Filling exhaust cross over

[Doom86]

I'm going to try a gallon of block filler wish me luck.

yes, wrong part of the head, while the package claims "cylinder walls" I think the max temp is only around 500*f....

And it's just that, "a claim". I would have to see it for my self at someone else expense to believe that. I started to use Quicksteel in the heads intake port but switched to moroso A&b. It would probably have worked but I think it's well established the moroso epoxy works great in a gasoline engine.

[RobZ28]

Hey Doom... TxTtopZ here - Are you going to post some pics with your findings here or are you going to post on TGO?

[beaker60]

My question,,,I have always just used the intake gaskets,,with the stainless block in them,,and now,,this post has got me to thinking,,and everyone on here has a lot more experience building high performance stuff than I,,so,,,my question is,,if you don't block the whole passage,,,at what point does that hole behind the exhaust valve start to create a flow issue.I have used these heads before,,but never in anything but a street engine,,nothing that is going to see the high side of 5000rpm,,if that.Have I been missing the boat by not blocking the entire passage,,or does it really matter on a mild street build.Thanks for any help

[Bob Hollinshead]

So what is the normal proceedure for filling with aluminum? Do you put something in the bowl to keep the aluminum where it needs to be and just drop in melted aluminum from the manifold side? Does it need to be poured in all one shot or can you melt and drop untill full?

[donc]

ThermoSteel, made by Blue Magic Conroe TX. 888-522-2746. It looks like castiron particles mixed in clear epoxy, takes a few days to cure in ex. crossovers.

[Dodge Freak]

I use those Fel Pro print-o-seal intake gasket with the steel shim in between but I drill a small 1/4 hole to allow some exhaust heat to the intake since its cool here in michigan more often then then hot.

I heard just blocking one head off shows some gain with allowing some heat to the intake. I tried it but like a small hole on both sides since its on the road till the winter salt trucks come out.

I believe for best power the whole port needs to be sealed so the middle 2 cylinders don't breathe each others exhaust fumes. That can be hard to do with iron heads, maybe today there is epoxy that holds up ?

[LoneRanger]

yes, as already mentioned I do believe Furnace cement works well, some claim up to 3,000 degrees resistance, I'm going to try it on my next engine build

In the past I've melted pistons to fill, & also made plugs to weld in, quite time consuming, using a cement would make it easier

I feel that blocking the hole in the bowl is the best approach

[bmahlosky]

Mondello sells zinc to fill the exhaust cross overs on the olds engines, I use junk holley carbs cut up and melted down to fill them for our nhra stockers, the alum shrinks after it cools and is loose in the cross overs.

[jeff swisher]

So are you stating the holley's melted are loose ..or the melted pistons are loose?

I know you can make a sheet metal dam in the ex port when pouring something into the hole.. this plugs it off pretty well.
Still some grinding in order when done though.

[rfoll]

I remember reading in one of Vizards books that "the heat riser crossover passage has little effect on flow".

[jeff swisher]

That is flow on a bench without reversion and pulses. completly different than what goes on inside of a running engine.

There are many things you can do to a head and lose flow but pick up power...Never rely on flow bench numbers only.

[bmahlosky]

By using zinc bars from Mondello or a cut up holley carb (made of zinc alloy) it seal up better, I have used alum once and when it cools it is usually loose. I think keeping the heat away from the intake manifold may have more of an effect than a flow increase.