I saw a 400sbc with the steam holes plugged? Is there an advantage to having that or a mistake.

 

i think if the rpm's are keep above 3000, you can plug the holes. there are alot of circle track guys around here that do that. race only in my opinion

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86 camaro 405 sm. blk. th 350 tranny 3.42 gears

 

my heads don't have steam holes drilled and i haven't had any problems. a couple guys i know said it wasn't necesary and they didn't have them drilled on their 400s either. i am definitely in the minority on this debate, though. i don't think there is an advantage to plugging them.

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88 S10
Dropped 3/4
18" Boyd Coddington Timeless 5s
Dart equipped 406
12.20 @ 115.25 mph

 

craig are your steam holes plugged on yours?
406 S10 Man does your block have steam holes?

 

My 400 has them, and I drilled them in the heads to match.

Since adjacent cylinders are joined together, there's no water in between them. When the engine runs at low RPM for a while, it's possible for the water in there to boil, because it's moving so slowly. The steam holes just let this steam out and allow water to flow around there, to keep it from developing a hot spot.

It takes a good 3 minutes or so to install them in a pair of heads. You use a head gasket as a template, mark the holes with a punch, and drill them with a 3/16" drill bit.

The hottest place in a SBC is almost always the part of the head right above the center 2 exhaust ports. People do all sorts of things to force coolant to flow through there in preference to anywhere else. In a race-only motor, the steam holes are unnecessary because the water is flowing fast enough to keep steam from forming; so they're plugged up in order to force more water to flow through that critical center area.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Thanks for the help RB83L69.My car is going to be a everyday driver.

 

my block has the holes. the reason i didn't drill them is because my motor guy and some other people i know said i didn't have to. it is a long story, but getting anything done over there takes forever, so i thought if i don't need them, i would get on with the project and get it done.