Once started, a high engine vacuum signal connected to a dashpot on the distributor rotates the internal advance mechanism forward to introduce more timing for good off-idle and part-throttle engine response. At 2500 to 3000 rpm 36 degrees total (initial + mechanical) is fine. I could lock it out and give it a go - I timed it based upon Lars methods. It should be between 32-36 degrees for premium gas... 30-32ish for regular. Repeat until the target 4 degrees BTDC … jmarkaudio. However, you will need to test and tune to determine the best setting for you. I have seen SBC that will ping on 10* initial and 32* max timing on premium gas and I have built 9.5 compression SBC that like 22* initial and 38* max on low octane gas. For instance, if an engine has 10° of initial combined with 21° of mechanical, the total timing is 31° BTDC. I think that what is confusing you here is how the total mechanical advance is read by using a timing tape and timing marks on the damper instead of the timing marks on the timing tab on the engine. Set your Timing Light to your desired total timing. Note that Total timing never includes vacuum advance. Post Aug 13, 2014 #1 2014-08-13T01:37. I have seen SBC that will ping on 10* initial and 32* max timing on premium gas and I have built 9.5 compression SBC that like 22* initial and 38* max on low octane gas. … ... {TOTAL_SLIDES}- Save on Timing Components. For example, part-throttle total timing would look something like this: 10 degrees initial + 10 degrees vacuum + 20 degrees mechanical = 40 degrees of total timing. 12-21-10 09:38 PM - Post# 2021258 Hey Guys, I'm new here and to the car world so cut me some slack OK, so, I have set the initial timing on my SB 350 to 10 degrees starting point, now I would like to know how to set my TOTAL timing @ 36 degrees, with a DIGITAL timing light and that part I'm having trouble with. (Usually, 3,000 - 3,500 rpm will do it.). Set the timing with the vacuum advance hooked up so you can do vacuum and mechanical advances at the same time. BigE383. This is done with a combination of initial advance, plus centrifugal or electronic controlled advance for engine speed, plus vacuum or electronic advance for engine loading and throttle effect. Start the engine. msd hei stock config., what would you guys recommend my total timing to be set at? For 45*, are you sure that you disconnected the vacuum advance before checking total timing? (Usually, 3,000 - 3,500 rpm will do it.) The term "Total Timing" refers to the maximum amount of Ignition Timing applied to the engine. If you have an … 350's Similar Specs Total timing is a term used to describe the combination of initial ignition advance at which a distributor is set, plus the amount of centrifugal (mechanical) advance that takes place within a distributor as the engine RPM increases. For instance, if an engine has 10° of initial combined with 21° of mechanical, the total timing is 31° BTDC. Rev the engine to about 3000 rpm and watch the timing light to see where the total is. Most unmodified production, daily-driven Chevy small blocks will need about 8 to 12 degrees of initial distributor advance at idle for ease of starting. Under full throttle loads, there is reduced vacuum available to the vacuum advance mechanism, and its advance is eliminated to avoid too much timing. (you won't see too many sbc strokers that like more than 34 degs total.) Note* this post assumes that you already know how to … 12-21-10 09:38 PM - Post# 2021258 Hey Guys, I'm new here and to the car world so cut me some slack OK, so, I have set the initial timing on my SB 350 to 10 degrees starting point, now I would like to know how to set my TOTAL timing @ 36 degrees, with a DIGITAL timing … Rotate the distributor until the timing mark lines up at zero with the light. But, some time and effort will be required.AdvertisementClick Here to Read MoreAdvertisement Let’s start with a simple explanation of why we need spark advance and how much of it we want. 10 degrees initial is definatly too low and that is why your engine is running rough. This video shows how to set Initial Timing and Total Advance Timing on 350 Small block engine. Ignition Timing (Total Timing Method) This issue's subject is about setting ignition timing using the total timing method. Do the same and set the total timing to 34 degs. Setting initial timing on a small block Chevy (SBC) John Milmont on October 20, 2012 — 8 Comments. The best way to check total timing if you don’t have a dial-back timing light is to use these simple timing tapes from MSD. Chevrolet has manufactured the SBC in displacements from 265 to 400 cubic inches for a variety of applications. I have seen some people claim that their Small block "needs" 40-45 degrees to "run right", these engines have some serious problems with combustion chamber design, low compression problems, or other very serious tuning and design issues. I am helping a guy with a sbc 406 with 18 degree eldebrock victor jr cylinder heads. BigE383. Disconnect and plug the vacuum advance when checking/setting the timing (as Al suggests). Hagerty’s DIY series is your handy-dandy, easy-to-use video guide to tackling small projects any classic car or truck owner might encounter during the course of ownership. Everything you need for anything you drive. < Previous Thread | Next Thread > Page 1 of 3 1 2 3 Next > tsb Joined: May 4, 2011. However when I checked the total advance at 2500 It was well over 40+ degrees and hence I didn’t try running it with that amount of advance. 