To Steam or not to Steam that is the question. [Archive] - Team Camaro Tech

: To Steam or not to Steam that is the question.


black1969
Apr 19th, 11, 04:15 PM
I'm getting ready to start my 406 build and my buddy that is old school and has built alot of motors is telling me to drill the steam holes into my $2000 Track1 heads. I know the 400's have the holes and i know there are people that have them and people that don't. I'm just trying to figure out if it's something i need to do. I don't know that it matters but it is a 509 block and i'm running a Meizere 55gpm water pump this year. I also live up here in northeastern ohio and it don't get really hot for the most part.

Any help would be great,
Dave

srode
Apr 19th, 11, 04:22 PM
You don't need steam holes.

Vintage 68
Apr 19th, 11, 05:03 PM
This is usually one of those 'which is better, Vanilla or Chocolate' discussions ... ;)
Gm didn't spend thousands more retooling their production line(s) to drill those holes for no reason :noway:

But, again it depends on the intended use of the engine.
A new GM Bowtie 400 block does not have the holes in the deck - the stock replacement service block (when available) did ...
They are intended for two different purposes - the 'racing' block will see mostly high RPM use and water circulation (or air pockets) should not be an issue. Besides, it will recieve much more attention during the installation and the system will likely be pressure bleed to remove andy trapped air - the 'stock' block will see lots of lower RPM use and will suffer from entrapped air issues at the deck if the system is not properly filled. Head gasket issues will follow shortly after that ...

Soooo -
1st, follow the instructions from your head manufacturer! If they recommend holes for you intended use and duty cycles then do it and don't listen to anyone else - if they say it doesn't matter, start a 'Pole' thread and use the vote outcome ... it won't matter ...(I believe Dart still recommends them for the Iron heads and says 'it doesn't matter' on the Aluminum ...)
2nd - make sure your machinist knows your intended use for the combo he's building and listen to him. If your starting with a block with no holes he may prefere to leave it that way - or not ...
3rd - listen to the "Old's Cool" guys, many of them (us) have fixed issues do to this before ;)

Hopefully Royce, Mark and others who have build reliable 4.125" blocks will chime in with their thoughts.

BTW - I ALWAYS drill them in Marine engines :yes:

prostreet69camaro
Apr 19th, 11, 05:22 PM
I had a 406 years ago when Lunati sold there Super Bracket Kits. It was a 4 bolt block. They took the big cooling holes and tapped them and put plugs in. The plugs had like a 5/8 to 3/4" hole. They used this to reenforce the block around those holes.

I also had the Track One heads and I called Brodix and they said I didnt need the holes so I did not drill them. They might have changed since then because this was about 10 years ago.

I never had any cooling issues with the motor. It was a great motor and is still going in a buddies 55 chevy.

DOUG G
Apr 19th, 11, 05:56 PM
509 400 +.030 (406) here

NO holes.....BUT !!!!!!!!!

If you have a high stall converter,low gears (4.XX +),don't drive it a lot on the street in stop and go traffic....NO holes are fine.

If you plan on cruising the hiway,driving in parades,and other slow/stop and go traffic...drill them.

This is my .02

black1969
Apr 19th, 11, 06:28 PM
My wife and I take the car to cruise-in's and car shows. I stay local and sometimes take it one the hwy depending on where we go. I don't beat on it but I do drive it like I own it. I built one a fews ago with these same heads that didn't have steam holes with almost the same set-up. The block did have some very small cracks by the head bolts. The machine shop didn't know for sure if it was from not having steam holes or not. So that is why on this build i'm trying to double check everything. My old block held up for almost 11 yrs before i tore it down.

markw
Apr 19th, 11, 07:14 PM
You'll hear from all kinds of people who don't drill them and say they are fine. Then again most head manufacturers recommend them. I haven't heard a convincing argument for not drilling them. If you swap the heads to a 350 block the holes are covered by the gasket so you're not limiting the heads to a 400. Steam pockets in the head can cause hot spots, leading to preignition and even cracking. Water pump flow won't help. Even a white water river has 'dead' zones near the banks if the shoreline forms a pocket. What's the problem with drilling the holes? And what's the problem with not drilling them?

