I've had people ask me in the past if I fill heat crossovers, yes I do fill in heat crossovers for people.

 

What material do you use the fill the cross over? Also the picture of the exhaust pockets is fuzzy, do you have a better one?

jerry

 

I'm also wondering what material you use to fill the exhaust crossover? That pic looks like it was an aluminum slug that was driven in.

 

Jerry

I use a piston for the filling material. The head behind the filled head is not filled, I will post better pictures.

 

Ok here's some better pictures.

 

So, when part 7 gets published, today or tomorrow, you will see how much power this is worth, it’s a lot. But I know people that have used aluminum and with expansion and contraction it comes loose. I know old pistons are cheap and easy, but zinc is a much better option as it has almost identical expansion and contraction rates as cast iron.

pontiac?

 

You're right Pontiac???? we did the machine work for a friend of ours. I've been filling the exhaust crossover for 40 years like this, 0 problems. I just could never build a engine where the crossover gets into both ports.

 

I did something similar, milled the opening with a tapered end mill, then made the plug, kind of like a cork. Lots of work, but it was fun, (semi-retired moldmaker) had to hand fit some of the corners with a file and blue. No sealant needed, taper makes the seal as pressure is applied. Plugs can be removed if needed.

Aluminum manifold plug

Milling opening with tapered endmill

 

That doesn’t have quite the same effect if it’s still open behind it.

 

Please explain why. Assumed blocking off port and the dead air space behind would be beneficial, vs filling with a heat conductive metal.
TIA.

 

have you ever considered or used zamak 12 alloy to fill the ports?

 

No I haven't, and why would I when I get a perfect fill with aluminum. I have a furnace which makes it easy for this procedure. Some may not know this, but I do several sets of high end cylinder heads a month for the last 35 years with ZERO problem with an aluminum heat cross over fill.

 

oh I must of read it wrong. I thought you used a piston to melt down? Or do you buy straight aluminum ignot for your work.

 

Use old cast pistons , never had a problem

I fill from the seat side and put a small dam across the seat so I have a filled bowl to work with. Also preheat the head so there isn’t much shrinkage

 

I use pistons.

 

Got a steel barrel with a hole drilled in the bottom for the air inlet. $3 hair dryer from goodwill forcing air into the wood burner, fire extinguisher with the head cut off and hooks welded to the side. Melt down old pistons and pour it in.

 

Old pistons have the best material to meltdown and use for crossovers

 

I use za-12 in mine

 

Leftover freebies always help, but do the pistons leave some crud to scrape off the top or does the crud burn-off good enough?

 

I've never had to skim the top, that crud just stays put on top when I'm pouring.

 

thanks!

 

I don't have olds cast pistons, so I have to use the za12