Need Rebuild Recommendations

[redman76]

I'm ready to rebuild my q-jet and have a couple of questions and need recommendations.  First, I have a 17054919 on a '76 Corvette.  Motor in not original.  I have done some mods on it, see specs below.  I plan to purchase one of your HP kits and I have a copy of your book and have read.  Carb runs good now except starting and hesitates slightly when pressing trottle (I have verified that accelerator pump is not working.)

(1) Does the fuel filter that is included in kit have a one way check valve?  If not, is that available.  I have issue with gas draining out of carb when sitting overnight and have read this will resolve.  I have one of the short filters.

(2) With the mods that I have done, do you recommend changing jets/metering rods?  I'm assuming mine are stock, but I do not know for sure.  I'm sure I'll need once I build out to 383 and can wait for now, just looking for your thoughts.

(3) Any other recommendations?



SPECS:

350ci (approx. 9:1 comp) with TH350 auto 3:08 rear gears

Heads - Brodix IK200 (plan on 383 stroker in the next couple of years) 64cc Chamber, 200cc Intake Runner, 2.02/1.6 valves

Cam - Lunati 60102 (mild performance cam so I don't blow out tired bottom end, will replace on 383 build with high lift roller)
Advertised Duration (Int/Exh): 256/262 Duration @ .050 (Int/Exh): 213/219 Gross Valve Lift (Int/Exh): .454/.468
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-5500

Intake - Edlebrock RPM Q-Jet

Exhaust - Hooker Sidepipes (1 7/8" Primaries) with STS Spiral Baffles

[Schurkey]

(1) Does the fuel filter that is included in kit have a one way check valve?  If not, is that available.  I have issue with gas draining out of carb when sitting overnight and have read this will resolve.  I have one of the short filters.

The check valve MIGHT resolve the fuel drainage.  The check valve is also restrictive.

If the check valve works...replace the fuel pump (test the new one...) because the fuel pump check valves aren't sealing.

The fuel drainage problem could also be the carb well plugs, or it could simply be evaporation due to hot intake manifold/ high under-hood temperature.

[redman76]

I didn't know the fuel pump had a check valve . . . I'll look into and check the other suggestions too.  Thx.

[73 Z28]

Carb runs good now except starting and hesitates slightly when pressing trottle (I have verified that accelerator pump is not working.

If accel pump isn't working, replace the pump seal with a blue one(ethanol resistant) and reseat the pump check ball with a punch. Open up the accelerator discharge nozzles to .028" and inspect the pump bore, it may need a light sanding with fine 600 grit paper. Do these and your accel pump circuit should work fine.

Paul

[Cliff Ruggles]

All of our kits will come with the modern accl pump assembly with the latest design Viton seal, and new springs/retainer.  Change all the parts, and gently form a new seat in the casting with the old check-ball.

I would NOT use the check valve, they are very restrictive.  Fuel draining out of the bowl is most likely a leaking bottom plug.  It can only drain back a small amount anyhow, as the fuel inlet seat sits pretty high in the carburetor.  It can't drain back at all if you leave the clip off the needle during assembly.

If it runs fine in all areas I would not change the jets and metering rods.  If it seems lacking anyplace, or exhibits any lean conditions, they tune it accordingly.  The carburetor number that you provided is a "Service Replacement", so I'm not exactly sure how it is set up from the factory, the liturature that I have doesn't include those part numbers.  If I were building it here, it would get new jets and metering rods, based on the size of the main airbleeds, and the engine specs.  If you can provide the MAB sizes when ordering, we can supply the correct jets and metering rods for what you are doing.......Cliff

[redman76]

THanks Cliff for the advice!  I'll start disassembly this week.  What is MAB?

[redman76]

Reread the post and think I've answered my own question . . . MAB=Main Airbleeds. 

[redman76]

I got it apart and it looks like I have the large ~.125 MABs.  It's between a 1/8 and 7/64 drill bit.  Does this sound correct?  Here is a pic:

[Cliff Ruggles]

Yes, they are the large MAB's, right around 1/8"....Cliff

[redman76]

Thanks Cliff, here is some more info . . . Looks like jets are 74, primary rod 433, secondary rod DA.  I'll call your shop to discuss and get pricing for everything, but curious what your thoughts are on this combo.