General Category > Quadrajet Carb Talk and Tips

Hay Cliff Needle and seat area in need of help heli coil?

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Mr.Pontiac:
Well i got lucky and bought a 70 carb. part no. 7020264 carb. basket case for parts and noticed the Body needle and seat had a pressed in needle& seat. Lucky enough to get it out and wondering if its possible to install a 3/8 heli-coil & try and save this carb.???O.d. right now measures close to .430 so no threads are left. Do they make special 3/8 oversize heli-coils for this application?? Do you have any??Interested in taking a look at it??? Rich in WV

Cliff Ruggles:
You are in trouble if its got the pressed in double "O" ring deal.  Even if you could get a heli-coil in there successfully there will not be any material left for the seal to sit on.......

Kenth:
If you can tap the hole to 1/2"-20 you should be able to install needle & seat oversize insert with 1/2"-20 Male Thread x 3/8"-24 Female Thread? Gasket seals on the insert.

Cliff Ruggles:
Kenth, every single carb that has came in here with that repair fails a pressure test, no exceptions.  I've even had a few come in with pressed in thread inserts and those failed as well.

Probably why I got all of them in the first place.  A small leak on the pressure side of the system makes fuel control impossible as the fuel level varies some depending on engine load and how fast fuel is being consumed.  Once the engine is shut down any remaining pressure continues to fill the fuel bowl until the pressure goes to zero.

A bad scenario all the way around........Cliff

Kenth:
I would install the inlet seat with gasket into the insert first, then install the assembly into carb and seal the outer 1/2" threads with Marine Tex as a last resort to rescue a rare carb.

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