ss27
Apr 19th, 11, 07:37 PM
Dave if the car spends any time at all on the street you must drill the holes if its a track car then dont drill . I am also old school and i have always drilled them and never had a problem with over heating or gaskets . Build the block right use deck plates for boring plateau finish square and surface the decks align hone the mains and lightlly hone the lifter bores with a worn out BRM ball hone if your using a F/T cam, and you will have a nice 406 . LISTEN TO YOUR FRIEND. ALEX

68rs406
Apr 19th, 11, 09:36 PM
Oh dear god, please do a search on this one and sit down with a nice cold drink of choice....:D

Short answer;
(1) drill them if you own a taxicab in Arizona that will spend hours idling at less than 1800rpm.
(2) don't drill them if (1) does not apply..... Which is the only reason GM did it to begin with. ;)

Remember this, GM did it for larger passenger cars and trucks which the 400 came in, to cover all bases. Dart, and every single aftermarket block manufacturer, including GM, that still produces a siamesed blocks does not put holes in the blocks. A high flow pump and a car that spends most its time above 1800rpm will not need them. My 500+ horse 406 spent 99% of it's life on the street and ran 180 all day long, and every single guy I know that runs or ran a 400 based gm block has never drilled steam holes.

Bottom line.. if your gonna lose sleep have them drilled (but have them drilled, I have heard many stories of incorrectly drilling them at home). But ya dont need 'em :D

97Z4C
Apr 19th, 11, 10:37 PM
i 2nd sean on this one too---i had my 406 with track 1 and run forever without any holes

spideynut
Apr 20th, 11, 01:00 AM
I had them drilled. My theory was its a 400 the heads have steam holes...

Straight-line-69
Apr 21st, 11, 09:03 AM
The engineers at GM thought the steam holes were needed on Granny's 1975 Caprice Wagon with a SB-400 which had 8:1 compression. I contend, that once you add HP (which is the same as adding heat), the holes are even more needed.

You could have steam pockets though your coolant gauge (temp) says everything is fine.

Not only GM, but engineers of aftermarket heads recommend drilling the holes.

Here's a bulliten from Dart:

http://www.dartheads.com/products/aitdownloadablefiles/download/aitfile/aitfile_id/101/

...that says:

"In applications where a 400 engine block is used, you must drill six 9/64” steam holes in the
cylinder heads,.."

From Edelbrock here:

http://www.edelbrock.com/automotive_new/misc/tech_center/install/6000/60899.pdf

...it says:

"NOTE: YOU MUST DRILL “STEAM HOLES” IN CYLINDER HEADS
FOR 400 ENGINES"

From AFR here:

http://www.airflowresearch.com/sbc_faq.php#400blocks

...they say that:

"Steam holes are recommended for all 400 block applications..."

If you bought a new GM 400 block, part number 12480159 for example, it comes with instructions that explicitely say to drill holes with any cylinder heads used.

Ask yourself, what's the downside to drilling the holes? Now ask what's the downside to not drilling them?

PRO 48 Fleetline
Apr 21st, 11, 06:07 PM
Solid roller 406...No holes here 210 Pro-Filers!
If the engine is kept at a pretty decent rpm via gears etc. the steam pockets are cleared out no need on a street/strip car!
http://img685.imageshack.us/img685/4153/039ut.jpg
By profleetline (http://profile.imageshack.us/user/profleetline) at 2011-04-14
http://img249.imageshack.us/img249/9522/profiler057.jpg
By profleetline (http://profile.imageshack.us/user/profleetline) at 2010-11-19

Straight-line-69
Apr 21st, 11, 08:36 PM
I believe it's dicey to recommend to others to NOT drill the holes for a street driven rig. It's also unconvincing to say "no holes, no problems". How in the world would these folks know if he had steam pockets in the block or not? Because nothing's cracked yet? Not much of an endorsement.

