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/6 Senior Dragster makes its first pass
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Author:  Dolmetsch [ Fri Aug 29, 2008 9:16 am ]
Post subject:  /6 Senior Dragster makes its first pass

:D
After a few years of fabrication in my spare time i finally finished the short little rail i call the Senior dragster (as opposed to Junior Dragster cause old people need fun too!)
This 60s style rail is 96 inches long and weighs just inder 1300 lbs without me in it. I loads easily into the back od my Dodge ram 3/4 ton for transportaion to the track. The engine is a 225 with a .140 overbore. Both block and head were planed to get some squeeze and compression is just above 10to1. Cam was an moderate hydraulic grind I found and engine was converted to hydraulics. Head is ported with big valves and narrower stems (11/32"), K motion springs with stock retainers and VK415 locks for 11/32 stem to 3/8 retainer work.
Reworked clifford headers handle the exhaust. Intake is an IR set up with 6 tillotson sidedraft carbs. Trans is a 79 Ply Carevelle unit with a MP econo converter of supposedly 2300 to 2600 stall. Everything possible was made in house including the front axle, shifter and steering wheel.
A used set of 35 year old firestone slicks , 29 X 9 were used to test.
I was nervous to say the least and hadn't raced a race car in almost 10 years. I left easy because I was unsure of everything in the car and wanted to get a feel for it befoe I went nuts. When the car beside me pulled alongside that plan went out the window and I floored it. The tires blazed on the one -two shift and again on the two -three shift. I was surprised.
Shakedown pass was 8.43 at 81.76 with a 2.0 60 footer from my easy start. I was so happy and it worked so goodthat I loaded it up and went home after making the rounds among my old friends. I wasn't going ruin this day. I wanted to savour it. [/img]

Author:  Dolmetsch [ Fri Aug 29, 2008 9:41 am ]
Post subject:  video

http://www.dropshots.com/GaryKWager
A freind took this video. His battery was almost dead so the colour is funny and the smoke exaggerated. We have more from another camera with good colour but I cant get it to upload yet from this computer. [/img]

Author:  Slanted66 [ Fri Aug 29, 2008 10:08 am ]
Post subject: 

VERY cool...cant wait to see more pics!!

Author:  Dolmetsch [ Fri Aug 29, 2008 11:28 am ]
Post subject: 

http://seniordragster.bravehost.com/mycar.html
Some here

Author:  Dart270 [ Fri Aug 29, 2008 11:51 am ]
Post subject: 

Great project. Congrats on the successful run. Should go in the 7s without much work, eh?

Lou

Author:  Dolmetsch [ Fri Aug 29, 2008 1:00 pm ]
Post subject:  yup

I hope. I am thinking might scrub a .4 off the short time with a full throtttle pass leaving higher on the converter especially if I add a burnout. This was a cold tire pass, just stage and go to make sure it drove ok. . Motor wise i have as much as i want right now. I am having troule sticking to the pavement as it frys them at will. I am trying to find a set of30X10s not far away for next weekend but i may have to buy new.
Even though I have been at the racing game for many many years I was totally unprepared for the powe rthis little animal makes with the IR set up. I had told my pals I wasnt worried about traction since I doubted it would turn the tires at all. First poke i gave it at the track sent me in a short tire frying skid. Might be the old tres but still it has way more poke than i thought it would. Time will tell i guess. Maybe i am just geting old.

Author:  Dolmetsch [ Fri Aug 29, 2008 1:03 pm ]
Post subject:  blacksburgh VA

I just saw your address. Do you know my old mopar friend Dave Hench? Same address same brand.

Author:  Joshie225 [ Fri Aug 29, 2008 2:31 pm ]
Post subject: 

Are those motorcycle carbs you're running? If so do you mind sharing what they are? I've considered trying the same thing and have a new project in the works that could use such an intake. I even have tapered steel runners I made to use on an EFI manifold.

