Q-Jet rebuild - round 2

[don t. - 72gmc]

Original post on this topic is here.... http://67-72chevytrucks.com/vboard/s...d.php?t=590375

Ran it a bit. Noticed top of carb has gas on it, had a real hard time getting it to stay running. Almost like no choke. I remembered I had very similar issues a few years back rebuilding a different carb.

Took carb apart again. Reinstalled old needle and seat, and the old acc pump. Put it back on, much much better. Did carb tweeks, now it does a 1 wheelie squeelie with easy. I still think the idle, carb jets, still need adjusting as my ear says its a bit to high RPM. Exhaust does not smell "gassy" as before the recent changes.

Anyway...Is there something with the needle and seats now-a-days? or is it just me? I tapped in and burnished the new seat on the initial rebuild. Did notice the old seat is red in color, where the new is black? I dunno.

Have fun....don t. ....

[Eddie H.]

I have had some problems with the needle and seats that come in the rebuild kits that I have used lately I think it's just poor quality. ( probably made in china). Q jets are also super sensitive to float level adjustments, since they have such a small fuel bowl.

[Steeveedee]

Originally Posted by don t. - 72gmc

Original post on this topic is here.... http://67-72chevytrucks.com/vboard/s...d.php?t=590375

Ran it a bit. Noticed top of carb has gas on it, had a real hard time getting it to stay running. Almost like no choke. I remembered I had very similar issues a few years back rebuilding a different carb.

Took carb apart again. Reinstalled old needle and seat, and the old acc pump. Put it back on, much much better. Did carb tweeks, now it does a 1 wheelie squeelie with easy. I still think the idle, carb jets, still need adjusting as my ear says its a bit to high RPM. Exhaust does not smell "gassy" as before the recent changes.

Anyway...Is there something with the needle and seats now-a-days? or is it just me? I tapped in and burnished the new seat on the initial rebuild. Did notice the old seat is red in color, where the new is black? I dunno.

Have fun....don t. ....

I don't understand what you mean about tapping and burnishing the new seat, and it being red or black. The seat is brass, and the needle has a coating of some petroleum-resistant material, which may be red or black. Some of the new kits use a material that is not resistant to E85 fuel, which has alcohol in it. The newer material may have been your issue. if by "tap", you meant that you tapped on the needle to get it to seat, that's the last thing you would want to do, as it will distort that material. Or did you run a tap into the carburetor where the seat threads in?

[don t. - 72gmc]

Originally Posted by Steeveedee

I don't understand what you mean about tapping and burnishing the new seat, and it being red or black. The seat is brass, and the needle has a coating of some petroleum-resistant material, which may be red or black. Some of the new kits use a material that is not resistant to E85 fuel, which has alcohol in it. The newer material may have been your issue. if by "tap", you meant that you tapped on the needle to get it to seat, that's the last thing you would want to do, as it will distort that material. Or did you run a tap into the carburetor where the seat threads in?

"tapping and burnishing".....
1-install seat and needle.
2-take a wood dowel. Place end of dowel on seat and tap it w/a hammer. Your not trying to pound the needle thru the carb, just tap it.
3- Using needle nose pliers, twist needle in the seat, 10-15 times back and forth.

"needle has a coating of some petroleum-resistant material, which may be red or black"....
The kit I got from Napa, the tip of the needle is a rubber/flexible type material tip. There is no coating.
I have since reinstalled the old needle. I have no desire to take it out to see how its made(big grin).

"to E85 fuel, which has alcohol in it."....
1-I would never run E85 in a 1970.
2-In my area, there has been a 10% alcohol mix for decades. I wish my area had 100% gas.

HTH...don t. ....