossmember...my 409 (400+.o40) only needed abt 1/4'' rise...tPi would probly hit the hood.
a 30 lb nodular iron 153t flywheel, neutral balanced for a 350 2-pc, can easily be rebalanced to 400 external balance and lightened additionally...some are bolting weights to the 350/L88 15lb wheel to get 400 balance but i like having two feet -no thanks.
GM power book sez steam holes are not req'd for operation over 3000 rpm, but lower speed use should have steam holes.
Last edited by redrose; Feb 7, 2008 at 08:38 PM.
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Not a big deal but you can nuetral balance the front of the crank with MALLORY METAL and use a stock 350 internal balance damper, with an exernal balance rear
Instructor
Joined: Jan 2008
Posts: 163
Likes: 1
From: Idianapolis Indiana
I was running an int balance 10.5:1 roller 383 with 215cc Iron eagles and a wide LSA camshaft with a tpi off an 86 vette. The only mods were a 58 mm throttle body, 30pph injectors, MSD 6A,a hot chip and an adj fuel press regulator. We advanced the cam 6 degrees and buddy the thottle response and torque was EXPLOSIVE. It did run out at 4000 rpm tho. But it didnt matter, I couldnt hook it up in an automatic/2.73 setup. If i had a locker, gears, and a torque converter man It woulda been fast. In my 92 camaro I was able to get 495 miles out of a tank. I was flabberghasted. Idled soooooo smooth too. Also hit 173 on a back road so in a vette it woulda been wicked.
Racer
Joined: Oct 2003
Posts: 304
Likes: 0
From: Marlboro NY
Why not stroke a 400 block???????
Check my avatar.
P.S. I at this moment have almost no cooling problems with my motor except for one incident last year while stuck in bumper to bumper traffic on the Garden State for almost 30 minutes inching along on a 98 degree day. Water Temp crept upwards of 230 and made me quite nervous but as aoon as I got moving above 30 mph it dropped back down to about 190.
My cooling system is all stock except reduction pulleys. Not too bad considering its 22 years old.
Check my avatar.
P.S. I at this moment have almost no cooling problems with my motor except for one incident last year while stuck in bumper to bumper traffic on the Garden State for almost 30 minutes inching along on a 98 degree day. Water Temp crept upwards of 230 and made me quite nervous but as aoon as I got moving above 30 mph it dropped back down to about 190.
My cooling system is all stock except reduction pulleys. Not too bad considering its 22 years old.
Last edited by Gold1986Vette420; Feb 8, 2008 at 11:15 PM.
