4mul8r

My 406 short block has the steam holes in the block plugged.

1) Will this cause any problems? I drive my car daily.

If so and I have to get them unplugged,...

2) I have afr 190 aluminum heads. Should I get steam holes drilled into them?

82355

Yes you need to drill the holes in the head. What do you mean there pluggedon the block? You sure it is the steam holes and not just deck plugs?

Martin

82355

Repost

RB83L69

If the engine RPM will be below 2500 RPM or so for extended periods of time (you drive it on the street and stop at traffic lights) then they're a good thing to have.

I'd recommend that you drill the plugs and the heads.

4mul8r

I want to think it's the steam holes....but I can't be 100% certain.

I will take a pic when I get off work tonight.

I bought the block off a guy who was going to put it in a daily driver and had the engine builder build it so that it was streetable and wouldn't overheat.....So why would he plug the steam holes?

He also told me that since I have aluminum heads that I shouldn't drill them.

Does any of this make sense?

RB83L69

No, not really.

The steam holes are in between the cylinders, and in between the head bolts. They're about 1¾" or so apart, centered on the narrowest place between the bores.

Their purpose is to allow any steam that is created from slow-moving coolant not flushing bubbles of it out that form, to rise to the top of the system and flow out and get cooled and condense, rather than getting trapped under the deck and creating a hot spot (steam being an excellent insulator of heat, rather than a conductor of heat, like liquid coolant).

I can think of no reason not to run them. That is, there is no circumstance I can think of where they would do any harm; and as mentioned, when the car is operated at street temps at extended low RPMs (drive-through, bumper-to-bumper traffic, etc. etc. etc.) they can prevent localized overheating that can occur even if the overall engine temp is satisfactory.

It makes no difference what the heads are made out of. They could be pure nonobtanium/singelsorceum alloy plated with a .6 microinch flash of irreplacium, and the steam could still accumulate in the block under the deck; and it would still be of benefit to allow it to escape.

Use a 400 head gasket as a template, and drill them with about a 3/16" drill bit. Angle the ones that are on the intake side over toward the exhaust side, as most aftermarket heads have thick casting right there next to those, to support the head bolts.

4mul8r

Thanks for your help so far with this.

Do you think drilling the heads is something that I would be able to do myself with just a common hand drill? Or would I need a drill press?

How far do the holes go into the head?

thanks,

RB83L69

I do mine all the time with a hand drill; so I'd suspect you could too.

Drill until you go all the way through and hit water. Probably ½" or so.

Here's a set I drilled recently (not stock).

4mul8r

Hit water? My heads are off the car and so is the short block.

Are you drilling with the heads still attached to the block? Drilling from the top of the head down or the bottom of the head up?

Momar

I believe he means till you hit the water passages. In other words, once you go though that layer of metal.

88TPI406GTA

The plugs may have been put in to help strengthen the deck surface.

I have gotten mixed advice on the steam holes issue from different people. It would seem like a good idea to have them, however, my Pro Topline 220cc heads are NOT designed to have the holes drilled...so says Pro Topline and Shaver Racing and Competition Products.

So, I decided that to be safe I would upgrade the cooling system to compensate. I found a good deal on an Edelbrock Victor Jr WP and Griffin radiator a while ago. BTW, this is a street driven car and hopefully, the upgraded cooling should be fine for what I need.

So you wouldn't HAVE to drill the holes if your cooling system is completely upgraded....Just IMHO...

HTH,

4mul8r

I just dug up an email that was talking about the block.

He told me that the steam holes were plugged for deck strength and that if I had alumnium heads that I should not drill.

However, when I went to buy a head gasket, the sales rep at Summit Racing this weekend, told me that I would need to drill the steam holes or else it would create hot pockets in the engine.

I have all the following cooling supplies in boxes ready to be dropped in with the engine:

New ~$200 radiator from Summit...I'll have to see which one it is though.

New edelbrock Victor series reverse pump

New thermostat

I already have a a be cool fan single fan from the previous setup along with a hypertech fan switch.

I will be getting a custom chip burned as well.


I could go with a better radiator,...but it seems like drilling holes for free (if I SHOULD) would be better than trading in my radiator and forking over an additional 200$.

