Fullauto head vs combat head vs standard head

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bwolfie said:
It would be cool if someone had a kick ass CNC setup for optimal porting. clamp down the head and push go. Should be cheaper than $2K, and repeatable. Just saying, hint hint.
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The problem is the port is too big already so you would have to put material in before you could machine it out. I have done it with epoxie but it only lasts for a while. Now if you could get your welder in there and add a bunch of metal to the floor leading up to the short side we might get somewhere. Jim
 
hobot said:
Us old bikers are sure a tight bunch. $2000 is dirt cheap for the engineering advance. Consider what it'd cost if a Duci or even a Harely hi end head.
It takes about 150 cfm per 100hp so 15 cfm = ~15 hp gain, REMARKABLE!
Then can play with cam profiles and bigger carb or injectors = oh my my.
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The math would work out to 10 HP gain fwiw...

So is this even close to true?!!! That would be quite the boost!

Russ
 
Hey Jim. Do you figure that my 71 head that you modified, with the tapered crescent inserts in the exhaust side, would be in the same cfm ballpark as the fullauto head? Just curious. You screwed and glued the inserts in to make sure they didn't come loose. Also cost a heck of a lot less than 2 large. :shock: Tony
 
rvich said:
hobot said:
Us old bikers are sure a tight bunch. $2000 is dirt cheap for the engineering advance. Consider what it'd cost if a Duci or even a Harely hi end head.
It takes about 150 cfm per 100hp so 15 cfm = ~15 hp gain, REMARKABLE!
Then can play with cam profiles and bigger carb or injectors = oh my my.
Click to expand...

The math would work out to 10 HP gain fwiw...

So is this even close to true?!!! That would be quite the boost!

Russ
Click to expand...

10hp would be a very solid gain. Dad always likes to regale me with stories of 5- and 6-speed Quaife transmissions as well as a 1000CC conversion (from an 850 lower end), but I've not been able to find the 1000CC conversion, so I assume it no longer exists.

5spd Quaife gearbox:
http://www.quaife.co.uk/catalogue/products/qmca2a5

6spd Quaife gearbox:
http://www.quaife.co.uk/catalogue/products/qmca2a6

I'm sure either one would cost a king's ransom, however..

-Jordan
 
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rvich said:
hobot said:
Us old bikers are sure a tight bunch. $2000 is dirt cheap for the engineering advance. Consider what it'd cost if a Duci or even a Harely hi end head.
It takes about 150 cfm per 100hp so 15 cfm = ~15 hp gain, REMARKABLE!
Then can play with cam profiles and bigger carb or injectors = oh my my.
Click to expand...

The math would work out to 10 HP gain fwiw...

So is this even close to true?!!! That would be quite the boost!

Russ
Click to expand...

The amount of power increase you will see depends on a lot of other things, just simply bolting the head in place of a standard head may get you ten horse more if you have twin 32 or larger carbs and a good working exhaust system. If the flow is restricted with a poor manifold or an exhaust system that does not scavenge very well then you would likely only see a bit more midrange torque. Jim
 
R Model Tony said:
Hey Jim. Do you figure that my 71 head that you modified, with the tapered crescent inserts in the exhaust side, would be in the same cfm ballpark as the fullauto head? Just curious. You screwed and glued the inserts in to make sure they didn't come loose. Also cost a heck of a lot less than 2 large. :shock: Tony
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Just doing the exhaust side as I did on your head is worth a gain but it doesn't get what the fullauto head is capable of. Jim
 
Ron L said:
Wow that brings back memories. We ran a set of Mondello ported heads on an injected small block Chevy powered dragster in the late 60's.

