Header options on ATC 200/200x pre '86

[Dave8338]

I sure appreciate the feedback ! Thanks.

I too, don't want to get things too large. It may be hard to tell from the pics so I'll explain how and what was done:
I've blended/port matched the intake side to 30mm (same as the intake and carb) and sloped the pocket to create a smoother transition below the seat. Stock, the pockets nearly make a 90 degree bend and have very little taper from the bottom of the valve seat all the way out the port. This I've certainly changed. Also, with this change, the reduction in diameter from 30mm down to ~ 26mm at the intake valve seat, I suspect that the charge velocity will increase going through the seat/valve.

On the exhaust side, things are very similar with gradual sloping of the pocket near the valve guide and an increasing taper out to the copper o-ring. In both cases, I reduced the size of the valve guide bridge a bit, hoping to gain a bit more capacity on the higher RPM spectrum.

Time will tell. If it runs like crap, is doggy on the bottom end and won't pull itself around in first gear, I still have a couple more heads that could be bolted on.

[Dave8338]

Found a web picture that better illustrates what I've done. One on the left is nearly identical to what I have going.

http://www.topplocksverkstan.se/bild...kt/fiddy16.jpg

[oscarmayer]

OMG!! PRON!!!!! :-) Good stuff man!!!
that's cool. if your folloqing that, you shoudl be in "ok" shape. One one fo the "test" heads we fill welded in on upper part of the curve to the seat and gave it mroe of a 40* hit than the normal 80* (more curved and less angle and it also allowed for smoother flow). we have not flowed it yet, but prelim tests show promising.

[Dave8338]

My little Nikon camera just won't do the macro photos. This is about as good as I can get, attempting to show the texture to both ports. You're going to have to trust me, on the shape... Sorry for the poor photos.

OMG!! PRON!!!!! :-) Good stuff man!!!
that's cool. if your folloqing that, you shoudl be in "ok" shape. One one fo the "test" heads we fill welded in on upper part of the curve to the seat and gave it mroe of a 40* hit than the normal 80* (more curved and less angle and it also allowed for smoother flow). we have not flowed it yet, but prelim tests show promising.

I THOUGHT about the welding but decided against it as I have NO/know idea, on how to weld aluminum! Thought I would go a little 'Ole school, on them... as with most things, time will tell.

[oscarmayer]

LOL good luck sir! O7

[Scootertrash]

Dave,
What tool are you using to do the material removal?

[Dave8338]

LOL good luck sir! O7

There is a good chance, that I'll need it. Thanks.

Dave,
What tool are you using to do the material removal?

The initial work was done with my die grinder and 4" extension bit(s).
I bought a micro die grinder that spins at 50,000+ rpm and a BUNCH of 1/8" bits, sanding rolls, etc.
The micro allowed me to get in and around the valve pockets and guides, blend things a little better, and final texture the intake side with 80 grit rolls and patience... I may hit the exhaust side one more time with the micro and buffing tips.

[Scootertrash]

Any particular brand of die grinder(s) and bits? Electric or pneumatic? I've had die grinders/bits on my tool list for awhile, a dremel just doesn't cut it *cough* :P

[Dave8338]

Any particular brand of die grinder(s) and bits? Electric or pneumatic? I've had die grinders/bits on my tool list for awhile, a dremel just doesn't cut it *cough* :P

Nice ! !

My die grinder is an Ingersoll Rand that I have had for 10+years. Done it's fair share of head work. The micro die grinder is a cheap Harbor Freight unit that I bought thinking, "if it makes it through this head, I'll consider it a win" and so far, it has worked better than I expected. It will go into the drawer with the rest of the air tools. OH... pneumatic. The electric dremel tools, don't spin fast enough to do a good job, IMHO.

[ironchop]

Ok Dave, here are those measurements.

DG Header: 1.374 OD
1.270 ID

SuperTrapp: 1.365 OD
1.232 ID

[Dave8338]

THANK YOU... THANK YOU... THANK YOU !

I now have a good comparison to the TRX pipe and it will definitely help me in getting this thing jetted in. Now to get home and measure up the TRX pipe.

[Scootertrash]

Nice ! !

My die grinder is an Ingersoll Rand that I have had for 10+years. Done it's fair share of head work. The micro die grinder is a cheap Harbor Freight unit that I bought thinking, "if it makes it through this head, I'll consider it a win" and so far, it has worked better than I expected. It will go into the drawer with the rest of the air tools. OH... pneumatic. The electric dremel tools, don't spin fast enough to do a good job, IMHO.

Thanks Dave!

[Dave8338]

Some better photos of the head. At least this gives an idea...

INTAKE: finished with #80 on 3/8" drums


EXHAUST: too much of a good thing


AND THE POCKETS: good enough


Now I can peel out the copper O-ring and get some guides in place...

[Dave8338]

Ok Dave, here are those measurements.

DG Header: 1.374 OD
1.270 ID

SuperTrapp: 1.365 OD
1.232 ID

I'm getting 38mm OD and 36.~5mm ID. ( 1.49 OD and 1.43OD )

Thanks, again

Dave

[Scootertrash]

Where did you find the extensions for the die grinder(s)? are they 1/8 or 1/4 extensions? Found the micro grinder at HF but I'm having trouble locating extensions.