400 block question
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
400 block question
i've read a lot about the steam holes and drilling the new heads, but i also see guys talking about tapping and plugging them(the steam holes). what are the details/ advantages/ disadvantages to plugging them? is that just something you do to a track motor because it doesn't matter anyway? :confused:
my block is gonna be used in normal traffic conditions and i want to give myself the best chance i can at avoiding heating issues. tia
my block is gonna be used in normal traffic conditions and i want to give myself the best chance i can at avoiding heating issues. tia
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: 400 block question (Caboboy)
The "poop" on steam holes, from my experience, and lore, is that they are not needed for sustained operation at speeds over 3500 rpms. I believe that the only reason to plug the holes in the block, is to stiffen the deck, for extreme usage applications. I have an old pick up with a factory installed 400. While doing a "quickie" rebuild years ago, I swapped on a pair of non-drilled, 350 heads. When I asked my machinist about the steam holes, he replied, "you don't need 'em". I think he might have been blowing my off, because he was too lazy to drill them. With my 4.11 gears, my engine spends a great share of its time in the 3-4000 rpm range, and even in around town driving, I've had no problems. I would, however, not chance this again. For everything but an all out racer, I would leave the steam holes in the block open, and in a street use application, I would make sure the heads and head gaskets had holes to match. I've had no problems, in my situation, but I wouldn't do it again. Good luck and RACE ON!!!
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: 400 block question (CFI-EFI)
Thanks CFI-EFI, great info and exactly what I was lookin' for. There's so much goin' around about 400s and heating, it's tuff to separate fact from fiction. First hand experience is so important. Nice to hear you're a few years into your swap w/o problems. And, I agree, why take the chance if there's no tangible return? I'll just go w/ 400 gaskets and drill the heads. Thanks again!
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: 400 block question (Caboboy)
Here is some more info from what I gathered when I built my street 406.
Street 400's need the holes in the heads (for the above stated reason-low rpm operation).
Many will plug the large deck holes (not steam holes) in the block with plugs,deck the block flat, and then drill smaller holes into those plugs-this increases block rigidity.
I haven't heard of plugging the block's steam holes...don't know why unless you want that little bit more rigidity...?
I left everything stock with drilled 350 300HP heads and Fel Pro gasket. Engine never ran hot with stock 69 Nova radiator.
Street 400's need the holes in the heads (for the above stated reason-low rpm operation).
Many will plug the large deck holes (not steam holes) in the block with plugs,deck the block flat, and then drill smaller holes into those plugs-this increases block rigidity.
I haven't heard of plugging the block's steam holes...don't know why unless you want that little bit more rigidity...?
I left everything stock with drilled 350 300HP heads and Fel Pro gasket. Engine never ran hot with stock 69 Nova radiator.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: 400 block question (Caboboy)
Nice to hear you're a few years into your swap w/o problems.
I have to agree with the above. I have never heard of anyone closing up the steam holes. Just the main holes like stated. RACE ON!!!
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: 400 block question (No Go)
thanx no go. did you plug yours? any problems? since i'm not gonna pound on it (too much :reddevil ) i'm inclined to just leave it alone and move forward like any other motor. am i thinking right on this?
Burning Brakes
Joined: Dec 2000
Posts: 1,023
Likes: 0
From: Marietta, South Carolina, USA
Re: 400 block question (Caboboy)
We have done a few 400+ engines and you plug the steam hole if you are going to O-Ring the block and run Copper head gasket, because the pleace where you have to cut for the o-ring is over the steam hole in the block.
Jay
Jay
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: 400 block question (MrJay)
MrJay, would I want to o-ring the block? Is that something done short term on a track motor but not a street motor? Does the o-ring just support the copper gasket to keep it from blowing and thereby allow you to reduce the quench?
Would my needs be best served with a 400 block felpro of appropriate thickness? Geeze, all these options are a new game to me from my last motor circa 1965......... I am SUCH a dinosaur :lol:
Would my needs be best served with a 400 block felpro of appropriate thickness? Geeze, all these options are a new game to me from my last motor circa 1965......... I am SUCH a dinosaur :lol:
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Burning Brakes
Joined: Dec 2000
Posts: 1,023
Likes: 0
From: Marietta, South Carolina, USA
Re: 400 block question (Caboboy)
No Caboboy you would not nead to do that, it is done on engines that are going to use blower or a lot of nitrous but since you are just going to use it on the street, you are ok just go with a good head gasket.
Jay
Jay
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: 400 block question (MrJay)
gotcha. thanks a lot for the info! i think i'm gonna put this together like any other motor and just make sure my cooling system is tight.
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: 400 block question (Caboboy)
Only thing I did was drill the cylinder heads for the steam holes...since they were originally on my 300 HP 350 engine. Fel Pro gaskets and ran like a top.
Will be reinstalling it with new rings/bearings/new cylinder heads/EFI (all for more power) when my Nova is off jackstands.
Will be reinstalling it with new rings/bearings/new cylinder heads/EFI (all for more power) when my Nova is off jackstands.