Seff

I got my hands on a ruined 403 engine, cracked block. The block's been sold to someone with a fetish for making a coffee table out of it. Pistons and connecting rods are stock and thus not worth much, and the crank is sold already.

That leaves me with the 4A heads. I have a few different ideas.
- I could use them for porting practice, and sell them if they turn out okay. Lots of guys with 403- powered T/A's over here.
- I could weld up the chambers to reduce the CCs and maybe try to fabricate a better combustion chamber?
- Could the roof be raised somehow? Spacer, maybe? I seem to have heard that it's the major problem with Olds heads.
- Could a chamber insert be constructed? I've had luck pouring melted aluminum, and wonder if it could be done. An obvious concern is that it'd get knocked loose or crack.


Give me your wildest ideas, I wanna experiment.

olds 307 and 403

Use them for porting practice, they have a lot that needs removed.

67 Cutlass Freak

You might want to check out this thread that talks about using the 403 heads on other CI Olds engines-
http://realoldspower.prophpbb.com/to...lit=combustion chamber
If you are serious about modifying the combustion chamber, check out this video-
https://www.youtube.com/watch?v=MTgo...ature=youtu.be


I have recently done some port customizing by raising the roof, and filling the floor by welding it up. Keep an eye on the porting thread, soon I will post up photos, and flow bench results.

Seff

Nice reads, just what I needed. I have an electrode welder, will get some cast iron electrodes and get to work at some point.

We agree that the "kidney shape" is what I should be going for, yes?

67 Cutlass Freak

Seff you need to be real careful with welding in the chamber. I spoke with Rich Albright from Midwest Cylinder Head. He wrote the program for the CNC work that you saw in the video. They do the welding in an oven @ 1600 degrees. I will not attempt to weld in the chamber. It has to hold up to a lot more pressure than anything in the runner. He explained to me that every time the head goes into the oven it weakens it. The molecular structure changes. Did you notice how the head looked perfect after the cutter passed through the chamber. You can't tell where material was added. Rich also told me they had some problems. They filled the water jackets in the heads because he was going to run a dry deck on alcohol. He used hard block filler on one and epoxy on the other. The epoxy expanded and cracked that head. If you really just want to mess around with the welder and the grinder, that's fine - go for it, but I think you will render these heads useless if you try to weld in the chamber with your electrode welder. The "kidney been" chamber is the hot set up, but most of the heads using that also have relocated the spark plug placement for flame travel. Take a look at these Bulldog and Wise chambers -
0504phr_07_zoldsmobile_enginecylinder_heads.jpg
wisecombustionchamber.jpg

Seff

Yeah, that's the shape I was going to go for.

I hear you on the dodgy qualities of cast iron when it's welded, at least when it's heated so much. The electrodes I found needed no heating and cause no change in structure or hardening (some kind of new electrode tech called Dual Flow Coating), but they cost $200 for 20 electrodes, and it'd take a bunch to fill the chambers enough to make it great. At that point you might as well throw in the towel and buy aluminum heads, which have other advantages.

So, until I figure out something better, I'll just start with some porting.