In addition to the docs posted above that recommend steam holes, here are a half dozen more (I could post a hundred):

From John Lingenfelter: http://books.google.com/books?id=GUC52-afG5EC&pg=PA20&lpg=PA20&dq=steam+holes+400+heads&source=bl&ots=H_ZPDnaLXq&sig=Oc6F49iyfH3Jagg3HneSWI3TO70&hl=en&ei=7PGwTcfcOZOFtgfRhKHjCw&sa=X&oi=book_result&ct=result&resnum=5&ved=0CDsQ6AEwBDgo#v=onepage&q=steam%20holes%20400%20heads&f=false

From David Vizard: http://books.google.com/books?id=G2kUibvRUo8C&pg=PA18&lpg=PA18&dq=steam+holes+400+heads&source=bl&ots=mkhxnPC0Ks&sig=Zj-fJWcXnWJ9zRGMAPTw2OATFCo&hl=en&ei=KvawTfWOMYiWtwfCla3iCw&sa=X&oi=book_result&ct=result&resnum=10&ved=0CGEQ6AEwCTh4#v=onepage&q=steam%20holes%20400%20heads&f=false

http://www.carcraft.com/techarticles/400_small_block/index.html

http://www.gmperformanceparts.com/_res/pdf/MagazineArticles/ChevyHigh_HighFlowHappenings.pdf (see page 4)

http://books.google.com/books?id=AatRNAMAF0YC&pg=PA74&lpg=PA74&dq=steam+holes+400+heads&source=bl&ots=l6Gq63XqZI&sig=q23VV1_1A649O_btCkOtePzFKzk&hl=en&ei=oPSwTe7kNoa3twe6-ODfCw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBQQ6AEwADhQ#v=onepage&q=steam%20holes%20400%20heads&f=false

http://www.chevyhiperformance.com/techarticles/0610ch_gmpp_cylinder_head/dyno_run.html

Perhaps the "no holes, no problems" crowd could post docs that disagree with the above and we could compare.

68rs406
Apr 21st, 11, 09:14 PM
Haha, so as you can see OP we are all pretty much in agreement on this.....;) :D

Straightline, you are certainly adamant about your opinion on this. Do you have or know of any firsthand experience of issues related to not drilling the steam holes? I'd love to hear about it. I have numerous firsthand experiences of cases that no steam holes didn't cause problems. How do I know? Not one cooling issue on any of them. All performance builds, from 450 horse or so to about 600 (after that everyone I know goes with an aftermarket block).
All the references you list are easily explained in my opinion, CYA on the manufacturers behalf, in case the purchaser uses the part in an environment that would cause an issue, same reason GM did it.

I know a good number of performance engine builders that say the same thing, if the car sees use above 1800 rpm typically the holes are not needed. Dart and many others produce siamesed blocks, none of which have steam holes.

As I always point out when someone asks about this, go ahead and drill them if you will lose sleep over it. Im not saying your opinion or rationale is not correct, but I can agree to disagree, can you? :)

spideynut
Apr 21st, 11, 09:38 PM
Am I missing something here? Why would you not drill them? I really don't think race motors count in this discussion. Race motors are a whole other ball game. So I ask again why not?

97Z4C
Apr 21st, 11, 09:41 PM
i am totally with sean on this--never had problems over here and thats with 12.7 -1 comp - just going from my set up -if your loosing sleep over it -drill her

Lonnie P
Apr 22nd, 11, 08:59 AM
I guess a better question is.... what would it hurt to drill them?

If the holes do not cause a problem, why not just drill them & forget about it. We spend so much time carefully assembling our cars, why not spend the extra hour & drill them in the first place.

Straight-line-69
Apr 22nd, 11, 09:20 AM
Haha, so as you can see OP we are all pretty much in agreement on this.....;) :D

Straightline, you are certainly adamant about your opinion on this. Do you have or know of any firsthand experience of issues related to not drilling the steam holes? I'd love to hear about it,...CYA on the manufacturers behalf, in case the purchaser uses the part in an environment that would cause an issue, same reason GM did it,..if the car sees use above 1800 rpm typically the holes are not needed.

Dart and many others produce siamesed blocks, none of which have steam holes.

68rs,..yes, I agree to disagree.