88TPI406GTA

Listening to the Summit guys for technical advice is the crux of your problem. They have rarely steered me right on anything of importance...they are great for helping figure out part #'s and placing orders though...

Keep in mind that my Pro Topline heads are not designed for drilling steam holes and hence won't have any...but I believe that the AFR heads can be drilled for the holes...

If I was in your place, don't pay extra to redo the block and/or the heads just yet. Drilling the holes in the heads now doesn't matter if the block holes are plugged.

You should upgrade the cooling system from stock REGARDLESS of the steam holes or not...the griffin rad is a much better design than stock with more surface cooling area.

Just out of curiousity, is this 406 going to be carbed or EFI?

EDIT: Let me also add that I am not trying to contradict RB or his experience...but I believe that the combo should work with a well matched cooling system.

82355

No matter how good your cooling system is the siamesed cylinders are going to create pressure there at low RPM street driven conditions. I have seen several set of cracked heads from overheated 400's. Where do you think the old wives tale about overheating 400's came from??? Dumb****s in the '70s throwing camelbacks on with out adding steam holes.

Martin

RB83L69

Drill the holes. It's free, hurts nothing, and may save your posterior.

I ran a 400 in my 83 car for about 12 years; with the stock cooling system. Stock radiator, stock fan switch, stock single fan, stock water pump (did I say "stock" enough times"?) Of course, 12 years isn't what I'd call long-term or anything, even is it's longer than some of the people on this board have been alive; but I suspect it's alot longer than most people, even mature experienced adults, get out of their motors that they build themselves. Steam holes drilled of course.

It works. Just do it.

88TPI406GTA

Not to hijack the thread...but what would you guys recommend to me then? My block is fine, but the Pro Topline heads can't have holes drilled due to the relocated cooling passage...

Should I worry then? Granted, I would rather drill the holes, but it would do me no good then with these heads...

Advice?

RB83L69

I'm not familiar with those heads.... but I'd bet money you could find a straight path from the area of the deck in question, upwards to water, if you looked hard enough.

Pay more attention to th eintake side; obviously, that side is "up" once the heads are installed in the motor. Steam rises through liquid water. "Be" the steam, imagine the path you would follow to get out of the "pocket" under the deck.

88TPI406GTA

RB...I appreciate the input....

You are probably right...I remembered that the reason that the cooling passage is changed is due to the larger 220cc intake runner...

The engine is assembled and dropped into the car right now...maybe it is me, but given that I am this far, I am going to leave it as-is...look for a post from me next year, after winter on the outcome

4mul8r

Here are the pics I promised. Sorry they aren't very detailed as my garage was a bit dark. I'll have to take a closer look tomorrow when it's light outside so that I can see these plug closer to see if they can be backed out with a screw driver or something.



Does it appear that only the top steam holes are plugged?

I think I will go ahead and drill the holes for them...it'll be a bit nerve-racking making holes in such an expensive set of very nicely ported heads.

I looked at my Summit receipt to see the brand of the radiator. It's Summit's brand. It's their aluminum two-row racing radiatorn SUM-380331. $179.95+tax. Would this be alright?....Or do I need something better? When I bought this I just had the Summit guy pick one out for me because at that time I just wanted something to replace my cracked radiator (which is one of the problems that killed my 350 just a day later) and didn't care as long as it worked. I didn't know I was going to end up with a steamy 406 or I would have probably spend the extra $200 for a real one.


The 406 will be EFI....fed by a ported Superram....which was supposed to go on the 350....Now it'll unfortunately probably end up being the biggest restriction on my new setup. But I don't want to nessesarily go with the stealth ram because the high rpm's it would require would probably tear apart the short block.

RB83L69

Yes, it looks like at that particular cyl pair, only the intake side one is plugged.

Just duct tape over the cyls and the valley and all, and take a small bit to it... doesn't have to be very large, just large enough to allow trapped gas to pass through, and not stop up with foreign matter in the cooling system. Like I said, 3/16" is what I usually use in heads; you could use that, or probably as small as 1/8", in that plug.

For the heads, lay a 400 head gasket on the heads with 2 drill bits in the dowel pin holes; mark them with a center punch; and go for it. On the exhaust side, drill them straight in, perpendicular to the deck. On the intake side, start the holes straight, and then once they get deep enough to hold the bit, angle them toward the exhaust side about 30°.