Author:  Dolmetsch [ Fri Aug 29, 2008 5:07 pm ]
Post subject:  carbs

They are similar Josh. They are snowmobile carbs from the 70s. I believe they were also used on early Harleys. They are diaphram or floatless carbs and are all position. Basically a giant version of a chainsaw carb. I had to remove the built-in fuel pump sections and tap and plug one passage then open up a precast hole and tap it for a different spot for fuel inlet. They are 1.5/8" bore. just barely big enough but big enough although any bigger engine would require bigger. I also put a taper in the inlet pipe using pipes that had a tapered step in it. These carbs are early so they have only two circuits . idle and power. I was very familiar with these during my snowmobile days and for 33 plus years I wanted to try them on a slant six. When i retired and sold all my machine shop equipment this one the one thing I hadnt tried that i wanted to. I couldnt think of a reason not to so i began building the intake. I just kept building till i had a whole car. (truer than one might think!) Biggest by far obstacle i had to overcome was getting a steady supply of low pressure fuel as they will not handle more than 2.5 PSI or they start to weep. I have been told mikunis would have been better bu tthis was my original plan so i had to try it first. Power? It is unbelievable! The torque was far greater than i thought possible. I keep rpm under 5500 as that is about all it seems to want but it pulls hard enough to scare me. I know the car is light but I have also had two hemi cars and a very successful 440 car and this engie and set up actually pulls hard enough to give me a good scare . Remember I have only one shakedown run on it. Still i think it is a good working combo. Not for everyone because it is complicated and required a lot of patience to set up and get working. Mikunis are probably better and miight be the way to go. I prooved to myself it would work and it worked n better than i would have thought so i am happy. We had a 32 bantam with a /6 years ago(76) and ran with a turbo first then a normally aspirated 225. This engine would eat them for breakfast i think since wieght of that car and this one would be within 200 to 250 pounds. I had driven the other car a few times. It ws fun but didnt even cause my heart beat to speed up. This one caught me totally by surprise and scared the dickens ut of my when i frst gave it a hard poke. Enough I am sure i may have cried out.
The diff gears are 3.91 and the tires were 29 high.
With the IR setup one can run CFM that would be impossible otherwise. I figure i am around 1400 to 1800 cfm. Because there is no overlap backwash from adjoining cylinders idle is stable , in fact very stable. cam s barely noticible. No bog on accel although i did have slight one at first when i began working with it. Carbs have adjustable jet scews both idle and high speed. I am very familiar with these from my snowmobile days and tried the stock style setting and then the leaner setting i used in the two strokes with a tuned exhaust. It liked the latter a lot so that is where they are. i also found the carbs preffered individual velocity stacks as oppsed to a combined air box or scoop. They seem to work best when they are completley independant of each other other than linkage which in my case is a long piece of welding rod shoved through all the set screw pivots. I also had to run a return line snce these carbs have constant fuel retuning to the tank. Mikunis would not since they have floats.
i think that is about it. If you think of anythng ask away.i will do my best to answer as i know it. Don
I paid about 150 dollars for 9 of these carbs to get six useable ones. He threw in the carb kits as well.

Author:  Joshie225 [ Fri Aug 29, 2008 6:33 pm ]
Post subject: 

Don,

Thanks for all the info! 1 5/8" is almost 42mm which is what I was considering. Mikuni HSR 42 carbs are darned expensive though. One costs nearly as much as a new Holley 390 CFM 4bbl. I'll have to find some used carbs as you did and play with them. If I come up with some carburetors I would resume work in the intake manifold. They do make the HSR 42 alcohol ready for the Jr Dragsters though. Might be interesting if I stumbled into $2000 I had to spend I carburetors. :shock:

Author:  Dolmetsch [ Sat Aug 30, 2008 5:37 am ]
Post subject:  used

We have several motorcycle wreckers in Ontario. What about your area?
Don

Author:  Dolmetsch [ Sat Aug 30, 2008 5:45 am ]
Post subject:  or

*EDIT* 530 character URL string replaced with the following.

http://tinyurl.com/5hns4h

Author:  dakight [ Sat Aug 30, 2008 7:24 am ]
Post subject: 

I have edited the above post because the 530 character URL string was blowing up the formatting of the forum. Tinyurl is one tool that can be used to great effect to help keep the forums compact and readable.

Author:  Dolmetsch [ Sat Aug 30, 2008 11:11 am ]
Post subject:  soory

My apologies, I didnt want to mess up this site. i am sorry.
Anyway i just searched "mikuni carbs" on ebay and found over a hundred. Also several motobike wreckers both here and in USA with many for sale. 100 to 250 for a complete bilke set up.

Author:  Joshie225 [ Sat Aug 30, 2008 11:36 am ]
Post subject: 

Well, my point was I do need to find used carbs if I'm ever going to do the IR intake. The problem is the dearth of cheap carbs that will feed a 616cc cylinder. Two sets of Polaris triple carbs as used on their personal water craft would probably do.

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