Chevy 400 cooling "mods"

[rockosocko]

Good morning guys.
I'm wanting to install a 406 that I built up about 20+yrs ago into a '95 chevy 2500/5spd as my daily (blew head gasket or cracked head) but i installed
Twisted wedge heads back then.
Well, Now I'm wanting to pull those off and install a set of ported Vortec's and several days ago read somewhere that you don't "NEED" the steam holes but rather
drill the deck with 3/8ths holes through the gasket and reroute the exterior cooling lines up top.
(in addition to that, I've also read of too many issues running the trick flow heads, and don't need to be pulling this motor again in a 1000mi or so..)

Well, it's my weekend and want to get this motor stabbed in (had to wait for the coldest days so far) and hopefully running by Monday or..

I CAN'T for the life of me find the Youtube vids and or threads showing what holes to drill in the BLOCK (not heads) I'm not going to get into a machine shop over the weekend, especially this close to Christmas and can drill the 3/8 ones myself here. (saw them at work but can't find them now at home..)

Anyone have the pics/vids of what and where to drill them? (THE BLOCK, NOT HEADS)
Oh, and the same for the lines in/from manifold?

Thanks in advance.
Errol

[pdq67]

Reading right along..

Also wanting to know.

pdq67

[cgarb]

Seems like a lot of trouble to drill the block when you can use the head gasket as a template and drill the steam holes.

[rfoll]

IMG.pdf

From How to build big inch Chevy small blocks.

[rfoll]

IMG.pdf

Sorry, no matter what I tried, the scanned picture doesn't show well. The description should help.

[Kevin Johnson]

https://books.google.com/books?id=tXkav ... 22&f=false

Hope this helps: scroll up to see the picture.

[pamotorman]

here is the drawing for brownfield heads

[DaveMcLain]

I would just drill the steam holes but only do the exhaust side ones. It is only three holes to keep residual air from getting trapped under the deck where two cylinders are adjacent.

[pamotorman]

the NASCAR chevy engines with siamese cylinders they drilled thru the side of the block and then drilled thru the wall between the 2 cylinders to allow coolant to flow there to cool the head gasket in that area between the cylinders

[pdq67]

[quote="pamotorman", the NASCAR chevy engines with siamese cylinders they drilled thru the side of the block and then drilled thru the wall between the 2 cylinders to allow coolant to flow there to cool the head gasket in that area between the cylinders[/quote]

I have read about this being done and to me, it's like a "root canal",..

And I did drill my virgin -461 big valve heads so know. And they have threaded and pinned studs and they are fine...

My virgin big valve -291 big valve heads are still stock...

pdq67

[rockosocko]

Thanks again guys! I've already drilled the trick flow heads back when I installed them.
I was more after the holes that get drilled in the deck of the BLOCK face.
Kevin Johnson-- Thank you. One of the pics of the link you gave shows the holes to drill.
PDq67-- click on Kevins link and scroll down to "COOL HOLES" That's what I was referring to.

BUT, don't want to get anyone upset but I think I'm just going to run the 406 as is. (with the trick-flow heads) It's more of a time constraint. (Well $$$ too)
I'm knocking on 54 and "things" just don't go as nicely and seems to take longer to heal. I don't think I'll be revving it up so maybe I'll be ok as a daily..

On a side note, When I took apart the 'stock' 350 I did find the worst headgasket blow AND something I've never seen, as in a crack going from cyl 4-6 Perpendicular..
I've seen the cracks go from jacket hole to stud hole, but not cross ways.. Don't really want to toss a good 4bolt block, and wondering if it can be decked past this crack. The pistons look to be about .040 in the hole, but will get a rough measurement tomorrow.

Errol

[F-BIRD'88]

On my vortec headed 400SBC I did not drill anything.

Get a vortec style intake manifold that has the extra water ports on the rear near the distributor.
Re route the heater hose from the front of the intake to the left (drivers side) rear water port. The other end goes to the water pump.
This improves overall cooling, eliminates thermostat surging during warm up
and eliminates trapped coolant.
Many of the aftermarket vortec type intake manifolds have these extra rear water ports. This is the early 1960's OEM pre emissions era heater hose circuit routing.

[JoePorting]

The deck hole you are talking about is the hole between the two exhaust ports. Some 400 blocks have them drilled already but others don't. Just use the head gasket as a template and drill the block. Make sure the head is also drilled in the same area.