Vintage Karting Forum

ok guys,
a extremely good friend has forwarded these pix to me to post.
he told me to also mention this

Quote:You might mention in the album that this is an exact duplicate of the pipe as used on my Hornet Marauder back in 1967-68

he'd rather stay private so i'm not posting his name.
those that know who this person is please leave his name out of your comments.

i'll comment on each pix as best i can.

Building the cone
cut cone pattern from flat stock
[attachment=2694] 
used dead blow or heavy rubber mallet shape on pipe
[attachment=2695]
this pix illustrated the holding angle that is best for hand forming a tapered pipe tube
[attachment=2696]
partially shaped cone.take you time and form it evenly
[attachment=2697]
getting closer
[attachment=2698]
you can see here how the angle you've been holding part at eventually lets the edges met smoothly
[attachment=2699]
nice even edge ready to tack weld
[attachment=2700]
tack pipe every inch or so starting on one end and working you way to the other.the originals (1967) were gas welded but these were welded with tig.
[attachment=2701]
short fat cone nearly done

[attachment=2702]
fat cone tacked up.note the body hammer.as you weld you can hammer the hot tacks flat if you're reasonably fast.
[attachment=2703]
cone finish welded
[attachment=2704]

part two
building the pipe and adapters to eliminate flex pipe.

finished expansion chamber a large washer still needs to be installed at the small end  for safety purposes. otherwise in a collision the e-chamber becomes a fine example of a coring tool. conversely a "sweet potato" style cover may be installed over the stinger to lower noise emissions.  a 1" hole needs to be added to silencer can for venting
 [attachment=2705]
expansion chamber adjustable frame mount detail.
[attachment=2706]
expansion chamber header end detail.jpg
[attachment=2707]


 comments from the builder will appear in quote boxes.

Quote:Hi David,

I made the header today. Now I have to make the slip joint that uses the outer race of an axle bearing and add the strap that goes up to the head. I made a form tool that I can pound into the end of the U bend to help shape the end to fit onto the exhaust flange. It still takes hand work to get it right, but the steel form saves me time. I machined .250 thick some flanges a few years ago. It would have more time effective to have had them laser cut. It's a hassle to do them on my cnc since you have to make a sacrificial tooling plate and pre drill the blanks to bolt to the plate before you can cut them. I probably wasted too much time on this project, but I want it to be as close as I can get it to my original Hornet as I last raced it.

finished adjustable header
this adjustable header eliminates the need for various length sections of flex pipe used to fine tune a kart to a specific track.
the u shaped header section is made long on the e-chamber side deliberately so adjustments are possible.
the slip section of this design is sized with the i.d. of the slip pipe being one size bigger than the o.d. of the header.
a simple slot with two attached hose clamps completes the slip /tighten function of the header design.
the connection between the header and e-chamber is accomplished by using the outer race of a standard 1" axle bearing - a pair of two hole axle flanges - two grade 5 bolts and a couple of compression springs.
the e-chamber also has an adjustable mount on the far end to allow easy moves when adjusting the e-chamber track side.

adjustable header detail blow up.
 [attachment=2708]
adjustable header detail fully closed
[attachment=2709]
adjustable header detail fully open.
[attachment=2710]

header build details

pix (a) 2 inch ball bearing and forming tool for flange side of header tool
[attachment=2711]
pix (b) bearing outer race being test fitted to expanded pipe
[attachment=2712]

below explains what else you need to start taper and hold ball bearing to expand pipe when pressing

Quote:Hi David,

There's two more tools I forgot to take a picture of. One is a tapered piece of round bar that I press into the short slip header pipe to start the expansion. The other is a piece of stepped round bar that I use to hold the now tapered slip pipe so I can hold it to press the round ball into it to expand it the last little bit to match the outer bearing race. I could have done it all with one tapered tool, but I was using a tapered round bar I made a long time ago to make KT100 headers and it wasn't long enough to do this header. In the old days I had to do all of this with hammers etc because I didn't have a lathe or mill to make form tools with. Making headers is a hassle and if I had more $$$ or could buy what I need I would. Making this crap is NOT fun, it's just a way to get what I need and want without spending $$$. The second flangette that goes onto the slip joint gets the bearing area shortened to make it fit on the bearing area better. This is a header style that is only needed on Hornet sprints or enduros that have the swing mounts. Allegros, SS sidewinders and other models don't have the rubber mounted pivoting swing mounts. If a person doesn't mind cutting various lengths of spiral wound flex you can easily get by without making this style of header. I liked the incremental adjustment this slip joint made possible. It was a real time saver when at the track.

building the slip section of adjustable header

• expand short pipe with tapered tool to start taper.
  [attachment=2745][attachment=2746]
  

• insert 2" ball bearing from pix (a) into stepped pipe and put in hydrolic press.
  

