| Author |
Message |
denbby
Samba Member
Joined: July 29, 2014
Posts: 3
Location: OHIO
|
 Posted: Tue Jul 29, 2014 4:07 pm Post subject: sputtering under normal acceleration |
 |
|
| I have a 1641cc 1974 thing motor in a dune buggy, mofoco 042heads 40x35 valves, pertronix ignition 30 degrees at 3000 rpm, bosch 7902 plugs,lightened flywheel 13 lbs, holley 0-4 psi fuel regulator running at 3lbs. I just installed a empi dual epc 34 carb kit from the line if I keep it floored the thing flies through all gears but if I just try and cruise it will sputter upon acceleration, example if I'm cruising at 2500 rpm in 4th and give it some gas the motor rattles and the shifter shakes. I've done the idle mixture over and over, set the carbs 5 mm on butterfly before install so they should be synced or at least very close. any ideas would be greatly appreciated |
|
| Back to top |
|
 |
Todd66
Samba Member
Joined: February 19, 2012
Posts: 461
Location: Utah
|
| Posted: Wed Jul 30, 2014 6:36 am Post subject: |
|
|
| Did you sync them at part throttle? From your description you only have the idle synced. |
|
| Back to top |
|
|
W1K1
Samba Member
Joined: March 04, 2004
Posts: 4919
Location: Southern AB
|
| Posted: Wed Jul 30, 2014 9:51 am Post subject: |
|
|
40x35 valves on a 1641cc ?
correct me if i'm wrong, I don't know much about motors but that seems like a big valve on a little motor which would be pretty lazy at low rpms because there is no port velocity.
_________________
http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php
1973 super
1965 squareback 1500E
1971 bay window westy- subi swap |
|
| Back to top |
|
|
hoghead5150
Samba Member
Joined: May 03, 2007
Posts: 989
Location: oklahoma
|
| Posted: Wed Jul 30, 2014 12:02 pm Post subject: |
|
|
gonna need a little more info on things. what jets are in the carbs? did you tear them down and clean them really well before installation?
_________________
"i got a friend that knows a guy who's best friend has an uncle that used to have a bug just like yours!"
i measured once, cut it three times, and the damn thing is STILL to short! |
|
| Back to top |
|
|
Teeroy 
Samba Member
Joined: April 20, 2003
Posts: 3685
Location: Eastern WA
|
| Posted: Wed Jul 30, 2014 12:51 pm Post subject: sputtering under normal acceleration |
|
|
2500 in 4th is lugging it, can be part of the sputter
_________________
Pres. Rivercity VW Club www.rcvwclub.org
Founder Derr Wheat Panzers (DWP)
ARR #3
www.autosportsnorthwest.org |
|
| Back to top |
|
|
denbby
Samba Member
Joined: July 29, 2014
Posts: 3
Location: OHIO
|
| Posted: Thu Jul 31, 2014 5:28 am Post subject: |
|
|
| I did tear down the carbs and adjust the floats they were at 3mm I set them at 5mm that did help some. I did not get the jet size but i'm thinking 1 size up all the way around |
|
| Back to top |
|
|
denbby
Samba Member
Joined: July 29, 2014
Posts: 3
Location: OHIO
|
| Posted: Thu Jul 31, 2014 5:35 am Post subject: |
|
|
| believe it or not it flies with those valves, i'm sure the lightened flywheel helps as well, it just does not want to cruise like a VW would. I'm waiting on the sync tool but I did it by ear with a heater hose to my ear over the throat of the carb and there was no big noticeable difference. |
|
| Back to top |
|
|
|
