Any timing experts ?
04-17-03, 03:12 PM
#1
Rotary Freak
Thread Starter
Any timing experts ?
I need tok now if over advanced timing will cause an engine to blow. even if it wasnt detonating or racing it ?
How much will cause harm. My engine died after 400 miles and im suspecting it was the timing. It was 3 inches to the left of the needle mark on the engine!!!.
How much will cause harm. My engine died after 400 miles and im suspecting it was the timing. It was 3 inches to the left of the needle mark on the engine!!!.
04-17-03, 03:19 PM
#2
Queer
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3 INCHES! I don't know how much that equates to but I am pretty damn positive it is A TON. If you fire the spark too early it will cause the rotor to go in the opposite direction.
Imagine this, the rotor is at "Top Dead Center", the point at which it has stopped compressing and is starting to expand. For explanation sake we will say it fires there and pushes the rotor. Now when you advance it you are telling the spark to fire BEFORE the rotor gets to the expansion stroke and therefore it hammers on the rotor when it is going in the wrong direction.
Hope that makes sense.
Imagine this, the rotor is at "Top Dead Center", the point at which it has stopped compressing and is starting to expand. For explanation sake we will say it fires there and pushes the rotor. Now when you advance it you are telling the spark to fire BEFORE the rotor gets to the expansion stroke and therefore it hammers on the rotor when it is going in the wrong direction.
Hope that makes sense.
04-17-03, 03:24 PM
#3
Rotary Freak
Thread Starter
Well the porblem with that is that I heard no detonation but you can be right. Mabey I wouldnt need to. Either way the engine would get really hot right ? and the header would glow to ? let me know if this is right. I need to know for warenty issues.
04-17-03, 03:25 PM
#4
Super Raterhater
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Well, I believe the distance between the leading and trailing is 15 degrees, so measure that distance (about an inch or so?) and figure out your advance. By what you're saying, it sounds like you're over 45 degrees advanced!
04-17-03, 03:30 PM
#7
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Well, 15-25 is ideal for the NA's, including ported from all that I know.... 45 man, that's just WAY out there. The good part is you might have only cracked a seal and not blew it apart and destroyed anything, so you could attempt to do a half-stack rebuild and only pull the front cover/front side housing off and attempt to fix that, but from your compression numbers for the rear they seemed to vary a good deal so I don't know.
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04-17-03, 03:40 PM
#9
I am trying to do the math on this...But given the extreme advance at idle, then the correction by the ECU, off idle, your total advance may have been some where in the range of 60-70 BTDC. Given stock timing is 5 deg ATDC, your total advance might have been WAAAAY out there.
Why so much advance?
Why so much advance?
04-17-03, 03:44 PM
#10
Rotary Freak
Thread Starter
Because this guy named doey the meckanic when he was helping start the engine was playing with the timing and I left it where he set it. He should cut me a deal but theirs no way I can prove to them that it caused my **** to break. Thier sorta nieve.
04-17-03, 03:54 PM
#12
Okay, near as I can tell, you were somewhere in the neighorhood of 70 degrees (assume measured at idle, HOW you got it to idle I will never know). Given ECU corrections off idle, you could have seen advance in excess of 100 degrees. Which doesnt add up. I am suprised the car ran at all.
04-17-03, 04:14 PM
#15
Rotary Freak
Thread Starter
Hey your right lol. When I was checking the timing earlier the timing was hitting different marks and was all over the place. It was set when the engine was bouncing around 3k rpms ... TPS probs but yeah after it was set we checked the idle awile later and thats when it was super advanced after it was not bouncing all over the place.
04-17-03, 04:23 PM
#18
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Well, depends on where you set it to, if you tried to put it on the marks at 3500rpm it'll be retarded, it's almost impossible to set the timing with the engine over 1000rpm because the ECU is going crazy with it. I don't doubt it was more than likely advanced and that was an issue, but how much i don't think anyone can really tell you.
04-17-03, 04:30 PM
#19
Rotary Freak
Thread Starter
No ill tell you how much!!! After the idle was lowered and the timing was steady , we checked it and it was three inches or more past the 0 mark on the front cover. So obviously it wasnt retarted.
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