As far as first hand experience with cracked 400 blocks, yes. It's one of the reasons there are very few 400 cores available today and if you find a good core, you'll need a large quantity of pesos to buy it. Don't take my word for it. Call your local machine shop and ask how many cracked 400 blocks he's seen through the years.

CYA? You help me make my point. The engineers and engine builders instruct us to drill the holes to keep warranty claims at a minimum. Also, if David Vizard and John Lingenfelter instruct us to drill the holes (see earlier links), that's all the recommendation I need.

I agree,..a few aftermarket 400 blocks are not tapped with steam holes. To solve the problem of steam pockets, they engineered much larger coolant passages in their 'no steam holes' 400 blocks. For instance, the World Products Motown II 400 block has "152 fluid ounces of coolant per side". That's 155% of the cooling capacity of a GM block from the 70's. Also, the water jackets are "expanded for better cooling". This info is found here:

http://www.worldcastings.com/products/motown-ii-400m-iron-block.html

As far as Dart, from here:

http://www.dartheads.com/products/aitdownloadablefiles/download/aitfile/aitfile_id/116/

...it says:

"In applications where a 400 engine block is used, you must drill six 9/64” steam holes in the
cylinder heads."

(Why is it that I'm the only one supporting my position with credible docs?)

FWIW

Vintage 68
Apr 22nd, 11, 10:17 AM
...

(Why is it that I'm the only one supporting my position with credible docs?)

FWIW

l:) because I knew that most "to drill or not to drill" threads tend to have folks on both sides - and I hate to 'cloud an issue with facts' :D

Like I stated - read the posts and the reasoning(s), review your build and needs and consult with your machinist - then make your choice and take the outcome ... it may, or may not, matter in the long run ... depending on who you've talked to :D

I've only done one build without them - it was/is a matchrace engine and only see's use a few times a year.
It's been just fine the couple of times it's been apart for inspection ...

I've replaced 6~7 marine 400 blocks for cracks - they happen.
I also started to drill/tap and install deck plugs in them years ago - it helps, but doen't completely eliminate the possiblility of cracking ...

97Z4C
Apr 22nd, 11, 10:38 AM
the cracks in the factory blocks is not from not drilling heads --from the thickness of cylinder walls

Vintage 68
Apr 22nd, 11, 10:49 AM
the cracks in the factory blocks is not from not drilling heads --from the thickness of cylinder walls

No one was saying they were ;)

Straight-line-69
Apr 22nd, 11, 11:42 AM
the cracks in the factory blocks is not from not drilling heads --from the thickness of cylinder walls

....caused by heat and stress.

68rs406
Apr 22nd, 11, 08:23 PM
the cracks in the factory blocks is not from not drilling heads --from the thickness of cylinder walls

Thats exactly right, they have nothing to do with the steam holes, they crack at the lifter gallery, they crack between the freeze plugs, and they crack at the head bolt bosses. Steam holes have nothing to do with it.
I don't need to call any machine shops to find this out either, I have several buddies that own machine shops and have seen it first hand. I have had 400 blocks with cracks, and all of them had factory heads with steam holes when I bought them as cores. Hmm. Why do they crack? Because they are 30+ years old and came from vans, trucks and big cars that have been abused for years, and the factory blocks are really marginal at best, they are a mass produced piece of sand cast iron.

I worked as a mechanic in the late 80's and the 400's had a bad rep then for overheating (back when the only guys using 400 cores where 410 class sprint car guys). That was with stock heads with steam holes drilled in them by GM. What was wrong with them? Cracks in the heads and at the steam holes in the heads... Talk to an old timer that knew 400's back when they came out in passenger cars new, they were legendary over heaters. Remember this is in a stock deal, with factory steam holes. Now that the only people that build them are performance guys (not race motors, I know very few who use a 400 gm block as an actual race motor, because they are not a great platform), how often do you hear of failures because of no steam holes? I know of none. They do crack though, just not from lack of steam holes, but from core shift, poor castings and old age.


