Sometimes respectable engine guys tell me they time all thier motors by ear and by the looks of it, it works good. So for everybody that times by ear what exactly do you lissen for and/or do?? Thanks
Printable View
Sometimes respectable engine guys tell me they time all thier motors by ear and by the looks of it, it works good. So for everybody that times by ear what exactly do you lissen for and/or do?? Thanks
Quote:
Originally Posted by tweaked250r
Well, you find the guy with the best ear, and I'll bet all my money on my timing light for accuracy....:LOL: :LOL: :LOL:
Setting by ear at idle only works for a start. When the advance comes in, you may need more or less timing. If it pings on accelleration, retard, if it bogs, advance.
Timing lights and book specs can't take into account the effects of age, wear and tear, and many small variables we introduce ourselves when we modify engines. I get them to run the way I want, then put the light on them and record the setting for future use.
Tuning by ear isn't a great way to set up an engine for optimum operation. First and foremost, you cannot always hear detonation (ping). This can cause damage as minor as a cracked spark plug to as major as broken pistons and bent valves - and you can't always hear it hapening. Secondly, todays gasolines are seldom consistant in antiknock (octane) compounds from one truck load to another and can be a deterrant to good mileage, detonation reduction and overall performance. A timing light and vacuum gauge along with known tuning specs are your best tools for good overall performance.
And yes, I do tune by ear, but only as my starting point for my light and gauge.
If it's timed by ear,should it be stroked by hand? Seriously,I always use a vacuum gauge as Denny described. Hank
If you don't have a timing light or vacuum gauge, nor the well-tuned ear, why not time the engine statically?
Commonly done on fresh engines.
You won't be able to get an exact read on the vacuum advance end of things, but you can tell if the vacuum advance is working.
Not to discount anything that has been said to this point, but this question did spark an old memory.Quote:
Timing lights and book specs can't take into account the effects of age, wear and tear . . .
why not time the engine statically . . .
Back when we had no tools or money we would -
Find #1 TDC using some down hole device like a wire or screw driver.
Set the point gap at the highest cam point.
Put a cigarette celophane between the points (while closed).
While pulling on the paper, rotate the distributor (counter clockwise?) until the paper 'just' released from the grip of the ponts.
That was the starting timing point to check rotor alignment etc.
From there - easy staring and no bogging under accelleration by ear.
Of course these were old tuners - not expensive 'built' engines.
My find on initial statically tuned engines is that my timing is generally way advanced as they all seem to idle very nicely 'way up'. I then need my light and gauge to put it into specs.Quote:
Originally Posted by C9x
As far as checking vacuum advance operation - you are correct on GM engines that use full intake vacuum. Ford uses ported(timed) vacuum from above the throttle plates which has no bearing on idle advance.
I remember some of the older tuner garbage. So and so could set the points, timing, and idle mixture by ear and when he was done you could stand a nickel on edge on the top of the air cleaner!!!!
When I get one of the real "pounders" put together, and set on front and mid engine plates with a urethene mount at the frame the engine usually thumps so hard a 3/8" drive socket won't stay on top of the air cleaner at idle, and when ya blip the throttle it's tough to keep your hand there!!!!!:LOL: :LOL:
Anyway, I set everything with my timing light with advance knob on the back, a tachometer, and an exhaust analyzer. Is vacuum even any kind of tuning device on the high performance stuff? Not sure I even have a vacuum gauge anymore. I just set my initial timing so it will start, sometimes with an ignition cut off switch to let it get cranking before the spark hits.... Then tune in my vacuum advance (if used), set the rate and point of the mechanical advance, then get the total timing where I want it. Only thing left after that is a couple pulls on the chassis dyno and a bit of tweaking on jets and timing.... Without power brakes (I much prefer twin master cylinders and a proportioning valve) where or what am I missing that a vacuum measurement would be an issue?????
http://www.secondchancegarage.com/public/186.cfm
There is alot that can be done with a vac guage and as a matter of fact I will have one in the dash hooked up at all times.