636 Posts . Your browser either does not have JavaScript enabled or does not appear to support enough features of JavaScript to be used well on this site. Set the timing with the vacuum advance hooked up so you can do vacuum and mechanical advances at the same time. This is when the initial timing is added to the mechanical timing. The proper amount of total timing is critical. Most Small Block Chevys like about 32-38 degrees total advance at WOT. Make small movements when turning. The small-block Chevy engines vary in the amount of total timing based on a number of factors, but most SBC engines require between 32 to 36 degrees of total timing, with some older, less efficient engines needing as much as 38 degrees or more. Ignition Timing for Modified Engines An often neglected but important area when tuning an engine is the ignition system. ), Rev the engine past the point where your mechanical advance is fully engaged. Watch the timing mark on the harmonic balancer using the timing light. In a spark ignition internal combustion engine, the purpose of advancing the timing of the engine spark is to get past ignition delay. I have seen some people claim that their Small block “needs” 40-45 degrees to “run right”, these engines have some serious problems with combustion chamber design, low compression problems, or other very serious tuning and design issues. Disconnect and plug the vacuum advance when checking/setting the timing (as Al suggests). At high RPMs with full throttle application (no/low vacuum), the total timing may be: 12 degrees initial, 0 degrees vacuum, and 22 degrees mechanical advance, for a total timing of 34 degrees. Just curious, does anybody else run that much on a SBC with AFR or aluminum heads? Total Timing = Initial Timing + Mechanical Advance. As an example, a generic tune might be 14 degrees BTDC initial with another 6 degrees of mechanical advance for a total of 20 BTDC at 2,000 rpm. At 60 mph in high gear, a typical small-block Chevy needs between 45 and 55 degrees of advance. way for most people to set the timing, and is not a good procedure for optimum performance. Optimum Timing. This allows the engine to run more efficiently at low speeds at part throttle with better throttle response and more complete fuel combustion. Ask Away! With factory steel heads , what total timing do u guys run . If you're above 36 degrees, go back and reset your inital timing back a few degrees.. if it's below 32, bump it up a hair and try it again. Build details include: Bored 0.030 oversize New pistons (7cc valve relief) and rods 5.7" Original cast iron heads - … Trending at $253.12. Im trying to set my timing on my 388. No I don't mean harder plugs, competition coils, lumenition etc., that only affect the efficiency of the spark, but the actual ignition advance supplied by the distributor. 35-38 degrees “total” is about where you will see your best power, again a factor of many other things beside the total timing. The engine is a 290-horsepower Chevy crate engine with a set of headers, a Holley dual plane intake, a 750 Holley 0-3310C Holley carburetor, and … with Jeff Smith: Solving SBC Ignition Timing Problems Posted by Jeff Smith on July 1, 2020 at 5:17 pm A melonized distributor gear at … I have not done any testing at the track yet with timing. Although the more initial it can handle the better response and feel it will have during normal driving. While most engines use a vacuum advance mechanism, some performance SBCs do not. For performance applications, some modifications will be required to the advance "curve." In most cases starting out … Should be "all-in" by about 2,500-3,000 RPM's. If you have Vacuum Advance, disconnect it. This can be done with performance kits which allow you to easily modify the rate and amount of mechanical advance. This is a little how-to for setting the initial ignition timing on a small block Chevy before its ever been run. This is a potentially destructive condition and can burn pistons, valves or spark plugs and can cause damage to the upper connecting rod-bearing inserts, as well. 88. Rev the engine to about 3000 rpm and watch the timing light to see where the total is. The engine has not be on any kind of dyno. How to set total timing on 79 350 SBC. 255 Posts . Ignition Timing for Modified Engines An often neglected but important area when tuning an engine is the ignition system. Newer engines with more efficient cylinder heads which promote high turbulence in a smaller combustion chamber reduce the need for timing advance. Small block Chevys (and most other GM performance V8 engines) perform best when the total timing (full centrifugal advance plus the initial timing setting with vacuum advance disconnected) is all in by 2,500 Œ 2,800 rpm and is set to 36 Œ 38 degrees. Setting initial timing on a small block Chevy (SBC) John Milmont on October 20, 2012 — 8 Comments This is a little how-to for setting the initial ignition timing on a small block Chevy before its ever been run. 4. and finally total timing at Wide open throttle. To do this, measure the circumference of the balancer with a flexible, cloth or paper tape, measurer or install permanent degree tape to the balancer. I should also point out that the best way to REALLY check your total timing is to buy an $8 "timing