Jet extenions

Is there different lenths, mine are the type that screw into the metering block and the jets screw into them. Tring to figure out whats wrong. Finally got my motor in my car, went and made some passes. Car leaves ok, 1.10 60 ft but about then it falls on it's face hard. Has a pause then picks back up and goes out the big end 5.14 at 139 mph. Haven't figured it out yet, wondering if gas is pulling away from jets. Any thoughts would be appreciated

I have the ones that push on to the jets and are oval on the other end, seems to work ok, I did not like the ones you have. hope this helps

and a 1.100 60' and a 5.14 @ 139 is hauling the mail!!!!

What is the attitude of your car when leaving the starting line...? It may be a rich sag after the initial launch.
You might try lowering the primary float level a bit along with a slightly larger pump shooter in the secondary.

My brother fought a similar problem the last season and a half and burned a few pistons because of it. Ended up replacing the fuel pump and a regulator And it's been fine since. My dad had a hiccup at the starting line a few years ago that he couldn't figure out, ended up being that Q16 had gummed up something in his carbs. Sent them back into prosystems and it ran fine when he got them back.
Fuel issues can be a real bitch trying to pinpoint

My car is a pipe rack so it stays level leaving. Carb is backwards, don't know if that will matter. same one I've been running for years without any trouble. But this motor is a lot more power.

sg86coupe wrote:My car is a pipe rack so it stays level leaving. Carb is backwards, don't know if that will matter. same one I've been running for years without any trouble. But this motor is a lot more power.

If your carb is backwards, I am sure you have those jet extensions, and the float to match, on the primary side, right?

Yes sir, I've had this carb on this car on a different motor for several years and it worked flawless until now. But it did sit for a while waiting on this new motor.

It sure sounds like a lean bogg after launch, but with your 60ft time that does not make a lot of sense. Extending the pump shot, by the way of smaller shooters might help if that is the case. A good cleaning would be wise also if it sat up a long time. I kind of doubt it has anything to do with your get extensions.

Usually the jet extension issue occurs long before the 60',usually just after initial launch.

Maybe fuel is coming out of your bowl vents.

Fuel dumping out of bowls? put some hose and extend the pipes.

I thought those numbers were in a door car??? well I too believe it could be in the fuel pump and reg and or vent tube or pick up in the tank because its bogging well after the 60' so that means that fuel pressure is not keeping up, hope you find it, good luck

sg86coupe wrote:Yes sir, I've had this carb on this car on a different motor for several years and it worked flawless until now. But it did sit for a while waiting on this new motor.

Plain ol' crap in the fuel filter and/or disintegrated foam from the fuel cell? Partially plugged at the fuel cell sump? Disconnect fuel lines from carb, put hoses on the lines, turn on the pump and run fuel into a jug or gas can. Look for free flow from front and rear carb lines. I'd rule out a delivery problem first...then look further downstream til you find your trouble.

Do you have a fuel pressure gauge you can monitor during the run? ^^^^^X3^^^^^^^ Very likely also.

Pump, filter, and regulator all new Barry Grant stuff. Just got a fuel pressure gauge for regulator. Took carb apart to inspect and clean, had alot of wax like pebbles that looked like sand in it. Thats all I found.

Hope you blew it all out good and ran some small wire through the air bleeds and other small passages while it was apart.

All it takes to clog a passage is a granule, also do you have a return line to the tank with a bypass.

Yes I blew air through all holes and could feel air coming out, so I think I'm good there. And yes my fuel system has a return after the pump to fuel cell.

Check the size of the passage through the jet extension and compare it to the size of the jet.
Those screw in jet extensions can be a restriction, depending on what size jet your at.

I'm good there, extenions has bigger hole than jet.