Q-jet inlet filter questions
 

These carb inlet filters seem to come in two forms - one with a check valve and one without.

In what situations does one need the check valve? Does it merely help with cold starts by keeping fuel from draining back in the line? Is there not a check valve in the fuel pump for that purpose?

As compared to a filter without valve, does it take significantly more fuel pressue to overcome that valve at the carb inlet?

Up and/or downsides of using one filter type or the other?

Thanks for any insights.

Re: Q-jet inlet filter questions
 

The reason the check valve was put in is to prevent fuel from leaking out on a roll over collision. I've used them both ways & can't tell the difference in the performance. I've blown through them orally & it takes quite a bit of pressure to open it.

Re: Q-jet inlet filter questions
 

Check valve filters can be more restrictive in high RPM situations. Many prefer the non-valve version for that reason. An old trick was to remove the valve and snip a couple coils from the spring. Partial to the sintered bronze style filter myself.

Re: Q-jet inlet filter questions
 

Thanks Wrenchbender and GRX - got it - now have a plan.