1.8 L-Jet to 2.0 L-Jet. Any advice? Options

[mapguy]

Howdy,

I have just torn down a bone stock '74 1.8 L-Jet from another 914 with plans to build it back to stock. Plan is to drive my 914 with this engine while I build the original 2.0 the way I want it. I get experience building my first type 4, and get my teener back where it belongs. On the road.

I have the parts available to swap out the crank, rods, and P/C from a '76 2.0 to make it a 2.0 L-Jet. I'm very tempted to do this, as I rarely turn down cheap horsepower! No replacement for displacement, right?

Any land mines I should look out for? Main concern for me is the stock L-Jet system. I understand I might have to tune the MAF for the extra displacement, but I can't find anything discouraging me otherwise. I found an article that details a 3-step process for MAF tuning, but am too lazy to look up the link. Do tell if you know something I don't.

More details:

As implied, stock '74 L-Jet system
Stock '74 1.8 heads (41x34, I believe)
web cam 142/lifters
necessary machine work
Cylinders honed and new rings (I have a set of 94s in excellent condition)
Full re-seal on engine and all peripherals
New fuel lines, vacuum lines, etc etc...

One other thing, I haven't built many engines, but all the ones I've been involved in pop through the intake when first firing them off, and one in particular did it several times before finally lighting off (my old bus engine was a PITA to get running first time). Won't this be dangerous for the MAF on first start? All my experience is with carbed engines. Does this just not happen on FI engines?

Any advice is greatly appreciated.

[revhi109]

I am also running 2.0 Cylinders with 1.8 heads. Now I'm curious about the restrictive throttle body. Does anyone know a part number or inner diameter dimensions for the bus 2.0 TB?

[MrKona]

I am also running 2.0 Cylinders with 1.8 heads. Now I'm curious about the restrictive throttle body. Does anyone know a part number or inner diameter dimensions for the bus 2.0 TB?

The stock L-jet throttle body has a 45mm bore. Vanagon with the 2.1 engine throttle body is 50mm.

I'm running stock L-jet on a 2.0 engine, but the project has been on hold for the past couple of years. It runs, but I haven't sorted it. But I have a Vanagon throttle body in my parts bin and this thread inspired me to switch out the stock L-jet body.

But I'm already finding that the flat spot on the lower shaft of the vanagon TB that engages the TPS is in a different position than the 1.8 L-jet shaft.

What is means is that when the Vanagon TB plate is in the closed position, the 1.8 L-jet throttle position switch is at about half throttle position.

I can't use the stock L-jet shaft because the recessed area in which the plate fits is sized for a 45mm plate and not the 50mm.

Since the TPS is a potentiometer, this will affect the voltage signal going to the stock 1.8 L-jet "brain." How would one (or can one) compensate for this with the stock brain? Does the input from the TPS have that much of an effect?