Q Jet Carburetor Air Flow
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Re: Q Jet Carburetor Air Flow
difference in Qjet CFM
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Re: Q Jet Carburetor Air Flow
[quote="Geoff2"]I don't think the window in the seat adds any flow. The restriction to flow is the small 0.125" hole. If you calculate the area between the needle & inside wall of the seat [ whee the fuel needs to flow to get into the bowl ], it will be greater than the area of a 0.125" hole.
I do not believe GM would have spent the money to machine those windows if not necessary.
I do not believe GM would have spent the money to machine those windows if not necessary.
Re: Q Jet Carburetor Air Flow
Well if the needle is tight enough in the seat housing to become a too big of a restriction the windowed seat certainly makes sense. I made sure feed problem is a non issue when I installed a surgetank with a Walbro pump in it. Would probably not have mattered if the seat was window or not in my case.
Re: Q Jet Carburetor Air Flow
All true about the air cleaner base profile shape and the lid and air flow amount and quality.
On the needle seat when you have 2 Qjets the fuel flow load is shared by the 2 carbs,, so...
But lots of good Qjet tech getting posted. All welcome.
On the needle seat when you have 2 Qjets the fuel flow load is shared by the 2 carbs,, so...
But lots of good Qjet tech getting posted. All welcome.
Re: Q Jet Carburetor Air Flow
You need to be very careful with needle and seat sizes in the QJets. Bigger is not better for several reasons.
Re: Q Jet Carburetor Air Flow
tenxal wrote:You need to be very careful with needle and seat sizes in the QJets. Bigger is not better for several reasons.
Yes you get better fuel control with the smaller .125" standard needle seat.
Modest fuel pressure is best too. You need volume (a steady supply) not pressure.
There is a .135" and a big .149" N/S but if you don;t need it you are better off with the small er stock N/S.
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Re: Q Jet Carburetor Air Flow
also make sure the needle tip has a blunt end and not pointy as the pointy one reduces the fuel flow thru the seat because some of it is still in the bore restricting the fuel flow