So when you time engines by vacume do you use the manifold or ported vacume? What if it dosnt change very much at all? Also, let me get one thing that I have been confused on for a long time... Vacume advance hooks up to manifold OR ported??? thanks
Manifold vacuum is the only way to go - ported is ABOVE the throttle plates therefore will show little or no movement without a constant throttle opening - like driving down the road. And then it will only move in relationship to that throttle plate relationship position to full or partial opening.
Ford uses ported vacuum, GM's use manifold vacuum. Usually!!
I've put together a lot of small block chevs in my day. most of the time I
set the timing by ear. Just did so on my chev 350 trk and runs great. I also
have a big blk in my hot rod which is advanced 36 degrees. I used a light
on it, but on stock engines I generally just go by ear. To be safe, use the
light.
rd
I'm with Dave up at the top. give me a timing light and a TDC tool of some sort and the timing will be spot on. Some hotrod motors run so rough at idle that it is hard to set the timing under the best of conditions. You have to set them at a point well after maximum advance. How do you know where this is?? If you have had use of a Sun Distributor machine and run distributors and with mag adaptor magnetos you will be able to find exact advance curves (if any) and be able to set the timing correctly and be prepared to make tuning adjustments.
Magnetos are set with a buzz box which works off the points and you can set them very accurately with these. For a long time it was the only way they were set. Today you can get timing lights that will work with mags.
Timing by ear is a good way to loose hp or blow holes in the tops of your pistons.Quote:
Originally Posted by tweaked250r
We used to run the engine up to 1800-2000 rpm with no load, advance the timing until it just started to slightly miss ,back up 2 degrees and tighten everything down. Ran good never lost a motor but those were the days of good gasoline
Erik, don't foget flat cam lobes on the generic camshafts to go with holes in pistons lost hp and lets not forget collapsed piston skirts. Good post there. Please please please, use a light to start and make sure it is a true TDC on the mark. Then you can get out the vacuum gauge and play. And never ever get greedy because "more" isn't always better. "A lot is good, more must be better".........nope!
Only by ear is ok for start up,but like every one mentioned befor theirs no substatute for a timing light,For my high-performance engines I like to use (MSD)adhesive timing tape on the Harmonic balencer to check my mechanical advance this is done in 500RPM increments from idle on up.On a mild street engine total advance should all be in around 3000RPM.This tape creates A timing curve similar to that of A distributor machine,Don't forget that when using this tape you're reading both the (Initial and the Mechanical advance at each RPM level.
Hay Tweaked hears some thing to consider,A typical street engine with 9.0:1 compression runs pretty good with 36 degrees of timing(initial plus mechanial)for a rough total of 15-55 degrees of total timing at light Throttle,when Vacume Advance is added in and the engine Detonates or Pings under (WOT)wide open throttle,reduce the amount of vacume advance.If the guy's you are talking to that set timing by ear are running A (CRANK-TRIGGER)on the Flex-plate they would be close because the timing is full advance at all times you only need to set the Initial timing,most people I no with this set up still use a timing light.
I didn't take it that way Denny,Didn't think you were saying that at all.If you took it that I was impling that you did, I appologize to you and every one I was refering to the people he mentioned in his post.:)
This one is just for grins. A local car enthusiast who once told me he had .015 clearance on a main bearing, SBC, and wondered if that was too much. He sets his timing this way, turn the distributer all the way clockwise and mark it, than all the way counter clock wise and mark it, set the distributer half way between the marks, tighten down the clamp and good to go.
If you don't have nothing --no vacuum gague, timing light or other stuff. Try proping the garden hose by the exaust pipe and use it as a sound horn. Assuming no water in it, it will sharpen your hearing of the engine. Also place a glass of water on the air cleaner and watch the ripples in the water this is particularily good for the idle adjustment on the carb.
First Post by a Newbie!