To the original poster of this thread destined for train wreck ;):D , ask yourself this, if you trust your machinist enough to build your motor, then trust him with his advice on steam holes, whatever that may be. I know what every machinist I know has said regarding this topic, but maybe they don't have access to all these cool links to articles on the 'net ;)

(Why is it that I'm the only one supporting my position with credible docs?)

Because apparently you have a whole lot more time on your hands than me, I guess I'll just have to speak on a basis of firsthand personal experience instead.... fwiw :D

Honestly straightline, I'm glad you are supportive of your stance on this, and nothing personal here. You keep drilling them and I'm going to go ahead and not (though I'm pretty sure I traded away the last GM 400 core I'll use).... If it makes you feel better I did drill the spark plug cooling holes in my siamesed little M block for the cooling holes in my SB2 heads, I guess you can say I have gone to the 'other side' now...:)

97Z4C
Apr 22nd, 11, 09:00 PM
lol--i believe the issue on strength on 400 blocks but i have done everything with a 400 block and never killed it, i had a 74 camaro that i installed a 406 for strip only-2yrs later tried a 377 on same block (destroked 400) and ran it for a season and sold the car without motor-3yrs later i got into texas outlaw 10.5--i took that factory and carved it out so my 434 assy would fit-i put the biggest small base circle cam i could get in it and put a 400 shot plate system to it(with the track 1 heads) 5.60s in 1/8---i never killed that motor, but my butt was sure puckerd up everytime i ran it because my whole clearance around --cam to rod---rod to block ect was between .032 - .039 if it blew , it wasnt gonna be nice--i sold the car after 1 full season but the motor was still getting it

68rs406
Apr 22nd, 11, 09:09 PM
lol--i believe the issue on strength on 400 blocks but i have done everything with a 400 block and never killed it, i had a 74 camaro that i installed a 406 for strip only-2yrs later tried a 377 on same block (destroked 400) and ran it for a season and sold the car without motor-3yrs later i got into texas outlaw 10.5--i took that factory and carved it out so my 434 assy would fit-i put the biggest small base circle cam i could get in it and put a 400 shot plate system to it(with the track 1 heads) 5.60s in 1/8---i never killed that motor, but my butt was sure puckerd up everytime i ran it because my whole clearance around --cam to rod---rod to block ect was between .032 - .039 if it blew , it wasnt gonna be nice--i sold the car after 1 full season but the motor was still getting it

Impressive! I have a buddy that ran a 434 with a stock splayed cap block (no steam holes..lol), it was a bracket car and he raced it season after season and it never gave up, leakdown never really changed. But I had another buddy that ran a 406 with about a 200-250 horse shot and the caps walked all mover the place and he played hell with the mainline, he put a killer LA Billet crank in it and that helped, but it still killed mains eventually. He was running high 9's in a 3200# 62 Nova, no dyno numbers to say what HP he was at. He has two little M based 400's now that go 9's on the motor. Some stock blocks just seem to live, maybe out of pure tenacity. :D

Texas outlaw 10.5? Is that like the true 10.5 classes? We run a car in outlaw 10.5 with a 10.5w, like PSCA rules. Fun class but it's getting stupid expensive unfortunately for us low buck (comparatively, lol) guys.

97Z4C
Apr 22nd, 11, 09:44 PM
yep its the same class--yeah i cant run with that anymore-that was 8 yrs ago-turbos has taken over--my friend has a 98 camaro with 421 sbc twin turbo and nos--212mph in 1/4 unreal

68rs406
Apr 23rd, 11, 12:17 PM
yep its the same class--yeah i cant run with that anymore-that was 8 yrs ago-turbos has taken over--my friend has a 98 camaro with 421 sbc twin turbo and nos--212mph in 1/4 unreal

Yeah the cars are insane now, they are basically race teams. We can run in the field at races like the SCSN in Vegas in outlaw, but we are top 20 or so now with a car than went 7.23 at 190 and we were top 10 running 7.50 when they first started running the event.
We were one of the rare nitrous cars, 706" and three stages. But you can't compete too well without really leaning on the tune up, we had the car pretty reliable but you have to step it up, then if you pedal it at all you are puttting slugs in it between rounds.... ask me how I know,lol.

