Welded combustion chambers?

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derrangedgadgeteer

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I was doing some looking for some ideas on what to do with a set of 360 smog heads I picked up at the junkyard, and since my car's a 318, and using them would kill my compression without a piston swap, I was considering doing a ton of port work to them, and brazing the combustion chambers up into a closed chamber configuration.

I figured I'd add material to the intake side, and leave just enough room to keep the valves unshrouded, and then fill in on the exhaust side until just before I get to the spark plug. I'd be trying to emulate the modern Cardioid shape combustion chambers with it.

I've heard of others reccomending spray welding for this sort of thing, but I've also been told of many, many people who have brazed up the chambers without trouble, (in fact, I've never heard of someone having a problem with brazed chambers)

I'm studying welding at school, and the class on oxy-fuel welding and brazing is coming up shortly, I figured I wouldn't embark on this project until I'm jolly well sure I'm ready to do it, but I'm looking for one thing in particular:

Does anyone have pictures of welded or brazed heads? and in particular, Before and after pics? I've been all over google trying to find such pictures, and I've had no luck. :violent1:.

And has anyone here done this, or had it done, or know someone who has done this or had it done? and what kind of results did you get?

This head, in the end, will probably be in the dartness, An effort to perk up the little 318 that's got stock heads and cam right now. It might or might not be followed up with a cam, but definitely not right away.
 
The general idea......is to CC' each combustion chamber.

Then......figure out how many CC's you want to reduce.

Then get some material.....(like .05$ Nickels) and weld the same amount into each chamber, and RE-CC' your chambers until you get the desired CC volume.

I have heard of it being done, but never actually seen it done/used.

good luck
 
302' casting cylinder heads, or even 587's would liven up your 318 for less investment/work/stress.
 
I know the other heads would probably work for less trouble, I'm just interested in being able to re-work the heads for the sake of being able to do it. Furthermore, I've got a slant six head that may react favorably to this sort of treatment as well... Besides, If I can do this kind of work, I'm sure there's work for me if someone else wants it done. ;)
 
There would be money in doing up slant six heads in this manner to a closed chamber, as there are no HP heads available. Neat idea.
 
I also have heard of this done but have not seen it. Prine explained that one well. I also suggest a different head to use, also like Prine suggested. Use the 360 heads valves in the 318 head. Port as needed.
 
when you get it all figured out, let me know, i will send you my 360 head to get this clay combustion chamber done up.

DSCN1890.jpg


Just kidding,....... kinda:-k
 
Cudafever said:
when you get it all figured out, let me know, i will send you my 360 head to get this clay combustion chamber done up.

DSCN1890.jpg


Just kidding,....... kinda:-k
Click to expand...

Well, that's just about exactly what I've got in mind to do, the only differences being:

combustionchamberreply.jpg


I'd have filled the area highlighted in green with brass, to close the spark plug side, and I'd grind the exhaust port out to the edge of the bore just like you did on the intake, (orange)

i'd also wonder, if that "Pocket" next to the plug would be entirely necessary if I got rid of the plug-side dead space it was meant to help ignite. I likewise would wonder if the flame would propagate better with or without it in a closed configuration. I don't recall seeing any aftermarket offerings that have it... :read:
 
derrangedgadgeteer said:
I know the other heads would probably work for less trouble, I'm just interested in being able to re-work the heads for the sake of being able to do it. Furthermore, I've got a slant six head that may react favorably to this sort of treatment as well... Besides, If I can do this kind of work, I'm sure there's work for me if someone else wants it done. ;)
Click to expand...

Interesting is there any info on the spray welding I have access to a unit at work id love to try something on a slant head if somebody would or could walk me through it
Aaron
 
I thing that pocket next to the to plug is kind a like a magnet.......Draws wet fuel away from the spark plug.

Just a complete guess.
 
Engine masters, they sprayed iron into 906 open chamber heads. I have the article.
The kit is around 400 bucks if you want to do this.

I really like the idea....of corse pistons would do pretty much the same and cost about the same too..
 
