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02-16-2009, 10:27 PM
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#1 |
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Registered User
Join Date: Sep 2008
Location: Huntingdon,TN
Posts: 95
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400 Block
Hey guys, I have a sbc 400 block with deck plugs, oil galley plugs, but what i find interesting is the steam holes have appeared to be welded up and then the block was decked. Have any of you ever done or seen this? Why would you go thru the trouble of doing this? My guess is for strength, but I cant imagine it would make a significant amount of differance. Also, why are the oil galley holes plugged up? Maybe keep the lifters supplied with oil? Is either of these things a good or bad practice? And why? Just trying to learn something new. Any insight is appreciated! Thanks....
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02-16-2009, 11:58 PM
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#2 |
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Registered User
Join Date: Jul 2005
Location: Kernersville, NC
Posts: 599
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Re: 400 Block
for the oil gally holes, probably was a racing motor at some point in time and they were plugged so the oil would drain down the back of the block and the front, though the time chain, elimantin drain back on the cam and rotating assembly for less windage which equal more horse power. As for the steam holes being plugged, I have no idea. eberything i've read and heard says if you dont have those opened, they'll over heat like crazy. Chris.
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its a work in progess. 71 c-10 lwb, in the middle of frame off restoration. 69 c-10 swb, drag truck, 406 sbc, balanced, comp 292 cam, ported, polished, gasket matched, and bowl blended pro comp 210cc heads, 2.02/1.60 ferrea valves,1.6 roller rockers, re curved hei with msd 6al box, 2-step rev limter, accel 300+ wires, ported victor jr intake, holley 750 double pumper carb, dynomax 1 5/8 headers, 4 spd munci m-20 with super case and iron midplate, mr. gasket vertigate shifter, 5.38 pro gears with full spool, 33 spline moser axles and c-clip elimators, line-loc, 5 gal fuel cell, holley blue pump.   7.807 @ 88.37mph 1.60 60FT 80 g-20 van, tow rig, cammed 305, th350, 10 bolt 88 jeep wrangler, dd, 258, ax-15 swap, 4.5" lift, 33x12.50's, lockers, 3.55's |
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02-17-2009, 02:15 AM
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#3 |
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Dr. Frankenstein
Join Date: Feb 2008
Location: beaverton,Or
Posts: 458
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Re: 400 Block
yea i was under the impression steam holes = GOOD! but they did some crazy stuff way back when so ya never know
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I Wanna Go Fast!! |
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02-17-2009, 09:58 AM
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#4 |
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Senior Member
Join Date: Dec 2001
Location: Redding,CA...USA
Posts: 4,736
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Re: 400 Block
On a drag engine, where your not running an extended time, we would tap and plug the steam holes then mill the deck.
400 blocks are notorious for cracking from the steam hole to the bolt hole(no big deal) or to the cylinder(bigger deal)
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It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA |
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02-17-2009, 02:57 PM
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#5 | |
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Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
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Re: 400 Block
Quote:
If I was going to build a 400 block based motor, I would not run factory heads. They just don't have enough meat in the deck. I would get some aftermarket casting, such as Enginequest or the other brands out there that are heavy cast and have about a half inch of deck thickness. Drill the steamholes, bevel the edges of the holes slightly, then call it good. As for the block, if you are planning on street use, it would be a good idea to drill out those steam holes.
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1977 GMC Sierra Grande |
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02-18-2009, 12:08 AM
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#6 |
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Registered User
Join Date: Jun 2006
Location: Jackson, Mo.
Posts: 607
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Re: 400 Block
The oil valley drain holes were tapped and plugged to keep the oil drainback at the rear of the block. On a street/strip engine, I wouldn't plug these holes.
As far as the steam holes being plugged, like BigJim said, it is done a lot on drag motors, but I wouldn't plug them on a street/strip deal. Factory 400 blocks are known to crack from the steam holes to the head bolt holes, which, once again, isn't a big deal. In my opinion, if you're using a factory 400 block, then you should run both head and main studs instead of bolts. This will, among other things, keep the small deck cracks from the steam holes from becoming a bigger issue. And, by all means, drill the steam holes in the heads if they don't already have them. Just my opinions...
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Chris 1966 Chevy C10 LWB, 434 sbc, TH350, 12-bolt, factory suspension, pump gas 7.02 @ 95.8, 1.45 60' 1965 Chevy C10 LWB, 355 sbc, TH350, daily driver |
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02-18-2009, 10:04 AM
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#7 |
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Registered User
Join Date: Sep 2008
Location: Huntingdon,TN
Posts: 95
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Re: 400 Block
Thanks guy's. I am going to remove the oil galley plugs because i do drive this engine on the street from time to time. I dont want to starve my roller lifters for oil. As far as the steam holes i will leave them as is, because i have driven this engine several times on the street and have not had any cooling issues at all. The engine is studded in the mains and the heads. i have just removed my current motown 220 heads and replacing them with the AFR 227's.
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02-24-2009, 10:33 PM
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#8 |
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Registered User
 
Join Date: Jan 2008
Location: St.Petersburg,Fl
Posts: 1,267
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Re: 400 Block
I had a 406 that had the steam holes plugged. I had it running for about 5 years and drove it every day and sprayed about 15 bottles at a 150 shot! I never had a problem with it , and that's driving in the Fla. heat.I ran this motor hard and never had a problem with it.
 My .02
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