Advance timing sbc install#

But more power sooner can be harder to control on the street, which is why you shouldn’t just throw in the lightest springs. Bringing total timing in faster will boost your throttle response. Be sure to inspect the balancer to ensure it’s not out of whack before proceeding. If your harmonic balancer is old and the rubber is worn, it’ll throw off your timing reading. To adjust your timing, all you need to do is turn the distributor housing one direction or the other, depending on whether or not you want to advance or move back the timing. However, there’s no universal formula, and you may still need to make some tweaks to the timing to please your engine. Loosen the bolt that secures the engine's distributor enough so that the distributor can be turned. That way, you can still double-check timing without timing tape. Depending on your cylinder heads, compression ratio, camshaft, and centrifugal advance curve in the distributor, 'normal' base timing for a street high-perf small-block Chevy is somewhere. It’s good practice to mark the location of the total timing number you desire with a notch and some white paint. When you turned the timing back down to 36, you were likely running 14 initial - which that cam probably didn't like much. But the reality is that they’re two different processes. Thus, if you are running over 20 initial and over 20 mechanical advance, you could easily be in the mid 40 range with your total timing. Advancing and retarding cam timing sounds similar and can have a seemingly similar impact on throttle response as ignition timing. This, however, is not perfect or optimum for any one combination.Ī street/strip car that runs on pump gas may “ping” with this much spark advance and will require less initial advance or heavier springs to slow down the “curve.” Where as a low compression, low stall speed converter car may respond better with more initial spark advance or lighter springs for a quicker “curve” – but watch it if you begin your mechanical advance curve at or below the idle rpm, the car will be a real pain in the ass to drive and tune.

Advance timing sbc install#

We usually install a 26° mechanical curve that starts about 100 rpm higher than the engines idle rpm and have all 26° in by 2,800 rpm, this is a good general purpose timing curve when used with 12° initial timing set at engine idle. If you send your distributor to a shop to be recurved they can get you pretty close to the correct curve on a distributor machine. For this reason we will deal only with mechanical advance. Most racing and street performance ignitions do not have vacuum advance and the stock type distributors that are sent to a shop to be recurved should have the vacuum advance removed and locked out. Now we know the timing tab is correct, and we have a 38° mark on the damper, we can now start to work on our timing “curve.”

The formula we use is Dia.×3.1416÷360×38 ( Diameter of the dampener/balancer × PI ÷ 360°×38°, or with numbers: 8×3.1416(25.1328)÷360(0.0698' per degree)×38°(2.6529' which you mark on your balancer away from your TDC mark ), this distance will be 38° on whatever diameter damper you are using. If you are building an engine or having one built at a shop, make sure the timing mark is correct use a dial indicator on the #1 piston head to find “top dead center.” Also, if the damper is easy to get to, put a 38° mark on it to use as a reference on the stock timing tab. If the engine is already in the car and running, we will have to hope the timing mark is correct. Now that we know why we want spark advance and that we want all we can get without detonation – How do we get it? Well, that changes with each application but in most cases it will be as much spark advance as we can get as soon as we can get it without having detonation or “ping”. Next – How much “time” or how many degrees of advance is correct. This “time” is measured in crankshaft degrees and is the difference between when the plug fires and the explosion occurs to push the piston down the cylinder – producing the power stroke. We want this to happen just as the pistons reach the top of the compression stroke, but it takes time for the spark plug to ignite the fuel mixture.

Let’s start with a simple explanation of why we need spark advance and how much of it we want.įirst – When you hook up the timing light to the #1 spark plug wire and it flashes a light beam onto the timing tab, it’s showing you when the spark occurs, NOT when the ignition occurs and the explosion that starts to push the piston down the cylinder.