My buddy that owns the car is actually working on getting a new program together, he got fed up with nitrous and getting beat by blower cars and sold his nitrous stuff, going with an F3R on his big block, 680" now. Should be pretty wicked. But we will still be out of our league....:D

Straight-line-69
Apr 23rd, 11, 09:18 PM
..they (machinists) don't have access to all these cool links to articles on the 'net,..Because apparently you have a whole lot more time on your hands than me. Honestly straightline, I'm glad you are supportive of your stance on this, and nothing personal here.

Ok, ok, 68rs,..you win . Steam holes are completely useless, a bad idea, and a waste of time. Besides, who says steam pockets are harmful to begin with?

OP,..forget what the engineers say. Forget what the manufucturers of aftermarket cylinder heads say. Forget what David Vizard and John Lingenfelter say (who are they anyway?). Just go with the unsupported opinion of a few blokes on the internet and move on. (You say you're working on your brakes next?). It's agreed 400's run hot, and drilling the holes will mitigate some of that (localized) heat, but think of ALL the things your could do with the hundreds of dollars and/or hours (upon hours) of time, instead of messing with pointless steam holes.

And just because GM drilled steam holes into the heads 500,000 small block 400's, that doesn't mean the engineers believed them to be necessary. Like me, GM probably "had too much time on their hands".

I'm glad this didn't get personal.

68rs406
Apr 23rd, 11, 10:36 PM
Ok, ok, 68rs,..you win . Steam holes are completely useless, a bad idea, and a waste of time. Besides, who says steam pockets are harmful to begin with?

OP,..forget what the engineers say. Forget what the manufucturers of aftermarket cylinder heads say. Forget what David Vizard and John Lingenfelter say (who are they anyway?). Just go with the unsupported opinion of a few blokes on the internet and move on. (You say you're working on your brakes next?). It's agreed 400's run hot, and drilling the holes will mitigate some of that heat, but think of ALL the things your could do with the hundreds of dollars and/or hours (upon hours) of time, instead of messing with steam holes.

And just because GM drilled steam holes into the heads 500,000 small block 400's, that doesn't mean the engineers believed them to be necessary. Like me, GM probably "had too much time on their hands".

I'm glad this didn't get personal.

Straightline, I think you need a hug....
I wonder if anyone else is reading what I said as "steam holes are useless..etc etc..." , there's a good chance you have misinterpreted.
To quote a Geico commercial, tissue? :)

97Z4C
Apr 24th, 11, 12:48 PM
nothing pwersonal here-if you think you need to -drill em----sean my other friend down here has run outlaw forever and has a speed shop-and he cant run withem because his fuel management system for his twin turbo 760 bbc is gonna cost 40 grand-its crazy-they built a home made 888ci bbc for a customer -heads was made from scratch billet alum. made 3600hp but only lasted 8 runs during that time -it set nationally 1/8 mile track record and the cost for that 8 run motor 120 grand --so i stay with my 6.0 heads up class good luck with that car and keep me informed-the 98 with the 421 makes the 8 races accross the country in outlaw--if you see that black camaro -check it out

Vintage 68
Apr 25th, 11, 08:59 AM
YouTube - BEATING A DEAD HORSE WHILE PLAYING FITTING MUSIC

I knew this thread was heading this way from the start l:)

Truth be told, I usually just drill them (like I said) and just don't bring it up when talking with the engine customer :D

68rs406
Apr 25th, 11, 05:47 PM
Now thats funny John....:D Remember Benny Hill?

The 'ol steam hole debate, I knew nothing good would come of it...;)

68rs406
Apr 25th, 11, 05:55 PM
nothing pwersonal here-if you think you need to -drill em----sean my other friend down here has run outlaw forever and has a speed shop-and he cant run withem because his fuel management system for his twin turbo 760 bbc is gonna cost 40 grand-its crazy-they built a home made 888ci bbc for a customer -heads was made from scratch billet alum. made 3600hp but only lasted 8 runs during that time -it set nationally 1/8 mile track record and the cost for that 8 run motor 120 grand --so i stay with my 6.0 heads up class good luck with that car and keep me informed-the 98 with the 421 makes the 8 races accross the country in outlaw--if you see that black camaro -check it out

Nice Darrell. The money spent on the pro street cars is really stupid, and they are running 5's now...wth? All they are anymore is purpose built race cars and pro mods at race weight. Some friends of ours are running their pro mod Camaro in the pro street class and have a helluva time making the field sometimes running low 6's, they have a bunch of money in it too, one of the few nitrous cars left in the class.