Last summer I happened to catch this episode of HorsePower TV :

http://www.powerblocktv.com/site3/index.php/horsepower-episodes?ep_num=HP2009-06&ep_sea=0901

It seems Joe is still building those mighty 455 Oldsmobile motors. Apparently he as moved the operation to Tennessee. And still teachin'!

broken link removed
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Joe is quite a character. He certainly had no qualms about telling you how it was. I spent half of a day porting a 5 horse Briggs motor in class and then we flow tested it. Then he picked up my grinder and in 5 minutes he doubled the gain I had gotten. I could have spent a year following him around.
I bought a 500 inch Olds motor from him in about 1990. It is still dragging my bread truck bike hauler around. Jim
 
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Thanks for the reply Jim. Yes, I now remember you saying that the dyno difference between inserts and no inserts on your own head was around 5hp. That's somewhere between a 5% and 10% gain. Good improvement by any standard. Regards, Tony
 
So where exactly, include pictures and diagrams, do the ports need to be built up with welding. I came agross an uber small TIG torch head, that might work. What would all be involved in this modification. Would the valve angles change? Or could any improvment be seen with welding, porting with the stock valve setup. This is getting me thinking, not good.
 
bwolfie said:
So where exactly, include pictures and diagrams, do the ports need to be built up with welding. I came agross an uber small TIG torch head, that might work. What would all be involved in this modification. Would the valve angles change? Or could any improvment be seen with welding, porting with the stock valve setup. This is getting me thinking, not good.
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Basically the floor of the port would need metal added from the edge of the valve seat to the carb flange up to nearly .375 deep in the center. I bought a miniature water cooled torch and totally destroyed it trying to add metal there. It took about 250 amps to flow the metal and the heat contained in the small port was too much for the torch. For several years I ported the stock heads by casting an insert and bolting in to the port floor and then grinding from there. The hours required to get this done right turned out to be more than I could do or charge for. Jim
 
pelican said:
Be lucky you have a job, as I don't think I'm ever going to find one again.
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I'm in the same boat, but maybe it's because I am not looking for one :wink:

Jean
 
Its very easy to reshape inlet ports using epoxy products such as Devcon Ti putty, and this is something thats been done for many years on various race cylinder heads. In most cases its rather silly to try and weld up ports without the proper gear, and using pencil type TIG torches which in most cases are rated at less than 100A, at much higher settings very often destroys the torch itself.

Reshaping the ports on old fashioned hemi type heads can mean big improvements, but ideally the valve angles need to be changed, and specific cams with modern grinds should also be used. I guess when Hobbit has altered his Norton head, top speed of his bike is likely to be closer to 200mph, up from the rather slow 160mph it is currently.................
 
On the subject of building up the floor of ports to mill, there was a product available for alluminium that was used like solder but was a mixture of alloy and ? It had a slightly lower melting point than alluminium, (within safe limits) and you would heat the part to be fixed and melt the rod using the heat from the part, not the flame. Ive used this on the farm for some items and works well, finished weld looks and behaves like ally. Could be better than epoxys and more successful than a TIG.
Foxy
 
Not sure I would want to risk using zinc based solder to reshape ports.............epoxy works well, and is easy to use, so no real reason to try alternatives.
 
Carbonfibre said:
Not sure I would want to risk using zinc based solder to reshape ports.............epoxy works well, and is easy to use, so no real reason to try alternatives.
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But these guys were talking about the "crescent inserts" on the exhaust ports...how many seconds wilol epoxy or even devcon last there???
 
Or instead of spending a bunch of money ruining Commando heads you could put on a Fullauto head and be done! LOL
 
Quote;
Its very easy to reshape inlet ports using epoxy products such as Devcon Ti putty,

I would not hesitate to use Devcon TI putty on a water cooled cylinder head, particularly cast iron and have done so many times.

Devcon TI putty is also what cracked off a large enough piece to wedge the intake valve open and bend the valve causing a DNF at Mid-Ohio several years ago on my Norton.

I still use epoxy fillers for testing and short term use but I would never modify an aircooled cylinder head with epoxy and sell it to someone. Eventually the fuel and heat will cause it to fail.

Only a matter of minutes in the exhaust port. Jim
 
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