I built a 383 with 6.0 rods, 10:1 flat tops, an XE274H cam, 1.5:1 RR, World Sportsman II heads (200cc) with 2.08/1.60 valves, and I recently got a 6AL and a pro-billet distributor. I know this seems kinda silly since I built the motor and put everything together myself, but I've never really been taught how to set timing or tune a carb. I kinda figured everything so far on my own, or asked people a ton of questions, but now I'm getting to something I'm not really sure about. How do I set timing on this beast? is it just guess and set, and then try somewhere else til i find what the motor runs best at? and the carb? right now I'm running a 600 edelbrock with mech secondaries, so I hear they're pretty easy to tune. but once i change the carb settings, don't i have to check the timing? wouldn't this become a never-ending cycle? am I reading too much into this? I'm setting timing and tuning the carb on sunday/monday. any help or advice you can give would be great.

 

a baseline or best guess?

 

tuning carb and timing, hmm.. well the object here is to set them so that what you built will give you the best performance. start with timing around 10-12 adv 36 total to get you running. if carb starts and runs car, its a good start. then its a matter of stomping, driving and tuning. watch for detonation (PINGING) to much timing, bad thing. then get back to us and let us know what its doing. ie. running rich, bogging ect. have fun.

 

ok. i can do that. silly question... what does pinging/detonation sound like?

 

to start with you know to put the car on top dead #1 cylinder. then aim the rotor at the #1 cylinder on the car as you stab the distributor. after this you can use what ever plug on the cap the rotor is aiming at to start your firing order. after you get that all worked out you can start adjusting it by advancing it until it is hard to start and back it off a little bit. this will get you close. then you really need a timing light and just advance it as much as you can and make sure you are running the kind of fuel you intend on continuing to run. pinging sounds like crap basically when you excellerate up a hill at slight throttle you will hear what sounds like rattling in your motor this is very bad on an engine so gotta get it right. but for performance you want as much advanced timing as you can get without that ping.

 

that makes a lot more sense. thanks.

 

too all those that helped, thanks a bunch. total success on the first crank, no major hiccups. fired right up sunday afternoon and drove around the block. I bumped it up to 12, and she liked that better, so I'm going to try 14. I think that'll do her just right. a little stumble under load, but it gets better with more timing. anybody ever run 16 degrees intial? I don't think she'll need that much, but you never know. also, should i mess with my carb settings at all? or just leave them alone? I'm running and edelbrock 750, and i think the car is running a little rich now that I advanced the timing. any more ideas? thanks again for the great help!

 

14* advanced (initial) seems to be the magic number. It smells like it's running rich as heck now that the timing is advanced. I just bolted the edelbrock on, i didn't tune it. how do i tune an edelbrock? I know that sems like a silly question, but no one's ever showed me how, and all my frinds run FI.

 

The Edelbrock site has an on-line owner's manual, if you didn't get anything with the carb. http://www.edelbrock.com/automotive_...ers_manual.pdf

Are you setting the timing with the vacuum advance disconnected and plugged? That isn't as much of an issue if you're using a timed vacuum port off the carb, but it should be disconnected when you set the timing. If you had the vacuum advance connected, you won't have enough advance and that can lead to a rich condition.

The only "tuning" you should have to do with the timing changes is to adjust the idle speed.

I have one engine that likes about 20 degrees intial timing (as set), plus full manifold vacuum advance. But, that's only because I set the timing for the full mechanical advance, and pretty let the rest fall where they were.

 

no, it was def. disconnected when i set it. I'm thinking it was rich before i started and i didn't notice because i was so happy it cranked. when i did some dummy math using head size to calculate carb cfm, i came up with 693.xx and that's why i switched from a 600 to a 750. what do you think? I'll check that manual and see if it makes sense.

 

In my experiences the edelbrock carbs were always in need of tuning. I dont care for them much but thats just my