Camaro350

Hey guys, I have a newly pro built 496 for my 1969 camaro, it was originally dyno’d by the company it was built by so it has been run. it got shipped to us and We installed it into the vehicle, its mated to a 700r4. When I first got it running it would run but not very well. It had about 6 inch of vacuum at idle. And didn’t like off idle much and would be around 700rpms and the exhaust would burn your eyes. It has a quick fuel 830 carb with electric choke on it and a msd hei ignition with mech advance. I first tried to tweak the carb setting the floats and then the mixture screws but no change. I changed out the fuel with fresh 93 and started messing with the distributor. I found that the cap was damaged so I replaced the cap and rotor, set the engine on tdc, at 0 on the crank verified it was on the compression stroke but I can’t get the distributor to point exactly to #1 cylinder, I can get close but not exact when at zero on the crank. i have verified plug wires are in correct location with running order but now after all that it starts and now dies right away. I’ve pulled all plugs they were wet with fuel mostly likely, I cleaned them took the carb off and reset everything I could see but still nothing. I am new to old school carbs and distributors, I am use to obd stuff, please help thanks!

Little Bear

As long as you are close to #1 when installing the distributor you're good, you'll be twisting it around to set the timing anyway. I would try to get it running and get the timing set to at least 10 degrees BTDC, then work the carb issues. What fuel pump are you running, with a carb you probably don't want more than 5-8 psi, more than that and you'll be pushing fuel past the needles and flooding the carb. I imagine that it has a lot of cam so 6 inches of vac is probably about right but I would be looking for more. Be sure you have the float levels set correctly, with a holley you remove the plugs on the side and adjust the screw/nut on the top so that fuel just comes out of the hole, of course the engine has to be running... I don't remember which way lowers the floats but I'm thinking either they are adjusted too high or are stuck, I would try to find out which way to adjust to lower the floats and crank them down a bit, you're sitting in the shop so the idea is to get it running and once it's smooth tweek this stuff in. Is the choke closed when you are running? May want to adjust it so it is open all the time, hold it closed if you need to when starting, something else to tweek later when it goes on the road. Once you get it running, I would put a degree tape on the dampner and crank it up to 1500-2K rpm, where ever your full mechanical advance comes in and set the timing for around 32 degrees BTDC, if you are getting pinging on hard runs back it down until it stops, then check the timing at idle and make that your new set point. Good luck old school can be fun

Camaro350

I have tried to adjust the timing by turning the distributor both ways and still no change. I am
running a mechanical fuel pump. I am waiting for my fitting to come in so I can install a gauge and see my pressure. My carb has sight glasses so I can see the float levels and they are set to just below half way. Right now I have the card choke set to be closed when starting. I have tried to adjust the idle throttle screw from full closed to slightly open with no change. My issue is I am not sure if it’s a timing issue or fuel issue. Once I pulled the plugs and reset the timing the engine fires right up but then dies a few seconds later. I talked to the engine builder and they told me that I should have around 14 inches of vacuum at idle. The timing should be 13 initial and 36 total. Not sure if it’s running to rich and flooding the cylinders, when I bore scope number one I have a little fluid built up in the corner of the cylinder wall on top of the piston but I don’t know if that’s oil or fuel. I am assuming it’s fuel because the plug is wet and smells like fuel not oil. I set the idle mix screws to 1-1/4 turn out from stop which is even leaner then what it comes from the factory. I was told that the engine parred with this trans should run rich but I have a feeling it’s too rich but I don’t know how to find that out or what to look for.

kevinkpk

You have a timing light? I'd say 8 deg btdc idle 750 ish rpm, 36 deg on the mechanical at about 3000 rpm. Since you have a mechanical fuel pump, you shouldn't need a pressure regulator, but as stated if you go with an electrical fuel pump, you do need a regulator 6-8 lbs. If the float is set 1/2 way, probably too low, but shouldn't be causing any fuel starvation issue with just idle. What I would do with idle adjust screws, is turn them all the way in, then back out to where they are half way as a start.

Irish_alley

when you set timing did you set it with the vacuum advance unplugged and plugged the hose? if you set it to 0° at DTC it should start anyway. hook the vacuum advance to manifold vacuum. i think you have more of a carb issue as it should be running. i would start with your screws like kevin is talking about then worry about your timing. i try to set most my engines around 13-15° for the initial and manifold vacuum. with it on manifold vacuum youll get better response and performance, for emission reason is why they use the ported vacuum.

Camaro350

I do have a timing light but I can’t get it running enough to check it. I am not running a pressure regulator but I am waiting to install a fuel pressure gauge so I can confirm I have around 6.5lbs if pressure. I can try going in more with the idle mix screws and see.

Camaro350

I have plugged off the vacuum advance on the distributor, and ensured all vacuum lines going to the carb are plugged, the only vacuum supply I have going to the carb is the brake booster which I have also clamped off in case of a leak causing a lean condition.

kevinkpk

Ok, so if it starts to die after started, can you keep it running with either gasoline (minor into the throttle body of the carb.} or slight pulse of either in the carb?

Camaro350

last night after the car sat all day I went and turned the mixture screws in all the way and backed them out only half a turn, opened the idle screw up a bit and tried to start it and it started instantly and ran at about 2200rpms. I let it run for about 4-5 mins and shut it off. Checked for leaks and then started it again, it was idling way too high so I closed the throttle screw a bit and it ended up dying again.

After that I pulled number one plug and Bork scopes the cylinder and found just a tiny bit of fluid built up on the piston. I opened the throttle a little bit and it ran again but at a higher rpm, I can’t get it to idle very well at regular idle but I didn’t have much time to let it run and warm up though

im pretty sure it’s a carb issue and possibly just an adjustment, just not sure which one without an o2

Irish_alley

i would google your carb and find out how to tune it. you dont need an O2 to tune it to get it running.