Inliners International Forums General Discussion Blown and Injected snowman4839 turbo build

I would prefer to see you use a electric fuel pump and a fuel pressure regulator. You can also get the regulator with a boost reference. You are definately running out of fuel under WOT.

The cruise and idle are going to need lots of tuning. Timing does play a large part here also. While not in boost, the idle will need about 20-26 degrees to be stable. This is achieved using the set timing, mechanical timing (almost none at idle) and the vacuum can. Cruise needs the very important mech timing to kick in. At cruise, the timing could go as high as 50 degrees! Remember, there is no load. But in N/A form the engine likes to see 34-36 degrees toatal timing.

So when figuring in your timing, add these 3 things up:

Fixed timing, this is what you set(ie 8-10 degrees)

Mechanical timing, your distributor mechanical weights set this curve up. Typically 20-26 degrees.

Vacuum can, the can is used for cruise. Can add 15-20 degrees and at different vac points(levels). In your case, kicks out under boost.

Snow,
You will not believe what the fuel demand is under full boost. That stock pump will not keep up.

Be sure to see if the pump cam on the carb is ready to squirt as soon as the throttle is moved, this is adjustable. As said before different cams are available as well as squiters sizes.

Harry had mentioned something that may be pertinant here. Large carbs on a small engine. Believe me the 500 has the same size primaries as a 750 4 bbl. You may need to drill 1 small hole in each blade near the shaft to get proper idle. Ussually this occurs with a large cammed engine. This is to allow further closing of the throttle idle screw. The blades will then be below the idle transfer slot and allow proper idle mixture adjustment.

You do need to get a dial back timing light!