Question for the group... Has anyone made their own high compression head out of an original? I know we can take .100 to .125 thousandth off the original cast iron head. I have seen his done a few times. Can any one recall welding up the combustion chamber and machining it out to raise combustion ratio. Kinda like the old dry lakes racers did on flathead V-8 before Vic Edelbrock and Barney Navarro came on the scene with their aluminum high compression heads after World War II for the venerable flathead V-8 's?
I have a 2 high heads and I am looking for a couple of low heads ( might have found them but does any one have for sale?) to try this old skool tech if possible.
Neighbor down the street is an Inliner club member and has built quite a few hot in line fours and sixes has said he can help with the welding and machining.
I have a Reeder high compression we are fixing casting flaws on now. I want to try making a high compression head out of a cast off original, if possible, and just for the fun of trying the old skool way.
On my 1926 touring I took 2mm of the head and build high compression pistons in it.
It works fine, hill up and down, but I don't know what is its horsepower.
In the dirt track days, iron heads were put on a charcoal grill till cooked then brazed in the low places. I can tell you Bill Stipe has some sort of a process to put metal in a stock head to make a HC head and it works. Too my knowledge he is not selling them but you might ask.
An easier way is use high compression (Domed) pistons with a low head. Have measured that combination by volume and you end up with compression very close to a Z head.
Brazing inside the combustion chamber is not recommended.....should be cast iron weld build up.
The latest high compression cast iron head may be the best choice providing greater coolant capacity compared to the low head.
That's the big secret of brazing cast iron Jim. It works darn good if the cast is hot enough and is kept hot. At work our welder repaired a cast connecting rod for the power metal bending brake that way. Roughly 1" square and shaped exactly like an engine connecting rod it had snapped in 2 for some reason. Maybe a casting flaw. That was 20 years ago and it's still going strong. He kept it hot while he filled the vee'd out parts with brazing.
Usually,major part's and machine bases are cast steel instead of cast iron? Bud in Wheeler.
So brazing or welding a head can be done. Cool! I would love to purchase another new high compression head but finances don't allow it at this time. We also just got done rebuilding the motor with new aluminum flat top piston 3/4 race cam & Double E crankshaft among other tricks as well.
I plan to get Z or Pruse head in the next couple of years or sooner. In the mean time just wanting to try something cheaper and different.
How much clearance do I need between the top of the piston and head keep from having a pre ignition knock or hitting the top of head?
I have measured approx. .050" between the piston and squish area in a Z head. Do not know how much the block was decked which is important. Without a head gasket, the piston would hit the head. With a copper gasket setting in place and putty, that's how the .050" was measured. Assembled the engine in this condition, no problems after 2 yrs. running. With a 280 cam, SCATT crank and HV out side oil line, no slingers or magnets...it a strong running engine. Pulls great on hills!
Two cast iron welders which specialize in cast iron repair that I have talked to do not recommend braze for inside the combustion or valve chambers. In those areas, they claim it does not hold up. Other applications....like outside water jacket repair it's very good.
If you are going to the Bakersfield swap meet this week and let me know in time, I will give you a high head to play with. Let me know so I can add it to my load of parts going to Bakersfield.
Interesting discussion. Since you have to use stock parts for the Montana 500, I would think that somebody would have welded up the combustion chamber of a stock T head and made their own Z or Ricardo chamber. Maybe it's not legal to add metal to stock parts for that race.
Interesting subject. Would love to see the inside of some old head modified by welding in the old days
The Montana 500 rules are clear about this type of modification: http://www.antiqueautoranch.com/montana500/rules/rules.html "B2s. Any cast iron original Ford script head is allowed, but the combustion chamber is limited to 270cc minimum. The head will be measured without the head gasket, without spark plugs, and the spark plugs holes will be plugged with clay to be flush. One stock combustion chamber is required, the other chambers to mimic the stock chamber. No material can be added to the combustion chamber to equalize."
(Original 1909-10 low heads with the highest compression ratio from Ford had about 262 cc combustion chamber volume and most high heads has about 294 cc according to the Model T Ford club of Tulsa's data: http://mtfctulsa.com/Tech/head_design.htm )
Les wish I could make Bakersfield swap meet. So it sounds like 09-10 heads had the highest compression ratio.
Low heads have more compression than high heads. However, they are much more expensive and 09-10 heads are not easy to find, it would be sad to possibly destroy an early head. High heads are low cost and easy to find. That's why I offered to give you a free one. If you are determined to up the compression by building up weld/braze in the combustion chamber.....use a high head. The high head has an advantage of holding more coolant compared to a low head.
If some one thinks high heads are valuable....I have a deal for you....5 heads for $50.00....you pick them up at Bakersfield....too heavy to ship.
There was 21 style head that has a thumb print on the back, Hi head, that you can grind easily a 1/4 off it and more and it will still seal, I learned this little secret years ago at a auction when I bought a pallet of heads, some guy wanted just one of them and I asked him why that one, he told me the info and it was his.
Les I understand what you are saying. I wouldn't want such a valuable head as an 09-10. I have high heads already so that is what I am going to play with.
Are those 21 heads the ones what looks like raised round spot on back center of the head?
Wonder if some careful thought on swirling the intake side of a high compression piston with some shallow grooving would make a stronger running engine. In my motorcycle days on two cycle engines the HP increase was very noticeable just by drilling holes through the webbing on the bottom of the piston giving better atomization. A NH is the bottom of the line on that issue. A Mikuni with seven levels and a variable venture is at the other end of atomization.
Chris , that is correct!
At today's machining prices $300 for a new head is not that pricey and infinitely quicker to do.
Anybody got any idea how much compression a high head milled only .060, would have? What about if used on a motor with high compression pistons?
I milled a high head .125 (1/8") a while back.
Couldn't tell any difference in power and after a year or so it cracked.
Not worth the trouble.
With reference to what Uncle Jack said, I've had a few (low) heads milled 1/8" and it costs $100 to have that done at my local machine shops. I use them that way combined with pop-up pistons and can tell quite a difference in torque (hill-climbing ability). Even with the extra cost for the pistons and the C-note for the milling, it's still less than a high-comp head, but it's certainly not free. I've never had one crack; luck of the draw, I guess.
Dang, Mike, You've got an expensive auto machinist. The head I had milled .060. only cost me a third of what you pay.
I just had one milled .050 and it cost me 45.00 and that was for a 1948 Dodge Power Wagon 230 flathead 6. The fellow who is helping is a certified welder for UPRR here in Portland and friend who is a retired automotive engineer who builds in line 6 and 4 cylinder dragster. Both are hot toddlers. We are just having fun and experimenting with cast off junk. In long run it might cost more than a Z or P head. We are just having fun. I am gonna start with one and plane the most I and check my clears few as weans try to get close to that .050 or .060 clearance with the top of pistons as possible. Can I check difference of the two by doing a compression test? We will weld the combustion chambers rather then brazing as I don't want to damage my motor.