Thanks, yeah we took last year off because the owner was out of work and kind of got burned out, then against my wishes (it's his car though..) he took it to Vegas and windowed the block from pedaling it.. not good. That was the end of nitrous for him. He's going FI too, on alcohol, using a big stuff III. Pretty nice stuff and seems pretty user friendly, guess I'll find out, lol.
I'll definitely keep you posted, and watch for the Camaro!

Vintage 68
Apr 26th, 11, 07:53 AM
:D Remember Benny Hill?


Sure do - it was as close as you could come to 'porn' on TV when I was a kid :thumbsup:


... The 'ol steam hole debate, I knew nothing good would come of it...;)


And never will :beers:

BTW - Vanilla is MUCH better than Chocolate :yes:

68rs406
Apr 26th, 11, 11:35 AM
BTW - Vanilla is MUCH better than Chocolate :yes:

Whoa whoa whoa now you stepped over the line, thats plain crazy talk! :D

black1969
Apr 27th, 11, 05:27 AM
Wow.. Just got back from vacation and didn't think this thread would get that much attention to tell you the truth. Hope everyone is still friends..lol. I did do some research on here before I put the post on here but didn't really see an ad that debated good from bad so that is why I started it. I guess i should have looked a little harder.
I have been building motors for a long time but this is my first 406 so I wanted to make sure i did it right the first time. My buddy built a 400 a long time ago and drilled his but he wasn't making the kind of power this one will, and he was running cast heads.
Anyway, sorry about the post I didn't know it would get out of control. Thanks for everyone's input it is very helpfull.

MW67RS
Apr 27th, 11, 06:59 AM
Dave,

I am also building a 406 with AFR heads and am considering this issue as well. I have read through this thread and don't think it is as clear cut as stated. I would think that the need for the holes would be the same no mater which aluminum heads you use but if you look at the head manufacturers they are all over the place. Brodix says you don't need any. Canfield says to drill the 3 holes on the exhaust side and the center hole on the intake side. Edlebrock says to only drill the 3 holes on the exhaust side. AFR says to drill all 6 holes. When the head manufacturers can't agree what is needed I causes customers like me to wander how many if any are needed.

Since most manufacturers recommend drilling the 3 holes on the exhaust side I plan to drill them. They make the most sense to me since they are on the bottom side of the cylinders and any steam that builds up in these locations has no where to go. I am not going to drill the holes on the intake side because any steam that builds on this side of the cylinders is free to move up the deck and into the intake stream and work its way out. Also, the holes on the intake side must be drill at a 30 degree angle from the deck. I am very concerned about drilling a hole at such a shallow angle.

I don't really have a recommendation for you. I think this is something we all have to decide for our selves. This is what I have decided to do and I am comfortable with my decision. Good look with yours.

Matt

Vintage 68
Apr 27th, 11, 08:06 AM
Wow...
Anyway, sorry about the post I didn't know it would get out of control. Thanks for everyone's input it is very helpfull.

Don't say we didn't warn you l:)

This topic comes as close to an 'off-topic' thread as I'd ever enter into, and I only posted in this one because it was in the "Engine" forum and not the 'Performance' forum - things get just plain crazy over there when this type of topic comes up :p
It's no big deal really - we won't be sending boxes of 'do-do' (PC ;) ) to each others houses after this ... well maybe that one guy (j/k!) :D
I think we'll all continue to build them the way we think best and probably get near equal results for our efforts truthfully :thumbsup:

As stated above, and in one of my earlier posts, do what the head/block supplier for your project recommends and you'll be fine - and covered under their policies if something were to go wrong, maybe ...

As the English say - 'Keep Calm and Carry On' :beers: