spmdr
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Bill Atalla made a batch of Big tube
Tri-Y headers some time ago.
Much thanks goes to the late
Dan Richardson for keeping the
heavily damaged/abused header in his parts
supply when others may have scrapped it.
The repair of it is here.
forum.sunbeamalpine.org
Looking over the header, I concluded the
final Y/collector could be improved.
And that change brought the decision
of what sized tubes to use.
I decided to go with a progressive
tube increase.
The primary tubes are 1 1/2"OD
The last Y steps up to 1 3/4" OD
Then it steps up to 1 7/8"OD,
Then finally 2" OD.
At this point I only have an open
pipe for Dyno testing.
And it goes through an old mod to
the X frame.
I think it's safe to say it's Quite LOW in the restriction Dept.
I later acquired another NOS Atalla
Header and realized the first one
had been modified quite a bit.
So, fitting this first one is not
the same as others.
The first header has had the tubes
re-welded on the Outside of the tubes
to the head flange.
And the original weld on the back side
of the head flange has been ground away.
The side Weber intake manifold needed
some trimming to fit with the header.
Some new custom stepped washers were made
to match up with the Weber manifold.
TESTING
The Atalla header replaced an early Stock
tube Tri-Y header set with 1 3/8" OD
Primary tubes.
The engine includes significant mods
including a head with larger exhaust
ports than stock.
BUT, not as big as the Atalla header!
More info about the test car is here.
forum.sunbeamalpine.org
The expectation was the Atalla Header
would Lose some low RPM Torque
and Gain some High RPM Horsepower.
To start, NO changes were made to
the Carb jetting.
Upon initial power up, the throttle
responds was noticeably improved!
The static stumble off idle was
noticeably reduced!
And the O2 sensor was reporting a
change from 14.8 down to 13.8 at
idle.
This was a surprise because in the past,
the idle mixture was quite consistent.
I was concerned the Carb jetting may be way
off, so risked a Noise ticket and took the
open exhaust Alpine for a Quick drive.
There was No obvious flat spots or lean
readings from the O2 meter.
So I trailered the Alpine to the Dyno day.
I'll leave the details for the Alpine
Chassis Dyno thread here.
forum.sunbeamalpine.org
But the quick results are an unexpected
Torque INCREASE across the board with an
increase of 5 FTLB at the Peak, BUT at a
LOWER RPM!
The Peak Horsepower was DOWN, But at a
LOWER RPM as well!
Old Header:
103.68 WFTLB @ 4560 RPM
103.32 WHP @ 5770 RPM
Atalla Header:
108.77 WFTLB @ 4350 RPM
101.29 WHP @ 5530 RPM
The Dyno O2 had the fuel mixture
LEAN at the upper RPMs, so likely
some HP lost there.
Clearly MORE engine Mods are needed
to take full advantage of this Big
tube Header set.
DW
Tri-Y headers some time ago.
Much thanks goes to the late
Dan Richardson for keeping the
heavily damaged/abused header in his parts
supply when others may have scrapped it.
The repair of it is here.
Header tube Dent repair
I picked up an old Bill Atalla header that had the front tube dented in for alternator clearance. I wanted to save it, but how? Replacing the tube is the typical process. I have occasionally thought of making a hydraulically powered device to take the dents out of Tiger headers, but, as with...
Looking over the header, I concluded the
final Y/collector could be improved.
And that change brought the decision
of what sized tubes to use.
I decided to go with a progressive
tube increase.
The primary tubes are 1 1/2"OD
The last Y steps up to 1 3/4" OD
Then it steps up to 1 7/8"OD,
Then finally 2" OD.
At this point I only have an open
pipe for Dyno testing.
And it goes through an old mod to
the X frame.
I think it's safe to say it's Quite LOW in the restriction Dept.
I later acquired another NOS Atalla
Header and realized the first one
had been modified quite a bit.
So, fitting this first one is not
the same as others.
The first header has had the tubes
re-welded on the Outside of the tubes
to the head flange.
And the original weld on the back side
of the head flange has been ground away.
The side Weber intake manifold needed
some trimming to fit with the header.
Some new custom stepped washers were made
to match up with the Weber manifold.
TESTING
The Atalla header replaced an early Stock
tube Tri-Y header set with 1 3/8" OD
Primary tubes.
The engine includes significant mods
including a head with larger exhaust
ports than stock.
BUT, not as big as the Atalla header!
More info about the test car is here.
"Weekend Racer" Alpine Back running!
The infamis "Weekend Racer" Alpine is back running under it's own power, after at least 26 years! The grainy picture is from the "Weekend Racers" movie, during the start of the May 1967 Santa Barbara Road Race. One of 6 Alpines that ran that race. Another of the 6 Alpines running that race...
The expectation was the Atalla Header
would Lose some low RPM Torque
and Gain some High RPM Horsepower.
To start, NO changes were made to
the Carb jetting.
Upon initial power up, the throttle
responds was noticeably improved!
The static stumble off idle was
noticeably reduced!
And the O2 sensor was reporting a
change from 14.8 down to 13.8 at
idle.
This was a surprise because in the past,
the idle mixture was quite consistent.
I was concerned the Carb jetting may be way
off, so risked a Noise ticket and took the
open exhaust Alpine for a Quick drive.
There was No obvious flat spots or lean
readings from the O2 meter.
So I trailered the Alpine to the Dyno day.
I'll leave the details for the Alpine
Chassis Dyno thread here.
Alpine Chassis Dyno pulls
Seeing I can't find any Chassis Dyno Threads, I'll start one. (Edit- another thread here http://forum.sunbeamalpine.org/index.php?threads/dyno-testing.13337/) And seeing the one I have handy is from a Vintage Race Alpine, I'll put it in the Racing section. BUT, I'd like to see Stock Alpine...
But the quick results are an unexpected
Torque INCREASE across the board with an
increase of 5 FTLB at the Peak, BUT at a
LOWER RPM!
The Peak Horsepower was DOWN, But at a
LOWER RPM as well!
Old Header:
103.68 WFTLB @ 4560 RPM
103.32 WHP @ 5770 RPM
Atalla Header:
108.77 WFTLB @ 4350 RPM
101.29 WHP @ 5530 RPM
The Dyno O2 had the fuel mixture
LEAN at the upper RPMs, so likely
some HP lost there.
Clearly MORE engine Mods are needed
to take full advantage of this Big
tube Header set.
DW
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