Model a engine knock after timing

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Dalejacob

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Default Model a engine knock after timing
I recently timed my model a with the newrex wrench. It runs better but now has what seems to be a lower end knock. Has anyone else had this issue or is it just coincidence that I now have a rod going out?
 
Back off the advance on the timing and see if it goes away. Sounds like detonation to me (ie, too much ignition advance).
 
Do you know what ping sounds like? As stated above, retard timing until it goes away. You do NOT want ping, it'll do some serious damage. However, running too retarded is not good either. Listen to the engine when pulling a hill or accelerating, advance until it just starts to ping, then retard one click or so. Of course it is possible you could have a main or rod knock, but seeing as it showed up with re-timing it sounds suspiciously like ping.
 
Was this knock present before the timing was set ? Try and determine exactly where this knock is coming from. It could be a loose main bearing.
I'd recommend tossing that timing wrench in the corner and set the timing correctly, the old fashioned way, its easy.
 
Patrick L. said:
Was this knock present before the timing was set ? Try and determine exactly where this knock is coming from. It could be a loose main bearing.
I'd recommend tossing that timing wrench in the corner and set the timing correctly, the old fashioned way, its easy.
Click to expand...

And don't forget that 'setting the timing' with the timing pin, etc., only sets initial, or base timing for starting purposes. Once the engine starts, the driver pulls the timing lever down, which resets the timing to whatever the driver likes. Some like to continually reset the timing lever according to engine speed and load, while others adopt a 'set and forget' method. Either way, wrong timing can cause damage: too much advance causes detonation (which can hammer out the Babbitt) while not enough advance can burn exhaust valves and make the exhaust manifold glow red hot and warp.,
 
From what I understand is that the timing wrench only works with the standard head. It seems to set the timing too far advanced for a higher compression head. This was the case with my timing. I donated the wrench to our club's pick a price table.
 
I've heard detonation before but never this bad! Ok, so I threw the wrench in the garbage and timed it using a test light. Knock is gone. Thanks guys. I didn't want to start messing till I asked. Runs as it should now.
 
When I originally timed my A, I could make it knock pretty bad when the timing lever was all the way down. Took a little fiddling but I found the sweet spot, as it sounds like you have as well.

I, too, was impressed by the amount of knock brought on by a small amount of timing. It's not hard to imagine how quickly things could get beat up if one were to drive around under those circumstances for any lengthy amount of time.
 
Everyone is correct that too advanced timing can beat up the bearings, mostly the rod bearings, especially with a higher compression head. PotvinV8 is correct in finding the sweet spot. This spot changes for different driving conditions. The engine performance improves with increasing advance up to a point where increasing the advance does no good, a knee in the curve. This is the sweet spot. Back off one notch from the point where no further advance will improve the engine performance.

One easy way to find the sweet spot is to run the engine at a fast idle, 1,000 rpm, with the car in neutral. Then move the ignition lever until you find the sweet spot. This is a good starting point and can be adjusted from there for different driving conditions. In my car I run the lever up one notch from horizontal most of the time and then advance it one notch if I am cruising down the highway at a high speed but not at full throttle.

My hearing is mostly gone so I cannot hear any knocking. So I have to use the knee in the curve to find the best advance lever position.
 
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