I just built a 383 stroker. It is a 350 block bored 30 over. It is a 383 crank, stock rods 5.7, dish .110 pistons for 9.7.1 compression ratio. It has 462 heads w/194 valves, performer rpm intake, 650 dp holley carb. I set the timing at 12 degrees but it idles too high in park but too low in gear. What can I do?
04-29-2012 05:38 PM
List the cam specs, carb and trans converter stall?
12 BTDC is modest
04-29-2012 05:41 PM
The cam is a comp energy cam flat tappet 507 lift, 650 holley double pumper carb and a 2000 stahl converter
04-29-2012 05:41 PM
Connect the vacuum advance to a full time manifold source for starters, this is a source that pulls vacuum full time, including at idle. Now recheck the timing, it should be around 20 to 24 degrees before top dead center. When you do so, the first thing it's gonna do is idle up, which you will lower on the idle setting on the carb. Once you have it at the correct idle speed, set the idle mixture on the adjustment screws. With just plain 12 degrees timing, it likely doesn't have enough advance so to get it to idle you have to open the carb up off the idle slots to get it to idle, this causes the carb to draw off the primary boosters which results in idle problems.
04-29-2012 05:47 PM
Most times a when U noitice a big drop in RPM from idle to gear is caused by a tight covertor and bigger cam. Sounds like a likely cause for your seanrio. If this in in fact the case then timing changes will help but never over come the root cause. A 2800+ stall will really help.
You can clean up the idle with more advance to help
What is the duration of the cam?
04-29-2012 05:52 PM
The duration is 284
04-29-2012 05:59 PM
Need more stall and more idle timing advance.
04-29-2012 06:33 PM
Hei Distributor And A 700r Tranny.
04-29-2012 07:52 PM
If this is going to be driven on the street on anything like a regular basis, I'd strongly recommend you use a mechanical advance curve and not lock out the mechanical advance. If you use more than around 22-24 degrees of initial, there's no point in adding more advance at idle by using manifold vacuum- so use ported in that case.
This is going to require tailoring the curve to match the combination, so start at a safe baseline and work your way up from there. KEEP NOTES! You may think there's no way you won't remember the changes you made, but trust me- you will not remember them all.
04-29-2012 10:02 PM
Didn't you just say yourself:
Or you can limit the mech advance travel stop to about 10deg of travel.
This will allow a 24-26deg inital base timing at idle.
and a total mechanical advance of 340-36deg at max mech advance.
use a 1 medium and 1 light mech advnnce spring combo once the mech advance travel is limited.
BTW that's total advance, not "total mechanical advance". Total is mechanical plus initial. Mechanical is the 10 degrees that comes in from the weights. Initial is the 24-26 degrees, the two added together is the total advance.