Blues4u has been around the site so long he commented on the thread in 05! Lots of thread cpr going on lately it seems... Lmao.
Bruce Lancaster has passed on, I noticed he contributed a nice summary. Most all OEM distributor curves as he put it, are "too long, and too slow" and that's a good way to put it. A lot of people really, really obsess about setting the initial timing to the exclusion of anything else without understanding the rest of the story.
I’ve done the ear, light, and vacuum methods. Kind of like the vacuum the best as doing it by ear seemed to take too many trials and errors. Right now I have an engine where the timing mark is completely gone. I know I can use a piston stop to get TDC but how would I get the remaining marks to 5 or 10 BTDC or ATDC.
Yep, since we revived this 16 year old thread, I guess I can comment that I recently went through this (sort of) needing to move the timing mark vs. where it was originally on the timing cover. Just got #1 to TDC and installed timing tape on the balancer to line up with my new mark. Seems to have been pretty cheap and easy to get it to where we knew where it was timed again. Still initially set it by ear as mentioned above and ended up only being a couple degrees from what I would have set it at according to the light.
Did you pay attention in Math class? /jk Once TDC has been established, the rest goes like this: Using either a string, ruler or a seamstress' cloth tape measure, measure the circumference of the damper. If you only have a straight ruler, measure the diameter and multiply by 3.1416 (pi) to get the circumference. Once the circumference is known, 1/10 (10%) of this figure represents 36º. Half of that is 18º, half again is 9º, etc. It doesn't matter what units are used to measure the circumference- metric, inch, or nanoparsecs. If you want to use the metric system, multiply the circumference by 25.4 to convert to millimeters. Divide this by 360 and you'll get the measurement in millimeters that equal one degree. Careful measurement and marking of the degrees in this fashion on a length of masking tape can then be applied to the damper, aligning TDC or "0" on the tape to the line on the balancer, with the degrees BTDC to the right of this mark. You can also measure the length between the timing tab marks and transfer them onto tape, i.e. if there's 3/4 of an inch (0.750") representing 10º on the tab, two marks 3/4 of an inch (0.750") apart on your tape will also be 10º. This will work- provided that the timing tab is correct for the application and not for a different diameter damper. 90 degree lines It's a good idea to mark the tape at 90 degree increments starting from TDC. These 90 degree lines can be used when adjusting valves, for example. https://www.crankshaftcoalition.com/wiki/How_to_make_a_timing_tape Speaking of ATDC, why do some crankshaft dampers have ATDC markings? What's the point of that?
Thanks for explaining that. You saved me the trouble of typing it all out. I have used this method for many years. Have never bought a timing tape. I always scribe the timing marks on the dampener and mark them with a yellow paint pen. If you establish TDC with a piston stop first you always have a true reference mark. I raced my whole life. With a timing light, this is the only way to get consistent performance. The guys that want to just wing the distributor around with no reference crack me up. The last SBC I put together, the factory TDC mark was 4 degrees off when checked with my piston stop. You must check it. I can guarantee that you will find a performance difference between 32 and 36 degrees of advance. But without timing marks and a light, you may never find that sweet spot.
Pretty sure at this point not only did Crease get the car timed but he had a baby boy, he grew up and now he’s driving the car lmao not even kidding
Very cool! Thanks for posting that @Tim Pretty dang cool video and so cool that his kid is involved. Folks that don’t get this stuff will never get the time spent with kids and talks about life that happen.
I always set the timing with a light, after I’m sure the marks are right. Timing is very important if you are turning your engine around 7000 for a while! Timing an engine by ear can easily get off 5/10 degrees! 10 degrees too fast at 7000 can cause some very expensive problems! Driving around at 60mph , maybe not so much. After I set my timing at what is supposed to be proper on my driver car, and I get no spark knock, I will advance it 1 or 2 degrees, with the light and check performance and knock. I continue this method until I have the best timing, for my application. The owner of the racecar I work on prides himself in timing by ear…..and he is real good at it! But after he does….. I still check it with the light! Lol Bones
The problem with that method, most all factory ignition distributors have a timing curve that is way too long and way too slow. Ordinarily there might not be a whole lot of adjustment range in the usable timing without running into problems, not without getting inside the distributor and shortening the curve. Most people don't want to do that, they just want to give the dizzy a big ole' twist and close the hood.
I agree, what I was suggesting is that he finds the best vacuum and compare that to what his timing mark is saying. That should give him some idea whether the timing mark is located properly. The best thing would be sticking something in the sparkplug hole to find top dead center.
Can you elaborate on that a little. I need to get educated more on ignition timing. Need to find a good resource, anyone got any links to good tech articles on engine timing and adjusting distributors please post them up. Thanks
Different engines like different timing, but the mechanical advance should be all in around 2500/3000 at around 30+ degrees. And you need to limit the mechanical advance so that your intail timing is around 14 degrees. You notice I alway say around, each engine may like a little more or a little less that even a similar engine. Most stock units won’t be all in till higher than that. And the stock advance sometimes actually has too much advance, too late, so you have to limit some of them! Spring kits are available to do this. You also need to smooth out the ramps and check for smooth advance and retard. Just some of the basic things you can do to improve timing over stock. There are recommendations for closer settings for each engine for a starting place, available! Edit: A lot of factors come in concerning timing. Compression, cam, combustion chamber design, carburetion ,fuel, etc. Also an engine timed correctly in LA, may not be right in Denver. Bones
Well it's complicated, depending on the era of manufacture, particularly smog era. This screwed everything up to degree. They reduced compression, valve timing buggered, and the timing curve itself. OHV engines all run best generally around with a "total" timing of 34° to 36° BTDC. There are some other factors - fuel quality, elevation, compression etc. This is without vacuum advance. Some engines a little more, some engines, a little less, but that's what you're looking at. The distributor mechanicals inside, they aren't adjustable at least not for the "average" person. The OEMs used a very conservative timing curve, probably in part to keep people from grenading their engines. The initial timing isn't nearly important as making sure it isn't retarded on the high side (or excessively advanced) Basically you can play around with this 36° BTDC, and have most of it come in early, or come in late, etc. You could set it 36° and just lock it in, and leave it. Drag racers do that. They might disable the ignition temporarily each time they run so the engine will spin over. Since they only run at balls to the wall full throttle, that works for them. But some OEM distributors, they are all different depending on the application might have 36° of advance built into the distributor already. So in this situation the initial timing specification will be by necessity be very low, it just won't tolerate more than a few degrees, or it will exceed safe limits on the far end. This is what Bruce Lancaster was referring to by a timing curve that is "Too long". By being willing to get inside the distributor and make some adjustments, limiting the mechanical curve to say, 20° BTDC, this allows the user some latitude to run a much higher initial timing of say, 16° or even more. Installing lighter weight springs on the centrifugal weights will allow the advance to come in much earlier in the RPM range. Bruce was talking about "Too Slow" timing curve here. I checked my stock factory Y-Block years ago and it wasn't done advancing all the way till around 4100 RPM or so. The "heavy" spring looked like it was made with barbed wire. Lighter springs are usually installed by enthusiasts to get the advance "all in" by about 2500 or under 3000 RPM or so. Even with crappy pump gas this is a lot more efficient. The best way to setup a distributor is to find someone with a distributor machine and have him set it up for you. But you can use the engine itself as a distributor machine, it just is a lot more tedious.
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