Im having an issue with tuning on my car. I installed a new carb and I don't know if I have timing issues or carb issues. I can get it to idle smoothly and rev quickly in park. Put it in gear, it surges I can't give it any throttle and I'm about to pull my hair out. Any suggestions on where to start? Where do y'all like initial timing? Anyone running a summit racing 600 vacuum secondary carb? That what I just installed. Thanks for any and all help!
There hasn't been a 302 built that won't run with 6-12* initial timing... Assuming yours is close, there is another problem... Make sure any unused vacuum port on carb is plugged off...
You think that's what's killing it when I put a load on it? Vacuum? I don't know a thing about carbs!!
No idea what's causing you Sorry but my 40+ year old crystal ball is clouded up, no replacement parts available... Assuming it was running better before the carb swap, a vacuum leak or maybe fuel mixture is generally the cause... Of course a carb isn't much more than a controlled vacuum leak, any other leak is going to cause issues...
Carb is new, gas is fresh, filter is clean, plugs are new, witness, rotor, cap, etc are all new. I'm just searching for clues. I don't know if this is a symptom of timing, fuel, vacuum or a combo of all...
It wasn't running at all before the new carb. Old carb was shot. I serviced the car about 8 years ago and then sat it up. So I've hit it with a lot of new at once...
Holley performance has some very good setup and tuning videos on YouTube. I'd say if you didn't change anything on the timing or distributor it's a vacuum leak or tuning issue. But, with that being said unless the balancer has been replaced I wouldn't trust the numbers to set timing with a light.
Probably be a good idea to get yourself a vacuum gauge and learn to use it... There is info all over the net... BTW, are you sure the firing order correct?? Original was 15426378, many of the newer performance cams use the 351/5.0 HO order of 13726548...
I've replaced the balancer a couple of times after they've slung apart, so hopefully it's be accurate. I'm using the 15426378 order. I need to dig out my vacuum gauge. It's somewhere in the shop. Thanks for yalls help so far!
The Summit 600 CFM carb is one of the easiest carbs to tune and an all around good street carb. You should have received a DVD with the carb that provides instructions on how to tune it for best performance. Krazy brought up some good things to check. In addition, make sure you also have sufficient fuel pressure,the filter is clean and the floats are properly adjusted.
I didn't read anything about the condition of your plug wires. If you have old or cheap plug wires they may have separated or cracked internally during plug and dizzy cap replacement. I've seen internal plug wire failures happen often with no indication of a problem externally. Bad wires many times will allow the engine to idle fine however, under a load is when things start to get ugly. Also as Krazy Komet points out, you have two firing order options depending on the cam installed in the engine. You indicated using 15426378. How do you know that is correct for your cam? Do you know what cam you have and its firing order? Just asking. I've run a Summit 600 cfm carb in the past. Great little carburetor!
Update- I got the car tuned and running great, until I hit 3500 RPMs. In gear, I have strong, even power until I hit that that area in the RPMs. At that point, it begins backfiring, popping and spitting and won't get past it. My distributor is about 12 years old, but the car has been sitting in the barn and shop the past 9 years so I have very little mileage on it, but I know sitting can kill stuff. I'm wondering if my vacuum advance is not working or if I'm leaning out too much. It runs great with good response and plenty of power until then. Any advice? Thanks!!
What are your timing settings? Initial number.. mechanical sweep spec's.. total number.. and at what rpm does it achieve that total advance number?