• press ball bearing till outer race will fit cleanly below shows a good fit
  

[attachment=2712]

• cut two slots opposite each other creating a slotted slip pipe
  

• weld and bearing to slip pipe bearing outer race to expanded pipe section
  

finished slip pipe should look like pix below
[attachment=2714]

here is a picture of the expansion chamber and header cleanly installed in kart

[attachment=2715]
side view of header and e-chsamber installed note spring in bolts for anti vib function
[attachment=2717]
installed header close in detail
[attachment=2716]

That is some nice work.

it really is nice work.
as you can see the guy building these knows a bit about welding!!
and
fabrication
new ideas
clean installs
simple effective designs
it's unfortunate that i can't credit him with the work but if you know him you know he's pretty private.

Quote:Hi David,

I still need to make one more sliding header section for my Mole FKE, so I will take some photos of the taper forming process. In the old days I used the sliding header parts from my Hornet on my Mole, since I had switched to FKE I with an open Mc91 and stock appearing light and heavy using my Saetta's. I modified the Mc header section to fit my Mole. In this case I have both karts, so I'll need 2 complete assemblies, minus the actual Mc header. On the Mole the shape of that part is different, so I didn't use the Hornet Mc header. I will include the pdf patterns for the swivel joint cone as well as the one sized to use a piece of tubing meant to accept a piece of vintage flex or straight pipe. I will email you a photo of my Marauder III with that pipe assembly in place. The photo was taken at the old Riverside International Raceway. I don't remember where I finished in that race, but I know I didn't win my class. I never won my f...ing class. By that time all I seemed to do was finish 2nd or dnf. In my mind I was happier leading and not finishing than ending up in second place.

  12 2 inch ball bearing and wedge tool
[attachment=2748]
  13 bearing outer race being test fitted to expanded pipe
[attachment=2749]
   14 adjustable header detail blow up
[attachment=2750]
   15 adjustable header detail fully closed.
[attachment=2751]
    16 adjustable header detail fully open.   
[attachment=2752]
     20 first jig 1 tapered to start flare in pipe.   

[attachment=2753]
    21 first jig 1 tapered to start flare in pipe set up in press.
[attachment=2754]
    22 jig 2 on left used in bottom of pipe when pressing ball bearing.    
[attachment=2755]
    23 jig 2 placed in adapter pipe ready for pressing.  
 [attachment=2756]
    24 jig 2 in press with 2 inch ball bearing on top to flare out opening.  
  [attachment=2757]
    25 ball bearing fits in flared pipe nicely now.    
[attachment=2758]
     26 jig 1 is tapered bigger near top.push in further to make flare in pipe longer.pix is jig  set up in press with blocking underneath. 
  [attachment=2759]
     27 pipe now properly flared still sitting on jig 2.
[attachment=2760]








Save

I don't blame him one bit wanting to be private obvious a craftsman with excellent welding skills
and the fact that he can produce a fine stinger doesn't mean he wants to do it for everyone
but still offers a way to make them if you want to hone your of metal working skills and how
to go about doing it thanks for this post

I think I met this gent at Avon this past summer.  Is this him?

ya know...love the workmanship...but...time and materials...wow...something like that has to take 15-20 hours and yeah,,i get it""I BUILT THAT"".....

would prolly take me 20-30 hours at 90 bux and hour...great, I have 2700 dollar expansion chamber,,that may help performance,,,yeah, I know,,,""I MADE IT "" overrides all else...

