D-Jet cam options?

vwfreek · Post by **vwfreek** » Tue Jul 04, 2006 2:37 pm

I'm rebuilding the engine for a 1969 Fasty automatic w/ FI. One of the lobes went flat on the cam. I was just wondering what my options are. I've searched and haven't found much information. Is there an aftermarket cam that will work well with a fairly stock motor, or will I need to locate another stock cam?

rallye · Post by **rallye** » Tue Jul 04, 2006 6:51 pm

from what i understand, D-jet is very sensitive to volumetric efficiency changes. so for the stock ECU to maintain correct fuel ratios you need to use a stock FI cam. if you want to run a different cam you will probably need megasquirt or something similar.

rallye · Post by **rallye** » Tue Jul 04, 2006 6:54 pm

incidentally, i have a savannah beige '69 automatic fastback into which i'm installing a 1600 FI motor with ratio rockers and extractors. I'm using Microtech MT4 for ECU.

raygreenwood · Post by **raygreenwood** » Wed Jul 05, 2006 1:31 pm

Use a web 73. It is made for D-jet. Yes....somewhat...D-jet is sensitive to changes in cam....but mainly because of intake valve opening point timing.
The main differences in the factory carburettor cams and fuel injection cams for bus/type 4 are the intake valve opening points....not lift and duration. On the web 73...the intake valve timing is set up for early 411. It has slightly more lift and duration than stock. Very nice cam all around. Works great ith D-jet. Good improvement.

Since you are working on a type 3....I would call Webcam or look at their website and get the equivalent cam for type 3/type 1 fuel injection.

By the way....in volumetric efficiency wise.....what D-jet is sensitive to...is also what most other factory based systems are sensitive too (other than the timing issue)...that would be too much lift.....causing stalling of the airflow velocity....which causes pulsations in both D-jet MPS and L-jet and digifant/digijet metering flaps in the AFM. This will cause problems as well in MAP based systems.
Also too much duration can cause exessive exhaust to intake valve overlap. Some overlp...is good for it.....like 6-12* max lobe center.Ray

72_square · Post by **72_square** » Tue Jul 11, 2006 1:18 pm

I used a CB cheater cam on a 1776cc type three engine (stock heads and valves, no port work , three angle valve job, 7.8:1 comp). Engine runs a bit lean with stock D-Jet. No other problems to report though. Idles nice and picks up clean. I swapped out to a type four D-Jet that made it slightly richer, but it still runs lean under power. I guess if you've got the time you can fiddle with the MPS (i've not touched mine). I'm going down the route of megasquirt now for more tuneability.

rallye · Post by **rallye** » Tue Jul 11, 2006 8:06 pm

Too much lift would upset D-jet for sure, but with an aftermarket ECU ratio rockers will hopefully be ok. i bought a set already so i guess i'll see.

i'm also using the MAP based MT4 on my 2.0L bus. it has a very noisy torque cam with lots of lift. it idles sweet, even on cold mornings, and goes surprisingly hard between 1200 and 4000rpm.