Hows if goin GbodyForum . i am going to be revamping a 400SBC i picked up awhile back and i am debating on running a set of aluminum heads. motor will be a decent street motor with 9.5:1 or 10:1 compression . I have seen people say that steams are only needed if using a cast iron head and aluminum heads may crack if steam holes are drilled out. i always thought on any 400 street motor that steam holes were a necessity. Would like some feedback on this.
400SBC WITH ALUMINUM HEADS
- Thread starter 81msw79
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Check and you may find out the aluminum heads you are interested in already have the steam holes, if not you may want to look at a different brand of heads.
Do the steam holes. Small price up front to avoid problems later. Choose the biggest valves to maximize performance later. Consider 5.7 or 6.0 rods when you choose pistons.
I will be running the factory rods and pistons. It is a low milage block with unmolested cylinder walls. Someone already went through the short block , looked like the weighed out rods and pistons then never completed the biuld. So i am having it fully hot tanked and cleaned up then using in my 81 malibu wagon. Finding heads with steam holes i only found one. Skipwhite on ebay with his "nbk" offers them with steam holes.
I have always drilled the steam holes in the heads using the head gasket as a template back when I had SBC 400's even aluminum heads and never had an issue.
I also have a set of the NKB heads from Skip White on the 355 SBC that's in my Regal project and I have them set up for hydraulic roller and with the PBM competition valves, nice heads for the money and it runs great even with me being in the beginning stages of tuning.
Any competent machine shop can drill heads for steam holes, particularly in aluminum. 400s are not so common anymore, so I expect this step gets skipped to save production costs.
I have an uncut 400 block, but I suspect it needs more than a hone. Saving it because 400 SBC. 😋
I have an uncut 400 block, but I suspect it needs more than a hone. Saving it because 400 SBC. 😋
For what it's worth, if you read the instructions for Edelbrock's aluminum SBC heads, they say that if the heads are going on a 400, the steam holes MUST be drilled. I had a 400 with heads (iron) that weren't drilled for the steam holes. It was a bad experience. I would drill the steam holes.
I am actually glad you chimed in and are also currently running the skipwhite heads. It makes me feel a little bit more comfortable considering some of the engine coverage you have shared with the forum with it steriod fed much larger big brother. i will probably just go for a set of those. maybe 2 sets as there is another 400 complete long block next town over from me.
thank you everyone for the input. i was pretty sure the guy saying they are not needed was either being lazy or just did not understand how much of a street motor this would be. this car usually sees 5-6000 miles per year. if it is nice out it gets driven.
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