any body have RLVs number...LOL

gw

Two comments for other DIY fans.... for Mac engines with just about any shape expansion chamber you need to end up with the length of the header in the range of 9 to 10" from the face of the piston to the small end of the scavenge cone. The system shown here is a neat idea but at least two inches too long in the shortest configuration to perform well. It would be virtually impossible to build a slip joint system such as the one shown that can place the chamber in the correct relationship to the engine.
Another consideration... Mac engines have fragile exhaust header mounting locations thus the use of flex between the header and pipe is highly recommended in order to provide compliance between the pipe and the header as the kart flexes and the motor shakes around. A rigid assembly such as the one shown here looks nice in the shows but it will end up tearing the inserts our of the two exhaust port screw locations if used on a runner, especially on bumpy tracks and on karts with swing mounts that are rubber mounted at the front end of the mount.
In summary....very nice fabrication of a system that looks great but is not engineered to run fast or long on the track.
Steve O'Hara

it looks like expansion chamber brackets are attached to the engine mounts and not the frame of the Kart
so that would eliminate any need for flex pipe as far as i see from the photo's posted , can anyone on
the forum comment on the type of clutch use with this type of exhaust set up i was told if your running
the original 2 shoe Max Torque its not the best way to go because of the power range/rpm changes with
clutch engagement

first i posted this article as a how to build an era correct pipe circa 1967 not a make your kart faster article.

i may not have been super clear about this pipe in earlier posts.
this pipe represents early pipe when they were still pretty new.
in 1967 oil clutches  were new on the scene so e-chamber development at first reflected dry clutch performance limitations.
as with anything kart racing the evolution was very fast.
within a couple of years oil clutches were common and e-chamber design became almost a science.

so if you are looking for a fast or cheap design this isn't what you want.
and building you own e-chamber is pretty silly in view of whats still commonly available.
but if you are matching an existing pipe repairing a rare pipe or just like building things this may be for you.

the article is more about how to hand build your own e-chamber pipe.
something that without a cone roller will occupy at least four hours of your life if you are a skilled welder and metal former.
rank amateurs can expect anywhere from 8-9 hours to never as a time result.

i think building pipes is something the hobbiest should consider if they have the time skills and inclination to do it.
or just swipe elements of the article to apply to your particular build so you install on a show kart is that much cleaner and era correct.

anyway without starting a war about anything i am posting the builders reply.

Quote:Hi David,

The pipe/header unit in the photos you are posting was both reliable and very competitive back in 1967/68. So Cal enduro races were held about once per month back in that era. I raced A-open light and A-open heavy with my Hornet. I drove approximately 3 - 4 hours of on track time at each race weekend using that pipe assembly. Since I ran the open classes I was always trying new ideas and different engines in the available practice time. The track was always full with racers testing things. Our races were one hour long. I NEVER had a problem with that design causing exhaust insert or bolt  failure on my Mc91's.  There was enough flex in the system to allow movement and yet remain leak free at the ball joint. That pipe design and header length won enduro races back then. I don't remember if anyone copied my design for the slide joint. Those of us running in the lead pack always seemed to have other racers looking at our setups. That header setup was something I created for my Marauder III. Judged by the design of pipes from the 70's and later it may seem like a pipe not worth using today, but for an accurate representation of a late 60's pipe, it works well. I used to sell pipes like it to a couple of So Cal kart shops to get the funds to buy Mc91's and other parts. I feel that vintage should be having our karts be like what was being raced then, rather than how we can add newer equipment to them to make them faster, so we can win an event without weight limits or engine rules as they existed back in the day. A vintage win now is pretty close to meaningless in my opinion, but others  may not agree with me. Back in the late 60's all of us were just starting to try to learn about pipe designs that seemed to work. A lot of the pipes I saw being raced in 67/68 were home built. At that time I was still using a dry RevGrip clutch and the typical gearing for the tracks I raced on was 14-56 to 14 -58, going up to maybe 14-62 for some of the shorter and tighter tracks. A-open light raced at 260 lbs. and A-open heavy raced at 320 lbs. Pipe designs and lengths changed as effective wet clutches became common. If anyone decides to build a pipe based on the photos you've posted I hope they keep in mind that that particular pipe is vintage and NOT meant to be the ultimate pipe/header combo that can be made using info from later years.

Save