Drilling Steam Holes for 400 Small Block Chevys in FloTek 102-505 Heads - Steam Hole Mod.
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- Опубліковано 27 сер 2024
- This is our way of modifying the wonderful FloTek 102-505 aluminum Small Block Chevy head for use on a 400 Small Block which requires steam holes.
I am SURE FloTek can provide this service if you contact them, as I rank their customer service A1+. I spoke with Stephanie and was told of I had ANY questions at all to just call and ask.
I had no problems (thank goodness) doing this mod on my back porch floor, although a drill press would have been the best way.
I have slinder fingers and could feel the "pads" and the support casting that is in between the cylinders and hit every one, adjusting the angle of the drill as needed for each hole. I started with 30* but ended up with what looks like 40* or so. No structural integrity was compromised with this modification if done without hitting the inside support cross casting.
I used a 9/64" bit for all of the holes and enlarged the exhaust side holes to 13/64" and radiused the holes with a 1/2" bit for the specifics on MY modifications. I may enlarge the bottom (exhaust side) holes if I feel it is needed.
I hope this helps others out with their questions and please give a like if you think its worth it!
I marked the spots to drill with a FelPro #8364PT gasket and center punched the holes so the drill wouldn't walk on me. Go SLOW!!!
Thanks to FloTek for the great customer support!!!
Marty Wilson
Wilson Racing and Engine Shop
I tried calling Flotek's customer service for answers about this since their website says "contact us about 400 sbc". Never heard back from them after numerous attempts. I found out more from your video than I ever could from the people that make and sell these heads. Thanks for posting!
@silverstreak232 Thank you! That is why I made the video. That sucks you can't get ahold if them because I have another 400 SBC that I wanted a set of their 200cc Hydraulic Roller heads too.
If I am able to get ahold of someone, I will post it here. Thank you again :)
My experiences ! I simply drilled them straight down and use the 350 head gasket for a template. I did at six pairs of heads that way with no problems. Great job
Thanks, I just wanted to show that you didn't have to have a machine shop do the work. A jig for the head and a DRILL PRESS would have made the work A LOT FASTER, but the hand drill works and the motor has 5k on it now and runs very good. The heads are on my son's 1986 Z28 that has my 400 SBC in it and they work very well. I wish I had bought the 210cc instead of the 180cc runner model is all. Flotek is a good American company and I would buy their heads again. Probably would upgrade to hi pressure springs, for those interested.
Good job man!
Have ran 305 heads on a 400, did not drill holes. Bigger valves n such but didn’t drill the holes. Ran circle track 1/2 mile 7000 rpm never overheated.
Just a note for all this is true although real street engines that expect to be used and get into daily stop and go traffic it could happen to though. i am have always been told or taught to drill the holes, automotive books and magazines, engine builders, shop class, etc. the common phrase is. " . . . and don't forget to drill the steam holes in the heads since its a 400 sbc"! And have seen or heard about many station wagons with 400 sbc overheating on side of road. The fact is the cylinder bores being larger and the block's original design water jackets are changed and make steam, weather or not it returns to coolant or water is the issue, once cavitation begins and nowhere for steam to return to water coolant, it cavitates, and the coolant or water boils at a lower temperature as pressure goes down and steam pressure builds up. In a moving race car this doesn't happen because of good coolant flow and cycling and other cooling and simply constant ventilation at high speeds. However, aftermarket block designs have fixed the steam pocket in the block issue because of superior design. The 400 sbc is a modified by gm '350' and they overlooked other design potential. However the 400 factory block is still a great engine And in my opinion should be the stock factory block design and should have replaced the 350. However, without the overlooked water jacket design flaw. Aftermarket blocks by dart and all others do not need steam drilled heads.
The idle is what kills it
That's how we do all of our 400 based sbc, circle track engines. Never have any issues as well.
Are they stock heads or aftermarket???
Put a drill bit into each hole and see if they are in fact drilled straight. The holes in the heads simply need to intersect the water coolant passage in the heads and the factory drills the bottom holes straight too but the top 3 are angled back and into the water jacket area. Idk what you might run into if the top holes were drilled straight. I spoke with FloTek before I attempted this mod myself and that is what they told me.
you really only need the bottom (spark plug side) holes in the 400. The top of the siamese cylinders will rise and flow to/ thru the top of the block/cylinder head coolant holes.
I have never seen a 400 block being sleeved, so no idea: does the block casting area serving the upper head bolt have a boss area capable of trapping steam near the deck? GM has gotten into trouble over the years where they repurposed old castings in a "bridge too far" moment - the most egregious one was late 70's where they took a gas block, resleeved it, and pretemded it was good for diesel service. Junk.
