big valve 2.1 motor runs sluggish. Ideas?

[Vgonman]

I just finished replacing my 2.1 stock motor with my own rebuild with stock everything but big valve heads from headflow masters. The old motor ran okay but was tired. Now with the new one, It feels like i am dragging an anchor at low speed..............Once the rpms get up ther over say 3k it takes off pretty good. It is timed per stock, but wants to die at idle until warm. Temp sensor 2 is fine. New AFM............set to 2% CO. Valves adjustedto zero lash plus quarter turn.........no clackety lifters.


This is in a vanagon.

[Danborn]

When you modify a Digifant/Digijet Motor you mess up the airflow meter and EUC, Do you use std. EUC/AFM? If you do, that may be the problem; the bigger valves make the motor run lean! when you change valve size or camshaft you have to tweak the EUC/AFM. Because it needs more fuel.. That?s a problem with Digifant and Digijet, it?s hard to tweak. I know there has bean some attempt to foul the EUC and AFM?.. Maybe not much help but I thinks that?s where the problem at..

Jesper

[JohnConnolly]

bad O2 sensor. Do NOT try to get the budget sensor and patch the wires to "work" (it won't, BTDT). Buy the good one from Bosch and it should solve the problem. I've seen them go bad in 6 mos, don't assume it's OK.

John
Aircooled.Net Inc.

[dave m]

you might want to try running the vanagon with an exhaust analyzer, to see how you are burning the fuel. Then make changes based on what you find. Sounds like you may need to do some tweeking. Might consider Go Westy, or Bob Hoover as source of info, as both these places build bigger than stock vanagon engines. they might have some good advice.

good luck dave

[Piledriver]

Bump. Did you ever get any joy out of this?