I took my 69 out today for the first time in a long time. Car started fine and was running good. Once it was warmed up it developed a stumble while cruising. Well it got worse and then I couldn't get it to go past 2000rpms and it had no power while driving. Car reved fine when I stepped on the clutch and idled fine. I thought my timing was really advanced, so when I got home, I checked the timing which was fine at 10 BTDC. Fuel pressure was 5.5 psi. I have edlebrock 1406 carb and a msd ready to run dist, msd coil, accel 8.8 wires and accel plugs. I probably put 500 miles on the ignition components over two years. The carb was on the car before I got it, so I don't know how old that is. Last summer I replaced the entire fuel system. I put in a new tank, sender, braided 6an line, new fuel filter, holley 130gph mech pump, aeromotive fuel pressure regular. I put a couple hundred miles on this set up and had no previous problems. The cap and rotor look fine. I don't know what causes this condition, so I don't know where to begin to check. Would a vaccum leak cause this or am I pumping in to much fuel?

Sounds like coil going bad. Need higher voltage to fire under load.

How lomg is a long time set up?My 1st thought is how old is the gas and did you use gas stabilizer in the tank if its sat up for 6 mo or so.Does the gas smell "vanishy"?

Check the choke and see if its open all the way when it is warmed up. It may be sticking from not being used.

Kev

I put stabilizer in the gas at the gas station back when I filled up in the beginning of Nov, so the gas should be ok. A few months ago I started it up to let it run for a while, and when it warmed up, it would barely idle and stumble until about 1500rpms. After about 10 minutes of this, it idled fine. It hasn't done that the past few times I started it up, so I thought I take it for a ride yesterday. This is when I experienced the loss of power, bogging, and 2000 rpm limit. It feels like its running out of gas, but when i step on the clutch and rev it, its fine. I'm thinking my carb needs a rebuild.

Well, shouldn't be too hard to figure out. Sounds like either fuel or spark, but can't rule out something else; perhaps timing chain skipped a tooth or broken valve spring.

I was gonna say "fuel filter" but you replaced that already. Still, I would check it, plus I would check the fuel pump flow. Get a small cup of gas, disconnect fuel line at carb and direct the line into a clean bucket. Start the car and keep it running by pouring tiny bit of gas into carb. You say you got 130gph pump, so run engine for 30 seconds and see how much fuel you got in bucket. Maybe try revving the engine a little (tough to do by hand-feeding gas) and see how much fuel flow increases. Of course, it's always dangerous to have gas spraying around, so be very careful if you do this test. Keep a fire extinguisher handy.

If fuel flow seems OK, I'd probably yank the carb, take it apart carefully, and hose it all out with spray carb cleaner, then blow out with some air. Chances are you can do this without having to buy an overhaul kit. Just be careful you don't lose any small check balls or knock anything (like float level) way out of whack.

If it still acts funny, I'd try substituting another distributor and see what happens.

When you did the fuel line, I'm assuming you replaced the short rubber pieces at front and back. I have often seen them crack and the fuel pump sucks air instead of gas.

Please post when fixed so we known what it was. I'm guessing fuel delivery issue................

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Hi Chevy SS

I have a new sending unit with a hard tube adapter, all braided 6an line and fittings. No rubber in the fuel system. Fuel flow checked out fine. I checked my owners manual and a few of the problems I'm having leaned towards either being to lean or rich or a vaccum leak. Since I initially had a idle problem, now a part throttle driveability problem, I'm thinking my carb is clogged or dirty. I bought a rebuild kit for the carb, so that is my next step. I'm not sure how old the carb is, but a rebuild can't hurt. I'll post my outcome. Process of elimination I guess.

Check the fuel filter before you rebuild the carb. You just never know............

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I had the same problem with my 69 RS and it was my coil. Ir would idle fine and even reved up fine in park or neutral but as soon a you put a load on it it would crap out.

Well, I took the carb apart for a rebuild since I had no idea how old it was or if it was ever done. It had carbon build up on the throttle blades, but overall didn't look to bad. However, the filter screens in the carb had all kinds of little particles on them and when I drained the carb, the gas was brown in color instead of the golden color. Not sure what caused that, but I'm definitely going to check the fuel filter and crank it over a few times to check fuel fuel and the gas color. Now I'm setting the floats according to the manual. When you flip the top plate over and check the floats, there is suposed to be 7/16" between the gasket and the bottom of the float. That measurement was about right, but when you flip it over and check the total travel, that was way off. Its supposed to be 15/16, however my total travel is over an inch and a half. Glad I took it apart. Either way, once I get it back together, I'll definitely check the fuel filter and fuel flow. I have a new MSD Blaster coil that I kept as a spare, so if the problem is still present after my fuel system checks out, i'll try that.

Sounds like you're on the right track. The float level being that far off is interesting, but you could have inadvertently bent the tab when dis-assembling. The downward limit stops the needle valve from going down too far when empty, which could cause the needle valve to get stuck in the open position.

The particles on the filter screens are puzzling. Are you using an inline filter? If so, those particles should have been caught by the filter.

I think you're doing the right thing though. Clean out the carb, new fuel filter (good one) and see what happens..............

Please post results, I'm curious.

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Some of the particles could have been from the braided line when I cut it. I used a jig saw with a metal blade in a jig that I made to cut the lines. I thought I cleaned the hoses out, but I could have missed some. There were bigger particles in there as well that I know did not come from the hoses. Who knows what the previous owner did to the car, but given how uncared for the car was, I bet he never changed the fuel filter. I should have the carb assembled today and put on the car tonight. Its going to rain, so I'll have to wait until tomorrow to see if I solved the problem.

Thanks

if you still have the problem hope not!! pull the vacuum adv.hose off and try to drive that way. let us know.Nick

Pull the cap & check that the mechanical advance is not sticking.

All I was able to do yesterday was install the carb and hitch up all the fuel lines, hoses. Didn't get a chance to start it and of course its raining today, so I'll have to wait until tomorrow to see how it runs. I'll keep you posted

Fuel filter was fine, fuel pump had go flow, and the distributor mech advance was functioning fine. I'm glad because they were pretty much new parts. Well, she fired right up and idled great. I let her warm up, adjusted the idle mix screws and went for a ride. Ran like a champ. Thanks to all who helped suggest possible problem areas. Turned out to be a dirty carb.

Cool, thanks for posting results!

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