#Advance timing sbc full

Considering this, it makes sense that there would be ways to affect the ignition timing process to increase vehicle performance. Ignition timing is an important process that plays a big role in the performance of an engine.

Ignition timing controls when the spark plug fires during this process. A car’s ignition timing comes into play during the compression stroke. There are four steps involved: intake, compression, power and exhaust. From the crankshaft and camshaft to the pistons, rods, and pulleys, all of these components are moving quickly and at specific times so things function properly.ĭuring this process, your car’s engine utilizes four distinct piston strokes in order But, I don't rev the 383 much past the high 5k's as my torque is more down low.There are a lot of moving parts in a car’s engine. I expect my idle to improve a bit and my top end to improve slightly, but I'm pretty happy with the 650. Since then, I picked up a 750 DP just to play with, but I have not bolted it on yet. Barry Grant (dating my build) told me to run a 750 all day long. Holley told me to run something along the lines of a 650 to 700 CFM - depending upon my shift point. Could you simply try out the 750 before you swap him?įor some perspective, I have a 650 HP/DP (4150) on my 10:1 CR 383 (manual trans / 3.73's) with a roller cam that is about one notch smaller than yours. I really couldn't tell you which particular 750 to get - other guys here know a lot more about them than I do. However, if you intend to really rev this thing, and spend some time about 6k, then a 750 may be a better choice for those heads and cam. It's cheap to experiment with air bleeds - I bought blanks and drilled mine out with numbered drill bits.

Force it to suck in less air and add more fuel. If you are truly lean at idle, then I would go a size down on the idle air bleeds. The smaller carb should have better throttle response. Then, take the carb tuning from there.įor a street car, I would argue that the 650 is a better choice if you can enrich the idle. Once you get the timing nailed, then set your idle mixture screws with a vacuum gauge (or better yet a wideband O2 ). I would not touch the carb until you get the timing sorted out.

#Advance timing sbc full

That is why I 'm suggesting that you keep your vacuum advance hooked up full time: your initial + the vac adv will feel like your timing is locked at idle, but you will have less initial timing for easier starting. I'm afraid if you truly 'lock out' your timing at 36° (lock your mech adv and set the initial to 36°) you may need a starter retarder. Perhaps 22 to 24°? Then, put a stop on the mechanical advance so that you can get the 36° only. I would first set your initial to get a good idle without bumping back on the starter. I'm hoping you can run enough initial to make the cam happy, but without bumping back on the starter. Just to be clear on the timing, at this point I'm suggesting that you keep your mechanical advance operational. is it normal or ok, in anyone's opinion to have the vac advance on manifold vacuum? the timing has me baffled and i know i'm not going to be able to tune the carb correctly before the timing is fixed. adjusted float levels (they were high as most new holleys) and idle air bleeds were 3 turns out, changed them to just a tad bit more than 1.5 turns out. initially i could get the secondaries to come in without bogging, switched the secondary squirter from a 28 to a 32 and that extra initial pump shot seems to have helped that. in the past i have run many weekend warrior cars with vac advance not even hooked up. when i tried to back the timing down and lock it out at 36 degrees total it didnt want to idle and the headers were glowing red like the timing was retarded. dart sportsman heads, 2.02/1.60's, comp 292h magnum cam, 10.5:1, old edelbraock tarantula intake, holley 650 dp, roller rockers, new hei dizzy, etc etc etc.Įngine makes good power but hasnt really been tuned, therin lies the ied to set the timing, just ddid static timing by ear initially, ran pretty good but showed 47 degrees total like this?!!! have 1 medium and 1 light spring on the mech advance and vacuum advance on manifold vacuum. Built a nice little 355 for my el camino.