Death on sudden opening of throttle

[Tony Bryant]

> > I've finally rebuilt my intake system (welded up from steel exhaust
> > tubing), but I've got the following problem:
> 
> What kind of engine, and how big is the tubing, and how long is it?
> 

Datsun 2L NA 4 cyl, 14" * 1.625" runners. 1.5L plenum.

> > When the throttle is mashed at lowish RPMs i.e. <2000RPM
> > the engine dies for about 1/2 - 1 second, before getting its
> > act together and then pulling strongly.
>  
> > My setup has a second set of injectors mounted on the runners,
> > if I switch to use these as the primaries the problem gets much
> > worse. This indicates to me its something like fuel dropping out
> > of suspension.
> 
> Are they the same type injector and same spray pattern? Mounted in the
> same direction?

They are exactly the same type, but due to physical limitations they 
could only be mounted to squit onto the floor of the runner (albeit 
angled 45 degree towards the valves).

> > Changing the injection timing (Sequential system) does help a little,
> > but not much.
>  
> 
> Possibilites:
> Ignition timing

At 2000RPM, I'm running 25 degrees @ 15" vac, and 15 deg @ 0" vac. 
This is very close to the factory carbed engine specs.

> Low port velocity due to runners being too large

This is a possiblity - the runners are designed for 4500-7000 RPM 
operation. But why would this be a problem down low? Surely it just 
lowers the VE somewhat?

> Valves too large/small

Standard size valves.

> Spark plug gap

.032" gap, with an HEI setup.

> design problems 

Like?