Dan Dvorak used to offer this service and sale heads that had the chambers spray welded and machined. I don’t know of anyone offering this service now.
 
derrangedgadgeteer said:
i'd also wonder, if that "Pocket" next to the plug would be entirely necessary if I got rid of the plug-side dead space it was meant to help ignite. I likewise would wonder if the flame would propagate better with or without it in a closed configuration. I don't recall seeing any aftermarket offerings that have it... :read:
Click to expand...
It's been well understood for a few decades that the combustion process gets completed faster with a closed chamber.... and that is another aid in avoiding detonation tendencies. As far as the oval shaped 'pocket', that is an interesting observation. You might want to read up on a topic called 'spark kernal'.

You ought to read up on this thread to get a bit of appreciation on how valve shrouding can hurt flow... some of it can't be avoided with a close chamber but at least you'll know not to crowd the valves too closely.
Intro to a port job
 
I gas welded up the chambers on a Slant head a few years ago, but canned the project before I had it machined down..ended up tossing it on the scrap pile. I do plan on welding up another for a current project.
Welding onto cast iron is actually pretty easy..it's repairing cracks when things get trick and special materials and techniques are necessary.
Mild steel rod, LOTS of heat and patience is all you need.
 
I have used the Victor powder flow torch for cast iron in the past. It seemed like an excellent way to make closed chamber heads except for the exorbitantly expensive iron filler powder. Do you care to share what series of rod you use and if you you SMAW ac or dc (if dc straight or reverse polarity) , or dc GTAW your chambers up? Ever try flux core gasless wire welding? I am thinking of doing a set of 360 heads but don’t want any more scrap iron than I already have! I plan using a fire pit and hardwood and laying plate on coal, place head on top and allow to heat before welding. Cover with half of a steel drum when through to smother fire and let cool off gradually overnight.
 
Marcohotrod said:
cast iron likes to be preheated, and the best filler material matches the iron of the head, and tig is best
Click to expand...
Hey, thanks much, that refreshed my memory a lot! A welding instructor I used to know way back when told about a high manganese TIG rod he used to weld the cast iron cam lobes of a Briggs & Stratton to grind in his own profile for kart racing. He explained to me made the carbon and nickel in the cast iron migrate into the weld and give the weld the same properties as the parent material being welded. Once complete, it was hard to the extent of requiring grinding instead of being machinable. I’ll see if I can find out exactly what he was using, should work perfectly...
 
Turns out he was using a bronze manganese copper blend rod, a better choice appears to be Lincoln Techalloy 99 rod, excellent weld adhesion and good machinability as well.
 
nm9stheham said:
It's been well understood for a few decades that the combustion process gets completed faster with a closed chamber.... and that is another aid in avoiding detonation tendencies. As far as the oval shaped 'pocket', that is an interesting observation. You might want to read up on a topic called 'spark kernal'.

You ought to read up on this thread to get a bit of appreciation on how valve shrouding can hurt flow... some of it can't be avoided with a close chamber but at least you'll know not to crowd the valves too closely.
Intro to a port job
Click to expand...
Ancient thread, deja vu...
I believe that little pocket was where the factory depth checked for machining.
 
Last time I was in Dan Dvorak's shop he was attempting to what looked like braze brass or something similar on the open chambers of junk big block heads.

As I understand welding cast iron: nickel rods, extreme preheat (glowing red hot) your iron piece, & after the welding is complete, it must be cooled down in stages, kinda like divers in decompression.

People do this for rare hemi, etc. matching numbers components.
 
just cut .050 off the 360 heads /and have the intake side also cut to match then get .030 rocker arm shaft shims its the cheapest way to go and you will not loose compression.
 
teringer said:
just cut .050 off the 360 heads /and have the intake side also cut to match then get .030 rocker arm shaft shims its the cheapest way to go and you will not loose compression.
Click to expand...

Yup and when you forget that smaller pushrod or rocker arm shims.............it won't start after the head shave......ask me how i know!:BangHead::D
 
While on the topic,what is the maximum safe shave for a 360 iron head? I have forgotten somewhere along the way...
 
yes when I did mine I used 273 rockers and had to get different push rods any way for hyd lifters so that's why I didn't have problems I guess.
 
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