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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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 Posted: Mon Jul 28, 2014 9:04 am Post subject: Losing power on the top end of the 1/4 mile |
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Hey everyone.. Well took the bug to the track yesterday. Everything seemed to be going good till I got about 30 to 50 yards from the finish line. Then it just seemed like I was slowing losing power. Everyone watching thought I let off the gas pedal. And after crossing the finish line and really left off the gas pedal it seemed like the motor wanted to bog out, and did a few times. And every time I would burn out or launch I would lose my alt. belt. This happened all 3 passes. I don't have a temp gauge hooked up but I was thinking the motor was overheating.
These are my tranny and motor specs...
tranny - 4.12 ring & pinion--3.75 1st,2.25 2nd, 1.56 3rd, 1.22 4th, threaded super diff, heavy duty side plate, SAW heavy duty axles, welded gears harden keyways, bus nose cone. Jim Kaforski @ Der Transaxle put the trans together
motor - 2175cc - 78.4mm welded crank with chevy rod journals, H beam 5.5mm rods, 8doweled for a 12.5lb. flywheel, 94mm Cima forged piston kit, engle 130 cam with 1.25 ratio rocker arms, CB performance CNC ultra mag plus cyl. heads 42x37.5 valves, 8.5:1 comp. ratio, 30mm oil pump, full flow oiling, 48mm IDF carb kit.that's all the major parts. |
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tripicana
Samba Member
Joined: February 13, 2003
Posts: 1164
Location: colorado springs
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| Posted: Mon Jul 28, 2014 9:08 am Post subject: |
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Carbs running out of fuel?
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74 Thing
Samba Member
Joined: September 02, 2004
Posts: 7389
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| Posted: Mon Jul 28, 2014 9:12 am Post subject: |
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Check fuel and spark (battery/ignition).
Also what jets are you using?
That cam likes a lot more compression like 10.5:1. |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 9:17 am Post subject: |
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| tripicana wrote: |
| Carbs running out of fuel? |
I did check the flow into the carbs and seemed to be fine |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 9:29 am Post subject: |
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| 74 Thing wrote: |
Check fuel and spark (battery/ignition).
Also what jets are you using?
That cam likes a lot more compression like 10.5:1. |
Now that you mention the battery. I do think the battery is on the dead side because just from losing the belt, and if the motor did die after reaching the finish line it would take a minute to start and if it didn't start right up the battery would start to die and I did have to push start it a few times. Bosch 009 distributor with electronic ignition. So if the ignition is electronic and the battery would die, could be screwing up the distributor? right?
Not sure on the jets. Have to check those out. What size do you recommend? |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 9:31 am Post subject: |
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| 74 Thing wrote: |
Check fuel and spark (battery/ignition).
Also what jets are you using?
That cam likes a lot more compression like 10.5:1. |
And I do plan on upping the compression |
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Dale M.
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Joined: April 12, 2006
Posts: 20377
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Mon Jul 28, 2014 10:14 am Post subject: |
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Once belt is thrown, its health and longevity is compromised.... Replace it....
You should not have a power problem with belt off, unless battery is on way out....
Cooling, losing belt is not acceptable.... Belt issue should be first order of business....
Dale
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"Kellison Sand Piper Roadster" For Street & Show.
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[email protected]
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Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Mon Jul 28, 2014 10:35 am Post subject: |
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What fuel pump are you using? What is your ET?
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Hotrodvw
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Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Mon Jul 28, 2014 12:15 pm Post subject: |
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And what method did you use to check fuel flow?
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vwracerdave
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Joined: November 11, 2004
Posts: 15302
Location: Deep in the 405
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| Posted: Mon Jul 28, 2014 2:04 pm Post subject: |
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What RPM are you shifting at?
What size venturies & jetting in the carbs?
What fuel pump & regulator are you using?
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 2:30 pm Post subject: |
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| Dale M. wrote: |
Once belt is thrown, its health and longevity is compromised.... Replace it....
You should not have a power problem with belt off, unless battery is on way out....
Cooling, losing belt is not acceptable.... Belt issue should be first order of business....
Dale |
Thanks Dale |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 2:31 pm Post subject: |
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right now stock fuel pump..
13.57 |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 2:33 pm Post subject: |
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| vwracerdave wrote: |
What RPM are you shifting at?
What size venturies & jetting in the carbs?
What fuel pump & regulator are you using? |
shifting at 7000rpm
dont know sizes
stock fuel pump but i got a holly blue on its way |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Mon Jul 28, 2014 2:39 pm Post subject: |
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let me guess, the stock 1/4" fuel line, right?
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It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 2:41 pm Post subject: |
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Yup.. what do you suggest?? I actually wanted to change out the line before the next race. |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 3:14 pm Post subject: |
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| well.. looks like the holley blue isn't on its way after all. my cousin already sold it. so what fuel pump do you guys think i should get?? |
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VWCOOL
Samba Member
Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Mon Jul 28, 2014 3:24 pm Post subject: |
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Welcome to the world of motorsport!
It is obvious you are emptying your carbs' float bowls. Your fuel delivery system - especially the pump - is not up-to-task.
Thankfully it's an easy fix: 8 or 10mm lines throughout and an electric pump (such as Facet) should be on your shopping list.
Mount the pump under the fuel tank (opposite the brake master cylinder) and depending on your class regs/what-the-scrutineers-want, you may need a 'kill' relay wired to the oil or gen warning light circuits so the pump operates only when the engine is actually running.
This works for me
Hope this helps! |
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20377
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Mon Jul 28, 2014 3:55 pm Post subject: |
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IF you go electric pump go rotary... Get yourself a Carter GP60504 it has 5/16 inlet/outlet (barbed) and is a 4 PSI pump... Pricing is from $35 to $75 depending on where you shop...
http://www.summitracing.com/parts/crt-p60504
http://www.amazon.com/Carter-P60504-Electric-Fuel-Pump/dp/B000BZX92K
Also if going electric fuel pump.... For EVERYONES safety....
http://www.revolutionelectronics.com/Fuel_Pump.html
I don't consider 'micky mouse' adaption to control fuel pump relay off oil or gen lamps reliable....
Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Mon Jul 28, 2014 3:59 pm Post subject: |
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the Rotary will work. Get 3/8" line, and don't forget the steel line in the tunnel, that has to be increased also. Get 250 Needle/seats for the carbs too.
_________________
It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
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and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
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solow
Samba Member
Joined: January 02, 2007
Posts: 259
Location: Terceira, Portugal
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| Posted: Mon Jul 28, 2014 4:03 pm Post subject: |
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will check those out thanks |
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