tape" that basically wraps around your harmonic balancer and puts 60 degrees worth of degree marks ON THE BALANCER where you can easily see them. Aisin TKT-005 Engine Timing Belt Kit with Water Pump for 4Runner/Tacoma/Tundra. Rotate the distributor clockwise to retard the spark slightly, lightly tighten the nut, and check where the timing is with the timing light. I have not done any testing at the track yet with timing. Lets deal with total timing first Total timing for a 350 sbc is almost always optimum at somewhere between 34 to 38 degrees of total advance. Discussion Starter • #1 • Oct 30 ... My 406 runs 16* initial and a total of 36* and I use ported vacumm which is a whole other issue with many opinions. advance line, hook up a timing light and read the timing while you or a friend opens the throttle a little. (you won't see too many sbc strokers that like more than 34 … To find out what your mechanical advance is, remove the vacuum line from the distributor, plug it, rev the engine, and get a reading off the timing marks on the harmonic damper with the timing … I think the timing needs to be more like 32 degrees. When initial advance is increased, mechanical advance needs to be reduced. The initial timing has nothing to do with it when racing because you are always above that and should be at your total. This article will be especially helpful on non-stock engines or … At 2,500 rpms it was only at 12 degrees btdc. advance line, hook up a timing light and read the timing while you or a friend opens the throttle a little. Tuned and modified engines have different The proper amount of total timing is critical. have a sbc that the more initial timing you run the faster it gets @ the track but it gets to the point that it blows gaskets like oil seals valve cover on 6 deg runs 8.40 1/8 on 12 deg btdc runs 7.30 on 16 deg btdc it runs 7.20 cant go up past … If we shine a timing light on the damper (with vacuum hose disconnected and plugged), at idle, we would see 10 degrees. Where should I set my ignition timing for the first start-up? 400 SBC Timing Specs. The size of the engine impacts the total timing requirements. This is intended for application with pre-emmission engines (generally pre-1975). Chevrolet has manufactured the SBC in displacements from 265 to 400 cubic inches for a variety of applications. The cool thing about ignition timing is you can usually get a considerable performance increase for little or no money. A: We would shoot for 34 to 36 degrees total timing at 2,800-3,000 rpm. So if you set total timing to for example 36 deg and the dist had 25 deg mech adv 36 total minus 25 deg mech adv = 11 deg base timing. Most naturally aspirated engines like a total timing of 34 to 36 degrees BTDC, (Before Top Dead Center) AKA "Advance". Total timing is dependent on many factors. i would set the initial timing at least 12. more importantly you should set the total timing which should be about 32-36 degrees. Too little timing can cause the engine to be sluggish and unresponsive. Loosen the distributor hold down nut a little more so the distributor can be turned. Because of the short cam, the vacuum advance in our current example will not need to come in until about 7 to maybe as much as 10 inches of mercury, and the amount required will be at most about 18-degrees distributor (36 crank). What Are the Symptoms of a Bad EGR Valve? The full energy from combustion is released too far after the piston has past top-dead centre (TDC). The tables below give some general guidelines. What is the Difference Between a Honda IDSI & a Vtec?→. SBC's normally run 32-34 degrees total Mechanical advance. A: We would shoot for 34 to 36 degrees total timing at 2,800-3,000 rpm. This timing … The 1966 versions have an ignition time of 2 degrees After Top Center (ATC). The highest timing I got was 16 degrees advance giving me a total of 24 degrees advance right at 3,300rpms. I know about 36 to 38 with aluminum, but this is with good aftermarket combustion chambers .do u run a little more with the factory stuff in a performance engine . The small-block Chevy engines vary in the amount of total timing based on a number of factors, but most SBC engines require between 32 to 36 degrees of total timing, with some older, less efficient engines needing as much as 38 degrees or more. Both of these combined gives total advance. At 750 rpms it was in fact at 6 degrees btdc. At this point, the timing should stop advancing and should remain steady. 2,940 147 2. I've been doing some tuning on my 400 SBC with the new AFR 195's (65cc chambers), and the things seems to like about 40 degrees of total timing. That is typically 15-35 degrees before TDC (top dead center) of the power stroke depending on the engine speed. First – When you […] Should be "all-in" by about 2,500-3,000 RPM's. All, this video was designed to help others. Copyright 2021 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. Chevrolet has manufactured the SBC in displacements from 265 to 400 cubic inches for a variety of applications. The engine has not be on any kind of dyno. To set total timing you must first mark the 36 degree, or total advance desired, location on the harmonic balancer. Total timing is the term given to the highest amount of advance. what rpm would i bring it in at 2500 to 3000? Adjust the timing light to find the total timing. You can also measure the diameter of the