@@flinch622 the bottom holes vent the steam/water trapped by the siamese cylinders. since steam/hot water rises it can escape thru the upper water vents in the head. The roundy-round racers and smart street guys provide a "vent" at the rear of the heads to increase circulation and help cylinders 7 & 8 run at temps similar to the front cylinders. This additional circulation also aids in removing any steam captured at the top of the block.
I had a 400 Chevy in my 1946 Chevy coupe, it kept running hot & overheating,put a wind high flow water pump, electric fan, bigger fan on water pump, still run hot ! Put built 350 in, no problems ! But it don't have the power or torque the 400 did ! The 400 was a brute !!
We run a 4 core Champion Aluminum radiator, high flow water pump and twin Spal fans with a fan shroud to keep our beast as cool as possible.
I actually had to drill a hole in my friends 350 Chevy block when he used trick flow heads .
What was the reason for needing that extra hole? You can use 400 heads on any other small block but not Visa Versa as GM designed it. Just wondering. Thanks for watching!!! It was nerve racking but worked out just fine and the motor is very street gnarly.
@Marty Wilson, Wilson Engine Shop Maby because the 400 had a simease block and it would help in better cooling ? I never really used the 400 small block only the 350 small block. I remember the 400 wasn't a proformance engine. But later realized it's actually a good engine but the heads GM used on it were junk as the combustion chambers were too big at 76 CC. Now a days companies like Dart make these blocks that are far superior to the old 400 blocks of the mid to late 70s
Oh I understand. In "my" day, a 400 was a "smog" motor. Thank you for the reply so others can have opinions! I appreciate all of the options and opinions.
Just curious what size holes did ypu drill
If I recall, it was an odd size but I matched the size with the block hole size.
BTW, that engine in a full wt Z28 took a V8 Swap S10 in Mexico last nite and never got over 195* . 😎
Do all SBC 400ci motors need those steam holes drilled?
Well GM did it to keep the cylinders as cool as possible since they are a siamese cylinder block, meaning there isn't enough room for water to flow BETWEEN the cylinders so I drilled my set of heads to flow like the block is made.
I have had comments that they don't need it but I build motors and modify them. I think that you SHOULD have the holes so you are cooling those cylinder walls but I am sure some racers may not deem it necessary. This motor is in a street car that drives anywhere we want so I took the precautions to keep it cool and all has worked out very very good.
FloTek, the head manufacturer, said I could send them in and they would do it but like our motto #WEMODIFYEVERYTHING, I did it myself.
Theses These were aluminum heads so they were easier to mod than a cast iron head.
Thanks for following!!!
This motor is in the 1986 Red Z28 that runs 13.4 in full stock weight. Check out those videos if you'd like :)
I heard it wasn't a bad idea to drill those holes, but if you want a performance engine don't use the stock heads GM installed on the 400 block as they were a crappy head at too big of a combustion chamber at 76 cc 's
Hi, I have a 400 and it looks like the holes were drilled straight in, not angled. Is this a problem? I pulled the motor apart because it got hot breaking it in, it ran hot immediately upon driving (225 going up n up n up) and oil pressure was garbage! So I pulled it apart and sure enough the mains are wiped
As long as the holes made it to the coolant area you should be good. The reason for the angled holes on the intake side is to break through the thick casting and into the coolant chamber. If you look in the passages on the exhaust side, you can see if it is hollow or has casting inside toward the other holes.
Use brake fluid for cutting lubrication
This gives me anxiety
Me too but you can do it. Just don't let the drill bit walk when you start so a center punch is a good thing to use. Put the headgasket on he head to mark the punch holes before anything, or that is what I did. I used it as a "template" for where to drill.
@@martywilsonwilsonenginesho7940 that's for the knowledge
If your going to. Make a video people need to be able to hear you. Fix the sound
I guess my speech impediment bothers you. I am sorry. Maybe USE YOUR EYES if you are watching this video, ya think?
It is a VIDEO not audio helping chore for others to follow. Maybe fix your grammar???
@@martywilsonwilsonenginesho7940 I wasn’t criticizing your speech. Lol. The volume on the video is so low you can’t hear what you are saying
I was interested to hear what you were saying. You should turn the volume up in your editing software before post videos
@@mikeeagle2653
Well dam. On my end it was a bunch of drill noise. I'm sorry about the audio. Was as much about the placement of the holes as the angle. I don't have an editor so it is raw video.
Thanks.
Or dude can make his own video and not complain