Well I just found out something that I have never known over the 40 years I have had Chevies and been a mechanic. Take a look, you will love it. http://www.youtube.com:80/watch?v=Ys80A6fL0_4&feature=related
I'm with the piston stop crowd on this one, forwards and backwards top dead center is dead in the middle.
Finger has always done it for me. By the time this guy gets all the crap connected I am done and having lunch.
Make a piston stop out of an old spark plug. Bust out the porcelain, drill the remaining body to a tap drill size, tap threads and experiment with extension of inserted bolt or screw till you find a point where the rotation stops about 10 or so degrees each side of TDC. Then halfway between these 2 points is ABSOLUTE TOP DEAD CENTER! No worries about getting in the middle of that point where several degrees of crank rotation bring little or no piston movement. But you should really have done this with a positive stop across the #1 cylinder before you ever put the heads on. Dave
what ever happened to setting the timing by vacuum gauge???? Maybe he should get his government involved.
piston stop works good for an assembled engine in the car..positive id..for TDC while in the car assembled finger in the hole gets you pretty close..if your timing mark is off on your balancer..might be time for a new one..the outer ring can slip on them old ones..JM2C that dudes way is over the top..and way complicated..and who has a meeter like that just laying around? poston stop can be made with things you have laying around for free
ive always used my thumb crank it until it pops off the hole works everytime if ya have 2 people but for 1 person thats a smart ass idea thanks for shareing
thats retarded no pun intended i always take out no 1 plug and felt the piston with my pocket screwdriver never let me down yet
I had a friend call me one day. Asking if I could come over and help him with the timing on his SBC motor in a '70 Elky he just got. He wasn't a handyman, mechanic, or even really a car guy, and he really only bought it so that I could live vicariously through him because I talked him into it. It was cool though. Anyhow, I stopped by he had the hood up, he had managed to change the plugs, wires, oil & filter, fuel filter, and bleed the brakes, all by himself. He said the motor idled funny and he read that the timing was probably off. I told him to find Top Dead Center while I got my timing light from the truck. When I came back I asked if he'd found it and he pointed to the air cleaner stud in the carburetor and looked at me like he accomplished something. Jesus fucking Christ, I couldn't help but laugh for about an hour, I still give him shit about that even though it's been almost 15 years.
Have used the positive stop made from an old plug for years, same plug body with thread down the middle also allows me to fit a hose tail and apply air pressure, or screw in a dial gauge addaptor. It's one of those things that once you have made one you would never want to be with out it again, but you only use maybe every couple of years, once a year at most.
I'm always amazed at how complicated we can make things if we really try. The easiest thing to do on a sbc engine is to find TDC. Pull #1 plug turn the crank by hand while inserting a small screwdriver/welding rod/10 penny nail, or whatever you have into the hole, when the device moves check your timing mark, if it's real close to the pointer move it a little more untill you're at 0 degrees. Pull the driver side valve cover off and make sure the # 1 valves are on base circle ( closed ) if they're not you're 180 degrees out, turn it one more reveloution, check the valves, pull the dist. cap, set the rotor to point at # 1 and it should start. Remember that # 1 plug wire on the dist cap can be anywhere, but pointing to the back of the driver side valve cover is best for timing adjustment. Remember sbc firing order is rotating CLOCKWISE. I've used this method ever since my dad showed me how in 1962 or 63 and have never had an engine that would not start, ( and run ) Works for me. The complicated stuff should be saved for when it's time to wire it!!!!
All though I'm not convinced that this method isn't possibly off a little due to the piston dwell time at TDC, which can be a couple of degrees, it is a hell of a lot more accurate than the "Finger method" or holding a screwdriver or welding rod. Those methods are fine if all you are trying to do is bring the piston up TOWARDS TDC but there is no way in hell that will give you absolute TDC. If you are only looking to get close for distributor drop in or to see if your marks are close those will work, but as this guy explained he had no timing marker to reference to. The piston stop method is really the only way to get a perfect marking every time on an assembled motor. Even the dial indicator method when going in through the spark plug hole can be off a bit.
+1. Making a simple job complicated, I'd wonder what his background is. I usually get the engine close to tdc with my finger over the plug hole and then use a breaker bar or my big SnapOn ratchet to rock the crank back and forth while I use a piece of welding rod through the plug hole and against the piston to get it as close to exact as I can. I would say that the positive stop method is probably a tad bit more accurate than mine though. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
I don't know how you think that, this way you feel the rod moving you can feel the dwell and watch the balancer, and get it as close as his method with out spending as much time.
I think he's the guy that does those "dry eyes" commercials you know the one with the blood shot beach ball eye ball, sure sounds like him
As stated, he had no timing indicator. If you believe that you can "feel" the degrees of rotation where the piston is at stopped during TDC, well then I guess that is accurate enough for some, but this can be as much as 4 degrees in a long rod motor. And that can be multiplied by the fact hat you are coming in sideways through the spark plug hole, decreasing the feel dramatically. If I am going to go through the trouble of setting up a timing pointer I want it to be accurate, not close enough. And the best way to do that with an assembled motor is the piston dead stop method.
You're right on the money with this one, I missed the part about not having a timing pointer, like I said, bring the timing mark around to the pointer, obviously if there is no pointer you can't do that, I thought he was looking for TDC to get the motor started and then to time it. My mistake, you're right the dead stop method is the way to do it to locate the pointer.
A good idea is to ALWAYS ck for TDC with a degree wheel and a positive stop when an engine is apart. That way you can remark the pully/dampner or move /relocate the pointer in case of an eng/parts swap if it is nessessary. While 2 or 3 degs won't really make a lot of difference on ign timing, it starts to make a big difference on cam timing. Its worth the extra trouble to slip your timing cover and crank pulley on to the short block and see that they DO line up with true TDC and that you actually DO know what the marks on the pully represent in degrees. Lots of times with older motors the pointer is bent or broken or the pully is so beat up you can't tell what is factory marks and what is battle damage. Another thing on this subject for the uninitiated is to turn the engine over VERY carefully when you are using the positive stop method as you can poke the stop thru the top of the piston when they come in contact. Don't use the starter or push the car in gear by hand.
the degrees of rotation where the piston is at stopped during TDC, ... but this can be as much as 4 degrees in a long rod motor. I assume you mean "relatively stopped"? The piston only stops for an instant. There is no "dwell' at TDC (or BDC) - the apparent lack of movement is simply all the clearances (piston to pin, pin to rod, rod to crank) stacking up the other way. The difference in motion for a short rod motor (1.5:1 ratio) and a long rod motor (2:1), both with 4" stroke, is only .0016" at 5°, and .0025" at 10°. Putting it another way, the time to travel down .030" is much less than 1° different between the 2 motors. The positive stop method is very accurate... if the piston has centered wrist pins. If not, the first 20 or 30 degrees of travel will always be a different distance in inches forward vs. backward from TDC. If you run the piston down 1" or more, the error almost vanishes. If you actually know the offset in inches, you can calculate the difference between CW and CCW rotation but it's pretty small.
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