balancer and multiply by "pi" (3.14). The way we do it is to set the timing at 30 degrees total advanced on the No. Set your total at where you want it 34-38 and let the initial be what it is. The only reason that this is done is that it is much easier to put timing marks up through 38 degrees on the damper AND they will be visible when the engine is running at 3,000 to 3,500 rpm. We use a timing belt on our engines and know the belt will stretch at high rpm, retarding the cam and therefore the ignition, so we check the timing at a relatively high rpm, such as 5,500 rpm. $140.25. i was thinking somewhere in the 32 to 34? Total timing is a combination of your initial timing (on the crank) and the amount of mechanical advance you get from your distributor. With mechanical advance, that would be about 55 to 58 degrees total at 3,000 rpm. SBC total timing iron heads Discussion in 'LS1, LS2, LS6, LT1, SBC Turbo and other GM Specfic Turbo Tech' started by tsb, Mar 6, 2012. Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it As an example, at high RPMs with part throttle (high vacuum) positions, the total timing will be: 12 degrees initial advance, 10 degrees vacuum advance, and 22 degrees mechanical advance (total timing is 44 degrees). Jump to Latest Follow ... well back to the timing issue. The size of the engine impacts the total timing requirements. I find that usually 12* initial and 36* total plus vacuum advance of about 15* is a good base to start with. Every engine will run a little bit differently. Disconnect and plug the vac. Once started, a high engine vacuum signal connected to a dashpot on the distributor rotates the internal advance mechanism forward to introduce more timing for good off-idle and part-throttle engine response. Rev the engine past the point where your mechanical advance is fully engaged. The timing can vary between 2 and 12 degrees BTDC, the recommended spark plugs are different and even the plug gaps vary. Most naturally aspirated engines like a total timing of 34 to 36 degrees BTDC, (Before Top Dead Center) AKA "Advance". Best power is achieved when ignition timing is set to fire the spark ahead of time to reach that peak pressure at about 2 degrees after TDC. As engine speeds increase above 3000 to 3500 RPM, the centrifugal force of the distributor mechanical advance weights overcomes the springs holding the advance mechanism in the retarded position and mechanical advance is fully introduced. I think the timing needs to be more like 32 degrees. SBC total timing E85 vs. race gas SBC total timing E85 vs. race gas. Do the same and set the total timing to 34 degs. Disconnect and plug the vac. The full energy from combustion is released too far after the piston has past top-dead centre (TDC). Jump to Latest Follow 1 - 13 of 13 Posts. (seems like a lot to me). I've never had timing that high before, and I don't know if it's OK/normal or not. The engine has 36 degrees total timing now. $7.99. Check to see what your total timing is when it's fully advanced. Small block Chevys (and most other GM performance V8 engines) perform best when the total timing (full centrifugal advance plus the initial timing setting with vacuum advance disconnected) is all in by 2,500 Œ 2,800 rpm and is set to 36 Œ 38 degrees. Additionally, the fuel burn is not as complete which increases emissions. Check to see what your total timing is when it's fully advanced. With the manual transmission, the 327 idles at 475 rpm (with an automatic it idles at 450 rpm). Engines with aftermarket camshafts change valve timing events (not to be confused with ignition timing), and this increases the amount of initial timing that is required. This is also known as having the timing "all in.". I am helping a guy with a sbc 406 with 18 degree eldebrock victor jr cylinder heads. Ignition delay occurs during the time that it takes to fully ignite the mixture with a spark plug. In my new distributor I put the "18 degree approximately" total advance stop bushing in the distributor. While most engines use a vacuum advance mechanism, some performance SBCs do not. Rotate the distributor until the timing mark lines up at zero with the light. C ... 4 spd. Timing - When I was static timing the engine picked up around 21 degrees and sounded keen. the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Watch the timing mark on the harmonic balancer using the timing light. He writes both technical information and market commentary as a private consultant and has researched and authored business plans. At idle, like 600 to 1000 rpm, 38* timing is normally excessive unless there is something wrong. 1 cylinder, with the engine at a predetermined rpm. A typical small-block Chevy's timing curve needs to be set somewhere in this range for maximum performance, when the engine is being revved at 3500 RPM. No I don't mean harder plugs, competition coils, lumenition etc., that only affect the efficiency of the spark, but the actual ignition advance supplied by the distributor. Engines with aftermarket camshafts change valve timing events (not to be confused with ignition timing), and this increases the amount of initial timing that is required. If your initial timing is 10 degrees, and we visually verified that mechanical advance allows 24 degrees, your total timing, theoretically, is then initial plus mechanical (10 + 24+34).
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