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Do I really have to drill holes in my alumn heads for use on a 400 chevy engine. There must be away to get around this. Any body out there tried to run with out. I am still working on the engine so I have not drilled them yet. Thanks. Granite
 

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i drilled out my set of vortecs couple weeks ago. its simple just place the head with the combustion chamber facing up with the intake face away from you. place a 400 head gasket over the deck surface and carefully mark the 6 holes with a starting punch. the holes on the exhaust side should be drilled straight into the head.the holes on the intake side must be drilled at a 30 degree angle toward the exhaust side. i did it with a cordless drill and a protractor. its not too critical. there is plenty of meat where you will be drilling just keep the holes nice and straight.
 

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I just finished building a 408 using Brodix IK180'S and did not drill holes. As per there instructions included with the heads I opted to enlarged the center water passge holes in the head gaskets rather than drilling holes (ill admit, I was scared to). Although I have not driven the car yet I did break in the engine on a test stand. It ran just over 20 minutes at about 2200 RPM with no fan shroud and didnt get above 190.
I then installed the engine and it idled for about 45 minutes as I tuned it, checked for leaks and shot the ***** with a buddy... it didnt get above 180.

Like i said, it has not been driven yet so who knows what will happen under load in the middle of summer.

The set up
509 block bored .040 over
Performer intake
Moroso aluminum water pump
4 core radiator (out of a 79GMC)
Mechanical fan
brodix heads
comp 280 mag w/ 1.6 rollers
probe forged rotating assy w/ 5.7 rods, flat top pistons (9.96 CR)
 

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gilby246 said:
I just finished building a 408 using Brodix IK180'S and did not drill holes. As per there instructions included with the heads I opted to enlarged the center water passge holes in the head gaskets rather than drilling holes (ill admit, I was scared to). Although I have not driven the car yet I did break in the engine on a test stand. It ran just over 20 minutes at about 2200 RPM with no fan shroud and didnt get above 190.
I then installed the engine and it idled for about 45 minutes as I tuned it, checked for leaks and shot the ***** with a buddy... it didnt get above 180.

Like i said, it has not been driven yet so who knows what will happen under load in the middle of summer.

The set up
509 block bored .040 over
Performer intake
Moroso aluminum water pump
4 core radiator (out of a 79GMC)
Mechanical fan
brodix heads
comp 280 mag w/ 1.6 rollers
probe forged rotating assy w/ 5.7 rods, flat top pistons (9.96 CR)
TORQUE MONSTER! Carb size? What are you putting it in?

Details please... "As per there instructions included with the heads I opted to enlarged the center water passge holes in the head gaskets"
 

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I'm a cylinder head guy in a race engine shop. We do mostly oval track stuff. We use A LOT of Brodix heads. There are different ways to do the same thing so I'm not saying that anyone is wrong I'm just saying what has worked for me and I'm always willing to learn.
On a street car I will drill only the bottom (the spark plug side of the head)three "steam" holes in each head but smaller than the gasket hole. That just bleeds of the small pocket of air that can form at that area with a low (7-9lb) pressure radiator cap and the slower water cirulation at street RPMs.
The Brodix IK heads are a little thinner castings than their race heads. I would not drill the top three holes in each head.
I like Corteco (ex Detriot) head gaskets material better than Felpro but,Felpro has better water hole design. Felpros got to hard when they had to take the asbestos out of them. On Corteco gaskets I punch a 3/8" hole between the two holes at the center lower exhaust area. Some blocks need that hole to be drilled also. The Felpro gaskets have that hole.
If the engine is together it is not worth taking it apart for those holes. The temperature change is not big enough to be noticed on a temp gauge but, it does help locally to even the temps.
It is a good idea to run a small ground strap from one of the accessory bolt holes on the back of the heads to a bell housing bolt on each side and then from the trans to the frame. Electrolysis can be a problem (eats away the aluminum)because todays head gaskets work like insulators.
Have fun,Smokey
 

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71C10 said:
TORQUE MONSTER! Carb size? What are you putting it in?

Details please... "As per there instructions included with the heads I opted to enlarged the center water passge holes in the head gaskets"

the carb is a 670 street avenger .. I feel the carb may be a bit small but its only 5 months old so I dont plan on replacing it.....Its in a 70 chevelle

I used the flepro head gasket as recomended by Brodix. They say to enlarged the 6 water passage holes to AT LEAST 3/8. I beleive I enlarged all holes to 7/16. Figured it would be easier to get the engine to run warmer than to make it run cooler.

Like smokey said, not all 400 blocks have the lower center water passage in the block and must be drilled if going this route...luckily my 509 block had this water passage
 

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Thanks guys,
I ask because I'm gathering parts for my first SBC 400 build. I have/have ordered everything below except the head gaskets, carb, headers and oil pan. I never heard of the extra water passage, I'll have to check my block.

.040 over SBC 400, 9.0?? deck height block, ARP main stud kit
Scat Pro Comp cast steel 3.750 internally balanced crank
Scat Pro Comp 4340 6.000 I-beam rods 7/16 bolts
KB -4.8cc forged pistons, plasma moly rings
Professional products damper and flex-plate
Moroso oil pan, Melling HV oil pump
4.165 x .0?? Cometic head gaskets
AFR competition ported 220cc heads, 76cc chambers, milled to ??cc
Comp 12-771-8, 242/248 @ .050 solid street roller
Comp Pro Magnum 1.6/1.52 rockers
Performer RPM Air Gap intake
Pro-Systems 850 DP carb
MSD Pro Billet HEI
1.75 primary tube headers

I was going to adjust the ??'s to achieve a compression ratio in the mid-tens. But I've been thinking I may install the cam straight-up at a 110 intake centerline, instead of 106 and bump the compression to 11:1 since this is only a weekend toy.
 

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steam holes in alum heads 400 block

I bought trick flow alum. heads for my 400 SBC i drilled the six steam holes. the three holes are hard to hit, the picture i had showed drilling 45 degree holes! You have to drill them at 30 degree angle to hit the water passage. we had a hard time because we started out drilling at 45 degrees and they would not hit water passage!!!!! Have to drill 30 DEGREES!!!!!!

Doug
66 chevelle 406 SBC
 
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